Severe and Snow

It looks like there really isn't too much to add from my last blog post. The snow threat has increased substantially with all of the thickness values now turning over to all snow. The soundings in South Dakota look very promising for snow as well, along with momentum transfer of up to 60 knots of winds! What does this mean? Blizzard conditions can be expected from Rapid City to Mitchell, SD and north. I wouldn't be surprised to see snowfall totals in the 6-10 inch range in much of central S/N Dakota.

The severe threat is still considerable, however the moisture return actually does not look like it will be has high as I expected. The tornado threat is still there, and we could see a few isolated tornadoes in the central northern Oklahoma to southeastern Nebraska region as the storms fire in the afternoon on Wednesday. Quickly, however, a strong squall line will develop resulting in a much greater wind threat. I wouldn't be surprised to see a vast area of 70 mph wind gusts as the line tracks through eastern Kansas/Oklahoma/Nebraska into Missouri/Iowa/Arkansas.

This is going to be a major fall storm. The strongest of the season so far. If you are in the Dakotas, make sure to keep indoors. If you are in the area with a severe threat, make sure to keep that weather radio on in the event severe weather threatens your area.

Severe Threat Wed-Thurs

A severe weather threat will materialize this coming Wednesday evening into Thursday as a strong storm system pulls out into the plains. Currently this system hasn't even interacted with the United States yet, but will pull on shore of the California coast tomorrow. The strong 500 mb trough will begin to dig into the plains early Wednesday, becoming slightly negatively tilted and bringing along a substantial amount of vorticity. The low will close off over Nebraska Wednesday afternoon and evening, deepening the low and enhancing the dynamics of the system.

Moisture return seems like it will easily be set up for a severe weather event with dewpoints already in the 50s in Wichita, KS. This will only increase as we go towards Wednesday, likely reaching into the 60s. Storm relative helicity values near 400 are predicted by the NAM Wednesday afternoon, resulting in high EHI values. The threat for supercells at initiation from northern Oklahoma into Iowa seems possible, with the greatest threat from central Oklahoma into eastern Kansas. The NAM and GFS initialize convection in the Wichita area. Could get interesting.

Quickly the strong dynamics of the system will take over, likely resulting in a substantial squall line / high wind event. However, as the storms initialize a tornado threat will be very much possible. The tornado threat could stretch from Iowa to Oklahoma before the line goes linear and moves to the east into Thursday. 850 mb winds in Kansas look to be 50 knots as the cold front and dry line approach. The triple point might move right through the Wichita area.

Out ahead of the storm on Tuesday will be a substantial synoptic wind event, with 55 mph wind gusts possible along the entire front range and much of New Mexico. Additionally, some wind gusts to 50 might occur in northern Arizona. Wind gusts to 45-50 mph could occur even in the Wichita area before storms develop on Wednesday.

A decent blast of cold air will move into the northern plains behind the storm, possibly leading to a snow event in the Dakotas. The central Dakotas look like to be the area of greatest threat currently, but knowing the last system and how it didn't quite get cold enough with much the same set up as this one...it will be close. However, the threat is there. Strong winds will also accompany any snow or rain on the backside, possibly leading to blizzard conditions if the precipitation is snow.

Also, watch out along the eastern coast as the models are now unanimously producing a substantial hybrid system that moves along the Atlantic seaboard bringing not only the threat of some heavy rainfall, but gusty conditions along the coast. The rip tide threat will be high.

Negative AO = Cold Weather

Now, I know I keep going over this, but just look at the 00Z GFS model and you will see it happening. The GFS has been keeping it warm for so long now, building that ridge in the center of the United States. Now, here is what it looks like at 500mb:

Thats 360 hours out, yes I know...its unreliable. But even go back to 240 hours out and you can see the cold shot developing. The negative AO is starting to pan out, the cold weather is on its way. A cold and snowy eastern United States is starting to look more and more likely for mid-November and on. I forecasted snow for Anderson, Indiana on November 14th. I will stick to that forecast. And I will also stick with snow in Wichita, KS on November 21st. It might be a white Thanksgiving for much of the country, just as Joe Bastardi keeps predicting.

PS: The storm for next week, from the Tues-Thurs period, is still looking like a large scale severe weather event. Of course, mesoscale features will be very important to the event, and we will have to wait and see how the thermodynamics pan out. However, right now the trough digs deep into the plains, produces the bowling-ball of positive vorticity, plowing into the panhandles of TX/OK into Kansas, and quickly becomes negatively tilted. The makings for a severe weather event, and then possible backside snow storm are there on the synoptic scale, there is no doubt about it at this point. Of course, as we know, models can change...so we will have to keep a close eye on this.

Wet west, plains storm to come.

The dry weather the western United States has enjoyed has come to an abrupt end. Three storm system will plow into the Pacific Northwest and northern California over the next 5 days, likely leading to flash flooding and significant snows in the highest elevations. Currently the 1000-500 mb thickness values do not support snowfall, even in the Sierras, but this will change by the 2nd, and definitely the 3rd system. With SEVEN inches of liquid equivalent precipitation forecast for the Sierras by the HPC, I wouldn't be surprised to see feet of snow pile up in the highest points of the Sierras.

On top of this, wind gusts to 50 mph look possible tonight in southern California into the Sierras, and could be even stronger in the mountains from the next two storms. 500 mb winds of 80-90 knots will interact with the mountains peaks and passes, likely bringing gusts to 65 mph...or higher!

And when this third system finally plows in, the fun begins in the intermountain west and then the plains states. By day 7 a significant vort max and longwave trough will have moved into the plains, becoming negatively tilted, leading to the risk of a severe weather event. Currently the environment looks marginal, however if moisture can return sufficiently and the mid-lat low doesn't occlude too quickly, we could be in store for a classic fall severe weather event. We will have to watch this over the next 5-6 days to see whats in store. One good thing, winter weather doesn't look like a strong bet with this system, at least in the great plains. Snow will likely occur in the mountains and possibly Montana/North Dakota through day 7, but big snow storm doesn't currently look in the cards.

And then there is the LONG RANGE. The Arctic Oscillation is currently starting its dive to negative, likely beginning the trend towards colder weather in the eastern United States. Even through the models aren't currently showing it, I wouldn't be surprised to see a shift in the models for the period from Nov 10-20th. I think a cold shot is in the making. But we shall see. The Arctic Oscillation isn't always 100% right, but it is a very good indication.

It's coming....

The cold is coming! What looked like a snow storm a while ago for the high plains and then turned to a mix or rain and snow has now changed back to a snow storm....possible blizzard Tuesday night into Wednesday. The weather service is now forecasting somewhere between 4-12 inches of snow in central Nebraska! Winter is going to make its first big showing in the central US this week.

The 500 mb low producing this storm will drive south tomorrow, pushing with it a cold front that will go as far south as the Gulf Coast. Winds behind the front will be gusting to 60 mph...or even higher...with sustained winds easily in the 30s or 40s in northeastern Colorado into Nebraska and south into Kansas/Oklahoma/Texas. The strongest winds and highest gusts will be in northeastern Colorado. Thunderstorms, likely some severe, will develop along and head of the front with such strong upper-level forcing and decent moisture return. Already today some severe storms developed in New Mexico...and this was only from a small shortwave trough travelling through the southwest at 500 mb.

Once the 500 mb low reaches central Kansas/Missouri....possibly further south....it will stall out, developing an area of heavy snowfall in central Nebraska and thickness values sit around 540 in the central plains. Up-slope flow and a possible deformation zone will lead to the heavy snowfall and cooling temperatures. Areas of heavy rainfall from Nebraska into Missouri and Kansas look possible during the time from from Tuesday afternoon into Wednesday night. After this time frame the 500 mb low will be completely cut off for a day now, losing some of its energy and will slowly pull off to the east/northeast.

However, the low will pull moisture out of the Caribbean north towards the east coast as it begins to move again late in the week. This moisture, along with the eventual movement, will help strength the system again as it approaches the east coast, likely impacting the World Series in Philadelphia either Saturday or Sunday...or both. Not good!

And on top of all this, the Arctic Oscillation looks to change to negative by the end of the month, allowing copious amounts of cold air to flow into the eastern United States as a strong trough drives down to the Gulf Coast latitudes near Florida. It looks like snow will be likely in much of the Appalachians and the lake effect snow machine might turn on with the lake temperatures still very warm.

The weather is about to get exciting. Enjoy it!

A hint of whats to come:

Look at the Arctic Oscillation right now:

What do you see? It is currently strongly positive....and what happens towards the end of the forecast period (the red lines following the black actual number line in the top chart)? It drops! By the end of the month we are back to neutral, and still crashing. It may be more like early to mid-November when the strong cold snap occurs.

And how about that upper-low that will cut off over the central US this week? Check this out:

That's the GFS forecast displayed using Bufkit at 7 am on Thursday, Oct 23rd. It is showing snow (though the snow growth region isn't fully supporting it here) and winds to 40 mph! Wow! And where is this? WICHITA, KS! If this verifies its going to be a very impressive early season storm.

2nd Cold Shot

We had out first real big winter system last week in which areas of the west received over 40 inches of snow! However, most of the snow occurred in the higher elevations of the inter-mountain west and didn't greatly effect high population areas besides Montana and parts of Wyoming. This looks like it could change this coming week with snow possible as far south as Nebraska or Kansas.

Basically, we have the same sort of situation as last week, only the trough will be closer to the center of the United States. This will bring the cold air into eastern Colorado, Nebraska and Kansas (and places further north)....areas that didn't really get the effects of the last cold snap. It will be interesting to see what happens, but just check out the last run of the GFS and you will see a very strong 500 mb trough dive down and the cut off over Kansas. This will drive down a lot of cold 'Canadian' air into the United States. The strong dynamics of the trough and then cut off low will enhance lift, along with decent moisture return into the central US...will likely result in a nasty winter storm somewhere in the plains. Not to mention possible severe weather and the possibility of a tropical system moving towards the Gulf or Florida if the models verify. This next 4-7 days could get interesting!

Following this system, the models aren't showing much...but the Arctic Oscillation is starting to hint at a cold period coming up. Currently the AO is positive, indicating building cold air in the arctic. If it stays positive, the cold air would stay up north and not influence the US...however the models are hinting at the AO becoming negative (with a strong ridge building into Alaska) which would allow this cold air to funnel down towards the US. This might be the start of the possible cold early winter Joe Bastardi has been talking about in his winter forecast and blog. Just be ready, late November and/or early December might be very cold (at least for that time of the year). I wouldn't be surprised to see a nice early season snow for somewhere from Colorado/Kansas/Oklahoma to the mid-Atlantic at some point during that time frame. Yippie! Enjoy!

Well....

The SPC has come out with their new outlook and they are definitely not as bullish as I was yesterday. I can see what they are saying about the further north convection in KS not producing anything because of a shallow stable layer...and that's reasonable. I guess the heavy rain threat from training convection might be the only threat in this area, but if things become surface based..... I still think west TX/OK/ and now far eastern NM are the best locations. I always forget to mention New Mexico since I consider them a western state, not a plains state. However, weather doesn't care about location or time of year, only the current conditions.

SEVERE WEATHER OUTBREAK?!?

Saturday into Sunday looks like we might be in for a big event. Every variable seems to be coming together. A strong upper level trough will be bottoming out in the southwest United States with abundant vorticity. The trough will begin its movement to the east/northeast, pushing small areas of vorticity towards western TX/OK/KS and NM. A strong upper level jet max will be swinging around the base of the trough during the morning and day of Saturday, placing it over the TX/OK/KS region it the afternoon. A region of strong diffluence will also be centered over this area. On top of this, a 500 mb shortwave trough will eject out of the base of the large scale trough in the afternoon, pushing through this same region.

A strong southerly to south-southeasterly jet at 850 mb will be in place, with great backing of the winds all the way from southwestern TX into western KS. Helicity will be plenty with areas of 500-750 in KS and 200-400 in TX. Instability will be the main mitigating factor, however the models are placing a bulls-eye of 1000 J/kg in western TX, with 500-1000 stretching up into southwestern KS. Of course, any areas of clearing will allow for these values to be easily reached or exceeded as dewpoints increase into the mid 60s throughout this region. The warm front looks to be situated on the northern border of KS. I wouldn't be surprised to see a tornado risk zone in western KS due to the high helicity.

The one factor that makes me feel like Saturday might be not at big as Sunday is that the trough will only have started to shift to the east in the afternoon of Saturday. By Sunday afternoon the main vort max will start to shift more into the TX/OK area, likely with the risk reduced in western KS as cold air advection commences. Never does the trough actually go negative, but rather pulls out staying positive the entire time as the main 500 mb low tracking through the Dakotas into Canada.

This event is also a perfect example of a SCEPT (Synoptically-Forced Convective Extreme Precipitation Training) event where a Closed Upper-Level Low is present(...from my thesis). I woudn't be surprised to see areas of heavy, flooding rainfall caused by training cells nearest the region of greatest moisture convergence in the warm sector of the mid-latitude cyclone. Western Kansas looks like the most likely location, stretching into the panhandle of TX. Watch for areas of 2-4 inches in just 2-3 hours.

Basically, I think we are in for a decent size severe weather event on Saturday and Sunday. The SPC already has a slight risk for southwestern TX on Saturday, but I would not be surprised to see them extend that further north. They even have a risk area circled on Sunday in western TX as well (4 days out). A risk area circled 4-8 days out is required to be considered as a moderate risk day for the SPC to include it. I am thinking they will end up going with a moderate risk both days.

On top of all this we have the snow forecasted in the inter-mountain west and a possible tropical cyclone developing later in the week in the western Caribbean. The weather is definitely about to get interesting.

Cooler Weather for the West

Get ready for winter! A strong long wave trough is about to impact the western states, primarily causing winter havoc in Montana, Wyoming, Colorado, and the Dakotas. It looks like the first real snow of the year is on tap for the higher elevations, including even the Black Hills of South Dakota (which really aren't that high). Right now forecasts range from 6-12 inches in north central Wyoming and 2-4 inches in the Black Hills.

This long wave trough has been forecasted by the models for quite a while now. The GFS, European, and CMC all had the trough digging into the western states starting tomorrow. However, there was disagreement on the placement 3-5 days ago. The European dug the trough into southern California and Arizona, then pulling it out quickly through the Dakotas. The GFS dug the trough into the Colorado/New Mexico area and cut it off...bringing it slowly up through the Midwest. The CMC was a mix of the two, closer to the Euro.

Now the GFS has switched to the European result, digging the trough into southern California and then pulling it up quickly through the Dakotas...and then traversing west through the Midwest. This seems like a reasonable solution, and I expect it will pan out. After e-mailing with Doug, we have hypothesized that the GFS was underestimating the strength of the sub-tropical ridge int he eastern US. Thus, the GFS wanted to push the trough in a bit further to the east. When the model finally figured out the ridge was stronger, it moved towards the European solution.

But what does this all mean? Get ready for cold weather and possible snow in the higher elevations of Wyoming (and even possibly in the valleys in this area as well), Montana, Colorado, and South Dakota. The original threat of snow from the GFS in Denver is gone now with the correct European solution panning out. However, don't worry...the Denver snow will come later this year. :)

PS: The GFS/NOGAPS/Euro are all showing a tropical system developing in the western Caribbean over the next week. The steering currents are interesting, and might even pull the system to the EAST rather than the west. This has happened in the past, so it is not unprecedented. All three models forecast a rather strong storm.

Severe Weather Threat Sunday into Monday

It looks like the weather will finally get active again. A considerable storm system moved into the western states on Friday into today and will be ejecting out into the western plains tomorrow. The dynamics and thermodynamics look decent for a severe weather event, at least on Sunday. However, many of my friend and co-workers are also interested in Monday as well. So, lets get into it.

SUNDAY:

Severe weather will almost definitely occur on this day. Already on Saturday a wind gust from a small microburst produced 59 mph winds in west Texas, and this was well ahead of the main storm system and was produced by only a small cell. What this tells me is that there is plenty of energy for a severe outbreak tomorrow with the upper-level energy beginning to move into the Texas panhandle, Oklahoma and possible southern Kansas.

The 500 mb trough will start to become slightly negatively tilted by the late afternoon into the evening hours with diffluence occurring over the TX/OK panhandles into western OK/north central TX. There might not be a 'bowling ball' of vorticity set to enter the TX/OK panhandles, but there is a considerable amount of vorticity that will be enough to help initiate storms. Backed winds at 850 mb, becoming more backed through the day as height falls ahead of the system increase, will result in a decently sheared environment. Also, a weak 200 mb wind maximum will be swinging into the area at this time. All of these variables indicate the possibility of severe weather. The question is whether or not the thermodynamic environment will be set as well.

And the answer is: quite possibly. It looks like showers, and possibly some storms, will be ongoing in the morning to midday hours, likely reducing the surface heating in far western TX. These storms, however, will put out outflow boundaries. As the storms die, or push westward, the thermodynamic environment will become more supportive of severe storms into the eastern panhandles or north west/central TX. CAPE values should reach above 1000 J/kg and 3 km helicity looks to be in the 100-200 range. This would not be the ideal environment, but still supportive of rotating storms. Add in 60F dewpoints, and storms should occur.

The mode is more difficult for me to predict. I could see some discrete cells early, likely able to rotate, but I don't see a massive tornado outbreak. Possibly one or two. However, with all of the wind energy, and knowing what occurred today, I wouldn't be surprised to see a large wind event occur if the upper-level winds easily are mixed to the surface, which seems like a good bet to me. A learning experience on my severe weather forecasting is to come tomorrow.

MONDAY

The severe weather threat might be there, but its difficult to say. The upper-level dynamics do look better, right up until the upper-level low begins to cut off around midday. At that point, the vorticity does not seem to be traversing much further west, but rather staying still in central Kansas. A diffluent flow aloft is still present, only now we have shifted towards eastern Oklahoma and Kansas, which should be the possible risk zone. Dewpoints will be nosing into the middle 60F, and 850 mb winds will still be backed. Helicity actually increases as well, approaching 400 in far northeastern Oklahoma.

The main threat to storms will actually be from the severe weather the day before. The remaining MCS will likely still be ongoing in the early to mid-afternoon hours into central and eastern KS/OK. This cloud cover will hold down the temps, thus reducing the CAPE potential. Without the high CAPE it will be difficult to have severe storms. However, if breaks in the cloud cover, or a dry slot causes a cloudless area, then heating could occur resulting in regions of higher CAPE. I think Monday will be a much more conditional situation where severe weather will be possible in areas that heated up, while heavy rainfall, due to the slow motion of the storm system as a whole, will be the primary threat from the others storms.

93L and 94L

So we have two systems that could possibly impact the eastern coast of the United States. 93L was weakened substantially by Hispaniola over the previous 24-36 hours, however it has since moved to the north and convection has increased around the storm center of (broad) circulation. It still looks possible that 93L could become a named tropical system if it can keep the convection near the center. My original thought that the system would continue to move westerward when it was still near Puerto Rico was correct, and it slowly drifted towards and then over Hispaniola. However, the steering currents have changed now (2-3 days later) and now there is no question that it will move towards almost due north. New England looks like it is in for a possible hit.

As for 94L, the system is thriving off of a very strong pressure gradient caused by a huge high pressure system over the northeast United States. The system itself is only 1003 mb, but has winds nearby of 55 mph or higher. Basically, we have a tropical depression, or extratropical system, developing in an area of very high pressure, thus resulting in higher synoptic winds. It is a very tough situation. Do you call this a tropical storm? Do you hold off and keep it a depression since the winds are mainly supported by the pressure gradient to the north and not the system itself? Very, very tough call. Some (Bastardi) think it should already be named. Others (NHC/TPC) think it isn't even a tropical system at all, but rather an extratropical system that just happens to be producing up to hurricane force wind gusts.

I think the best explanation as to what type of system it is can be described by the tropical models. They, as Greg Nordstrom pointed out, are forecasting the system to substantially weaken when it moves over land near the SC/NC border. Extratropical systems do not weaken when they move over land, but tropical systems do. It is possible the models are wrong, and the system is not tropical in origin...but it is an indication that it is likely to at least become tropical. Right now I find it very difficult to think that the NHC will call it a named storm considering its satellite appearance, but if convection increases over night, we could see Kyle in the morning.

Oh, and if Kyle does form near the Carolina coast...and then 93L forms in the Atlantic, it will be named Laura.

TD 11 or TS Kyle?

It looks like 93L is rapidly getting its act together right over Puerto Rico at this time. Robust convection has continued through the day today as upper-level divergence has increased over the system. Currently great outflow is present in almost every sector and the greatest convection is currently just south of Peutro Rico. Wind shear has weakened some and should remain weak directly over the system for the next few days. High wind shear will be present just to the north of the system, which if entrained into 93L, could slow down development. However, models are unanimously developing the system at this time. The Hurricane Hunters investigated the system earlier today and did not find a closed low level circulation, but this could occur tonight or tomorrow if the convection persists.

The models have locked into a track to the north of Puerto Rico and then into the open Atlantic west of Bermuda. At that point, many of the models want to start to track 93L back towards the east coast of the United States, from South Carolina to New England. A lot of uncertainty is still in the track forecast because of the potential sub-tropical system that might develop off of the southeastern seaboard. However, as 93L continues to develop, it may take away some of the energy from this southeastern storm, allowing 93L to blossom into a stronger system. However, if the southeastern storm gets strong enough, a Fujiwara Effect may take place, which models have a very difficult time forecasting. Needless to say, anyone along the east coast needs to be watching the system (including Canada and Bermuda).

High Plains Severe Threat

The SPC has placed a slight risk of severe weather over the High Plains. The risk tomorrow doesn't look as robust as on Monday, but there is still a risk of thunderstorms able to produce strong updrafts with hail and isolated winds. A strengthening low-level jet in the event will allow the storms to transition into a greater wind threat, but the upper-level energy will have pulled to the north by this time, likely reducing the chance of damaging winds.

SPC Severe Weather Outlook for Sunday

The NAM 500 mb chart tomorrow at 18Z shows one large upper-level trough in the west with two very apparent short waves. The first will be moving through the High Plains by 18Z (or near noon local time). This will be the initiator of the storms during the mid-day time frame, or early afternoon. Decent difluence will be present, along with a good vearing wind profile which will support rotating storms. However, with this shortwave moving through this area by 18Z, the energy will move off to the north before the greatest heating, thus keeping the severe threat low. The greatest threat should be in western South Dakota, southwestern North Dakota, and western Nebraska.

NAM 500 mb 18Z Sunday

Monday's shortwave looks much more potent and moves through the Dakotas during the 0Z-6Z time frame (6pm to midnight). This is much more ideal for severe storm development and I believe the severe threat will be greater on Monday slightly further east than on Sunday from north central Nebraska into the central Dakotas and then east into the overnight hours. The greatest threat will be hail and strong winds, but with a forecast shear profiles suggesting strong rotation, supercells will be likely along with isolated tornadoes. However, I wouldn't expect a major tornado outbreak as dewpoints will not be very high enough (low to mid 50s).

SPC Severe Weather Outlook for Monday

93L Tropical Disturbance Organizing

The tropical disturbance in the western Caribbean is slowly strengthening and has a rather robust area of convection near the low level circulation at this hour. The system is in an area of moderate wind shear, which is forecasted to drop to near 5-10 knots over the next few days (per the SHIPS model). This looks reasonable considering the upper air maps. Sea surface temperatures are not a problem, and the steering maps seem to want to move the system towards to west. However, model data indicates that the storm should move more to the northwest over Puerto Rico into the southwest Atlantic. The eventual development of the strong low level center will help determine where 93L will track.

A high pressure system will move into the northeast US or just off the northeast coast, beginning to push energy strongly into the area just off the southeast coast. This pile up of energy should lead to extra-tropical, or tropical, development in this area. Considering the development of 93L, it is possible that some of this energy, or all of this energy, becomes absorbed into 93L...or visa versa. What results off the southeast coast will be very important towards 93L's long term life span.

Further development is possible in the eastern and central Atlantic from strong tropical waves moving off the coast of Africa. The European, NOGAPS, CMC, and GFS have all been trying to produce at least one tropical system from the next 2-3 waves, including the one currently in the eastern Atlantic. However, they have jumped from one wave to the next many times (except for the GFS, which has continually forecasted the first wave to develop), so it is difficult to say which wave might develop. The current wave is very far south where coriolis is weak. As the system moves further north the development chances will increase.

Right now I am sure something will develop off the southeastern coast...the question will be whether or not 93L is able to develop quickly before the southeastern storm develops later in the week. If 93L does develop, the storm along the energy being piled along the southeast coast might actually go into 93L and result in a stronger system. There is still a lot of uncertainty off the southeast coast...but a strom will definately be there.

Check this out:

Greg Nordstrom, one of my good friends from Mississippi State University, recently chased Hurricane Ike in Galveston. He wrote a great blog post about his experience and you should really check it out if you haven't already:

http://longdistancechaseteam.blogspot.com/2008/09/galveston-island-and-hurricane-ike.html

Tropical Update

I have been busy the last week moving to Wichita, KS...but I am here now and I will try to write updates more often.

The tropics have been rather calm now for about 4 days. However, this 'lull' in activity (if you can call it a lull after just dealing with Ike) looks to end soon. A few models are forecasting a system to form from the disturbed area in the eastern Caribbean in the next 2-5 days. The NHC has this area as a moderate risk of development. Atmospheric conditions look moderately favorable over the next three days, with shear holding steady between 10 and 20 knots. If the shear is in the upper end, the disturbed area will take a longer period to develop, but if its near 10 knots, we could see a depression from in the next two days.

Currently a mid-level circulation is trying to develop, but no closed circulation is noted at the surface. Upper-level divergence has developed over the system, as well as some low-level convergence. Decent 850 vorticity is also present with the system. Sea surface temperatures are not an issue.

So, it does look like it is possible for a system to develop in this area as long as Hispaniola and shear do not disrupt the system completely. The models have two possible solutions: one north of Hispaniola into the Bahamas and the other through the western Caribbean. Looking at the upper-level steering winds, it looks like the system should track just south of Hispaniola rather than cross over it. However, the cloud pattern is very large, and it really depends on where the low-level circulation develops.

Another issue is a building high pressure system over the northeast, which will funnel energy towards the southeast coast. If energy keeps getting piled up in this region for days, history tells us that a system can develop just off the GA/SC/NC/FL coast. Many of the models do predict a system to develop in this area. However, it will likely be a hybrid system rather than completely tropical at first. Over time it could transition if the high holds on not allowing the system to track up the east coast and out to sea. This will be something to watch.

The last system, that looks the most likely, is a wave currently coming off the African coast which the GFS, NOGAPS, and CMC all predict will develop into a depression by early next week. The European also forecasts a storm off the African coast, but not until the next wave. I think it is safe to say we will see something out near Africa by the end of the next week.

The tropical season is far from over. Don't let your guard down.

NWS Houston Discussion About Galveston

I think this discussion says it all:

SHORELINE OF GALVESTON BAY...15 TO 22 FEET

LIFE THREATENING INUNDATION LIKELY!

ALL NEIGHBORHOODS...AND POSSIBLY ENTIRE COASTAL COMMUNITIES... WILL BE INUNDATED DURING THE PERIOD OF PEAK STORM TIDE. PERSONS NOT HEEDING EVACUATION ORDERS IN SINGLE FAMILY ONE OR TWO STORY HOMES WILL FACE CERTAIN DEATH. MANY RESIDENCES OF AVERAGE CONSTRUCTION DIRECTLY ON THE COAST WILL BE DESTROYED. WIDESPREAD AND DEVASTATING PERSONAL PROPERTY DAMAGE IS LIKELY ELSEWHERE. VEHICLES LEFT BEHIND WILL LIKELY BE SWEPT AWAY. NUMEROUS ROADS WILL BE SWAMPED...SOME MAY BE WASHED AWAY BY THE WATER. ENTIRE FLOOD PRONE COASTAL COMMUNITIES WILL BE CUTOFF. WATER LEVELS MAY EXCEED 9 FEET FOR MORE THAN A MILE INLAND. COASTAL RESIDENTS IN MULTI-STORY FACILITIES RISK BEING CUTOFF. CONDITIONS WILL BE WORSENED BY BATTERING WAVES. SUCH WAVES WILL EXACERBATE PROPERTY DAMAGE...WITH MASSIVE DESTRUCTION OF HOMES...INCLUDING THOSE OF BLOCK CONSTRUCTION. DAMAGE FROM BEACH EROSION COULD TAKE YEARS TO REPAIR.




I really hope my friend doesn't decide to stay in the Galveston area...

Major Hurricane Ike?

Ike has rapidly dropped its pressure today, down to a current 944 mb. However, the winds have not yet caught up to the pressure drop. The NHC's discussion talked about the possibility of the tight eyewall breaking down overnight as the system moves over a cool eddy of water in the Gulf. If this occurred, the storm would quickly weaken back to near 950 mb, but would still be enough to jump the storm to a major category 3 hurricane. If the eyewall keeps its structure through the night, explosive convection should continue and the storm could be a 'weak' (funny eh?) category 4 hurricane by morning! This would be a very bad sign for the future of this storm, as still another two days over warm waters are forecasted.

Ike will likely make landfall as a major hurricane along the Texas coast. If the eyewall holds the structure through the night, the storm will likely be a Category 4 hurricane...if not stronger. If the eyewall breaks down, I expect no more than a mid-range Cat 3. A lot will depend on its life through tonight.

The storm has slowed down considerably today, which will be a major factor in its final landfall location. The trough, which is forecasted unanimously by the models to pull Ike to the north, will be approaching Texas on late Fri into Saturday. With Ike's slower motion, it wont reach the coast as quickly as the models had originally been predicting, and thus had been predicting an impact with Texas further south, possibly south of Corpus Christi. Now the slower motion has resulted in a model trend to the north, now north of Corpus and possibly as far north as Galveston. If you can imagine that this storm holds its eyewall together tonight and goes towards Galveston...it is a bad scenario. Right now we can only hope for the moderate shear to infiltrate the eyewall tonight before the storm really gets its act together and end up holding the storm back, just like with Gustav.

I think we will likely have a Category 4 hurricane make landfall just south of Galveston...My friend Greg Nordstrom is headed down to Galveston to be in the middle of the storm. His blog is linked on the right (LDCT blog). I wouldn't go down there if you payed me a million dollars.

Did I say northern Texas?

I guess I should have said central to southern Texas!! The models have completely shifted from LA to southern Texas in one day, which tells me the weakness that was forecasted has almost completely gone away, and the trough (which will move in later in the week) has slowed down. Ike is definitely headed towards Texas, now the task is to pinpoint a landfall location.

The greatest clustering is from Brownsville to Corpus Christi. The main difference between a northern track and a southern track is the potency and timing of the strong front/trough which will move through the central US this week. The front is forecasted to move through the upper plains on Wednesday into Wednesday night. By Wednesday night Ike will be in the southern Gulf moving west towards the TX/Mexico border. It will likely be intensifying over very warm Gulf waters after having re-organized its core over the Caribbean. (Gustav was greatly disturbed moving over the same section of western Cuba, but I don't expect this with Ike because the shear is so much lower).

Ike should be able to reach Cat 3/4 hurricane strength while in the central to western Gulf. This means the storm will be strong enough to easily feel any weakness to the north of the system. The GFDL, GFS, and NOGAPS forecast Ike to make landfall near Brownsville. The European, HWRF, and CMC forecast closer to Corpus Christi. The interesting thing here is that the GFS is usually the model which forecasts a stronger trough, but it is the one forecasting a further south location. The European has continued to be relatively consistent with its forecast, only moving a bit from the Houston area to Corpus. The CMC and European have been the two most consistently furthest west models all along with Ike, and now they are the ones furthest north. There is a lot to think about with this storm.

So the question is, how strong, in comparison to the models, is the trough?

Here are the current upper-air conditions at 500 mb:

European 0Z model initialization:

GFS 6Z model initialization:



What do you notice? Both models are reasonably close to the upper-air data! The GFS then slows this trough down and stalls it in the southwest US. The European is a bit stronger, pushing the trough a bit further east, pulling Ike towards Corpus in 4-5 days. So considering these variables, knowing model biases and situations, it seems reasonable to think Ike will not be picked up by the trough...but with the model flip-flop (European now further north/east than GFS) it makes me want to think the European is on to something. The European will often indicate when a trough is stronger than the GFS is thinking, definitely when the European coincides with the CMC (which it does). Its very tough, but if I had to put out a guess right now I would say Corpus, likely just to the south of the city. However, I think we will know more in about 24 hours, when the trough in the Pacific northwest moves further south and we get an idea of its strength. By then we should be able to pick up on where Ike will be making landfall.

Ike Models Are Nuts

That's about all there is to say about them. It started with Ike moving up the eastern seaboard a week ago, and then the models picked up on the trough not being strong enough. So then it turned into a storm hitting the western coast of Florida...and then the models picked up on the ridge being stronger. And then it was Ike moving up the spine of Cuba towards Louisiana...and now the storm is on the western side of Cuba and the models are trending towards central to northern Texas!

Basically, the models have been very poor with Ike, completely underestimating the strength of the ridges and troughs, trying to break down the ridge much more than has occurred. This is a VERY common error in the models, but it is also VERY difficult to forecast exactly when the models are making this mistake. There were two big clues this time.

The first was the European model, a model which often does not over-strengthen a trough. The European consistently brought Ike into the Keys or Cuba before Ike moved into the Bahamas. Also, when Ike finally reached the Bahamas it has consistently been bringing Ike towards Texas...so it has been the best performing model so far in my opinion.

The second clue has to do with teleconnections. In asia, 7-10 days ago, the troughs that swung through Japan were not as strong as being predicted by the models on the eastern seaboard of the United States. Since eastern US weather is often hinted at by Japanese weather 7-10 days in advance, this would have been a good indication that Ike might not have been pulled up the eastern coast of the US, or even into Florida.

So here we are now, with Ike still moving west, over the warm waters of the Caribbean, likely headed towards Texas...somewhere. I am giving up pinpointing a location right now, and instead I am just going to go along for the ride. Like I said a few days ago, Ike is giving us a show. A show that was not very well anticipated. A strong hurricane has NEVER done this track before, from the mid-Atlantic at a latitude of Florida, to hit Cuba or even go into the Gulf! History is being made by Ike.

Note: Ike will likely be retired as it has done catastrophic damage so the islands of the Turks and Caicos, Bahamas, and Cuba...and its not even done. Already estimates of over 90% of buildings in the T&C and Bahamas islands effected have been damaged or destroyed and over 70 people have been killed in Haiti. This has been a very bad tropical year for the islands and there are still many months to go.

In Stone Now

Ike has moved well into Cuba, making landfall as a borderline Cat 3/4 Hurricane. The storm has weakened down to 100 mph and should continue to weaken as long as the system is over the Cuban land mass. However, Ike has continued its westward movement and looks like it could make it over the Caribbean before it moves back across Cuba into the Gulf. This would reduce Ike's weakening and possibly allow it to regain its structure more quickly in the Gulf. We will have to wait and see what happens today.

Once Ike gets into the Gulf, the short range and global models are converging on a solution near the TX/LA border. I give each state a 50/50 chance of landfall. However, the GFDL and HWRF, the two hurricane models, are forecasting a central LA landfall at this time. Considering the great job the GFDL has done this year, and its near perfect solution of Ike's (so far) traverse over Cuba, it seems like it would be a good idea to highly weight this solution. I still think central LA is the best bet, but with all of the others converging towards the border region, a Texas hit is not out of the question. It really matters whether or not Ike feels the trough moving to the north as it approaches LA. If it does, its moving into LA. If not, its going towards the border or Houston. Right now I think it will feel just enough to move inland in central to western LA.

Trying and Failing

Ike has resumed the westward motion, the GFDL forecast which went just over the northern edge of Cuba has shifted to over Cuba into the Caribbean, and the global models have shifted even further west into Texas during the 12Z runs (which I had not looked at when I last posted). Hopefully the westward trend continues (in the United States perspective), but there is still the possibility the storm turns west-northwest fully before reaching the Cuban coast. Nothing is in stone just yet.

Ike Is Trying To Surprise

If what I am seeing is true, then the Keys are going to be in the worst possible location. This morning Ike was travelling west-southwest, but the westward turn began as Ike approached the large southern island of the Bahamas (Great Inagua Island). This was fine, and expected. However, since Ike moved away from the island a stronger west-NORTHwest turn has started. A west-northwest track would bring Ike along the entire northern coast of Cuba, never allowing the storm to make landfall...which is a very strong possibility. Remember, the track has called for this west-northwest track, only over the entire length of Cuba. Thus, the forecast strength has been for Ike to weaken to a strong Tropical Storm or Category 1 Hurricane. Now, if Ike tracks right along the coast, over water, Ike will likely keep its strength and impact the Keys as a Category 4 Hurricane (or worse...).

I can only hope that this shift is a wobble, but if I was living in the Keys I would not be liking what I am seeing. I am sure the NHC update at 5 pm will give us a lot more information. But with the models trending further and further north (the GFDL and HWRF now bringing Ike just inland along the northern coast of Cuba), a complete miss is still possible. The models are now performing even better than yesterday because the hurricane hunters have sent in their high density data missions into the hurricane and sent up special soundings from Florida. All of this extra data has resulted in this northern shift in the models.

I will update again before 6 pm EST with what I am thinking this storm will do. Obviously we need to watch this current motion and see if it continues. If it does, Ike will likely be stronger than forecasted, be able to get into the Gulf as a major hurricane, and track a little to the east side of the forecasted cone. This would put LA/MS/AL in the greater risk zone. I have been thinking since Ike entered the islands that Ike was going to central Louisiana...but we shall see.

Hurricane Ike

There really isn't much to add today regarding the track, however strength is another issue! Ike has restrengthened into a Category 4 Hurricane and is currently moving west-southwest. This west-southwest motion has moved the system away from the strongest shear. Ike should steadily strengthen until its expected landfall somewhere on the northern coast of Cuba. A Category 5 storm could be very possible now considering Ike has another 24 hours (at least) over warm waters. The stronger Ike gets, however, the greater chance the storm will 'feel' the weakness to the north and it is still possible Ike parallels the Cuban north coast into the gulf. I personally think it will make landfall, but not for very long.

The storm will then head into the Gulf of Mexico, likely weakened by the passage over Cuba. If its anything like Gustav, Ike will need 2-3 days to re-organize. Luckily for the storm (not good for the US) the storm should have 3-5 days to re-organize while the trough that will pull it into the gulf pulls out and a ridge builds in before the next trough. I think Ike could easily re-strengthen into a Category 4/5 storm in the Gulf. The real question will be whether or not the storm is interfered by the next trough, increasing shear before the storm makes landfall, hopefully weakening the storm. Right now the GFS, CMC, and European models do not look good for those in the gulf coast.

A landfall location can still not be pinpointed at this time, but I think the northern Gulf from the Big Bend of Florida to the TX/LA border looks to be the area of most danger after the storm passes into the gulf (after the Cuba landfall and close encounter with the Keys).

Quick Hanna Thoughts

I thought I would point out that Hanna never made it back to hurricane strength, so my initial prediction was correct. The NHC said the hurricane hunter SFMR instrument was over estimating the wind speeds at the surface by 5 knots, thus the 75 mph wind speeds really should have been 70...and no hurricane. That's what I get for writing an entry that explained why I was wrong!

And as for the North Carolina landfall: Hanna decided to go back west and ended up making landfall right on the South/North Carolina border. That is still much further north than the original NHC forecast at the time, but not quite North Carolina. Either way, both SC and NC got hit hard from the storm, but luckily it was a fast mover and it is already moving up through NC into Virginia.

IKE

Hurricane Ike is still trending south. Actually, the European has went completely south of Cuba now and takes Ike into southern Texas! I am starting to think, with each model run, that Cuba (not Florida) will be the strike location of a nasty Category 3 or 4 storm...not good for a country that is so small and was hit only a week and a half ago by Cat 4 Gustav. I half want the storm to stay north of Cuba since they have already been hit hard...but if it does that, and goes through the Keys into the Gulf, it would explode and head for the US...There really isn't a good solution right now.

Hold on to your hats folks, Ike is going to give us a show the next few days. Just not a happy one.

Hurricane Ike Model Issues

The models seem to be coming into better agreement of Ike continuing its west-southwest motion until it comes very close to hitting Cuba, or hits Cuba. Then, a trough diving through the east will interact with Ike pulling it northwest towards Florida. All of this makes sense, but then the models either stop (GFDL, HWRF,BAMS, all other tropical models) or do something interesting (besides the GFS)...they do not pull Ike north and out with the trough, rather they leave Ike behind near Florida to push westward into the central Gulf to a landfall who-knows-where. Yes, the models have went from an east coast storm, just one day ago, to a gulf coast storm that could stall in the center of the Gulf (European model). That is a huge change!

So what can a little model knowledge get out of this? Well, one thing is important to remember, models tend to over-strengthen troughs at this time of year (Fall). They want to push the troughs further south, influencing a potential tropical system to pull north, and this is probably what they were doing a day or two ago. The European was the first to start hinting at a Gulf storm, and the European is also the one model that has the least issues with driving a trough south. Interesting! So in other words, it looks like the European might have been the correct model.

Right now the European, CMC, UKMET, and GFDL (of the reliable models) push Ike into the Gulf of Mexico. The GFS, HWRF, and NOGAPS bring Ike to Florida and then pull it north along the peninsula, slowly (a worse case flood threat). And the models keep trending further west! As of this time, I am completely on board with a Florida or Cuba landfall. Now the question is whether or not the trough pulls Ike to the north. Considering model biases at this time of the year, and this trough not influencing Ike for another 4-5 days, I think the trough will NOT pull Ike out to the north. The rebuilding ridge will likely push Ike into the central Gulf, where it could move very slowly (not like Gustav). I could picture Ike being pulled north but the trough towards the Keys, then being left behind just over southwest Florida or off the coast (in the Gulf), to be pushed out into the Gulf. Depending on the strength of the ridge building in from the east, Ike could go anywhere in the Gulf...in other words, everyone needs to be watching throughout the Gulf coast!

Another Hanna Point

The center is much further east than originally thought, and it now moving due North...which can only tell you one thing: All those model runs that pointed towards South Carolina are now off and need to be shifted east as well. I now think Hanna will make landfall in North Carolina rathern than South Carolina...unless she jogs back west again. Here I go again with a bold prediction...

So I wanted to be bold...

And go with my gut that Hanna wasn't going to be a hurricane...and then the Hurricane Hunters find 75 mph winds...oops. Maybe the winds are finally catching up to that 980 mb pressure. I can admit when I am wrong, and here might be another good case of it. The convection tried to wrap around, started to die (when I was writing my blog) and then has now reintensified near the center again. If the storm keeps itself together through the daylight hours, we could see Hurricane Hanna at landfall. Its a big if though, with all this shear. The models aren't as bullish with Hanna as when she was in the Bahamas. Will have to wait to see if the NHC ups Hanna to a Hurricane at 2pm EST...


And the update is in: Tropical Storm Hanna at 981 mb and winds of 70 mph. So its close, but not there yet per the NHC. Except, looking at the Hurricane Hunter data over the last update, they are finding abundant surface winds of 75 mph, which makes me think its almost a sure bet we have Hurricane Hanna by 5 pm.

Tropical Update

Tropical Storm Hanna

Hanna is looking very ragged right now in satellite imagery. The system has gained considerable convection over the last few hours, but shear and dry air are still battering the storm. The satellite image above (IR because visible wasn't showing much at the moment) indicates the convective burst by the bright red colors. However, notice the sharp transition from red to no clouds on the south side of the system. This is because of southerly shear pushing the cloud tops off to the north and abundant dry air on the southern side that has been entrained into the storm.

Hanna is currently trying to wrap this convection around the center, but it appears the shear might be winning out, pushing the strongest convection towards the north away from the low level center. This does not bode well for Hanna (or, in SC and NC case, bodes very well!) for as long as the shear holds up, the storm is going to have a very difficult time strengthening. Hanna is not doing what it did earlier in the southern Bahamas, where it was able to strengthen to a hurricane even though it was in a high shear environment. Even on radar imagery the system does not look to be organizing its low level center.

Right now the track forecast for Hanna looks fairly certain with a landfall in norther south Carolina. If anything I could see it move slightly to the east of there, but I don't see much of a reason to doubt the great model consensus. My original prediction of a GA/SC border landfall wasn't too far off considering I was thinking it would most likely make landfall on the SC side. However, my strength forecast of a Category 2 hurricane was well off, mainly because the shear did not die down like the models has suggested it would.

Hurricane Ike

Ike is looking a bit worse today, having undergone northeasterly shear for the last 24 hours or so. The shear has bit into the eye of the hurricane and we should see some weakening, kind of like what occurred with Gustav as it moved into the Gulf, over the next 1-2 days. I wouldn't be surprised to see Ike as a Category 1/2 storm in two days time if the shear stays as it is currently. However, after two days the upper-level low will pull northward, removing the shear, and a ridge will build in from the east. This will put Ike back into a favorable upper-level wind pattern, and the storm should begin to restrengthen.

My theory is if Ike is able to redevelop its circular eye, this storm is likely to bomb out on its way to the Bahamas and then Cuba/Florida. If the shear has so degraded the system that 1-2 days will be needed to restrengthen the storm, Ike may make it to the Bahamas before getting its eye structured again. A weaker storm will be more likely to push further south than a strong system, so this could have major implications on storm track. However, considering Ike's presentation at the moment, and the favorable conditions ahead of it, I am leaning towards the stronger end. I wouldn't be shocked to see a nice eye form in 2-3 days as it approaches the Bahamas, allowing the system to charge up off of the warm (relatively un-disturbed from a weakened Hanna) waters.

Right now, with great model consensus, southern Florida looks as the greatest threat location. However, the models have been trending more and more west/south with the system, and Ike could try to go through the Florida Straights towards Key West and then curve up the western coast of Florida...or hit Cuba. A few models still turn Ike up the eastern seaboard into the Carolinas, but its looking less likely. I wouldn't rule it out since five day forecasts can be full of errors (ex: Hanna, Gustav for strength!), but the tracks forecasts this year, by the models and NHC, have been extremely good. The GFDL (except for Fay) has been right on this year in regard to track, and it currently has Ike plowing into Cuba and then moving up the western coast of Florida.

Tropical Storm Josephine

This system can easily be described by the image above. As they say, a 'picture' says a thousand words. (Quickly: Highly sheared, exposed low level circulation. Often described as a 'naked' swirl. A good indication of a weakening, or dissipating, system. Jo is going to need a new burst of convection or its done.)

Update coming...

I will be updating on Hanna and Ike in an hour or so. Until then some quick info:

Hanna is a moderate Tropical Storm moving towards South or North Carolina. The high has built in from the east and is now pulling Hanna northward along the Florida coast. She will likely make landfall sometime Friday night or Saturday (haven't looked at anything really, so my timing could be a bit off).

Ike, last time I checked as a Category 4 hurricane, but shear has done a number on the system and it will likely weaken over the next two days. Ike looks like it could be a monster storm heading towards either Cuba or Florida. Florida is the model consensus location at the moment (specifically, Miami...).

More in depth update coming!

Hanna Update

Tropical Storm Hanna has been moving east-southeast over the last 5 hours, a little different than yesterday. The map below shows the vortex messages (red circled the most recent) produced by the Hurricane Hunters. They have not been able to find any flight level winds above 70 mph, so the storm has stayed a Tropical Storm, with reduced wind speeds of 65 mph. I have no problem with that forecast.



Also since last time, the 18Z models have come out, and the trend has been to go back eastward again! Basically, the models are not really sure what Hanna will do and we won't know until she starts moving north. I am still sticking with my GA/SC border landfall location, mainly because I put forth that forecast yesterday. However, my confidence is low at this point. Definitely a wait and see situation.

Ike and Josephine have both intensified over the day, up to 65 and 50 mph respectively. Ike will likely be a hurricane tomorrow, and if shear doesn't get too strong in 48-72 hours, could be a category 2 storm. The SHIPS model is forecasting stronger shear during that time, so Ike could weaken back to a Tropical Storm, but conditions will once again become more favorable in 5 days. Ike looks like it could be a major threat for some land mass in the future. I question the shear forecast, but we shall see. Currently Ike is under an upper-level anti-cyclone which has helped the system strengthen.

Tropical Storm Hanna

Hanna has weakened slightly this morning and is currently a 70 mph hurricane. The Hurricane Hunters are currently in the system and have found a minimum pressure of 985 mb and flight level winds near 70 mph. The instrument that measures surface winds has been recording near 100 mph winds over the last 20 minutes...but the upper-level winds do not support this. So, I am thinking their instrument must be recording bad data, and if I was at the NHC right now I would keep Hanna a Tropical Storm.

The storm has continued its drift to the southwest today as strong shear continues to batter the system from the northwest. The shear has been produced by Gustav, and should decrease in the next 24 hours-48 hours. Until then, Hanna is going to have a very difficult time strengthening. When the shear lightens up, the storm may then go through a strengthening phase as it is pushed to the northwest as a ridge builds in from the east. The models have been trending further and further west/south with each model run, and right now the consensus is in southern GA/northern FL. Generally the models bring Hanna close to Florida and then drive it right up the coast, just out to sea, towards the GA/FL border. With Hanna still not showing any desire to move north, it is still very difficult to pinpoint a landfall location.

I still think Hanna could become a Category 2 hurricane once the shear dies down. The storm has been very resilient and should be able to strengthen once the atmospheric conditions become a bit more conducive for strengthening.

A little note on Ike: The storm has strengthened some and is still moving west. Atmospheric conditions and models still support the same conditions as yesterday, so the track should keep west-northwest and then west to west-southwest over the next 5-7 days. Any forecasting of a storm's path beyond seven days is foolish, but a US landfall is definitely possible. Josephine has also developed in the far eastern Atlantic, the 10th named system of the season.

Hurricane Hanna Forecast

Currently Hanna is located in a high shear environment created by the outflow from Hurricane Gustav. Gustav has made landfall and should weaken substantially now, and is already down to 80 mph winds from 115 mph this morning. As this continues, the shear caused by Gustav will weaken, which the models also confirm. However, this shear will not weaken substantially for another 36 hours. Luckily for Hanna (or un-luckily for the southeast US), she will stay in the southern Bahamas for this time period as Gustav's strongest shear moves north. Thus, considering she has survived the near 20 knots of shear over her now, she should be able to hold her strength or strengthen over the next 36 hours.

After 36 hours, things begin to change substantially. Gustav's shear will be minimal to moderate over Hanna, closer to the 5-15 knot range, allowing her to develop further. Upper-level divergence should be established over the system and the storm will still be over warm sea surface temperatures. Thus, I wouldn't be surprised (if she can survive the shear for the next 36 hours and keep her strength) to see Hanna reach Category 2 strength.

At 36-48 hours, a building ridge should begin to slide from the central Atlantic towards Hanna. With clockwise rotation around a high, this should begin to push Hanna towards the north-northwest. The GFS and European produce a stronger ridge than the CMC model. Thus, they push Hanna a bit further to the west into the GA/SC border region, while the CMC tracks the storm into NC. Right now, considering the CMC completely bombs out the system (which is unrealistic), which is likely a reason the ridge isn't depicted as strong, I am thinking on leaning on the European and GFS models. This also happens to be the area of greatest clustering of the rest of the models as well. Thus, right now I predict a GA/SC border landfall as a Category 2 storm.

As the system moves north, shear should remain low until 24 hours before landfall. At that time the models want to increase shear slightly over the North Carolina area. Considering Hanna's ability to keep her strength (and strengthen!), and Gustav's ability to stay a Category 3 all the way to landfall in a high shear environment, I think she should stay together and make landfall as a Category 2 storm. The landfall location will be very important in regard to Savannah, GA. If it lands on the GA/SC border the city will be spared from the surge. If it makes landfall to the south, the city will be inundated. Savannah is a city that can easily be washed away because of its close proximity to the water. Add on a local mentality that storms always miss their area, and a disaster could be on our hands. Hopefully Hanna turns more than expected, and maybe even goes out to sea...but I don't see that right now.

Tropical Storm Ike

Ike has been initiated with 50 mph winds and a pressure of 1000 mb. I don't like the looks of this one at all, but I won't get too much into it right now with Gustav and Hanna currently the main issues. I am going to give Ike until Friday until I go out on a limb with this one. But, the Gulf or southeast US looks very likely.

Hanna has also strengthened to an 80 mph hurricane with minimal pressure of 983 mb. Considering it is holding together very well in this high shear environment, once the shear dies down a bit, I wouldn't be surprised to see it strengthen into a Category 2 before landfall on the southeast coast. More to come...

Hurricane Hanna

Is still strenthening....Hurricane Hunters just found 983 mb (down 2 mb from the 1:30 pm advisory) and 86 mph winds (up 10 mph). The next advisory will come out within the hour and I will update this post then.

Update

The NHC has increased the chance of the system off of the African coast to a High chance of development and state that it might become a depression today or tonight! That's much faster than I expected, but I wouldn't be surprised either. The system does look well structured, but it is rare that the NHC calls a system a depression within only one day of it moving off the coast because they like to see persistence. But we shall see...

Scary European model run at 12Z. The run brings Hanna up just off the Florida coast into Savannah, Georgia as a substantial hurricane. That alone is a bad solution, but add in future Ike (Tropical Depression 9) moving into the Gulf after traversing over Cuba...but instead of zooming to the Gulf coast, it sits around and regenerates into a monster. This season is FAR from done.

I am not saying Ike will be in the Gulf just yet, but it is a little worrying when the European continues to be so consistent with its track. Currently the GFS loses the system after 48 hours, so it is difficult to determine what it is saying. However, the models are very consistent with the upper-level environment surrounding Hanna, and track it about to the same area. So, it can be assumed that they are consistent with future Ike as well and the GFS might bring it to the Gulf. The CMC, GFDL, and UKMET also bring it towards Cuba or Florida.

In my next update I will take a close look at Hanna and try to make some predictions of strength and landfall location. I don't expect Hanna to strengthen much more before 48 hours passes (until Gustav's effects weaken), but I also wasn't expecting it to already be a hurricane. I didn't pinpoint the center of Hanna very well, and I thought it was on the northern edge of the convection. Instead it was within the convection, indicating that it was organizing better than before. We will have to watch and see if this convective burst continues through today.

Tropical Depression 9

Here is the track, which seems reasonable to me:





The wave coming off of Africa also looks very good, and is holding its convection together even with its transformation from a land based storm to a water based storm. The NHC has designated it a moderate chance of development into a tropical depression in 48 hours. I still think it will likely take the entire 48 hours, at least to be designated a depression, but a decent circulation and good convection indicates it has a good chance of being the 10th storm of the season. Tropical Depression 9 will be called IKE when it reaches Tropical Storm strength (which the NHC says it might already be).

Breaking News

- Industrial Canal is currently being over topped in New Orleans

- Islands completely submerged off the Louisiana coast

- TROPICAL DEPRESSION 9 has formed in the central Atlantic. Track looks to be west-northwest just north of Puerto Rico.

Tropical Atlantic Heats Up

Beyond Gustav, 5 other areas are of interest in the Tropical Atlantic:








TROPICAL STORM HANNA



On the IR image/map, with the numbers, # 1 is Gustav and #2 is Hanna. The others are all areas of interest. Hanna is looking a lot better than it did yesterday. It is still in a favorable area of sea surface temperatures and tropical cyclone heat potential waters for tropical development, but shear out of the north produced by Gustav and a weakening upper-level low is hampering its development. However, a large plume of convection occured during the night, and now great south side outflow is present. This indicates that once the shear dies down on the north side, the southern side is already ripe for strengthening. This shear will likely start to wane as Gustav weakens over land. I give Hanna another 24-36 hours of difficulty developing, followed by an excellent period for a day or two afterwards. The models generally have Hanna stalled for 48 hours, and then moving north-northwest until a landfall in FL/GA/SC/NC. I think Hanna will likely be a Hurricane by that time as it moves up through a weakness in the ridge.



# 3 AND 4



# 3 on the map is a disturbed area which is in a high shear envionment. There is no low level circulation at this time and the system had little chance of development as it moves northwest. The NHC gives it a low chance of development. # 4 is a new area of disturbed weather near the islands that generated over the night. Nothing has really come together at this point and no models are forecasting development in this region. It is something to watch, but is unlikely to develop with its proximity to Hanna. If thunderstorms were to persist into the central Caribbean when Hanna moves north, something could come if it, but right now I give it a very low chance, same as the NHC.



# 5 AND 6



# 5 is the best looking system at the moment. A low level circulation looks to be developing and the NHC says that a depression is likely developing as I write this. Great circulation is present and the area is in a location of low shear. Development looks likely, and we should have a new depression today. The storm will move towards the westnorthwest for a while, as a ridge builds in to the east of Hanna and then back in where Hanna will move north. This should push # 5 well to the west, into the northern Caribbean islands, or just north of them. This is something that must be watched as it has a chance of being a land interacter. #6 is a wave currently moving off of the African coast that has a chance of development over the next few days. However, it is going to need some time to transition into its water environment and I don't expect immediate development.

Gustav Makes Landfall

The eyewall closing off last night did not lead to more rapid strengthening as I had thought. Dry air once again infiltrated the system which I thought wouldn't happen since the eyewall was shut. However, it did and the system held stead through the night, which is a good thing for the coast. Currently the winds have dropped to 110 mph as the eye has started to come on shore. The 'landfall' will probably be in an hour or so.

Gustav has followed the NHC track quite nicely in the last few hours before landfall, which might have saved the city of New Orleans. Any further east and the surge into the city would have been much worse. Right now we will have to just wait and see what happens in New Orleans with its levees. Just like with Katrina, it might not be until late in the storm when we get any news of any levee breaches and the levees continue to take a beating through the day.

Gustav should continue its northwest or westnorthwest movement for the next day or so, then stalling out drifting slightly to the west for 3-6 more days. This will likely lead to flash flooding in many parts of LA, TX, and AR. Much like Fay, Gustav plans to hang around for a while.

Closed Eye!

The water vapor shows it clearly, the eyewall has closed off now and intensification could become much more rapid. If this trend holds up we could see an eye visible on satellite within 6 hours, just before Gustav makes landfall in southeast/central Louisiana. The green circle indicates the center of circulation of Gustav.

Hurricane Hunters found 952.7, but the dropsonde is not yet in, so we don't know the specific pressure. I am guessing 954 mb, a continued drop in pressure.

Gustav Shows Its Eye

Not on satellite, but on radar! Yes, on the long range radar out of New Orleans you can now see the center of circulation and the eyewall. It won't be long until it make landfall moving at 18 mph. A slow down is expected, and thus why the storm wont hit Louisiana until tomorrow morning.

Another Hurricane Hunter aircraft is entering the center of the storm as I type this, so another update will come shortly.

954.4 mb and now 952.6 mb

Its still strengthening. And the eyewall is getting its act together. It is starting to look like a Category 3 is a certainty, now it will be whether or not Gustav can bottom out before landfall.

Hurricane Hunter Pass

The Hurricane Hunters have found lowest pressure of 957 mb. This confirms that the storm is increasing in strength. The wind speeds have not yet started to increase, but this is not uncommon as often tropical systems reduce their pressure (deepen) before the winds catch up. I would expect the winds to increase in an hour or two. The next Hurricane Hunter mission will likely confirm this.

We should see two Hurricane Hunter planes in the storm at the same time over the next hour or two, so very good data should be available as the system strengthens over the warm Gulf.

Gustav Approaches Northern Gulf

Gustav has been steadily strengthening over the last few hours. Convection has increased on the western and southern sides of the storm, but has not yet developed on the northeastern side. The center of circulation is located near the gray colors in the middle of the highest cloud tops (red colors) on the image below. If this steady intensification continues, Gustav could regain substantial Category 3 winds on the right side. Already upper-level winds support 110 mph, up from the last pass by the Hurricane Hunters, and the center pressure is back down to 960 mb. A second pass is commencing as I write this, so more information should be available very soon.

The storm is still headed on the NHC track, if not just on the east side. I think it is safe to say that it should stay on this track through the rest of its time over water. Afterwards steering currents degrade and the system should drift around in the LA/TX area for a few days. I wouldn't be surprised to see mass flooding in the area.

I will update in a bit with the new Hurricane Hunter information.

11 am EST Update

The 11 am update has come out reporting Gustav with at 962 mb and winds of 120 mph. Where they found the 120 mph is puzzling me. However, I am sure they are doing this so that people along the coast don't think that the risk is reducing. The NHC is still forecasting a major hurricane at landfall. I think we currently have a 105 mph Category 2 Hurricane Gustav rather than the Category 3 the NHC is currently reporting. But, like I said in the last post, the storm is starting to look a bit better in satellite images, and the radar image showed a restructuring southern eyewall. Another 2-4 hours should tell us a lot!

As for the track, the storm still looks to the east or right on the NHC track. The NHC talked about a shift in the models back to the west a bit, which makes sense with a weaker system. However, the models have been to the left all long with this system and the ridge doesn't yet seem to be moving the system. Right now, I think New Orleans (or just to its west/south) gets the worst of this storm, whatever strength it will be at landfall.

Clarification

In my last post, I wasn't saying that the storm shouldn't strengthen, it should....but it is going to have to in the next 12 hours before it reaches a cooler eddy of water in the central Gulf. Right now the storm is actually starting to look like it is strengthening the eyewall on the western side. However, the eastern side still needs work. If it can develop this in the next 3-5 hours, that will give it time to get stronger. The storm is definitely being influenced by these warmer waters right now.

UPDATE:

Hurricane Hunters found central pressure near 960 mb and peak flight level winds of 91 knots. It will be interesting to see what the NHC says in the next update at 11 am EST.

Gustav Weakens

Hurricane Gustav has weakened quite a bit during the night. As it crashed into Cuba Gustav was a Category 4 hurricane with winds of 150 mph, only 6 mph short of a Category 5! However, Cuba disrupted the eye of the hurricane during passage over the island and now Gustav has weakened all the way down to a low Category 3, or possibly now a Category 2. The latest Hurricane Hunter recon pass did not find flight level winds above 100 knots, indicating the surface is somewhere likely between 80-90 knots at best, or between 92-103 mph, or only a weak to moderate Category 2.

Why such the strong weakening? Well, first the passage over Cuba was much worse than expected. Earlier the models and forecasters were thinking Cuba would only reduce the winds a little bit (5-20 mph) and not completely disrupt the eyewall of the storm. Instead, Cuba broke down the eye allowing the pressure to come up from close to 940 mb at landfall to 960 mb now. Also, some shear (10-15 knots) has been influencing the system. Earlier the shear was not a factor because Gustav was located under an anti-cyclone which helped eject mass out of the top of the system, and because strong Category 3-4-5 hurricane eyewalls can protect the center of a storm from shear. Now, however, the eyewall has broken down some and the anti-cyclone did not follow the system into the Gulf. Thus, shear is impacting the storm more, not allowing it to go through rapid intensification while over the loop current. Actually, if this storm doesn't get its act together soon, we might not see more than a weak Category 2 hurricane at landfall, which would be great news!

Another issue that could come into play here is the building ridge to the north of the system. Now that it was weakened, the storm is less likely to plow through the ridge and should feel a bit more of a turn to the west. However, the ridge is now building in a bit weaker and the storm has sped up its arrival. Thus, the balance between these variables should be a wash and the storm looks to make landfall just about where the NHC track places it, to the south of New Orleans moving northwest. This still brings in the greatest surge to the New Orleans area, so any strengthening could lead to levee failures. If the storm stays as weak as it is right now (relatively, of course!) then the levees may hold. However, there are still weak points and it is definitely not the time to be in that city. One good thing, the system weakened as it passed over Cuba, so all the surge it had built up smashed Cuba but didn't continue into the Gulf. Hopefully Cuba was able to get everyone out of harms way.

In the words of a very good forecaster....

NOT GOOD!!!!


I remember when Katrina moved through Miami, diving to the west-southwest in a direction that was unexpected, I said to my friends and current wife: "This is the big one, the one that hits New Orleans." Of course, I wasn't 100% sure at the time and the models were still only starting to trend towards New Orleans, but I could just feel it. That same feeling is starting to get into my head again. Gustav has rapidly strengthened, it has a very symmetrical eye, great outflow, warm waters ahead of it, and nothing (besides a small passage over Cuba) stopping it. This storm has went from a hurricane that we should definitely be worried about, to a storm that can't be messed with.

Hurricane Hunters have found a minimal pressure of 945 mb and peak surface winds of 145 mph. Gustav is only 10 mph away from a Category 5 storm, and the NHC is now predicting it to become a Category 5 storm as it hits Cuba or just afterwards. The storm has consistently been tracking to the east side of the forecast and model tracks. This allowed it to mostly miss the Isle of Youth, not giving the island a real chance to weaken the system. Gustav is also flying right along, faster than most of the models had expected. This forward speed is only allowing it to burst through the ridge and beat the strengthening ridge that will later build as the storm approaches the coast. Things do not look good for the New Orleans area.

I am not going to definitively say this is Katrina 2, but it is starting to look like it. We need to wait an additional 6 hours, letting the storm interact with Cuba, to get an idea of where Gustav might be heading. Wherever Gustav does make landfall though, NO ONE should be within 10 miles of the coast. Be smart and get out of the way.

Gustav Cat 4 strength

Hurricane Hunters just found 943 mb! Western Cuba is about to get pummeled, and the eastern portion of the Isle of Youth is about to take a direct hit...and the storm still has plenty of time to strengthen before it goes over mainland Cuba. Gustav keeps going to the right side of the track, and it is making me a bit worried that things might go east of the NHC track...but we must look at Gustav over the next 6 hours to really get an idea of where it is going. If Gustav stays to the right side of the track through the 11 pm advisory tonight, as it lands in Cuba, then I might shift a bit east.


NWS Update:

000WTNT62 KNHC 301718TCUAT2HURRICANE GUSTAV TROPICAL CYCLONE UPDATENWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072008

120 PM EDT SAT AUG 30 2008

DATA FROM AN AIR FORCE RECONNAISSANCE AIRCRAFT INDICATE THATGUSTAV HAS CONTINUED TO STRENGTHEN AND NOW HAS MAXIMUM WINDSNEAR 145 MPH...230 KM/HR WITH HIGHER GUSTS. THIS MAKES GUSTAV ANEXTREMELY DANGEROUS CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSONHURRICANE SCALE. A SPECIAL ADVISORY WILL BE ISSUED AT ABOUT 200 PMEDT TO MODIFY THE INITIAL AND FORECAST INTENSITIES. THE SPECIALPUBLIC ADVISORY WILL TAKE THE PLACE OF THE INTERMEDIATE PUBLICADVISORY PREVIOUSLY SCHEDULED FOR THAT TIME.

$$FORECASTER KNABB

Gustav Predictions

I still think my landfall location might be OK, primarily because the models often under estimate a building ridge, and thus it should push the storm slightly to the west at the end of the track near Louisiana. Creole, LA is still my pick.



The models are currently in great agreement with a central Louisiana landfall. A few, however, are still hinting at a shift to the west. Many of the GFS ensemble models are even further west, more in line with the UKMET, turning the storm completely around to the southwest near the Louisiana coast. The HWRF also thinks this will happen. So, the building ridge is definitely being picked up by the models, it is just a matter of how strong it will be. I am thinking it will be some sort of blend of the models, pushing it just a bit further west along the LA coast.

Note: Starting position is not even close to current position.

Of course, these are just my thoughts, not the official forecast. It is always best to follow your local law enforcement officials and NHC forecasts. Even if you are in an area that the storm doesn't look like it is heading for, but evacuations are ordered, it is best to evacuate. There is a reason the local officials call for evacuations: To save YOUR life!