94L and Jimena

In the tropical Atlantic the tropical wave named 94L currently has intensified significantly overnight. A large mass of thunderstorms have developed directly over the broad circulation, and now looks destined to be a Tropical Depression by the end of the day. I still think this system is going to have to fight the dry air, but looking upstream to the northwest, where this system will have to go to survive, the moisture increases significantly. Additionally, a stalled out upper low is currently spinning about to the north of the system, and this will help to ventilate it as it passes to the south. So, if this system can fight off the dry air it is experiencing now, I don't see why it can't make it to a named system anymore. 10-20% chance.....bologna. The new name will be Erika.

One thing to point out though, that lingering trough and frontal boundary is still holding off of the eastern coast, and that ridge of high pressure is still supposed to build in. This could lead to three possible solutions. 1) A new low develops and consolidates, weakly (tropical or not tropical) and heads out along the boundary or stalls out...thus interfering with potential Erika as it moves east. 2) The energy is left behind as the ridge builds but does not consolidate, but is instead entrained into potential Erika to make the system stronger as she is pushed back south with the building ridge towards the west. 3) The trough is still just strong enough to leave a weakness to allow Erika to head out to sea.

These three solutions are all possible, and thus make forecasting Erika's track difficult at this time. The CMC right now believes the weakness will be strong enough to pull her north. The Euro, GFS, and HWRF all take Erika west. (The GFDL does not develop the system). Usually for track I like to believe the Euro and CMC in the Atlantic...so I am a bit split. But considering the Euro has been the best this year, I will follow that track. The one issue with the Euro....it doesn't strengthen Erika very much at all, and this could be a limiting factor of the model. The only models to forecast a stronger system are the CMC and HWRF.

Now as for the Pacific, Major Hurricane Jimena is moving north-northwest towards the Baha and is now forecast by the NHC to make landfall a little north of Cabo. This would bring the right side of the storm into the Cabo area, which tends to be the strongest side (more wind, rain, and tornadoes). Not good for the beach resorts! However, right now the track takes it far enough out to sea that the eyewall should miss Cabo directly. Any shift east however could be disastrous. Lessons learned (if the currently forecast track holds true): 1) The GFDL and HWRF were once again too far east...but did better than the Euro and CMC. 2) The models like to lose the moisture once the system makes landfall...which seems highly unlikely. A trough moving in to the northwest US should entrain the moisture from Jimena and lead to heavier rain that expected in the west and northern plains (possible also central plains later).

Danny Boy Is No More

Danny was absorbed into a new developing low off of the North Carolina coast at around 3 am CT last night. It was very interesting to watch on satellite. Danny's circulation within 6 or 9 hours shot due north towards the North Carolina coast leaving it's convection completely behind. At that time the circulation became elongated, the Hurricane Hunter's found little surface circulation, and Danny was dead. It wasn't too much of a surprise considering the strong upper level trough moving into the area. As usual, a low developed off the coast and began to dominate the environment overpowering Danny. Now there is a rather strong mid-lat cyclone with a lot of tropical energy moving up the east coast. Wind gusts to 50 mph are still going to be possible along the Cape (or at least could have been...the storm is already moving north and away from Mass.) and then in the Canadian Maritimes. Heavy rainfall of 2-4 inches will be common in coastal New England and Canada as well.

Now the attention, at least for the Tropics, turns to invest 94L east of the islands in the central Atlantic and off of the western Mexican coast as a significant tropical system is taking shape. 94L currently doesn't look too impressive and the system continues to have to fight off dry air. Otherwise the environment around 94L isn't all that bad for development. Thus, I could see a weak system developing out of the wave as long as it moves northwest and away from the Caribbean which is extremely dry and has more shear. Odds of a named system...10-20%.

Now as for the western coast of Mexico, a storm that was only designated a depression yesterday evening is now a Hurricane moving towards the northwest. Hurricane Jimena is now a Category 2 hurricane with sustained winds to 105 mph. The current NHC track keeps the storm out to sea as a major hurricane and then turns it slightly further west once it reaches west of the Baha. What concerns me most is that the GFDL and HWRF are bringing this storm into Mexico as a major hurricane rather than keeping it out to sea like all of the other global models. Currently the NHC is sticking with the global models, which makes sense considering the current track record of the HWRF and GFDL this year. Both models, in general, over forecast strengthening and pull the system out to to the north more quickly. However, in this case we have a land mass to the north rather than a Bermuda High. I am not sure how these two models work in this type of environment, so it will be something to watch.

If the system does move north rather than northwest it will be a major disaster in western Mexico as the system will be flooding rains, high storm surge, and very strong winds. Additionally, this type of track would bring a lot of moisture into the southwest US and into the Plains. Track in this case is very important in regard to flooding potential in the US as well.

The next chance of a real close to home system near the US will once again be off the southeast coast as a ridge of high pressure builds in the northeast north of a lingering frontal boundary in 5-10 days. Often when this occurs energy begins to pile up off the coast of Florida to North Carolina. If this energy can consolidate...or a wave (maybe 94L?) can enter the mix in this area, a system can develop. Often these system then pull out towards the northeast, but if the high that has built in is very strong, which the GFS is hinting at, the storm could move west into the southeast.

Obviously I meant...

further west rather than east in my last post...oops.

Right now my original thoughts still look good for Tropical Storm Danny. The storm is fighting the dry air ingested from the upper level low that influenced the system earlier. Additionally, the trough off to the west is causing increased wind shear over the system pushing the most intense convection off to the east. Basically, this storm is doomed. We might see baroclinic strengthening along the coast as the trough advances eastward, but a true tropical system is pretty much done. The low level circulation is exposed with no convection anywhere near the center. If things continue, this storm may even be a depression by the end of the day.

The low will track north just off the NC coast and then head north-northeast into the Canadian Maritimes and that will be that. People in the east will experience heavy rainfall...but it wont be directly related to Danny, instead it will have more to do with tropical moisture from Danny being enhanced by the trough moving east. Basically, this is a non-issue system that if we didn't name storms no one would have any clue it ever occurred.

The next storm may develop further out in the middle Atlantic ocean as a strong tropical wave moves east. This system will have to fight the very dry air in the central Atlantic and I foresee another Ana situation. We might see a name, but a strong system is unlikely. Watch for the next wave following this one as it moves off the African coast and takes advantage of the moistened environment following the wave in the central Atlantic. We could see another situation like Ana and Bill where the second system was stronger. However...the wave moving off the African coast is not quite as impressive as the Bill wave was, so the odds are a little lower we see a major hurricane out of these waves. But hey, just my opinion.

Possible Additional Tropical Trouble

A new tropical wave is moving westward near the far eastern islands. This wave will move north of the islands towards the southeast coast and combine with some left over energy from the front that just moved off of the eastern coast. An upper level low northwest of this wave is helping to ventilate the system leading to thunderstorm development. However, this upper level low is also creating some wind shear over the wave. Until the low weakens or moves out of the way to the northwest the wave will likely not organize substantially. However, give it 2-4 days and there is a good possibility of a tropical system developing off of the southeastern coast. Many of the global models develop this system...except for the GFS which splits the energy leaving some behind off the southeast coast and the rest pulling out to the northeast. This is a common problem with the GFS, so I wouldn't be surprised to see the energy consolidate in later runs.

The next question will be whether or not this potential system impacts land. Current trends indicate the system might take a track similar to Bill, only slightly further east, thus moving right along the eastern coast or clipping it. As the system develops we will be able to get a better idea. The European model did the best with Bill 10 days out (off by 150 miles) so I am going to lean towards its solution, which is a weak tropical system off of the coast of Florida, moving north and then northeast just off the coast of North Carolina and then off to the Canadian Maritimes. Could be an interesting next week.

Tropics.....finally.

There are three entities in the tropics that need to be watched at this time. The first is Tropical Depression 2....which is barely a depression at that! The system developed quickly after it moved off the coast of Africa into a decent environment. A few waves had moved off of Africa before TD2 and had moistened up the environment, thus TD2 was able to form and for a few hours could easily have been a tropical storm. However the NHC never upgraded it and it lost all of its convection yesterday afternoon. A small burst of convection occurred during the night so the NHC has not dropped the system. However, it was contemplated last evening....

TD2 is fighting a lot of dry air and has moderate wind shear present over the system. Both of these variables do not add up to a strengthening system, but as long as it holds together there is still the possibility it gets named. At this point I don't see it being named any time soon as TD2 moves west towards the islands. As long as the system stays weak it could move all the way across into the islands in a few days. I think there are two scenarios that could play out with this system: 1) It completely dies and 2) It holds together as a depression, or even weak storm if the convection can refire, for 3-5 days and then track just north of the islands.

The most immediate threat at this point is a burst of convection associated with a positively tilted (I think positive) wave stretching from north of Hispaniola into the eastern Caribbean. Wind shear is in the 15-20 knot range north of Hispaniola where the main burst of convection is located, which isn't great, but not awful either. Sea surface temperatures are not a hindrance. However, the upper level winds are not quite what would you except for a tropical system to be imminently developing. An anti-cyclone is currently progged at 300 mb....which is exactly opposite of what you would need with a tropical system. Unless a high can build over the convection we wont see this storm develop in the next 2 days. However, once this system moves into the Gulf of Mexico all bets are off. An upper level high begins to build in and there is the potential for a system to form from this wave. Luckily it won't have much time to organize before landfall along the coast. I would be amazed if we saw more than a weak TS out of it at the strongest. Just something to watch.

Further out east is going to be the big story down the line. A strong tropical wave has moved off the African coast and every model currently has it forecast to become a tropical system in the next couple of days. The NHC has just upped the risk to HIGH for this wave to develop into a tropical system and I do not see much of a reason for it not to. The one hindrance I have noticed is its large envelope. This is a HUGE wave...often when large waves move off the coast it takes some time for the wave to organize all of that energy into a more concentrated area. The wave has been off the coast for a couple of days now and the system still does not appear to be getting any better organized. I think we will have to wait another 2 days before a depression forms.

But once it does form there is a good chance this is our first big system of the year. Be it Ana, Bill, or Claudette (depending on the two other system in the Atlantic right now) it's name might be the big story of the year. Currently models are forecasting the system to move west across the Atlantic into the Caribbean, then turn north through Hispaniola or Cuba up along the eastern seaboard possibly making landfall on the east coast. The GFS and European both develop the system into a strong tropical system. A building ridge in the Atlantic should allow for the system to easily make it to some landmass....be it just the islands and then out to sea or the USA. The main issue will be the timing of a trough moving off of the eastern United States as the tropical system approaches. Currently the models move it just off the eastern coast....but other runs have had it as far west as New Orleans. So, as always, we don't really know where this system will be headed, but right now if I had to throw out a guess I would say the east coast needs to be ready.

Ok, more to come tomorrow.