Tuesday, July 1st: 3rd of July Wx Forecast

Yes, I did say the 3rd of July and not the 4th because Mt. Rushmore does their large fireworks display on the 3rd (for some odd reason). If they had picked the 4th, the weather would likely cooperate fully...but as for now, it looks like there might be a chance of showers, and possibly a thunderstorm, into the afternoon on the 3rd. Hopefully they move out by dark and the firework show can go as planned. I have heard it is very good, we Shaina and I will definately be there.

As for the forecast:

Currently:

Philip, SD is located in westerly flow aloft to the surface. Winds are blowing at 13-14 mph at the Philip weather station with a current (10 am) temperature of 80 degrees, up only two from the hour before. Skies are clear in Philip, but here in Wall they are mostly cloudy (which makes me wonder about the Philip report). Visible satellite shows mid-level clouds moving to the east, and higher level clouds traveling a bit more wsw over the area. Clearing could occur over the Wall/Philip area as these clouds continue their eastward movement, but cumulus is forecast to rebuild behind it. Looking at the surface map, a weak dryline/cool front boundary has moved through the area, and might be the trigger for some of the cloudiness. Just to the east winds are out of the south. It might be 80F here, but just to the north in ND its already 89F. Obviously the cloud cover is holding back the temperatures.

Today:

The models have changed a bit, enhancing rainfall over the region as compared to yesterday. Actually, the NAM is forecasting rainfall in SW SD in the next 6 hours, which does not look likely considering the clear skies over that region. I think the NAM was likely seeing the cloudiness over west central SD, over the Wall/Philip region, but no rainfall is seen on the radar besides a small blurp in SW WY. An area of vorticity will traverse over the region this evening, brining the chance of showers tonight, but should keep the area dry today. The vorticity max is associated with a very small shortwave. For today, as a second area of vorticity moves east of the region currently, the cloudiness should wane, resulting in clearing skies by afternoon except for high terrain convection, and likely heating. Considering how easily temperatures got to near 90 in ND, and the possibility of clearing in the afternoon, I still think low 90s are possible. However, 93 might be a stretch. Watch for temperatures to increase slowly through the day with 850 mb temps still 26C. My forecast: 92F. (NWS: 95F)

Tonight:

The shortwave will begin to move into the region, resulting in a chance of thunderstorms during the evening and overnight. Often in these conditions, with a strengthening nocturnal low level jet, storms are able to form over the higher elevations and roll out over the plains. This usually results in storms around 3 in the morning (not to our liking!). It is possible this is one of those days, but it doesn't look too likely with cold air advection starting tonight. This cold air advection is in conjucture with the frontal passage that is occuring currently, but lagging a bit behind in the upper levels. RAW NAM is forecasting 0.03 inches of rain tonight, while the GFS is forecasting none. I think I will stick with no rain tonight for my official numbers, but with a 20% chance. The RAW NAM is still forecasting a low of 69F, which seems way too warm with clearing skies and dewpoints in the 50s for the raw. The ETA/GFS MOS are saying 63F/64F, respectively with dewpoints near 60F for the ETA. I don't see much reason to go against them today, except that the low has been very close to the dewpoint each of the past 4 nights. This would lead me to undercut the guidence and go with 62F instead. (NWS: 63F)

Tomorrow:

A much cooler day in store. The frontal passage will be complete, cold air advection at 850 mb will be underway, and cloudiness will dominate the area (as per the models). 7oo mb moisture will increase in the afternoon, leading to thicker cloud cover and possible rain showers. Under a cold air advection regime, thunderstorms seem less likely, but could still occur down wind of the higher terrain (such as the Black Hills). The possibility of rainfall is enhanced due to vorticity maximums swining through the area and another small shortwave trough at 500 mb. The RAW NAM is spitting out 0.05 inches of rain, mostly in the afternoon, which makes sense. It should be a showery affair, rather than a thunderstorm day. Thursday looks more active to me than tomorrow. That being said, 0.03 inches of rainfall. As for the temperatures, the RAW NAM says temperatures should max out at 80F, ETA/GFS MOS say 78F/80F with dewpoints dropping into the mid- to low-50s. 850 mb temps are 16C, which supports 24C/75F. Considering the cloudiness and 850 temps, it makes sense to definately go below guidence! 74F looks good, definately if there are any sunny periods early. Otherwise, it might be a low 70s day right after highs in the mid 90s! (NWS: 74F)

For Thursday, Fireworks day:

Questionable. Thats all there is to say. The NAM model is forecasting some rainfall in the morning, but lingering it to the afternoon. The festivities at Rushmore begin at 7 am, so rainfall at any time of the day is bad, however if it moves out by the afternoon it should be ok for fireworks. As for the wind, little mixing should be going on due to thick cloud cover through mid-afternoon per the NAM. Still, even if mixing is possible, gusts to 20 looks like the highest will be seen. The GFS is not quite as bullish with the cloud cover, but still shows some throughout the afternoon. Highs look to be similar to Wednesday, in the mid to upper 60s in the hills. So, if the rain holds off, such as the GFS says, it should be a wonderful day for fireworks, maybe even feeling cold. Philip might have highs only near 70F! Wow, and this is July!