7/29/09 Severe Weather Discussion/Forecast

Wednesday 7/29/09 Severe Weather Outlook

Tomorrow could be a decent day for severe weather across much of the Mid Atlantic and Northeast if the atmospheric conditions and parameters corroperate. The 00z GFS has CAPE values of 500-1500, LI values of -3 to -7, and Shear of 25 to 35 in the area. The 00z NAM has CAPE values of 500-2000, LI values of -3 to -8, and Shear of 25 to 30 in the area. The culprit is a front that is currently in the Mid West area, and this should slowly approach the region Tomorrow and this will spark up Thunderstorms, with some severe across the region. Tomorrow I see highs mainly in the 80s with 70s possible inland, most regions should wake up to mostly cloudy to mostly sunny skies which may be good for instability and daytime heating. Combined with that, I see high humidity Tomorrow which will be the trigger for storms to pop up over the region. I am about 70% confident of this forecast because of the timing and the speed of the front, the atmospheric conditions and parameters, and the amount of sunshine in the morning hours will control how much instability, moisture, and storms we get. Overall, I am predicting the best potential to be from Virginia to Maine as that area will have the best parameters for severe weather, hence I put them in the 10% risk zone. We should have more reports than yesterday across the area. Now what could change is what I stated earlier in the discussion, If the front speed's up quicker than forecasted, I may have to take Kentucky and Ohio out of the 5% zone and put them in the 0% to 5% zone, if there is more instability involved, I may upgrade the 10% area to a 15% area. For the 5% zone, I am expecting CAPE of 500-1000, and LI of 0 to -3, in the 10% zone, I am expecting CAPE of 1000-2000, and LI of -3 to -8. So basically Tomorrow looks like a decent chance for severe weather, and it is mainly responsible from the front. Main risk's Tomorrow will be damaging wind, small hail. and maybe even an isolated tornado. If I see any major changes, I will have a Mid-Day update.

Comments would be appreciated.