A front currently located in W PA will move toward the coast bringing with it a slight chance of thunderstorms for CT, W and C MA, S VT, C PA, and most of Virginia. A Moderate risk of thunderstorms will be located in E PA, MD, W NJ, and S NY. CAPE forecast from the 12z NAM suggests 2000-2500 J/Kg in SE PA down through Virginia which is more than sufficent instability. Elsewhere CAPE is commonly 1000-2000 J/Kg. Deep LI's commonly -4 to -6 are found in all area's inside the slight and moderate risks with the highest levels in E PA, MD, and NJ. Moisture is also abundant with this system with dew points in the upper 60's, low 70's. This and good LL lapse rates indicate that storms should have no problem firing tommorow and become severe. The biggest thing tommorow though is backed winds in the moderate risk zone. This is typically seen in severe outbreaks in the midwest. It is for this reason I am going 5% tornado probability inside the moderate risk as well as 2 % in the slight risk. A 40% wind probability is included in the moderate risk and 20% in the slight risk. Finally Hail probabilities will be 15% in all zones. A word of caution: Other models suggest possible cloud cover inside area's of the Moderate Risk. If this happens, most of the instability number will go down and may decrease the risk of Severe thunderstorms inside the risk zones. My next update is expected around 14z tommorow.
--Justin- Lead Severe Forecaster 03z Update
0 comments:
Post a Comment