Last Saturday we saw an unusual episode of Severe Thunderstorms across Pennsylvania which included an EF-1 Tornado in York County and an EF-2 Tornado tracking from the Plains area(Luzerne Co) to Moosic(Lackawanna Co) leaving a trail of damage in it's wake. Now we could be looking at a repeat performance on Wednesday except it could be a little bit more potent than what we saw on Saturday so let's disect the ingredients leading up to this event:
Temperatures: Just like the event we just saw, there will be a surge of very warm air coming up from the south and southwest around an area of High Pressure which will be located off the East Coast. Temperatures on Wednesday will be approaching record levels as we will be in the mid 70s across much of the area which will serve as fuel for these storms.
Wind Shear: There usually isn't much to worry about with wind shear in this part of the country but there may be on wednesday as we will not only have plenty of Bulk Shear, but we may also have some Speed Shear as well as we could have winds at the surface coming in out of the South or Southeast, and winds coming in from the West aloft. These changing winds with height may support Supercell Thunderstorm development out ahead of the main squall line which could produce Isolated Tornadoes.
This is Brand new Data off of the 0Z NAM model for Philadelphia on Wednesday Afternoon which illustrates the seriousness of the situation that we could have with the soundings showing a tornado threat even for Philadelphia late Wednesday afternoon and Wednesday Evening.
Brand New 0z GFS:
The Bottom Line is that we will be seeing more Severe Weather on Wednesday which may very well include some Isolated Tornadoes. If you live anywhere in the Northern Mid Atlantic States you are being advised to keep an eye out for rapidly changing weather on Wednesday Afternoon and to heed all warnings which may be issued during that time frame..