Saturday, June 30, 2012

Tonight's Thunder Threat

Temperatures have been saved a bit this afternoon in Pennsylvania by a cloud deck from a dead complex of storms that moved across the Great Lakes overnight.  That deck of clouds has stabilized the atmosphere somewhat and while it's still plenty warm to hot out, the atmosphere in Pennsylvania and in Central and North Jersey will not be able to destabilize much with clouds in place.

It also helps last night's storms did a number on the instability in the atmosphere.  While the atmosphere is still unstable -- dew point values run around 60 (enough fuel to fire storms), the level of instability is significantly lower compared to yesterday and the derecho complex can be "thanked" for mitigating what looked like a potentially bad severe setup tonight across the region.  That said, we're looking at two areas for some activity through the course of the night.

Locally, showers over South Central Pennsylvania continue to move east towards Philadelphia.  These are associated with that cloud deck pictured above.  Those will pass through Delaware and South Jersey, with perhaps a sprinkle in Philadelphia around or just after 5 PM.  No big deal but there could be a few showers or sprinkles over the next couple of hours.

The next area to watch may be for areas south of town late tonight.  These thunderstorms are in Illinois and Indiana as of 4 PM and are moving east for the most part.  These would not get here until after 2 AM or so, at the earliest, and if they were to even impact us they'd probably impact areas south of Philadelphia.  Given the atmosphere is a good bit more stable than yesterday, these may weaken before getting here.  If not, another round of sound and light is possible later tonight.  However, it should not be anywhere near as strong as last night's storms.