Tuesday, May 29, 2012

Toasty & Thundery Tuesday

After yesterday's 91 degree high in Philadelphia, another run at 90 or warmer than that is in the cards for this afternoon in the Delaware valley.  Given the already warm start in place through the region (mid 70's at 4 AM, yikes) we're going to have an easy task to get to 90 provided nothing fouls up the works over the next few hours.

The expectation is that this morning will be dry and mostly sunny.  Unlike yesterday, clouds will be quick to develop towards midday as convective temperatures aloft are a bit lower and the cap in the atmosphere a bit less rigid in place.  We might hit 90 a bit earlier today than yesterday but with clouds developing ahead of an approaching cool front we probably don't get any warmer than yesterday's high.

With the approaching cool front coming in from the west, thunderstorms will fire up along the boundary across Ohio and Western Pennsylvania, spreading east and northeast through the state over the late afternoon and into the evening hours.  A slight risk of severe weather is currently in place west of a Stroudsburg-Chambersburg line (roughly along/west of I-81, give or take a bit on either side) today but if thunderstorms fire sooner ahead of the main cool front and work into the region during the late afternoon hours we could see a few severe storms closer to Philly.   Today's thunder threat will be greater northwest of the city during the day, spreading through the rest of the region after dinner tonight as storm activity moves in.  

Timing it out for the region:  Storms are possible northwest of the city after 3 PM, city after 6 PM, Shore after 8 PM.

Thunderstorms will also bring a threat for heavy rain as they move east and northeast through the region.  Unlike the storms of the past few days, these storms won't be as slow moving but it's possible a few cells track over the same areas, leading to some localized flooding.  Rainfall could exceed a couple of inches in localized spots but not on a widespread basis...all dependent on how the storms track through later on today.