Enjoy the break in the heat over the next couple of days -- the refreshing winds of change will not last long around here as the cool trough that's passing through the Northeast will lift out later Wednesday, allowing for a steady warm up and temperatures pushing back towards 90 by Thursday afternoon. From there, how high do they go?
The Euro is advertising another heat wave -- with the potential for mid and upper 90's for Friday and Saturday, with lower 90's on Sunday as the core of heat nudges to our south a bit...but with enough of a hold in place over the Mid Atlantic to give us 90 for at least three, perhaps four days. Saturday's 5 PM temperatures from yesterday's afternoon Euro are listed below -- notice the wide swath of upper 90's from Philly on southwest and west.
Contrast with yesterday afternoon's GFS (below), the Euro definitely is running much warmer. One of the bigger differences between the two models is that the GFS is a bit more "dominant" with the presence of a frontal boundary nearby starting late Saturday and continuing into early next week, providing the possibility of thunderstorms each afternoon. This front is a bit more potent in the GFS' world than on the Euro's...which results in temperatures that aren't quite as toasty -- generally around 90 on Saturday afternoon but a lot more 80's in place nearby. The GFS, for what it's worth, does also suggest a "heat wave" but with highs only around 90-93 through Monday, about five degrees cooler than the Euro on Friday and Saturday. Both models are holding serve with similar looks in the early morning computer model runs this morning...with the Euro the hotter, the GFS the more aggressive with showing the frontal boundary nearby for Friday and Saturday afternoon.
The aforementioned frontal boundary may serve as a channel for systems to traverse along...or for MCS thunderstorm complexes to develop and track east along as it separates toasty from merely summery. Its placement is still very much up in the air since it's only Tuesday but it may lay across the region this weekend and provide a thundery ruination at times for weekend plans.