There was plenty of sunshine on Saturday and despite some fair weather cumulus popping up by the afternoon(just as forecasted); we managed to reach 89 at Philadelphia International Airport after a low of 70 just after 5am. There were a few isolated showers and thunderstorms just after the dinner hour(primarily to the north and west), but fizzled out once the sun set as the daytime heating(their "fuel") was exhausted.
Overnight there will be a partly cloudy sky thanks to the cloud debris as well as milder juicer air working northward; lows will be around 70 with a continued southerly wind. Don't be shocked if there's some fog by morning. Sunday itself shall be sunny to start, but then clouds will roll in by the early afternoon with showers and thunderstorms popping up by the late afternoon(dinnertime hour). Highs will be in the upper 80s with a continued southerly wind.
The front will take its time coming through so scattered showers and thunderstorms will continue through the overnight and into Monday with lows in the middle 70s and highs in the lower 90s. In the late evening into Tuesday the risk of storms not only goes up, but also be on the strong to severe side thanks to the upper-level(500-millibar, or 18,000 feet) low swinging on through. What this will do is create a lot of instability aloft so as we'll have a warm "juicy" airmass on top of the region it just takes the rising of air parcels to pop up a storm; the issue comes in with the strong wind shear(wind direction and/or speed changing with height) along that can cause gusty winds, large hail, and also the threat of a few spinups(funnel clouds and tornadoes). Tuesday itself will have showers and thunderstorms continuing with highs around 90, but then FINALLY overnight into Wednesday we'll begin to clear out the moisture as drier air will try and work in from the north.
We'll be under the influence of high pressure once again with unseasonably cool and dry air from Canada; highs will just be in the upper 70s come Wednesday while overnight lows will be in the upper 50s! That's almost TEN degrees BELOW average! It will feel more like Mid-September than Mid-July! You will be able to give your air conditioner a rest for a few days! But for now you can view my 7-day forecast(any time) at www.scottderekwx.com/forecast.html.