Thursday was the typical late July day; after a low in the middle 60s at Philadelphia International Airport we reached 86 for an afternoon high thanks to a mixture of sunshine and fair weather cumulus once we reached the convective temperature(the estimated temperature that the surface must warm to in order for clouds to develop). No rain fell at the airport this afternoon, but there were a few isolated showers and thunderstorms that popped up to the north and west in the late afternoon(and fizzled out for the most part once the sun set).
Overnight it will be partly cloudy with lows in the upper 60s to around 70 as there will be an area of low pressure across Virginia advecting high clouds northward and preventing us from cooling down tonight; Friday shall be dry, but the sky will have that "milky" appearance to it with more clouds than sunshine as highs will be in the lower 80s. It will feel a bit more humid as well thanks to a south-southeasterly wind around 10mph. There may be some scattered showers and thunderstorms in the afternoon, but that should be primarily across the I-81 corridor.
Friday night into Saturday morning is when we'll have the rain(heavy at times) pushing northward with lows in the upper 60s and Saturday itself will pretty much be a washout with showers and thunderstorms as highs approach the middle 80s. The potential for 1-2" of rain is possible and especially in thunderstorms as well. The area of low pressure will continue to push to the north-northeast overnight into Sunday so although there will still be a rain threat Sunday afternoon the showers will be isolated in nature so not everyone will see one. It will feature a mixture of sunshine and clouds however with highs in the lower 80s.
Finally that gets all out of here and high pressure takes control; this means that Monday will be sunny with highs in the middle 80s and overnight lows will be in the middle 60s with a clear sky. Tuesday will start off sunny, but it's warmer with highs in the upper 80s by the late afternoon as a warm front approaches from the west to provide clouds by the late afternoon(and maybe an isolated shower north and west). Overnight Tuesday lows will be in the upper 60s while Wednesday will be mostly overcast with showers and thunderstorms by the afternoon ahead of an approaching cold front to the west. Highs will be in the middle 80s.
Remember that you can check out the rest of the 7-day forecast(any time) at www.scottderekwx.com/forecast.html.