Friday was a warm day, but the humidity was lower thanks to a northerly wind; the high reached 80 shortly after 3:30pm at Philadelphia International Airport after a morning low of 70. There were a few isolated showers and thunderstorms in the afternoon, but the trace of rain(as of the 5pm climate report) was from the showers overnight Thursday. Overnight Friday we'll have a few clouds as some isolated showers fizzled out once the sun set; lows will be around 70 in Center City.
Come Saturday we will have sunshine and some fair weather cumulus popping up in the afternoon just like Friday as we reach our convective temperature(the estimated temperature that the surface must warm to in order for clouds to develop). Highs will be in the middle to upper 80s with a light southerly wind.
Sunday we'll continue the southerly wind, but the humidity will creep back up as well; highs will approach 90 as well as with a cold front swinging eastward there will also be a threat of showers and thunderstorms in the late afternoon and evening. Since the front will be very slow moving the scattered showers and thunderstorms will continue overnight into Monday with lows in the middle 70s and highs in the lower 90s. Tuesday's continued hot and humid with highs in the middle 90s, but also the storms may be strong to severe as the as the upper-level(500-millibar, or 18,000 feet) low swings on through and creates a lot of instability along with wind shear(wind direction and/or speed changing with height).
Behind that cold front we'll be under the influence of high pressure once again with unseasonably cool and dry air from Canada; highs by Wednesday will just be in the upper 70s 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!
But for now enjoy the second the half of your weekend and as always you can view my 7-day forecast(any time) at www.scottderekwx.com/forecast.html.