After reaching a high of 63 on Saturday at Philly International you can kiss the mild air away until the end of next week! We have Arctic high pressure back on top of us for the next few days, but it will also help steer a potent low further south(you have to take the good with the bad); so even though temperatures will be well below the average high of 52 at least we won't have a foot of snow!
Overnight it will be clear with lows in the middle 30s with a continued northwesterly wind. between 10-15mph. Come Sunday the wind will be out of the north and highs will just be in the lower 40s. There will be increasing clouds by the late afternoon as a system from the Tennessee River Valley will push northeastward.
Temperatures at Midnight shall be in the upper 30s, but fall throughout the early morning from top to bottom; this means that we may have some sleet at the start, but as temperatures cool we will see a changeover to snow. We will also be dealing with dry air from the north acting like Pac-Man as it eats up the moisture. That's why I feel just a couple of inches shall fall with the highest amounts will be the further south you go. It's all gone by the late afternoon and then it shall make for a cold night Monday night.
Don't forget that you can check out the rest of the 7-day forecast(any time) at www.scottderekwx.com/forecast.html.