The day started off with an overcast sky and there were light rain showers to the west so many didn't think we'd reach the middle and upper 60s this afternoon; I was hopeful last night thinking that we would have breaks in the clouds and we'd get close, but I didn't expect to have a mostly sunny day overall!
The official high at Philly International Airport this afternoon was 67(set at 3:58pm) which is now the new record high for December 21st! Mind you the old record was 66 set in 1895 and if that trend were to continue we would not see the record challenged again until 2131(wishful thinking!). Either way it's not too shabby for the first day of winter(although we meteorologists prefer full months for seasons; with that in mind we are almost through the first month on Meteorological winter).
High clouds were seen just before sunset pushing in from the west and more clouds throughout the lower levels will move in overnight with lows around the middle 50s(and that's still warmer than our average high of 43!). Since we will start the day mild the only way to go is up; we shall get to 70 or better despite an overcast sky as rain will hold off until the afternoon. Mind you the record high for Sunday is 64 set back in 1998 and that should easily fall. As for rainfall amounts the heaviest rain should fall AFTER the Eagles/Bears game is over and then the heaviest rainfall will occur for the Monday morning commute(resulting in the potential for an inch or more). If you truly want a football weather timeline here it is:
4pm(tailgating): 69, mostly cloudy
8:30pm(kickoff): 64, few showers
Halftime: 62, fog, on-and-off showers, mist
End of game: 61, rain
You may have noticed that temperatures won't drop off much overnight; that is because we still will have mild air on top of us and enough cloud cover to prevent the air from the day to escape back into the atmosphere(we call that radiational cooling). This sets up Monday being filled with some potentially heavy rain in the morning during the AM commute, but then push east as the cold front finally comes through in the afternoon(and drags the moisture with it). As for high temperatures we will start off mild into the lower 60s, but slowly drop throughout the day and getting down toward the upper 20s by nightfall as colder air filters in from the north.
This sets up for a dry(albeit cold) Christmas Eve with a few clouds to the north as a weak system passes by, but behind that another reinforcing shot of cold air only allows temperatures on Christmas Day to warm to the middle 30s. I'll keep you posted if there's any changes, but you can check the forecast any time of day at www.scottderekwx.com/forecast.html.