We reached a high of 60 degrees at Philly International Airport at 6:17am before a squall line of showers pushed through along with a cold front; there was 0.35" of rain that fell, but as colder air filtered in there was some sleet and even some wet snow flakes as well(officially recorded at the airport as a trace)! How many times in your life can you say that it was 60 AND snowed in the same day?
Now that's all a distant memory and now we have very cold air on top of us; you may have heard on TV or on social media about a "Polar Vortex".....
Now what exactly is the Polar Vortex? It's just the lowest geopotential heights found in the upper levels of the atmosphere(a geopotential height is the actual height of a pressure surface above mean sea-level); since colder air is denser than warm air it essentially takes up more "space" in the atmosphere. Guess what? It's nothing new at all, BUT it's very rare that a piece of the polar vortex branches south across the United States. A good read(with an image of a 500mb geopotential height map as well) can be found here: a http://www.theweatherprediction.com/habyhints/327/
With this cold air on us there are chances for record lows these next couple of nights; the record lows for Philly Int'l is as follows:
1/6: 4 (1896)
1/7: 7 (1988)
1/8: 2 (1970)
I don't feel that we'd achieve a record low Monday night as the cold air is still settling in AND there's enough of a wind to prevent all of the "mild" air from today to fully escape back into the atmosphere; Tuesday night into Wednesday morning would be the best shot to break a record with lows in the middle and upper single digits.
For other local areas here's some record lows possible(all obtained from the National Weather Service in Mount Holly NJ and Upton NY):
Atlantic City Int'l(Pomona): 1/6: 4(1981), 1/7: 4(1884), 1/8: 2(1981)
Trenton: 1/6:5(1904), 1/7: 6(1912), 1/8: -12(1866)
Wilmington, DE: 1/6: 7(1942), 1/7: 10(1988), 1/8: 0(1970)
Newark Liberty Int'l Airport: 1/7: 10(1996)
Central Park: 1/7: 6(1896)
La Guardia Airport: 1/7: 11(1968)
JFK Airport, NY: 1/7: 8(1968)
After a cold start Tuesday morning the afternoon won't be that much warmer with highs in the lower and middle teens! Factor in a northwest wind between 20-25mph with gusts over 40mph and you're easily talking about wind chills between -10 to -15(that's 10-15 degrees BELOW zero!). This is why the entire region is under a Wind Chill Advisory from Midnight until 5pm.
We'll have another cold night Tuesday night with lows in the upper single digits to lower teens and Wednesday will still be cold with lows below the freezing mark. Now once high pressure shifts a bit to the east we will get a more southerly flow as highs will get into the lower 40s on Thursday with a little impulse coming through at night; right now there can be some wet snowflakes Thursday night into Friday with lows around freezing, but I would wait and see EXACTLY how warm we get on Thursday before I'd lock in that idea. Friday will be in the middle 40s after the weak piece of energy pushes away and then for the weekend we can get in the 50s before a cold front comes through and provides some rain Saturday night into Sunday.
The rest of the seven day can be seen any time at www.scottderekwx.com/forecast.html.