1:45 PM | ****Accumulating snow threat increases for Saturday following likely record-breaking cold on Friday morning****

gfs_18z_sat[12Z GFS forecast map for early Saturday afternoon (blue=snow); map courtesy "tropicaltidbits.com"]

Discussion

The Friday morning extreme cold The coldest air mass of the season is flowing into the region today on strong NW winds and low temperatures by early Friday could very well be in record territory up and down the I-95 corridor. Sub-zero lows are possible early Friday; especially, in the normally colder suburban locations of the big cities along the I-95 corridor. The record low for Friday at Philly International Airport is 1 degree above zero and that daily record is in jeopardy. The record at Reagan National Airport in Washington, DC seems to be an easy one to reach at 8 degrees (above zero) which has amazingly held since 1896 (when temperatures were measured downtown at 24th and M St.). Not only are record low temperatures quite possible tomorrow morning in the I-95 corridor, but it could turn out to be the most extreme cold in this area since January 1994. That winter (1993-1994) featured numerous severe ice storms in the Mid-Atlantic region and there was one incredible cold air outbreak during the second half of the month that followed significant accumulations of ice and snow. If DC manages to set a record low on Friday, it will be the first time it has done so in any winter month since 1994 (source: Washington Post/Capital Weather Gang).

The Saturday snow threat A large area of moisture is headed our way this weekend and it looks like it will arrive during the day on Saturday in the form of snow and accumulations are quite possible. Eventually, advancing warmer air will likely cause a changeover of the snow to sleet and/or freezing rain and perhaps even to plain rain in parts of the I-95 corridor. However, before the snow changes to sleet and/or freezing rain, it is possible for snow accumulations to occur in much of the region from DC-to-Philly-to-NYC on the order of a few-to-several inches. The snow should arrive in the DC metro region during the morning, mid-day-to-early afternoon in Philly, and by late afternoon in the NYC metro region. There will likely be a period of icing late Saturday or Saturday night - at least in DC and Philly - before any possible changeover to plain rain ever takes place (NYC could stay as all snow). The milder conditions on Sunday will quickly be followed by another Arctic blast by early next week and more accumulating snow may threaten the Mid-Atlantic region by the middle of next week.

Stay tuned on the weekend precipitation event – a complex forecast.