Thursday 11:10 AM | *First accumulating snow of the season in the I-95 corridor comes late Friday night/Saturday…colder air for the weekend…even colder next week with another snow threat*

12Z GFS forecast map for early Saturday afternoon with snow (in blue) in the I-95 corridor; map courtesy NOAA/EMC, tropicaltidbits.com

Overview
Now that the (sustained) colder pattern has set up in the Mid-Atlantic region, it is time to focus on the threat for snow and indeed there are multiple chances over the next several days.  The first legitimate chance for accumulating snow in the immediate I-95 corridor will come late Friday night and Saturday as low pressure pushes from the Southeast US to a position off the Mid-Atlantic coastline.  A second shot will come Saturday night/early Sunday as deep upper-level low passes by just to our north.  Finally, as a significant cold air outbreak arrives late Tuesday into early Wednesday, low pressure may try to form over the Northeast US and it could generate some snow for parts of the Mid-Atlantic.  Following the passage of that low pressure system and its associated strong cold front, very cold air will flood into the region at mid-week.

12Z GFS total snowfall forecast map by early Sunday; courtesy NOAA/EMC, tropicaltidbits.com

Discussion
Low pressure will pull out of the Southeast US early Saturday and move to a position off the Mid-Atlantic coastline by later in the day.  The big cities from DC-to-Philly-to-DC will be on the western edge of its precipitation shield, but there is a decent chance for some snow in the immediate I-95 corridor.  In fact, small accumulations of up to a couple of inches are not out of the question in the immediate I-95 corridor and in areas just to the east of Route 95 (from southeast Virginia-to-Delmarva Peninsula-to-New Jersey coastline).  Once this surface low pressure system passes by, we’ll see the upper-level low passby just to the north on Saturday night and early Sunday and it could generate snow showers in the Mid-Atlantic region – perhaps even a heavier snow squall.

Another significant cold air out break will arrive in the Mid-Atlantic region late Tuesday and it will be accompanied by strong energy in the upper atmosphere.  This setup could very well result in the formation of surface low pressure in the Northeast US and perhaps some snow in parts of the Mid-Atlantic. Very cold air pours into the region on Wednesday following the passage of this system and highs at midweek will struggle to pass the freezing mark.

Stay tuned.

Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com