12:40 PM | *Accumulating snow a threat for late Saturday as well as ice and rain*

Preliminary snowfall estimates by the 12Z GEFS for the weekend system; map courtesy NOAA/EMC, Weather Bell Analytics (Joe Bastardi)

Overview
Even in an overall mild weather pattern, there can be some accumulating snow if the timing is just right between low pressure systems and the usually brief cold air outbreaks that can still take place.  We are currently experiencing a mild weather pattern here in the Mid-Atlantic region with 70 degrees possible tomorrow afternoon in parts of the I-95 corridor and there will be another significant warm up in the early-to-middle part of next week, but there is also a shot at some accumulating snow this weekend.  A strong cold front will usher in much colder air by the weekend and low pressure will pull out of the southern states on Saturday and head towards the Mid-Atlantic coastline threatening us with accumulating snow as well as ice and rain.   

12Z GFS forecast map for early Saturday afternoon with high pressure pushing off the coast and precipitation closing in from our southwest; (snow in blue, rain in green, ice in pink/purple); map courtesy NOAA/EMC, tropicaltidbits.com

Details
A warm front will pass through the region in the overnight hours and likely result in some shower activity for DC, Philly and NYC and there can also be some patchy fog.  After some lingering early morning light rain or drizzle on Thursday, temperatures will soar to 70+ degrees in DC, and well into the 60’s in the Philly and NYC metro regions and much of the day should turn out to be rain-free. This warm up, however, will be rather short-lived as a strong cold front arrives on Friday with additional rainfall on Thursday night and Friday and then much colder air will push in by the beginning of the weekend.

12Z GFS forecast map for late Saturday night with low pressure centered off the Mid-Atlantic coastline (snow in blue, rain in green, ice in pink/purple); map courtesy NOAA/EMC, tropicaltidbits.com

On Saturday, cold high pressure will start the day to our north and low pressure will begin to pull out of the southern states and head towards the Mid-Atlantic coastline.  This high pressure system will push off the coast by late Saturday and precipitation will head in this direction from the southwest-to-northeast.  With the high pressure system pushing off the coastline, the cold air in place early in the day is likely to begin a slow retreat to the north as the precipitation arrives in the DC-to-Philly-to-NYC corridor late on Saturday and this is, of course, not favorable for a long-lasting snow event.  On the other hand, the likely storm track for the weekend system will be one that sees the low pressure push off the Mid-Atlantic and well to the east of the major cities and this is quite a favorable track for snow in DC, Philly and NYC as cold air would tend to hang around longer.  The precipitation will likely be in the form of snow at the onset; especially, in areas north of the PA/MD border, but a changeover to ice and rain is possible later on during this event in at least parts of the I-95 corridor.  

The trend in the European computer forecast model during the last 24 hours has been slightly colder in the I-95 corridor and more "juiced up" with the weekend system (12Z Tues Euro left; 12Z Wed Euro right - verification time for both forecast maps is late Saturday night); maps courtesy WSI, Inc.

There can be some accumulations of snow in the I-95 corridor before any potential changeover – at least on the order of a few inches – but these are very preliminary estimates and they will have to be fined-tuned over the next few days.  In general, it appears that the best chance for accumulating snow will be north and west of the big cities with lesser chances to the south and east.  One ominous sign that points to more in the way of snowfall is the fact that the European model has trended colder in the past 24 hours and a bit more "juiced up" with the system - if this trend continues, more significant snow accumulations would be on the table in the I-95 corridor.  The low pressure system will be a rather fast-mover and precipitation should be out of here for most of Sunday and then another big warm up is likely to take place in the early and middle parts of next week with 70+ degrees possible in what is still an on-going overall mild weather pattern for the Mid-Atlantic region.

Pitchers and catchers report this week...spring can't be far behind.

Stay tuned, many details need to be ironed out and there is some good news...pitchers and catchers are reporting this week.

Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com 

Morning video discussion on the weekend system: