Updated thoughts from Tate at WPC...
Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
216 PM EST Mon Jan 17 2022
Valid 12Z Thu Jan 20 2022 - 12Z Mon Jan 24 2022
...Snow/ice are possible along the Eastern Seaboard late this week
and weekend on the eastern periphery of an Arctic high...
...The 00Z and incoming 12Z ECMWF are generally on the western side of the model spread with these features, leading to more precipitation over the Eastern Seaboard, while the GFS runs have been suppressed farther east into the Atlantic. The 00Z cluster analysis and ensemble member low plots showed that the GEFS and EC ensembles followed their operational runs, with GEFS members farther east than EC ensemble members. Tended to favor a position for the surface low near the 00Z EC ensemble mean as somewhat of a compromise, which was not too far off from the 00Z CMC position, but the 12Z CMC is now showing a more suppressed pattern. This forecast approach led to a trend west of the previous WPC forecast with the surface low and frontal placement, but not nearly to the western extent of the ECMWF runs.
...On the southern and eastern periphery of this high, moist air spilling into the cold air could lead to wintry weather on the northern periphery of precipitation spreading across the Gulf Coast states and then possibly up the Eastern Seaboard. Once again, uncertainty with the evolution of shortwaves and surface lows leads to low confidence in placement of wintry precipitation and precipitation type in some locations at this time, but the current forecast shows the potential for notable snow, sleet, and freezing rain particularly in the Carolinas and southern portions of the Mid-Atlantic for the latter part of the week, with some chance of spreading into the Northeast this weekend.
Tate