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USNA News Center

Winter Storm Likely Sunday Through Early Tuesday; Winter Storm Warning Issued

  POSTED ON: Saturday, January 30, 2021 4:31 PM by METEOROLOGIST A.R. DAVIES

Overview:

A “Type B” winter storm impact Maryland Sunday through Tuesday. These type of systems are characterized by an “initial” storm approaching from the west before transferring energy offshore to a rapidly developing coastal Low. Plowable snow is likely in Annapolis on Sunday with 4.0 to 6.0 inches anticipated. Additional snow/mix is likely on Monday/Tuesday, but it remains unclear how the storm will develop off the Mid-Atlantic coast and impact snow/sleet totals.

The National Weather Service (NWS) has issued a Winter Storm Warning from 0400 on Sunday through 0600 on Tuesday. Here is a link to the NWS Baltimore/Washington Winter Weather Forecast page: www.weather.gov/lwx/winter

Details:

An initial area of Low pressure will approach on Sunday with snow overspreading Central Maryland by late morning (between 0800 and 1100). Snow will likely continue at a light/steady rate throughout the afternoon and early evening. The initial Low will gradually weaken and shift energy to a rapidly developing offshore Low Sunday evening/Monday. As this happens, warmer and drier air will work into the area. As a result, the snow will likely mix with sleet/freezing rain between 1800 and 2000 on Sunday before gradually mixing to rain sometime after 2000. Widespread snow/sleet accumulation between 4.0 and 6.0 inches is likely on Sunday (see Snow/Sleet Forecast Map for Jan. 31 below) with up to 0.1” of freezing rain early Sunday evening. Confidence in the forecast for Sunday is fairly high with only a 15% chance of <4.0 inches of snow in Annapolis and a 10% chance of >6.0 inches. Temperatures are expected to remain at or below freezing in Annapolis through early evening on Sunday, before gradually rising just above freezing in the late evening and overnight. Colder air is expected to holder longer to the north and west.

20210130_a

As the coastal Low develops Sunday night/Monday morning, a light mix of snow, sleet, freezing rain, and/or rain is likely to continue through midday on Monday. In fact, precipitation could be reduced to passing showers (wintry mix) if drier air wraps into the system. Temperatures will likely be hovering in the low- to mid-30s in Annapolis on Monday morning (likely colder north of I-95).

The big question on how the coastal Low develops on Monday remains a bit of a mystery. Model guidance over the last 24 hours has suggested that the coastal Low will linger just off the Mid-Atlantic coast on Monday, fueled by a deepening mid-level atmospheric trough across the U.S. Southeast coast. If this validates, it would mean two important things for Central Maryland:

  1. Precipitation would likely linger through the day on Monday, before intensifying for a period of time (duration still unresolved) Monday afternoon and evening;
  2. Winds out of the north will pull colder air back into the area.

As a result, additional snowfall accumulation is likely on Monday afternoon and evening (perhaps even overnight, depending on how long the coastal Low remains in the area). There is significant uncertainty still in the forecast for Monday. However, at this time it looks like 2.0 to 4.0 inches of additional snow/sleet accumulation is possible in Annapolis on Monday (see Snow/Sleet Forecast Map for Feb. 01-02 below). Uncertainty is high with a 25% chance of <2.0 inches and 25% chance of >4.0 inches. Higher snowfall totals are likely north of Baltimore.

20210130_b

Another significant concern is the wind as gusts could approach 30 mph Sunday night and Monday as the coastal Low develops. Surface air temperatures should drop back close to freezing in Annapolis Monday afternoon/evening. Another update will be posted on Sunday.

ISSUED: 30 January 2021 at 1630
FORECASTER: Meteorologist A.R. Davies


Category: Press Releases, General Interest

Press Contact

Alexander R. Davies
Meteorologist & Oceanographer
Oceanography Department, USNA
  adavies@usna.edu
  410-293-6565