Storm shifts to Tues. P.M.; 5 inches or less due
Snow chances for Tuesday in Central Maryland have now reached 100 percent, and forecasters at the National Weather Service have issued a Winter Storm Watch for Central and Southern Maryland, as well as much of the Eastern Shore.
UPDATE: 3 p.m.: The latest Winter Storm Watch out of Sterling has the snow starting in the late afternoon or early evening Tuesday. No problem for the morning rush. And light snow in the evening may spare us a really bad commute home. Earlier post resumes below.
The Watch means snow accumulations of 5 inches or more are possible within 12 hours as the snow falls, but most areas would likely see less. The snow totals will fall off sharply from east to west. Carroll and Howard counties are at the western edge of the Watch area.
A lesser Hazardous Weather Outlook statement has been issued for the western counties to Allegany, calling for "accumulating snow." Garrett County is under a Winter Storm Watch calling for 6 inches or more.
Forecasters at the Baltimore-Washington forecast office in Sterling, Va., say they expect the snow to begin falling at BWI-Marshall airport a bit later than previously stated - around mid-day Tuesday or during the early afternoon. It is likely to continue through Tuesday night.
Daytime highs during the storm will be in the low 30s. The precipitation is expected to be all snow in the Baltimore region, but could become mixed with sleet in Charles, Calvert and St. Mary's counties in Southern Maryland. The Lower Shore should expect a mix of rain, sleet and snow, with little or no accumulation, forecasters said.
The snow comes as two storm systems approach the region. The largest system is hitting much of the South today with snow, ice and rain. It is expected to move east and emerge off the Carolina coast tonight. That one will be sending increasing moisture into the region from the Gulf and from the Atlantic.
The second low is approaching from the Great Plains, with the center passing to our north on Tuesday, putting Central Maryland in between the two systems.
AccuWeather.com says the twin storms will merge to our northeast and hit New England especially hard after whitening the mid-Atlantic corridor:
"Plenty of cold air will remain in place to support snowfall along much of the heavily populated I-95 corridor in the Northeast, while some mixing, including treacherous ice will occur farther south through the mid-Atlantic Coast. This means that heavy snowfall with amounts of up to a foot could slam a corridor from perhaps as far south as New York City and northern New Jersey to Boston and eastern Maine."
"Philadelphia also looks like it is line for plowable snow that will disrupt travel, while the Baltimore-Washington, D.C. corridor may only get a couple of inches of snow from the storm. It should be noted that the storm track is still not set in stone. A wobble in the storm's track by only 50 miles can make a major difference in snow totals for the big Northeast cities."
The map at right shows the snow cover for the continent on Sunday. You can see the new snow in Oklahoma, Arkansas and Mississippi from the developing southern storm.
Eric the Red, a professional meteorologist in Baltimore, has chimed in with this:
"Early morning data has the phasing occurring just in the nick of time to give the region 2-4" ... with the heavier snow across northeast MD. The WRF/NAM [models] has the snow arriving in DC about 4-7 p.m. on Tues., and shortly after 7 [p.m.] in Baltimore. This would be ideal, giving everyone a chance to get home.
"The WRF also has a quick burst of moderate to perhaps even heavy snow during the late evening hours, and then cuts the [precipitation] off abruptly between 1 and 4 am Weds morning.
"Still have other model data to come in, but the early guidance supports 1-3" south and west of Baltimore (even in DC) ... while 2-4" from Baltimore and points north and east."