New NWS snow estimates: 16 to 24 inches
Wax down those shovels, Maryland, there's snow on the way. The National Weather Service has posted Winter Storm Warnings for everybody from the Chesapeake west to Allegany County. The warnings call for 16 to 24 inches of snow for the Baltimore area.
UPDATE: Blizzard Warnings have been posted for central and southern Delaware and southeastern New Jersey. The Winter Storm Warnings in Maryland have been extended to the Lower Eastern Shore, where six inches or more are expected.
UPDATED UPDATE: The snow estimates for Central Maryland have been bumped to 18 to 24 inches.
The first flakes are expected sometime Friday morning, (by early afternoon in Baltimore), and they're likely to continue through Friday night, all day Saturday and into Saturday evening. I suspect, if the forecast holds up, this timing will discourage school officials about opening their doors at all on Friday. No point in bringing everybody in only to send them home in a storm.
The snow chances are about as high as they get - 100 percent for Friday and Friday night, slipping to 90 percent (UPDATE: now 100 percent) on Saturday. Temperatures at BWI should be near freezing for the duration of the storm, in the upper 20s and low 30s. Here's some of the Winter Storm Warning, just to give you the flavor of the thing:
"CONDITIONS WILL DETERIORATE RAPIDLY
FRIDAY AFTERNOON...WITH HEAVIEST SNOWFALL OCCURRING BETWEEN
SUNSET FRIDAY TO SUNRISE SATURDAY. THE MOST HAZARDOUS WINTER
WEATHER CONDITIONS WILL OCCUR FRIDAY NIGHT...WHEN THE
COMBINATION OF HEAVY SNOW AND STRONG WINDS WILL REDUCE
VISIBILITIES TO BELOW ONE-QUARTER MILE...PRODUCING NEAR-BLIZZARD
If the forecasters at Sterling are right, this snow will rival the 21-inch storm that struck just before Christmas. Although we have had more snow in a single season before, neither Sterling nor I could find any examples of two 20-plus inch snowstorms striking Baltimore in a single winter season since they started keeping snow records here in 1883.
There are actually two storm systems cranking up and headed our way - one is gathering strength and plenty of Gulf moisture today across the Gulf Coast states. The second is moving out of the Northern Rockies; it is expected to drop its snow here on Saturday, on top of whatever the Gulf system delivers.
The Gulf system is forecast to move east and become the latest in a series of coastal storms that have punctuated our weather since autumn. It's expected to intensify over the ocean on Friday, and pump lots of Gulf and Atlantic moisture into the cold air that will be settling over our region. That's the recipe for heavy snow.
That storm, another low over southeastern Canada and a high to our north will combine to draw more cold air south into the region, keeping the snow machine spinning for us. Exceptions may include extreme Southern Maryland and Central Virginia, where warmer air moving in with the maritime moisture may produce a wintry mix.
Forecasters say the heaviest precipitation is likely to occur late Friday afternoon through Friday night, with several inches on the ground by the Friday evening commute.
Elsewhere, AccuWeather.com is calling the event "paralyzing" for our region, with the potential for as much as two feet of snow in some locations. Adding insult to injury, AccuWeather.com is now touting another snowstorm on Tuesday. Let's not go there yet.
Mr. Foot's forecast team is predicting "an historic and extremely heavy wet snowfall" for our region Friday and Saturday. Mr. Foot spins out two possible scenarios, depending on how much mixing there is and when it all begins. One scenario would bring us 12 to 18 inches, the other 18 to 26 inches. Which one gets your vote?
For the geekier among us, there is the U.S. Hydrometeorlogical Prediction Center's discussion, which includes such highly technical terms as, "prolific accumulations," and "incredible amount of Gulf and Atlantic moisture..."
And after the snow? Expect skies to clear by Sunday, with highs near freezing and overnight lows Saturday and Sunday nights in the teens as the new week begins. This new snow will not go away as rapidly as Tuesday night's did.
(MANDEL NGAN/AFP/Getty Images/December snow in Chevy Chase)