“Accumulating Snow” Expected Overnight into Sunday

March 25, 2011

Central Maryland could see “accumulating snow” early Sunday as a low-pressure system moves out of the Gulf Coast states into the southern Appalachians. There’s even an outside possibility suggested by some forecast models that Southern Maryland could see as much as 4 inches. But forecasters say that outcome “seems unlikely.”

This wintry weather in early spring comes as Washington, D.C. prepares for its annual cherry blossom festival, and trees across the region begin to bud and bloom. Willows, forsythia, bulbs are showing some color, and many other species seem ready to burst, Tellingly, tree pollen counts are also up.

The problem seems to be a stubborn high-pressure system over Quebec that keeps sending cold air south into the eastern states. It was 24 on the WeatherDeck in Cockeysville this morning.

Add a series of disturbances traveling along the jet stream at the southern edge of the cold air, and you get repeated bouts of cold rain and the occasional snowflake.  And it’s not going away quickly. Here’s AccuWeather.com’s take.

Snow flurries could mix with sprinkles as soon as tonight, forecasters said, as a disturbance in the Central Plains states begins to move east. Sunny skies Friday morning will begin to cloud up, and winds will shift to the northeast as the low gets closer. There’s a 30 percent chance we could see rain or snow showers before 10 Friday evening, forecasters said. Western suburbs and the higher elevations to our west could see a dusting.

The main event comes late Saturday into Sunday. After some clearing behind tonight’s precipitation, forecasters expect temperatures by Saturday morning will drop into the mid-20s north and west of the urban corridor, with lows near freezing in the cities.

Saturday should be dry and partly sunny, but the next disturbance moves out of the Gulf states into the southern Appalachians Saturday night into Sunday. That will turn winds back to the northeast, adding relatively warm, moist air on top of the cold air at the surface – the recipe for snow in the winter months.

Accumulating snow is expected Saturday night and Sunday,” forecasters said. The forecast for Baltimore calls for snow to begin after 2 a.m. Sunday, continuing Sunday morning before changing to rain after 2 p.m. The overnight lows are expected top be in the upper 20s, recovering to a high of only 37 on Sunday. That’s 20 degrees below the average for this time of year in Baltimore.

The most moisture will be to the south of Baltimore, but the coldest air will be to the north, making it difficult for forecasters to predict accumulations with any confidence.

Eric the Red, a professional meteorologist in Baltimore, parsed it this way on Thursday. He said several models predict “decent” snowfall in central and northern Maryland – 2 to 4 inches on grassy surfaces. Others put the same snow across northern Virginia and Central Maryland.

I’m inclined to think that much of the region will see 1 to 3 inches of snow, with the lighter amounts in far northern Maryland” he said. “The heaviest precipitation at this juncture appears to be aimed ay northern Virginia. This snow – if it materializes – will not impact traffic, and I don’t think you need to worry about shoveling it.”

It won’t be hard to break a record. The heaviest snowfall on record for Baltimore on a March 27 was the 0.4 inch that fell in 1924.

The unseasonably cold weather is likely to moderate slowly as the new week begins. Sunshine returns with high pressure Monday, and highs are forecast to reach the mid-50s – near normal – by Wednesday. More precipitation is possible on Tuesday night, but it’s expected to fall as rain showers.

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