In the Hot Seat, Tracking Snow's Advance
Saturday, February 11, 2006
There was no doubt the snow was coming. Meteorologist Steve Rogowski, watching the weather system unfurl on three big computer screens, predicted four to eight inches. The question for the forecasters at the local National Weather Service office yesterday was: How much more to tell you?
David Manning, the warning coordination meteorologist, suggested adding the words "blowing and drifting snow" to the forecast. But Meteorologist-in-Charge James E. Lee warned that could be too much data. Plus, coastal storms produce moist snow that doesn't blow. And the storm they had been tracking all day was 12 hours and 1,000 miles away.
Better to be succinct, Lee said: "Heavy Snow Warning."
That seemed to sum things up yesterday as the year's first significant winter storm drifted across the South and veered up the Atlantic Coast, threatening the Washington area with up to 10 inches of snow today and tonight and New York and New England with blizzard conditions.
The snow, perhaps mixed with sleet, was forecast to begin early this morning in some areas. It was expected to intensify this afternoon and evening, then taper off overnight, the weather service said.
More snow would fall east of the District -- in Southern Maryland and eastern Virginia -- with areas west of town getting less, the weather service said.
The storm, accompanied by low temperatures, marks a return to the full spectrum of winter. The government said last month was the nation's warmest January on record.
Aided by a northern flow of the jet stream, last month's average temperature was 39.5 degrees -- 8.5 degrees above the mean, according to the National Oceanic and Atmospheric Administration (NOAA).
But the jet stream brought back the cold, and the Gulf of Mexico and the Atlantic Ocean provided moisture, prompting the Washington region to lurch yesterday into storm preparation mode. Snowplows and shovels were readied, and Metro canceled track work scheduled for today and tomorrow.
At the weather service's Baltimore-Washington field office, in Sterling, a team of meteorologists worked to sift and weigh an avalanche of computer modeling data and put it into plain forecast language.
Much of the work involved comparing the output of three huge computers, nicknamed Red, White and Blue, that use mathematical models to process weather data and generate forecasts, a NOAA spokesman said.
But the models don't always agree, and the forecasters, often under intense pressure, must reach conclusions based on conflicting data. "The models vary from system to system," Lee said, "and that's part of what we do here, is analyze which model is going to work best for each particular situation."