As snowfall begins to melt, flood dangers become concern

Weather service to assess risk as temperatures rise, chance of rain develops

The Snowstorm Of 2003

February 18, 2003|By Frank D. Roylance | Frank D. Roylance,SUN STAFF

Now that the snow has stopped falling, weather forecasters are looking ahead warily at the danger of flooding as temperatures begin to rise and rain approaches later in the week.

"Rain is a wonderful melter of snow," said National Weather Service meteorologist Michelle Margraf. "When temperatures start warming up a bit, and rain comes Friday ... we could have some river-type flooding."

The forecast called for daily highs in the mid-40s beginning tomorrow, with a chance of rain developing by Thursday night and continuing through Saturday.

With 24 to 48 inches of snow and sleet on the ground in parts of Maryland and Virginia, there is the equivalent of up to 3 1/2 inches of rain locked up in the snow cover, ready to melt, Margraf said.

`It will be high'

"Right now it doesn't look like a massive, flooding rain," she said. There should be none of the sort of flash flooding that follows huge downpours. "But in channels where water normally runs, it will be high."

Weather service hydrologists were expected to assess the risk today and issue flood watches as needed later in the week.

Public works officials in Baltimore said they would deal with potential for street flooding after they've dealt with the snow.

"The snow's being pushed to the side of the street, and that's where the storm drains are," said Kurt Kocher, spokesman for the Department of Public Works. "But it's something that we're going to send our regular storm drain crews to deal with."

Kocher said residents should do what they can to clear the storm drains on their streets to prevent a damming effect that would back up the system.

The snowmelt will help the continuing recharge of Baltimore's reservoir system in the aftermath of last year's severe drought. The reservoirs stood at 67 percent of capacity last week, still well below normal for the season.

Meteorologists were busy yesterday toting up the weekend storm's impressive statistics. The 2.4-inch snowfall that fell Saturday is not being counted as part of the larger storm Sunday and yesterday, weather officials said, because there was a long break in the snowfall. But that decision could change today after weather service officials review their data.

2nd-heaviest snowfall

More than 30 hours of snow at Baltimore-Washington International Airport on Sunday and yesterday delivered a total of 24.4 inches, according to the weather service. That makes the 2003 Presidents Day weekend storm the second-heaviest snowfall in 132 years of record-keeping in Baltimore.

The record is held by a three-day storm that dropped 26.5 inches on the city in January 1922.

There were deep snow totals elsewhere across the region. Frederick received 24 inches, and 48 inches were dumped in Garrett County, the weather service said. Thirty-seven inches fell at Berkley Springs, W.Va.; 30 inches fell in Winchester, Va.; 35 inches in Linden, Va.; and 31 inches in Keyser, W.Va.

Sunday's one-day snowfall total was 21.8 inches, setting a record for the date. It was nearly 4 inches more snow in a single day than BWI typically receives in an entire season. The 30-year seasonal norm is 18 inches.

So far this season, BWI has recorded 48.1 inches of snow. That is more than 2 1/2 times the seasonal norm. This winter ranks as the fourth snowiest in Baltimore since record keeping began in 1871, eclipsing the 47.9 inches that fell in the winter of 1933-1934.

The snowiest winter on record remains the season of 1995-1996, which ended with 62.5 inches at BWI. The runners-up remain the winters of 1963-1964 (51.8 inches); and 1898-1899 (51.1 inches).

8 inches of sleet

"What was very interesting to us was the amount of sleet accumulation that occurred, mostly south of Baltimore in Southern Maryland," Margraf said. "They got about 8 inches of sleet. I can't remember the last time I heard of 8 inches of sleet accumulating."

The snowstorm began Sunday about 3 a.m. as warm, moist air from the Gulf of Mexico, drawn north by a storm system moving eastward from the Central Plains, began to override the blanket of cold, arctic air that had settled over the Northeast.

The snow became heavy at BWI before 6 a.m. and continued throughout the day. Accumulations topped 1 inch per hour, accompanied at times by flashes of lightning and claps of thunder.

The snow changed to ice pellets late Sunday, adding weight to what had been a light, fluffy blanket of snow. Shoveling suddenly became much harder work.

But light snow resumed by 5 a.m. yesterday as the storm center reorganized off the Carolina coast and began tracking northward toward New York and New England. The snowfall became heavy again briefly after 9 a.m. before ending after 10 a.m. as the storm swirled out of the region and entered the record books.

Sun staff writer Athima Chansanchai contributed to this article.

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