Meteorologists Develop Ways to Predict Floods
Jan. 17, 2001 — -- Tom Cunningham of Hyndman, Pa., remembers what January rains can do.
Five years ago winter rainfall melted snow that had wrapped the nearby Appalachian Mountains. The snowmelt cascaded off the mountains and burst the banks of the local Will's Creek which then flooded the town.
"Three-quarters of the town was underwater," remembers Cunningham, who was mayor of Hyndman at the time. When he drove to work that day, Jan. 19, 1996, Cunningham recalls "a wall of water came up over the hood of my car and swept over the whole road."
Now forecasters at the National Weather Service warn residents in the Northeast should be alert for another season of possible winter flooding. For the first time in three years, fairly heavy snowfall and below-normal temperatures in the past two months have made waterside communities in the northeast vulnerable to sudden and severe flooding.
And since predicting rain is key for predicting floods, many meteorologists are working on finding new ways to search the skies for moisture so residents like Cunningham might have more warning in the future.
"We're putting up a red flag," says Bob Chartuk of the National Weather Service in New York. "What we need to watch for now is a catalyst of heavy rain."
How can snow and cold lead to floods?
The equation goes like this: After the "Millennium" Nor'Easter that swept up the northeast coast in late December, large masses of snow remain in many states, particularly in mountainous regions. Meanwhile, a cold trend that has gripped the same region for the past two months has frozen much of the ground and choked up rivers and streams with large chunks of ice.
Melt that snow with rain and it has nowhere to go since the waterways are stopped up by ice and frozen ground makes a poor sponge.
"A dry earth absorbs water well," says Chartuk. "But a wet, soggy Earth won't and a frozen Earth won't absorb anything."
With conditions ripe for a flood, forecasters are keeping a close watch for rain. Chartuk says the weather service is well-equipped to predict wet weather after recently completing a $4.5 billion modernization effort that added new tools including 123 new weather radar systems, 800 automated observing systems and rows and rows of sleek new, powerful computers designed to crunch weather data from multiple sources.
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