WET NORTHEAST SUMMER INCREASES HURRICANE FLOOD THREAT
August 24, 2000 With much of the Northeast still soggy from an unusually wet summer, NOAA's National Weather Service is wary of the increased threat of flooding from hurricanes and tropical storms. (Click image for larger view. Note: this is a large file.)
"The earth's ability to absorb heavy rain has certainly been limited by the unusually wet summer we've had so far here in the Northeast," said Sol Summer, hydrology chief for the NWS Eastern Region. "The wet conditions would make flooding from a hurricane or tropical storm that much worse."
According to the hydrologist, the ability of soil to absorb additional moisture, and the higher levels of rivers, lakes, and streams, are key factors in the increased flood potential this hurricane season. Cooler temperatures and increased cloud cover are also affecting local conditions this season as evaporation has been slowed and more water is staying on the ground.
"Last year, we were looking at drought conditions and many areas were actually hoping for a dose of tropical moisture," the hydrologist explained. "This year, with so much water around, it would be difficult to absorb a heavy rain which could result in flash floods and river floods," Summer said.
"And keep in mind, extensive flooding from Hurricane Floyd last year occurred when the region was experiencing drought conditions," Summer added. "If a storm similar to Hurricane Floyd were to make landfall now, you would see not only localized flooding and flash flooding, but many of the main stem rivers could overflow their banks as well."
Much of the northeast from New England south through southern New York, Pennsylvania, and New Jersey have above average soil moisture, while parts of Maryland, Delaware, Virginia, and West Virginia are slightly wetter than normal. These areas are in stark contrast to the south, the west, and parts of the Midwestern U.S., which are still grappling with abnormally dry conditions, the Weather Service said.
Example's of the wet conditions can be found throughout the northeast: New Jersey's Lake Hopatcong, for instance, was at its highest level since record keeping began 114 years ago breaking the previous record set during Hurricane Diane in 1955.
The Delaware River at Trenton, N.J., is flowing at a rate 250 percent above normal for this time of the year and the Passaic River at Little Falls, N.J. is at 90 percent higher than normal. Streamflow at Montague, N.Y. on the upper Delaware River is 237% of normal and the Susquehanna River is 169 percent of normal at Wilkes-Barre, Pa.
More telling is the state of the region's water supply, noted George McKillop, NWS Service Hydrologist for New York and New Jersey. The northeast New Jersey reservoir system is holding an estimated 76 billion gallons of water, which is about 94 percent of capacity. "The reservoir system is holding about 20.5 billion gallons, or 20 percent, more than last year right before Hurricane Floyd hit," McKillop noted. The New York City reservoir system is at 96 percent of capacity, which is 12 percent above normal for this time of the year.
"The lingering effects of La Niña are the culprit in this situation," said Ants Leetmaa, director of the NOAA's Climate Prediction Center in Camp Springs, Md. "La Niña first brought persistent wet and cool weather conditions to the Northeast leading to soggy conditions and now is expected to possibly bring enhanced rainfall through an above normal tropical storm outlook for this hurricane season."
The Weather Service cautioned that freshwater flooding from tropical rain can occur hundreds of miles inland and can be as dangerous as the storm surge normally associated with hurricanes as they come ashore.
"With flooding one of
the leading causes of weather related deaths in the United States,
coastal residentsand those living well inlandshould
always be wary of rising waters," Summer said. "Particular
caution should be taken while driving in flooded areas since
more than half of the country's flood related deaths take place