RIVER FLOOD POTENTIAL BELOW NORMAL FOR WINTER AND EARLY SPRING THROUGHOUT EASTERN UNITED STATES
January 28, 2002 NOAA's National Weather Service forecast for flood potential remains below normal through the remainder of this winter and into early spring for the eastern United States. In fact, conditions in many areas of the East are so dry that drought conditions may be more of a concern than flooding.
The Winter/Early Spring Flood Potential Outlook is published by the Eastern Region of the National Weather Service. It states that streamflow, river ice, ground water conditions and reservoir storage are all running below normal in the East.
In some regions of the mid-Atlantic and Northeast, reservoirs are at or near record lows. December brought the third consecutive month of very dry conditions to the East Coast. The Delaware River Basin Commission declared a drought emergency in the middle of the month for the 13,539-square-mile watershed which drains portions of New York, Pennsylvania, New Jersey, and Delaware.
While this was the third driest October-to-December period for the Southeast, the Northeast experienced its second driest on record. Overall, 2001 was Maine's driest year, and the drought there has resulted in record low streamflow and well levels, with numerous wells going dry.
Contributing to the low flood potential and drought are the significant precipitation deficits throughout the East and below normal snowpack and snow water equivalents in most areas. There are a few locations of normal snow pack on the lee side of lakes Ontario and Erie which are the result of the tremendous lake effect snow in late December and another substantial snowstorm in mid-January.
Forecasters caution, however, that the lower-than-normal flood potential at this time of year does not mean that the region will entirely escape river flooding this spring or even late winter.
"It is very early in the winter-spring flood season and current conditions are only part of the ingredients to cause a flood," said Sol Summer, division chief of NOAA's National Weather Service Eastern Region Hydrologic Services. "The primary factor is heavy rains, which can result in river flooding any time of the year in the Northeast, even when overall flood potential is considered below normal."
NOAA's National Weather Service Eastern Region has issued the Winter/Early Spring Flood Potential Outlook since the massive Northeast floods of January 1996. River flood potential is gauged by analyzing numerous hydrometeorological conditions and incorporating the information into hydrologic models.
Recently, NOAA's National Weather Service began the Advanced Hydrologic Prediction Services, a new program to provide improved forecast information in assessing flood potential.
"AHPS is an invaluable forecasting tool, and has greatly increased our confidence of extended river flood forecasts," said National Weather Service Eastern Region Director Dean Gulezian.
AHPS is implemented in the Susquehanna, Lake Champlain and upper Ohio river basins. Its value was proven by the accurate forecasts issued spring 2001, which forecast near-record lake levels on Lake Champlain.
"AHPS allows us to make longer-range streamflow forecasts, predictions that we could only dream of a decade ago, by using a combination of data to create a range of future streamflow predictions," Gulezian said.
Plans are currently underway for NOAA's National Weather Service to implement the AHPS nationwide to contribute to more accurate long-range flood forecasts.
NOAA's National Weather Service is the primary source of weather data, forecasts and warnings for the United States and its territories. NOAA's National Weather Service operates the most advanced weather and flood warning and forecast system in the world, helping to protect lives and property and enhance the national economy.
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