Contact: Solomon Summer For Immediate Release
1/22/97
The major flooding experienced last year following the Blizzard of 1996 is not likely to occur in the northeastern United States this year, according to Flood Potential Outlook statements issued by National Weather Service field offices.
Current flood potential conditions are in sharp contrast to one year ago when the mid-Atlantic experienced widespread major flooding due to excessive snowmelt, heavy rain, and ice jams that caused 32 deaths and more than $2 billion in damage.
Present forecasts and outlooks do not indicate the formation of any significant weather events that will change the flood potential, the weather service said. In addition, heavy snowpacks with the ability to cause major flooding do not exist.
The flood potential outlook is valid until the end of the month with the next flood potential statements to be issued from National Weather Service Eastern Region offices on Friday, Jan. 31, 1997.
According to Solomon Summer, National Weather Service Regional Hydrologist, much above normal precipitation during the past autumn has resulted in above average soil moisture conditions throughout the Susquehanna River basin, the middle/lower Delaware River basin, New Jersey, Delaware, northeast Maryland, and New England. However, with low snowfall totals and below average streamflow, the potential for flooding at this time is average.
"Current conditions are in sharp contrast to a year ago when an exceptionally deep snowpack highlighted by the Blizzard of 1996 set the stage for historic floods," Summer said. "The catalyst for last year's flood event was the very warm, windy and wet weather system that moved into the Susquehanna River basin in mid-January."
The flood potential for the Ohio basin is also normal and although the soils in the Ohio River valley have been wet since the fall, snowpack and snow water equivalent are low. These combined factors make the flood potential normal for this time of year, the regional hydrologist noted.
In New York and New England, the potential for snowmelt flooding is below normal. Snowfall in New England and New York State, except near the Great Lakes, differs from last year not by inches, but by feet. Many areas in New England are without any substantial snowpack and little snow water equivalent.
In the local areas downstream of the Great Lakes, lake effect snows have dropped heavy amounts on localized areas east of Lake Ontario and significant amounts across Buffalo and across the southern tier of New York. In western New York, the snow water equivalent is below normal in the Allegheny and Genesee basins to near normal in the Buffalo area and Black River basins.
Ice-covered rivers and streams will also be on the increase in New England, northern Ohio and northwest Pennsylvania. Ice jam conditions should be monitored closely, as ice jams and ice jam breakups historically cause flooding in the same locations along rivers.
In the southeast, moderate rain events over the past week have caused minor rises on rivers within the Pee Dee River basin. Specifically, the Lumber River is flowing full and the forecast points are just above flood stage. This trend is expected to continue as most flooding in the coastal plain in the southeast is driven by rainfall and runoff. In the Piedmont of the Carolinas, the flood potential is below normal as both snowfall totals and streamflow are below normal for this time of year.
With respect to water supply, no shortages are expected during the upcoming spring or early summer assuming near normal precipitation during the next several months. Ground water levels are generally above average, and water supply reservoirs are normal in most areas. The New York City Reservoir system is at 98.9 percent capacity, which is above average, while most reservoirs in central and northern New England are at normal capacity for this time of year.
The flood outlook estimates the potential for flooding across the eastern United States based on a current assessment of hydrometeorological factors that contribute to flooding. It should be recognized that heavy rainfall is the primary factor that leads to flooding and heavy or excessive rainfall can rapidly cause flooding in any month of the year, even when the flood potential is considered below average. Other factors that contribute to the potential for flooding include recent precipitation, soil moisture, snow cover, river ice conditions, streamflow and forecasted precipitation.