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1
Historic Spring FloodingOhio River Valley and Mississippi River
Ernie WellsHydrologic Services Division
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Snow Water Equivalent
Substantial stored water in the snow pack represents significant flooding potential in the North Central and Northeast as the spring thaw begins
March 18, 2011
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National Hydrologic Assessment Spring 2011 – Issued March 17, 2011
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River ObservationsMay 3
Observations of major to record crest levels in the Ohio River Valley along the Mississippi River
http://water.weather.gov
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Observed PrecipitationApril 18, 2011 – May 2, 2011
During the previous 2 weeks, a broad area of Central US received 10-20+ inches of precipitation; 600% of normal precipitation
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Forecasted PrecipitationMay 2, 2011 – May 7, 2011
During the next 5 days, a broad area of Central US received 0.5 - 2 inches additional rain (much has already fallen)
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Extended Range Forecasts
6-10 Day Forecasts
Precipitation (May 8-12) Precipitation (May 10-16)
8-14 Day Forecasts
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Hydrologic “Perfect Storm”WFO Paducah, KY
Confluence of Ohio River and Mississippi River
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Hydrologic “Perfect Storm”Cairo, IL - Confluence of Ohio River and Mississippi
Historic levee break at New Madrid relieving flood crest at Cairo
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Hydrologic “Perfect Storm”WFO - Memphis
Crest Moving downstream – expect flooding through June
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River ForecastsMay 3 – next 48 hours
Short-term streamflow forecasts predict minor to major crest levels in the Northeast, Ohio River Valley, and Alabama and Mississippi
http://water.weather.gov