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M eteorological C onditions A ssociated with the 2008 Midwest Flood. Ray Wolf NOAA / National Weather Service Davenport, Iowa. University of Iowa – Learning from the Flood, October 6, 2008. Outline. About the NWS The NWS role in the flood event The weather behind the flood
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Meteorological Conditions Associatedwith the 2008 Midwest Flood Ray Wolf NOAA / National Weather Service Davenport, Iowa University of Iowa – Learning from the Flood, October 6, 2008
Outline • About the NWS • The NWS role in the flood event • The weather behind the flood • Event perspective
National Weather Service -an agency of the Federal government US Department of Commerce National Oceanic and Atmospheric Administration National Weather Service
NWS Mission • The National Weather Service (NWS) provides weather, hydrologic, and climate data, forecasts and warnings for the US, for the protection of life and property and the enhancement of the national economy.
NWS Operations • ~4500 people • 174 offices
NWS Operations • Collect data – surface, upper air, radar, • satellite, solar • Forecasts and Warnings • Public – severe and winter weather • Aviation • Rivers • Fire Weather • Marine • Tropical • Climate • Space
NWS Partnerships Research Community FEMA
And now the weather… • Heavy winter snow • + Significant flooding in April (high river levels) • + Extremely moist soils • + Heavy June rains • -------------------------------------- • = Historic flooding
River Basins Extended period of heavy snow then heavy rain from November through June in the red shaded area
Precipitation Summary Cedar Rapids, Iowa - 2008
Jet Stream level • << Mean from Jan – Jun • Anomaly >> 6 miles up
500 mb Height Anomaly chart 3 miles up
850 mb moisture 1 mile up
La Nina? • La Nina – cold event • Normal – neutral • El Nino – warm event
La Nina? – likely not a key factor La Nina precipitation composite brown = drier than normal green = wetter than normal
Global climate change? • No single event can be attributed to climate change • Regional climate is trending wetter • There are indications that heavy precipitation events are becoming more common
Perspective • 1 in a 100 year = 1% chance each year • 1 in a 500 year = 0.2% chance each year • Climate is becoming wetter – fact • Climate change suggests higher probabilities of such events • Land use changes, i.e., urbanization increases rate of runoff
?? Questions ?? • ray.wolf@noaa.gov