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 o About the NWS o The NWS role in the flood event o The weather behind the flood o 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 Davenport

NWS Partnerships NWS EMUSGSMediaUSACE 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

Winter Snow – mid February

Winter Snow Water Equivalent

Winter Snowfall Totals (inches)

April Precipitation

April Soil Moisture

April River Levels

June Rainfall

Precipitation Summary

Cedar Rapids, Iowa

June Soil Moisture

Hydrograph – Cedar Rapids

Hydrograph – Iowa City

Satellite View – Polar Orbiter

Cedar Rapids

Iowa City

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? o No single event can be attributed to climate change o Regional climate is trending wetter o There are indications that heavy precipitation events are becoming more common

Perspective

o 1 in a 100 year = 1% chance each year o 1 in a 500 year = 0.2% chance each year o Climate is becoming wetter – fact o Climate change suggests higher probabilities of such events o Land use changes, i.e., urbanization increases rate of runoff

?? Questions ?? 