The Mississippi River spring snowmelt flood of 2001 was the second or third highest flood on record for points from Dubuque, Iowa to just upstream of Quincy, Illinois, within the hydrologic service area of the National Weather Service (NWS) Forecast Office in Davenport, Iowa. A deep snowpack combined with untimely and heavy spring rainfall in the upper Mississippi Basin combined to produce high water (i.e., above flood stage) from early April through the end of May. Although final figures are not yet available, damage estimates along this reach run into the millions of dollars, and nearly all counties bordering the Mississippi River were declared Federal disaster areas.

Flood damage could have been much worse, however, the lead time and accuracy of the crest forecasts for this extreme event were sufficient to permit a major effort to mitigate successfully what was nearly a flood of record at some locations. The quality of the forecast was a direct result of the cooperative effort and sharing of expertise of the NWS’s North Central River Forecast Center and Davenport Forecast Office, and the U.S. Army Corps of Engineers (COE) Rock Island District Water Control Section.

The presentation will focus on the role of consensus forecasting for this event as well as issues of both a technical and service nature which were encountered during the event. Some of these issues include: (1) the importance of the NWS and COE consistently issuing the same (consensus-based) forecast with a unified voice, (2) the use of ranges to address uncertainty in crest forecasts, (3) potential rainfall as the crest was passing the high impact point of the Quad Cities, (4) the importance of extended flow forecasts for planning the reopening of the river and cleanup operations, (5) workload impacts in the NWS Davenport Forecast Office, (6) the benefits of NWS Modernization in contrast to the Great Flood of 1993, (7) the utility of daily Iowa Emergency Management Division conference calls with county emergency managers, and (8) the role of the Internet as a key link in the information dissemination process.