Service Assessment Central United States Flooding of June 2008 U.S. DEPARTMENT OF COMMERCE National Oceanic and Atmospheric Administration National Weather Service Silver Spring, Maryland Cover Photograph: Downtown Cedar Rapids, Iowa, Friday, June 13, 2008, as the Cedar River crested more than 11 feet above its previous record. View is upstream. (Used with permission. ©2008 Iowa Homeland Security and Emergency Management Division. Photograph by the Civil Air Patrol.) ii Service Assessment Central United States Flooding of June 2008 December 2009 National Weather Service John L. Hayes, Assistant Administrator for Weather Services iii Preface During June 2008, record or major flooding occurred across large areas of the central United States. The flooding had devastating impacts, with 11 people losing their lives. Damages have been estimated at over $5 billion. The states most severely affected were Illinois, Indiana, Iowa, Missouri, South Dakota, and Wisconsin. Also, heavily impacted were Kansas, Michigan, Minnesota, Nebraska, and Oklahoma. In all, 143 National Weather Service river forecast locations experienced major flooding, with 73 of these locations establishing records. Because of the severe impact of the flooding, the National Weather Service of the National Oceanic and Atmospheric Administration formed a Service Assessment Team to evaluate National Weather Service performance during the event. Special attention was given to National Weather Service coordination with other Federal, state, local, and private entities. The recommendations from this assessment will lead to improvements in the quality of National Weather Service products and services and enhance the public’s ability to make more informed decisions associated with flood events. The ultimate goal of this report is to further the National Weather Service mission of protecting lives and property and enhancing the national economy. John L. Hayes Assistant Administrator for Weather Services December 2009 iv Table of Contents Page Preface............................................................................................................................................ iv Table of Contents.............................................................................................................................v List of Figures.............................................................................................................................. viii List of Tables ................................................................................................................................. xi Service Assessment Team............................................................................................................. xii Acknowledgements....................................................................................................................... xii Executive Summary..................................................................................................................... xiii 1. Introduction.................................................................................................................................1 1.1 NWS Mission......................................................................................................................1 1.2 Purpose of the Service Assessment.....................................................................................1 1.3 Methodology.......................................................................................................................2 2. Summary of the Meteorology, Hydrology, Damage, and Other Impacts of the Event ..............3 2.1 Rainfall and Flooding Overview.........................................................................................3 2.2 Impacts................................................................................................................................8 2.3 Comparison to Flooding of 1993 ......................................................................................13 3. Summary of NWS Flood Forecasting Operations for the Event ..............................................15 3.1 Internal Operations............................................................................................................16 3.2 Intragovernmental Cooperation ........................................................................................16 3.3 Emergency Management Community ..............................................................................17 3.4 Media/Public.....................................................................................................................17 4. Facts, Findings, Recommendations, and Best Practices...........................................................18 4.1 Usefulness of the Tools and Data in the Forecast Process................................................18 4.1.1 Observed Precipitation...........................................................................................18 4.1.2 Forecast Precipitation.............................................................................................20 4.1.3 River Flow Observations/Rating Curves ...............................................................21 4.1.4 Time Series Analysis .............................................................................................22 4.1.5 River Flow Modeling.............................................................................................23 4.1.5.1 Site-Specific Headwater Modeling...........................................................23 4.1.5.2 NWS River Forecast System Modeling....................................................23 4.1.5.2.1 Impacts Regarding Rating Curve Extensions ..........................23 4.1.5.2.2 Limited Ability to Account for Levee Failures........................24 4.1.5.2.3 Impacts of Changing Land Use Characteristics.......................26 4.1.5.3 Ensemble River Forecasts.........................................................................26 4.1.5.4 Forecast Dissemination Tool ....................................................................28 4.1.6 Collaboration Tools ...............................................................................................28 4.1.6.1 IEMChat/NWSChat ..................................................................................28 v 4.1.6.2 12Planet.....................................................................................................29 4.1.6.3 River Forecast Product..............................................................................30 4.2 Collaboration among the NWS, USACE, and USGS in the Flood Forecast Process.......30 4.2.1 Agency Roles.........................................................................................................30 4.2.1.1 USGS ........................................................................................................30 4.2.1.2 USACE .....................................................................................................31 4.2.1.3 NWS..........................................................................................................32 4.2.2 Interagency Collaboration—Successes and Lessons Learned...............................33 4.2.2.1 Prior to an Event .......................................................................................33 4.2.2.2 During an Event ........................................................................................33 4.2.3 Opportunities for Enhanced Collaboration ............................................................34 4.3 Accuracy and Effectiveness of Service.............................................................................35 4.3.1 Forecast and Warning Accuracy............................................................................35 4.3.1.1 Quantitative Precipitation Forecast Verification ......................................35 4.3.1.2 Flood Warning Verification......................................................................36 4.3.1.3 Qualitative Verification ............................................................................41 4.3.2 NWS Responsiveness ............................................................................................42 4.3.3 Usefulness of Products and Services .....................................................................43 4.3.4 Reliability of Products and Services......................................................................44 4.3.5 Enhancements to Products and Services Requested by Partners and Other Users............................................................................................................44 4.3.5.1 Flood Impact Statements...........................................................................44 4.3.5.2 Flood Inundation Mapping .......................................................................45 4.3.5.3 Communication Methods..........................................................................45 4.4 Societal Perceptions..........................................................................................................46 4.4.1 Communication, Forecast Uncertainty, and the Decision-making Process...........46 4.4.2 Experience with the Central United States Flood of 1993.....................................48 4.4.3 Integrating the Behavioral Sciences, Meteorology, and Hydrology......................49 5. Concluding Remarks.................................................................................................................50