Gary M. Carter

The Challenge of Forecasting Heavy Rain and Flooding throughout the Eastern Region of the National Weather Service. Part I: Characteristics and Events

Abstract Heavy rain and flooding are of particular concern to forecasters throughout the eastern and southeastern United States. In this paper, the unique combination of synoptic-scale and mesoscale weather conditions and topographic factors that contribute to and enhance convectively produced flash flooding and river flooding are described and categorized. A classification system for synoptic-scale flooding events is developed, which is then used to identify the distribution (by month and synoptic-scale weather system) of major floods in the region of interest. Also, examples of flooding caused by synoptic-scale weather systems are presented. Characteristics of mesoscale heavy-rain events that result in flooding are discussed. Topographical and geographical factors in the region, which play a role in these events, are described, along with examples of mesoscale, flash flood events. Finally, floods produced by warm-top thunderstorms, which pose a unique and challenging forecast problem throughout the east...

Comparative Verification of Recent Quantitative Precipitation Forecasts in the National Weather Service: A Simple Approach for Scoring Forecast Accuracy

Abstract Comparative verification of operational 6-h quantitative precipitation forecast (QPF) products used for streamflow models run at National Weather Service (NWS) River Forecast Centers (RFCs) is presented. The QPF products include 1) national guidance produced by operational numerical weather prediction (NWP) models run at the National Centers for Environmental Prediction (NCEP), 2) guidance produced by forecasters at the Hydrometeorological Prediction Center (HPC) of NCEP for the conterminous United States, 3) local forecasts produced by forecasters at NWS Weather Forecast Offices (WFOs), and 4) the final QPF product for multi-WFO areas prepared by forecasters at RFCs. A major component of the study was development of a simple scoring methodology to indicate the relative accuracy of the various QPF products for NWS managers and possibly hydrologic users. The method is based on mean absolute error (MAE) and bias scores for continuous precipitation amounts grouped into mutually exclusive intervals. ...

The Challenge of Forecasting Heavy Rain and Flooding throughout the Eastern Region of the National Weather Service. Part II: Forecast Techniques and Applications

Abstract Over the years, as the recognition and understanding of the structure and climatic frequency of heavy-rain events has expanded, there has been a corresponding improvement in the available forecast guidance on both the national and local level. Numerous operational procedures, forecast applications, and objective techniques have been developed at National Weather Service (NWS) field offices to assess the potential for heavy precipitation and flooding. The use of simple models and operational checklists, as well as the identification of precipitation enhancements due to the effects of terrain and local climatology, provide forecasters with useful tools that help interpret and improve upon the central guidance products. In addition, the NWS Eastern Region has devised and implemented an aggressive and comprehensive program to support the daily formulation of quantitative precipitation estimates appropriate for the production of more timely and accurate river forecasts. Finally, access to high-resolut...