On Development of a Performance Measure for Extreme Quantitative Precipitation Forecasts Using Data from HMT-2006 in California
Abstract
Quantitative precipitation forecasts (QPF) are extremely important for many applications, but have remained one of the major challenges in meteorology. Improvements have traditionally been measured using a "threat score," and by this measure annually averaged performance nationally has improved very slowly from ~0.25 to ~0.30 over many years. In addition to the slow rate of improvement, the measure itself is not as effective as needed in cases of extreme precipitation. These, and other drivers, led to the creation of the NOAA Hydrometeorological Testbed (HMT), which was first implemented in California. Out of this effort has emerged a potential new performance measure for QPF in extreme precipitation events associated with land-falling Pacific winter storms. The new method is presented here, along with results from the very wet HMT-2006 field season. The analysis included sites that received up to 100 inches of rainfall that winter and a number of events that produced >5 inches of rain in 24 hours. Working closely with NOAA/NWS providers of the formal QPF for the area, i.e., NCEP's Hydrometeorological Prediction Center (HPC) and the California/Nevada River Forecast Center (CNRFC), a data set of forecasts and verification for 17 sites representative of coastal, inland valley, and mountain conditions, was collected. A methodology was then developed to determine the probability of detection (POD) and false alarm rates (FAR) for events characterized by 1-3 inches, 3-5 inches and >5 inches of rain in 24 hours at each site for forecast lead times of 1, 2, and 3 days. These results include 16 events that had >5 inches of rainfall, of which 2 were predicted to be extreme at 1 day lead time.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.H14D..06R
- Keywords:
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- 1816 Estimation and forecasting;
- 1817 Extreme events;
- 1840 Hydrometeorology;
- 1854 Precipitation (3354)