Evolution of the NWS Hydrologic Ensemble Forecast Service (HEFS)
Abstract
In 2014, the Hydrologic Ensemble Forecast Service (HEFS) of the U.S. National Weather Service (NWS) began implementation at streamflow forecast locations across the U.S within the Advanced Hydrologic Prediction Service (AHPS). To support and accelerate that implementation, NWS's Office of Water Prediction initiated a Baseline Validation (BV) program in 2016, a collaborative effort with the NWS River Forecast Centers to conduct hindcasting and evaluation of the HEFS forecasts. The major steps to implement HEFS for each new location are, first, to calibrate and implement the HEFS, in order to produce ensemble streamflow forecasts, second, to conduct hindcasting and evaluation of the streamflow forecasts over an approximately 30 year retrospective period (i.e., BV) and, finally, to "turn on" the HEFS and release the forecasts publicly. As of July 2019, the number of locations with HEFS forecasts has expanded to nearly 1,200 locations, including important locations for strategic partners. Forcing inputs to the HEFS include precipitation and temperature forecasts from the National Center of Environmental Prediction's (NCEP) Global Ensemble Forecast System (GEFS). In 2019, OWP began efforts to prepare for transitioning the HEFS to use the upcoming version 12 of the GEFS (GEFSv12). In addition, efforts are underway to improve the HEFS, by implementing a streamflow post-processor to remove bias and, separately, by developing and implementing a technique to reduce conditional bias in the precipitation forecasts during heavy precipitation events. In this presentation, we will summarize the on-going and planned efforts of BV, the transition to GEFSv12, and the proposed improvements to HEFS.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H53G..07F
- Keywords:
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- 3354 Precipitation;
- ATMOSPHERIC PROCESSES;
- 1807 Climate impacts;
- HYDROLOGY;
- 1840 Hydrometeorology;
- HYDROLOGY;
- 1854 Precipitation;
- HYDROLOGY