The Hydrometeorological Prediction Center -- Its future role in Quantitative Precipitation Forecasting

The Hydrometeorological Prediction Center of the National Weather Service provides forecast guidance products to support the daily public forecasting activities of the National Weather Service (NWS) and its customers and provides tailored support to other governmental agencies in emergency and special situations. In fulfilling this mission, the HPC is striving to be recognized by the NWS field offices and other forecast groups as the center of excellence for heavy precipitation forecasting, medium-range forecasting, real-time numerical model diagnostics and interpretation, and surface analysis. On a daily basis, the HPC issues numerous forecasts and analyses in graphical and narrative format on a schedule-driven basis to a wide range of customers, including the NWS field offices, news media, private sector, academic community, and general public. During weather-related emergencies the HPC is often called upon to provide special products, such as to the Federal Emergency Management Agency and the U.S. Army Corps of Engineers during significant flooding events.

The highest priority role of the HPC is to provide quantitative precipitation forecasts (QPFs). These QPF products are used by a spectrum of customers to predict such things as main-stem river flooding and flash flooding, to manage river commerce and hydroelectric power generation, and to balance the opposing reservoir requirements of flood and drought control.

Currently the HPC, and especially its QPF function, is in the midst of significant change. In April 1999, the decades old process of product generation using grease pencils on acetates was replaced by a process completely workstation based. One benefit of this monumental change for HPC's partners and customers is increased production efficiency, permitting the potential expansion of HPC's product suite. Other benefits include the greater use of science in the production process by allowing the forecasters to display and overlay new and additional meteorological fields, as well as the generation of most HPC products in gridded form in addition to the traditional graphics.

Beside those technological advances, change at HPC is being driven by the increasing requirements of NWS customers. Published in January 1999, "The modernized end-to-end forecast process for quantitative precipitation information: Hydrometeorological requirements, scientific issues, and service concepts" document serves as the road map for the various components of the NWS in meeting customer QPF needs. These expanding requirements include extending QPF further in time (out to Day 3), increasing the temporal resolution (to 12 hours for Day 2, for example), and increasing the frequency of product issuance. Additionally, the current deterministic predictions will need to evolve to become probabilistic QPFs in gridded format to convey the forecast and its uncertainty in a format easily applied by customers.

Lastly, the NWS has undertaken an extensive, enterprise-wide study of how best to meet the needs of its customers for QPF information. The results of this study, which should be widely available by the conference, could have a long- and far-reaching impact on the way the HPC and the rest of the NWS provide QPFs in the future.

This paper will detail the changing requirements for HPC products, discuss the future QPF product suite of the HPC, and provide the latest information on the future role HPC will play within the end-to-end NWS process for providing high-quality QPFs to its customers.