Hydrometeorological Prediction Center

The Hydrometeorological Prediction Center (HPC) is one of nine Service Centers under the umbrella of the National Centers for Environmental Prediction (NCEP), operating under the aegis of the National Weather Service, which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the U.S. government. The HPC serves as a center of excellence in Quantitative Precipitation Forecasting, Medium Range Forecasting (three to seven days) and the interpretation of numerical weather prediction models.

The HPC issues storm summaries on storm systems bringing significant rainfall and snowfall to portions of the United States. Advisories are also issued for tropical cyclones which have moved inland, weakened to tropical depression strength, and are no longer the responsibility of the National Hurricane Center. The HPC also acts as the backup office to the National Hurricane Center in the event of a complete communications failure.

History

From the early days of organized weather collection in the United States, a central facility was used to gather and disseminate data. Originally, this task occupied a single room within the United States Army Signal Service in Washington, D.C. Reports were collected via telegraph and general forecasts were made for the country. By December 1942, an office known as the WBAN analysis center was created in order to centralize efforts of the civilian and military weather services and minimize duplication of effort. It was at this time when medium range forecasting first began nationally, through five days in the future. Charts and maps were created at this facility for national distribution. [http://www.hpc.ncep.noaa.gov/html/historyNMC.shtml A Brief History of the Hydrometeorological Prediction Center.] Retrieved on 2008-09-03.]

In July 1954, the Joint Numerical Weather Prediction Unit was created to test out numerical weather prediction techniques using a new device known as a computer. This unit co-located with the WBAN analysis center to form the National Weather Analysis Center, which was located in Suitland, Maryland. When the two units merged, the name changed to the National Meteorological Center (NMC) in January 1958. Research and computer processing abilities increased over the years, which allowed for the first global forecast model to run by June 1966. By January 1975, much of the facility, minus the computers, moved to the World Weather Building, located in nearby Camp Springs, Maryland.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/historyNMC.shtml A Brief History of the Hydrometeorological Prediction Center.] Retrieved on 2008-09-03.]

NMC changed its name to NCEP, the National Center for Environmental Prediction in October 1995. The HPC become a subunit of NCEP, as did a number of other national centers such as the Climate Prediction Center, Environmental Modeling Center, National Hurricane Center, Ocean Prediction Center, Storm Prediction Center, Aviation Weather Center, NCEP Central Operations, and the Space Environment Center.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/historyNMC.shtml A Brief History of the Hydrometeorological Prediction Center.] Retrieved on 2008-09-03.]

Mission

The mission of the HPC is to provide forecast, guidance, and analysis products and services to support the daily public forecasting activities of the NWS and its customers, and to provide tailored support to other government agencies in emergency and special situations.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

Products and services

Quantitative precipitation forecasts (QPF)

The QPF desks prepare and issue forecasts of accumulating (quantitative) precipitation, heavy rain, heavy snow, and highlights areas with the potential for flash flooding, with forecasts valid over the following five days. These products are sent to the National Weather Service forecast offices and are available on the Internet for public use. Heavy snow forecast products, in association with the short-range public forecast products (described below), serve as a coordinating mechanism for the national winter storm watch and warning program.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

One desk of the National Environmental Satellite Data and Information Service (NESDIS) is co-located with the HPC QPF desks, which together form the National Precipitation Prediction Unit (NPPU). NESDIS meteorologists prepare estimates of rainfall and current trends based on satellite data, and this information is used by the Day 1 QPF forecaster to help create individual 6-hourly forecasts that cover the next 12 hours. With access to WSR-88D/Doppler radar data, satellite estimates, and NCEP model forecast data as well as current weather observations and HPC analyses, the forecaster has the latest data for use in preparation of short-range precipitation forecasts. Meteorological reasoning discussions are regularly written and issued with the forecast packages to explain and support the forecast.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

Winter weather forecasts

The HPC Winter Weather Desk issues heavy snow and icing forecast products, which support the NWS winter weather watch/warning/outlook program. These forecasts are for the contiguous United States (CONUS) and issued from September 15 to May 15 each cold season. Graphical forecasts are issued twice daily at 0900 UTC and 2100 UTC (4AM/PM EST respectively), although updates may be warranted by rapidly changing conditions.

The Winter Weather Desk issues probabilistic heavy snow and icing guidance products for the next three days. The forecasts represent the probability that freezing rain or combined snow/sleet accumulations will meet specific criteria within a 24-hour period. These products are issued in probabilistic form to better represent the forecast uncertainty associated with a particular event. The Winter Weather Desk produces a heavy snow and icing discussion that provides the meteorological reasoning for the 24-hour probabilistic heavy snow and icing guidance graphics. This text message is used by internal and external clients including NWS field offices, Department of Homeland Security, FEMA, the White House, Department of Commerce, FAA, and the general meteorological community (private sector and the media).Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

Graphical short term forecasts

The short range forecasters are responsible for preparing forecasts for the time period of 6 through 60 hours. These products are issued twice daily using guidance from the NWS's Global Forecast System (GFS) and North American Mesoscale model (NAM), as well as guidance from the European Centre for Medium Range Weather Forecasts (ECMWF), the United Kingdom's Meteorology Office (UKMET), the Meteorological Service of Canada, including ensembles. Coordination with the surface analysis, model diagnostics, quantitative precipitation, winter weather, and tropical forecast desks is performed during the short range forecast process to maintain internal consistency. The short range forecast products include surface pressure patterns, circulation centers and fronts for 6-60 hours, and a depiction of the types and extent of precipitation that are forecast at the valid time of the chart. In addition, discussions are written on each shift and issued with the forecast packages that highlight the meteorological reasoning behind the forecasts and significant weather across the continental United States.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

Medium range forecasts

Medium range forecasters are responsible for preparing forecasts for three to seven days into the future. Surface pressure forecasts are issued three times per day, with temperature and probability of precipitation products issued twice per day, using guidance from the NWS medium range forecast model (GFS) as well as models from the European Centre for Medium Range Weather Forecasting (ECMWF), the United Kingdom's Meteorology Office (UKMET), Canadian model, the Navy NOGAPS model, and ensemble guidance from the GFS, ECMWF, Canadian, and North American Ensemble Forecast System (NAEFS).

The medium range forecast products include surface pressure patterns, circulation centers and fronts, daily maximum and minimum temperatures and anomalies, probability of precipitation in 12 hour increments, total 5-day precipitation accumulation for the next five days, and 500 hPa height forecasts for days 3-7. In addition, a narrative is issued for each set of forecasts highlighting forecast reasoning and significant weather over the Continental United States. Separate forecasts, similar to the 5-day mean products, are prepared for Hawaii.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

Alaska medium range forecasts

The Alaska medium range forecasters review the latest deterministic and ensemble model guidance (e.g., GFS, Global Ensemble Forecast System, or GEFS; Canadian GEM Global; Canadian GEM Ensembles; ECMWF; ECMWF Ensembles; Navy NOGAPS; UKMET; and the North American Ensemble Forecast System, or NAEFS) to compose the most likely forecast for Alaska and surrounding areas valid from four to eight days into the future.

The Alaska Medium Range Discussion, 500 hPa height graphics, and surface fronts and pressures graphics for days 4-8 are issued experimentally. Additionally, gridded guidance for the forecast period is issued experimentally for the following fields: maximum/minimum temperature grids, twelve hour probability of precipitation grids, as well as derived dewpoint temperature, cloud cover, precipitation type, and wind speed/direction grids at a 5-km horizontal resolution.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

Model diagnostics and interpretation

The purpose of the HPC Model Diagnostic Discussion is to provide objective information and subjective interpretation concerning the current runs of the NCEP short range numerical models. The HPC model diagnostic meteorologist prepares the Model Diagnostic Discussion twice per day in two parts, corresponding to the 0000 UTC and 1200 UTC model runs. This narrative consists of three sections: an evaluation of the initialization of the NAM and GFS, a review of model trends and biases, and a description of model differences and preferences. The meteorologist reviews how the suite of models from the latest forecast cycle differ from each other in their forecasts of significant features, and makes a preference based upon all relevant current information.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

urface analysis

[
United States on October 21, 2006.] The HPC Surface Analysis is part of the NWS Unified Surface Analysis and a collaborative effort with the Ocean Prediction Center and the Tropical Prediction Center. The HPC focuses on the synoptic and mesoscale features over North America, north of 31N. The surface analysis is a manual analysis of surface fronts and pressure over North America and adjacent oceans performed every three hours. The analysis utilizes a variety of weather data in addition to observations of surface weather conditions, such as upper air observations, global satellite imagery, Doppler radar, and model mass fields to ensure that the product is meteorologically consistent.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

Tropical cyclone forecast duties

The HPC is the official backup center to the National Hurricane Center (NHC). In this capacity, the HPC is responsible for issuing all tropical cyclone products, including discussions, graphics and watches and warnings that would normally be issued by the NHC for any tropical system in the Atlantic Ocean or eastern Pacific Ocean basins, if NHC is unable to so.

During the tropical weather season which runs from May 15-November 30, the HPC has several other routine duties pertaining to tropical weather forecasting. The first duty is to provide track forecast guidance to the NHC whenever there is a tropical cyclone in the Atlantic Ocean basin west of 60W longitude. As required, this guidance is provided to the NHC four times daily for use in the tropical cyclone package issued by the NHC at 0300 UTC, 0900 UTC, 1500 UTC and 2100 UTC. The HPC also participates in the Hurricane Hotline call with the NHC and other forecast offices and government agencies for tropical cyclones in the Atlantic Ocean basin west of 60W longitude. Also, points for days 6 and 7 for existing tropical cyclones east of 140W longitude, [United States Department of Commerce. [http://www.weather.gov/om/assessments/pdfs/Katrina.pdf Service Assessment: Hurricane Katrina, August 23-31, 2005.] Retrieved on 2008-09-03.] and days 3-7 to possible future tropical cyclones, are coordinated between the medium range pressures desk and NHC each day at noon during the hurricane season.

Within the HPC tropical program, the lead forecaster on shift, who prepares the day 1 QPF, is to provide the rainfall statement for tropical cyclones that are expected to make landfall. This statement is included in the Public Advisory issued by the NHC, and is a forecast of expected rainfall amounts that will occur with the tropical cyclone. [David M. Roth. [http://www.hpc.ncep.noaa.gov/research/roth/TC_QPF_talk032008.ppt HPC’s role in providing Tropical Cyclone Rainfall� Products.] Retrieved on 2008-10-01.]

Finally, the HPC tropical desk also has the responsibility for issuing Public Advisories whenever a tropical cyclone has made landfall in the U.S. or adjacent parts of Mexico, has weakened below tropical storm status yet the system is still capable of producing flooding type rains. This HPC Public Advisory will continue to be issued until the flooding rainfall threat is over. The advisory will contain information on how much rainfall has occurred with a particular tropical system, and will also include forecast information on the remnants of the system.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

International desks

The International desks have a variety of responsibilities, primarily the training of foreign visitors in the use of Numerical Weather Prediction products. The International desk routinely hosts visitors from Central and South America and the Caribbean. Visiting meteorologists train, and also generate forecasts for their own national centers, and assist HPC forecasters with QPF related to tropical cyclones in Central America and the Caribbean.Hydrometeorological Prediction Center. [http://www.hpc.ncep.noaa.gov/html/about2.shtml About the HPC.] Retrieved on 2008-09-03.]

New building

Construction has started on a new building to house the headquarters for NCEP and its Office of the Director plus five of the centers, including HPC. The new building will replace the current World Weather Building, located in Camp Springs, Maryland. The new building will be in College Park, Maryland. It will be part of M-Square, a new crossroad where government, private industry, technology and science converge to be one of the nation's largest research parks. The new convert|250000|sqft|m2|abbr=on. building will employ approximately 800 people. The other centers to reside in the facility are the Hydrometeorlogical Prediction Center (HPC), the Climate Prediction Center (CPC), the Ocean Prediction Center (OPC), the Environmental Modeling Center (EMC), and NCEP Central Operations (NCO). The building is expected to open in 2009. [National Centers for Environmental Prediction. [http://www.ncep.noaa.gov/news/ncwcp/s043.shtml Construction Pictures from the NCWCP Site August 6, 2008.] Retrieved on 2008-09-03.]

References

See also

* Hydrometeorology

External links

* [http://www.hpc.ncep.noaa.gov/index.shtml Official website]