The
Hydrometeorological Prediction Center (HPC) is one of nine service centers under the umbrella of the
National Centers for Environmental PredictionThe United States National Centers for Environmental Prediction delivers national and global weather, water, climate and space weather guidance, forecasts, warnings and analyses to its Partners and External User Communities...
(NCEP), a part of the
National Weather ServiceThe National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
, which in turn is part of the
National Oceanic and Atmospheric AdministrationThe National Oceanic and Atmospheric Administration is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
(NOAA) of the U.S. government. The HPC serves as a center of excellence in quantitative
precipitationIn meteorology, precipitation is any product of the condensation of atmospheric water vapor that is deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel...
forecasting, medium range
forecastingWeather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. Human beings have attempted to predict the weather informally for millennia, and formally since at least the nineteenth century...
(three to eight days) and the interpretation of
numerical weather prediction modelsA computer simulation, a computer model, or a computational model is a computer program, or network of computers, that attempts to simulate an abstract model of a particular system...
.
The HPC issues storm summaries on storm systems bringing significant rainfall and snowfall to portions of the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
. Advisories are also issued for
tropical cycloneA tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air...
s which have moved inland, weakened to tropical depression strength, and are no longer the responsibility of the
National Hurricane CenterThe National Hurricane Center , located at Florida International University in Miami, Florida, is the division of National Weather Service's Tropical Prediction Center responsible for tracking and predicting the likely behavior of tropical depressions, tropical storms and hurricanes.When tropical...
. The HPC also acts as the backup office to the
National Hurricane CenterThe National Hurricane Center , located at Florida International University in Miami, Florida, is the division of National Weather Service's Tropical Prediction Center responsible for tracking and predicting the likely behavior of tropical depressions, tropical storms and hurricanes.When tropical...
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.Washington, D.C. , formally the District of Columbia and commonly referred to as Washington, the District, or simply D.C., is the capital of the United States, founded on July 16, 1790...
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.
In July 1954, the Joint Numerical Weather Prediction Unit was created to test out
numerical weather predictionNumerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. While the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer that it was feasible to do in real-time...
techniques by
computerA computer is a machine that manipulates data according to a set of instructions.Although mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century . These were the size of a large room, consuming as...
. 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, MarylandCamp Springs is an unincorporated area and census-designated place in Prince George's County, Maryland, United States. The population was 17,968 at the 2000 census. Camp Springs is not an official post office designation, but rather the area is divided between the surrounding mailing addresses...
.
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 CenterThe Climate Prediction Center is one of the National Centers for Environmental Prediction, which are a part of NOAA's National Weather Service. It is located in Camp Springs, Maryland.-Products:...
,
Environmental Modeling CenterThe Environmental Modeling Center , improves numerical weather, marine and climate predictions at the National Centers for Environmental Prediction , through a broad program of research in data assimilation and modeling...
,
National Hurricane CenterThe National Hurricane Center , located at Florida International University in Miami, Florida, is the division of National Weather Service's Tropical Prediction Center responsible for tracking and predicting the likely behavior of tropical depressions, tropical storms and hurricanes.When tropical...
,
Ocean Prediction CenterThe Ocean Prediction Center , established in 1995, is one of the National Centers for Environmental Prediction’s original six service centers. Until January 12, 2003, the name of the organization was the Marine Prediction Center. Its origins are traced back to the sinking of the Titanic in 1912...
,
Storm Prediction CenterThe Storm Prediction Center , located in Norman, Oklahoma, is part of the National Centers for Environmental Prediction , operating under the control of the National Weather Service , which in turn is part of the National Oceanic and Atmospheric Administration of the United States Department of...
, Aviation Weather Center, NCEP Central Operations, and the
Space Environment CenterThe Space Weather Prediction Center , formerly the Space Environment Center , is a laboratory and service center of the National Oceanic and Atmospheric Administration National Weather Service located in Boulder, Colorado. SWPC continually monitors and forecasts Earth's space environment,...
.
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.
Quantitative precipitation forecasts (QPF)
The
QPFThe Quantitative Precipitation Forecast is the expected amount of melted precipitation accumulated over a specified time period over a specified area. A QPF will be created when precipitation amounts reaching a minimum threshold are expected during the forecast's valid period...
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 ServiceThe National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
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.
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.
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).
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 ModelThe North American Mesoscale Model , refers to the numerical weather prediction model run by National Centers for Environmental Prediction for short-term weather forecasting. Currently, the Weather Research and Forecasting Non-hydrostatic Mesoscale Model model is run as the NAM, thus, three names...
(NAM), as well as guidance from the
European Centre for Medium-Range Weather ForecastsThe European Centre for Medium-Range Weather Forecasts is an international organisation based at Reading, England that was founded in 1975.- Objectives :The objectives of the ECMWF are:...
(ECMWF), the United Kingdom's
Met OfficeThe Met Office , is the United Kingdom's national weather service, and a trading fund of the Ministry of Defence. Part of the Met Office headquarters at Exeter in Devon is the Met Office College, which handles the training for internal personnel and many forecasters from around the world...
(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.
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.
Alaska medium range forecasts
The Alaska medium range forecasters review the latest deterministic and ensemble model guidance (similar to how the broader medium range forecasts are created) in an effort 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 once per day, year-round. Additionally, gridded guidance for the forecast period is issued 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.
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.
Surface analysis
The HPC
Surface AnalysisSurface weather analysis is a special type of weather map that provides a view of weather elements over a geographical area at a specified time based on information from ground-based weather stations...
is part of the NWS Unified Surface Analysis and a collaborative effort with the
Ocean Prediction CenterThe Ocean Prediction Center , established in 1995, is one of the National Centers for Environmental Prediction’s original six service centers. Until January 12, 2003, the name of the organization was the Marine Prediction Center. Its origins are traced back to the sinking of the Titanic in 1912...
, the Tropical Prediction Center, and the Honolulu Weather Forecast Office. The HPC focuses on the synoptic and mesoscale features over North America, primarily 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.
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, 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.
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.
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.
New Building
Construction began in May 2007 on the
NOAA Center for Weather and Climate Prediction (NCWCP), a new building to house the NCEP Office of the Director plus five of the nine NCEP centers. The NCWCP will replace the current World Weather Building, located in
Camp Springs, MarylandCamp Springs is an unincorporated area and census-designated place in Prince George's County, Maryland, United States. The population was 17,968 at the 2000 census. Camp Springs is not an official post office designation, but rather the area is divided between the surrounding mailing addresses...
and will be located on a new 50-acre section of the
University of Maryland, College ParkThe University of Maryland, College Park is a public research university located in the city of College Park in Prince George's County, Maryland, just outside Washington, D.C. Founded in 1856, the University of Maryland is the flagship institution of the University System of Maryland...
M-Square Research and Technology Park.
The 268,762 square-foot building will be the new home for NOAA's Center for Satellite Applications and Research, Air Resources Laboratory and National Centers for Environmental Prediction and the NOAA/DoD/NASA Joint Center for Satellite Data Assimilation. The NCWCP building will employ approximately 800 people.
The NCEP centers to reside in the facility are the Hydrometeorological 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 was expected to open in 2010, but a work stoppage in December 2008 has brought all progress to a halt and the completion date of the new building has been indefinitely postponed.