| 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.
Click here for a brief history of the HPC.
Click here to view a slide presentation describing the HPC in more detail, including
| 1) Vision and mission |
| 2) Partners and customers |
| 3) Products and services |
| 4) Value added by HPC forecasters |
| 5) HPC and the dangers of inland flooding from tropical cyclones |
| 6) HPC plans |
The primary functions of the HPC:
Quantitative Precipitation Forecasts (QPF)
The QPF desk prepares and issues forecasts of
accumulating (quantitative) precipitation, heavy rain, heavy snow, and
highlights areas with the potential for flash flooding. The basic QPF products
are primarily directed to the NWS's forecast offices, but are available
for anyone to use. The heavy snow forecast products, in association with
the short-range public forecast products (described below), serve as a
coordinating mechanism for the NWS's winter storm watch and warning program.
Through a continuous watch for excessive rainfall, heavy snow, and winter
storms, this desk ensures that the highest quality forecast products are
constantly available.
The QPF desk is collocated with the National Environmental
Satellite Data and Information Service (NESDIS) and together, they comprise
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 QPF short term forecaster as part of
the input for 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.
Medium-Range (days 3-7) Public Forecasts
The medium range forecasters are responsible for
preparing forecasts for the 3 to 7 day period. These forecasts are issued
once per day using guidance from the NWS's medium range forecast model
(MRF) 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's NOGAPS model, and ensembles. The medium range forecast
products include: 1) surface pressure patterns, circulation centers and
fronts for days 3, 4, and 5 into the future, 2) daily maximum and minimum
temperatures and anomalies for days 3-7, 3) daily precipitation probabilities
for days 3-7, and 4) total 5-day precipitation for days 1 through 5. These
products are issued once per day along with a supporting narrative. Separate
forecasts, similar to the 5-day mean products, are prepared for Hawaii.
Numerical 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 corresponding to the 0000 UTC and 1200 UTC model runs.
This narrative consists of three sections: 1) An evaluation of the analyses of the three primary models (Eta, NGM, AVN). The meteorologist compares the model analyses with available observed data (radiosondes, aircraft, surface observations, satellite imagery, etc.), and notes any features that do not appear to be properly represented, and thus could have an adverse impact on the models' forecasts after the analysis time. 2) A review of model trends and biases. This section describes how the models are trending in their evolution and progression of important features when compared to previous runs. This section also includes any significant persistent errors that recent model forecasts have been making with respect to a particular feature or over a general region. 3) A description of model differences and preferences. The meteorologist reviews how the models from the latest cycle differ from each other in their forecasts for significant features. Where differences exist, he or she takes into account other available models from previous cycles (ECMWF, UKMET, Canadian, NOGAPS, MM5, etc.) and the information in 1) and 2) above to formulate a preferred model or model blend.
Surface Analysis
The HPC Surface Analysis Team issues manual analyses
of surface fronts and pressure systems over North America and adjacent
oceans at 3 hour intervals (from 0000 UTC to 0600 UTC and from 1200 UTC
to 1800 UTC). Analysts utilize a variety of weather data in addition to
observations of surface weather conditions, such as upper air observations,
global satellite imagery, and Doppler radar to ensure that all analysis
products are meteorologically consistent and of the highest quality.
International Desks
The International desks have a variety of responsibilities,
the main one being the training of foreign visitors in the use of Numerical
Weather Prediction products. The International desk routinely host visitors
from South America, the Caribbean, and the Middle East. |
