Click here for a brief history of the HPC.

Click here to view a slide presentation describing the HPC in more detail, including

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 co-located 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 twice per day using guidance from the NWS's 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's NOGAPS model, and ensembles. The medium range forecast products include: 1) surface pressure patterns, circulation centers and fronts for days 3-7, 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. In addition, a narrative is issued for each set of forecasts highlighting forecast reasoning and significant weather over the Continental United States and Alaska. 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 Analysts issue manual analyses of surface fronts and pressure systems over North America and adjacent oceans at 3 hour intervals. 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.