About the National Forecast Chart

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The National Forecast Chart

Description
The HPC National Forecast Chart provides an overview of today’s national weather with an emphasis on certain hazardous and significant weather. It summarizes forecasts from several NCEP Service Centers including the Storm Prediction Center (for severe thunderstorm and tornado outlooks), the Tropical Prediction Center (for Tropical Storm and Hurricane forecasts), and the Hydrometeorological Prediction Center (for information concerning heavy rainfall, flooding, winter weather, and general weather). With an overlaid frontal forecast, this display serves as a good overview of the weather for the current day.

The chart is available on the HPC web site at: /noaa/noaa.gif.

Purpose
This chart is intended for use by anyone who needs a non-technical display of the expected weather including the general public, the media, and the emergency management community. It shows the large-scale weather features and the associated significant weather. This chart is especially useful to travelers or others needing a big picture forecast. It is not intended to provide detailed local forecasts for any particular area. See http://weather.gov/ for access to detailed local NWS forecasts and warnings.

Format
The National Forecast Chart is distributed via the Internet. The valid time for this product varies depending on the weather feature for which you are interested. See Table 1 for the valid times of the various weather features depicted on the chart.

Feature	Valid time
Surface features such as highs, lows, and fronts	1800 UTC (1 p.m. EST)
General precipitation areas	Daytime – the 12-hour period from 1200 UTC through 0000 UTC (7 a.m.-7 p.m. EST)
Severe weather and flash flooding	Daytime and the following night – 24-hour period starting at 1200 UTC (7 a.m.) of the current day
Heavy snow and freezing rain forecasts	Usually daytime, from 1200 UTC through 0000 UTC (7 a.m.-7 p.m. EST). If particularly significant, however, it may extend an additional 12 hours through the night to 1200 UTC of the following morning.

Table 1. Valid times for various features shown on the National Forecast Chart.

Basis of the National Forecast Chart
The National Forecast Chart depicts the location of frontal systems and pressure centers over the continental United States and includes several weather parameters derived from forecast charts prepared by other NCEP Service Centers. See Table 2 for the sources of the forecasts included on the chart.

Weather Feature	Origin	URL (Internet Address)
Severe thunderstorms and tornados	SPC convective outlooks	http://www.spc.noaa.gov/products/outlook/
Tropical Storms and Hurricanes	TPC forecasts	http://www.nhc.noaa.gov/
Heavy snow and freezing rain	HPC winter weather forecasts	/ww.shtml
Flash flooding	HPC excessive rainfall chart	/qpf/94ewbg.gif
Fronts and general weather	HPC short-range public products	/basicwx/basicwx.shtml

Table 2. Sources of forecasts depicted on the National Forecast Chart.

See /html/fntcodes2.shtml for an explanation of the symbols used to depict frontal systems on the National Forecast Chart and HPC surface charts.

Availability
The National Forecast Chart is prepared each morning at HPC and made available on the HPC web site by 1000 UTC (5 a.m. EST). The chart is available on the Internet at: /noaa/noaa.gif

Feedback
We are always seeking to improve our products based on user feedback. Comments concerning this and other HPC products can be sent through the “Contact Us” section of the HPC webpage at /


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Page last modified: Thursday, 01-Mar-2007 18:20:16 GMT