States Counties River Basins
River Forecast Center Boundaries
Image Last Updated:
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0.5 to 7.0 MB
The precipitation data are quality-controlled, multi-sensor (radar and rain gauge) precipitation estimates obtained from National Weather Service (NWS) River Forecast Centers (RFCs). The original data are in XMRG format and projected in the Hydrologic Rainfall Analysis Project (HRAP) grid coordinate system, a polar stereographic projection true at 60°N / 105°W. Our software reads each participating RFC's XMRG file and grabs the hourly precipitation estimate for each HRAP grid cell.
Use the form above to download these files. Alternatively, you can download a program called wget that mimics ftp capability. Due to increased web security, the anonymous FTP server is no longer available. When using wget, the proper URL to provide is: http://www.srh.noaa.gov/ridge2/Precip/qpehourlyshape/latest or http://www.srh.noaa.gov/ridge2/Precip/qpehourlyshape/YYYY/YYYYMM/YYYYMMDD (where YYYY is the year, MM is the month and DD is the day of month).
We currently only provide a online archive back January 9, 2013. For data prior to that, please contact SR-TUA.Precip@noaa.gov . At this time, the offline archived data goes back to 2010. If you have any questions or problems, please contact SR-TUA.Precip@noaa.gov
The shapefile contains the following fields:
The second download option "Legend File" will help you reproduce the color scheme we are using. If using ArcView, you will need to copy it into your c:\esri\av_gis30\arcview\legend_avl\ directory and load it manually through the legend editor. This file does not change from day to day.
About the Hourly Precipitation Analysis Pages
These pages graphically show the latest short-term observed precipitation across the majority of the National Weather Service (NWS) CONUS and Puerto Rico.
"Observed" data is the water equivalent estimation of all types of
precipitation (rain, snow, sleet, freezing rain, hail) derived from
NWS River Forecast Centers (RFCs) , and is displayed as a gridded
field with a spatial resolution of 4x4 km. "Observed" data is
expressed as a short-term duration total ending at the hour indicated
in UTC (same as Greenwich Mean Time, or GMT). For example 1200 GMT
coincides with 8 AM EDT, 7 AM EST, 7 AM CDT, 6 AM CST, etc.
When viewing "NWS" data, you may notice that "Observed" data extends
beyond the U.S. border into Mexico. The West Gulf RFC has service
areas that extend beyond the U.S. border, in order to model rivers
that flow into the United States, (i.e. tributaries of the Rio Grande
along the Texas-Mexico border.) Although no forecasts are provided
outside of U.S. boundaries, precipitation estimates are created over
these areas in order to simulate streamflow along these rivers as they
cross into the United States. When viewing the data, it may be helpful
to turn on the "RFC Boundary" overlay as a geographic reference.
RFCs derive the "Observed" precipitation field using a multisensor approach. Hourly precipitation estimates from WSR-88D NEXRAD are compared to ground rainfall gauge reports, and a bias (correction factor) is calculated and applied to the radar field. The radar and gauge fields are combined into a "multisensor field". Human quality control then seeks to remove gages that appear to be malfunctioning as well as radar artifacts that may appear. This is done on an hourly basis. In areas where there is limited or no radar coverage, satellite precipitation estimates (SPE) can be incorporated into this multisensor field. The SPE can also be biased against rain gauge reports.
Quality of Data
"Observed" data is vulnerable to inaccuracies that can be caused by either radar or precipitation gages. For radar, problems would include freezing or frozen precipitation, low topped convection, bright banding, the reflectivity/rainfall relationship in use, calibration of the radar, radar location and elevation, range degradation, and the radar's effective coverage. For precipitation gages, problems come from freezing precipitation, windy conditions, gage siting, under measurement by tipping bucket gages in high intensity rainfall, and gage maintenance.
Production / Update Times
The hourly precipitation analysis pages are routinely updated each hour, at approximately 50 minutes past the hour. The data for each hour are preliminary and subject to change, they are neither official nor certified. Please contact the National Climatic Data Center for certified past weather information.
The precipitation fields are provided in GIF format for viewing, and shapefile and netCDF formats for download and use in other projects and research. More information about using netCDF files is available from the University Corporation for Atmospheric Research (UCAR).
10 of the 13 NWS River Forecast Centers (RFCs) provide hourly estimates of precipitation for this project. The two western most RFCs, CNRFC (California/Nevada) and NWRFC (Northwest) do not at this time contribute data. AKRFC (Alaska) also does not contribute data.
The first downloadable shapefiles available at http://www.srh.noaa.gov/ridge2/Precip/qpehourlyshape/ are from March 26, 2011. The archive of images available for viewing at this site using the Hourly Archive button begins on September 17, 2010 at 11Z.
"How much rain fell, and where?" These pages help answer this question, but the real question is "How can I use this information to make decisions?" This page provides links to various National Weather Service resources that you may find relevant. The list is by no means exhaustive, so please visit http://www.weather.gov for more information.Current Weather Information
The National Weather Service needs your feedback to assess the usefulness and quality of this web page.
For more information about this product, please click on the tabs at the top of this page to explore the website, or click here to view the entry in the National Catalogue of NWS Products.
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