Skip Navigation 
NOAA logo - Click to go to the NOAA homepage National Weather Service   NWS logo - Click to go to the NWS homepage
Advanced Hydrologic Prediction Service
Local forecast by
City, St is the U.S. government's official web portal to all federal, state and local government web resources and services.

The precipitation output files are changing formats

Due to Critical Weather Days (CWD) for the Tropical Storm, implementation of the new file formats has been rescheduled for Monday June 26, 2017. This date is subject to change if other CWDs are declared. For further details on this update, see the Service Change Notification.

Warnings & Forecasts Graphical Forecasts National Maps Radar Water Air Quality Satellite Climate
River Observations River Forecasts Experimental
Long-Range River Flood Risk
Precipitation River Download Other Information

QPE: Quantitative
Precipitation Estimates
DownloadAbout NWS
Precip Analysis
Other Useful
Survey &
Regional / RFC
Precip Data

Last Update: 06/26/2017 1902 GMT

(1) Choose Format (2) Select Time Range (3) Select Date (4) Select Download (5) Select Product (6) Press the "Download" Button

General Information

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 24-hour 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.

If you wish to use wget (see above), shapefiles are stored at:

If you have any questions or problems, please contact


The following links provide more information about the observed precipitation, normal precipitation, and derived precipitation products:

Shapefile Information

The shapefile contains the following fields:

  1. ID - a unique value for each grid bin
  2. HRAPX - column number of the HRAP grid cell (higher numbers are further east)
  3. HRAPY - row number of the HRAP grid cell (higher numbers are further north)
  4. LATITUDE of the HRAP grid point
  5. LONGITUDE of the HRAP grid point
  6. GLOBVALUE - 24-hour precipitation value in inches. "-2" values correspond to "Missing Data", i.e. an incomplete dataset.

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.

Worldfiles (.GFW extension) and Projection files (.PRJ extension) are available at:

Please note, grids with no precipitation (i.e. 0.00") are not in the observed data shapefiles. A shapefile with all points is available at

A precipitation data legend file can be downloaded at

A problem was discovered on August 9, 2007. The shapefile coordinates for each HRAP grid were indicative of the lower left corner of the grid rather than the center of the grid. The entire shapefile archive has been updated to correct the lat-lon issue. The shapefile shows both the old and new coordinates for each point.

NetCDF Information

The three netCDF files (one for CONUS, one for Puerto Rico, and one for Alaska), may be used independently of one another. Each file contains the following fields:

  1. hrap_xor and hrap_yor - the lower left corner of the grid
  2. hrapx and hrapy - grid dimensions
  3. amountofprecip - an array with the 24-hour precipitation values in hundredths of a millimeter (a value of 2540 corresponds to 1 inch). "-1" values correspond to "No Data", e.g. data over the ocean. "-2" values correspond to "Missing Data", e.g. an incomplete dataset.
  4. other metadata - date and time of creation, lat-lon of the bottom-left, bottom-right, top-right and top-left corners of the grids, et al.

NOTE -- Latitude and Longitude are not explicitly stated in the netCDF file. The second download option "HRAP-to-LatLon" contains source code for a C-program. The program contains a function that reprojects HRAP coordinates to Lat-Lon coordinates. The fully compiled program reads the netCDF files and writes ascii files with the following fields:

  1. id - a unique value for each grid bin
  2. hrapx - column number of the HRAP grid cell (higher numbers are further north)
  3. hrapy - row number of the HRAP grid cell (higher numbers are further east)
  4. latitude of the HRAP grid point
  5. longitude of the HRAP grid point
  6. value - 24-hour precipitation value in inches

To compile the C-program you will need to install the netCDF library on your computer. More information about using netCDF files (including the netCDF C-library) is available from the University Corporation for Atmospheric Research (UCAR).


NWS Information
Spacer Image
US Dept of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
1325 East West Highway
Silver Spring, MD 20910
Page Author: NWS Internet Services Team
Page last modified: 12-Apr-2017 4:08 PM
Information Quality
Privacy Policy
Freedom of Information Act (FOIA)
About Us
Career Opportunities