NOAA Atlas 2 Precipitation Frequency Estimates
in GIS Compatible Formats

Note:  Effective August 6, 2003, NOAA Atlas 2 has been superseded by NOAA Atlas 14 Volume 1 for Arizona, Nevada, New Mexico, and Utah. Effective April 8, 2011, NOAA Atlas 2 has been superseded by NOAA Atlas 14 Volume 6 for California. Visit the Precipitation Frequency Data Server for more information.

This web page provides access to high-resolution (15-sec) NOAA Atlas 2 precipitation frequency grids for 2-year and 100-year average recurrence intervals and for 6-hour and 24-hour durations for 6 states in the western U.S. (Colorado, Idaho, Montana, Oregon, Washington, Wyoming).

To view a scanned version of current NOAA Atlas 2 document for a specific state, please visit our PF Documents page.

To view a complete set of scanned maps from NOAA Atlas 2, visit the Western Regional Climate Center page.

• PRECIPITATION FREQUENCY ESTIMATES AT A POINT
  To obtain the precipitation frequency estimates at a given point, enter the latitude and longitude (as a negative number) in decimal degrees:
                 Latitude: Longitude:
• PRECIPITATION FREQUENCY GRIDS
  These spatial data sets are provided in an ArcInfo ASCII grid format. Please read the metadata before making any use of the datasets.
  
  The files can either be downloaded via pull-down menu or anonymous ftp:
  
  1) Via pull-down menu:
  
  Western U.S. Colorado Idaho Montana Oregon Washington Wyoming 2-year, 6-hour 2-year, 24-hour 100-year, 6-hour 100-year, 24-hour
  2) By anonymous ftp:
  

  Action	Type
  Open ftp to the server	ftp hdsc.nws.noaa.gov
  Login as anonymous user	anonymous
  Give the password, your email id	myemail@company.com
  Switch to binary mode	bin
  Change directory	cd pub/hdsc/data/westus/
  Get the file	Example: get na2_westus_100yr24hr.zip (this will download the 100-year 24-hour ArcInfo ASCII grid for the Western US)
  Optionally, get other files	Example: get na2_*_100yr24hr.zip (the wildcard '*' in this case will get all regions for 100-year 24-hour)
  Quit ftp	quit

  The GIS formats are provided as a convenience to users and do not imply endorsement by or represent opinions of the U.S. Government.