National Weather Service United States Department of Commerce

Proposed national expansion of Partial County Alerting for NOAA Weather Radio All Hazards (NWR) and the Emergency Alert System (EAS) for very large or uniquely-shaped counties.

The NWS broadcasts weather warnings and Non-Weather Emergency Messages (NWEMs) via NWR and NWR serves as a primary source of information for the nation’s EAS.

Both NWR and EAS are generally viewed as county-based systems.  However, this is particularly problematic for very large or uniquely-shaped counties because even if only a small portion of a county is included in a warning, the warning’s NWR and EAS dissemination translates to the entire county. 

However, both NWR and EAS allow a county to be divided into fixed partitions, with the number of partitions ranging from two to nine.  Each partition is associated with a unique, six digit location code.  Five WFOs (Duluth, Glasgow, Las Vegas, Rapid City and Tucson) successfully assigned partial county codes to one or more of their counties. We refer to this more-targeted dissemination of polygon-based warnings via NWR and EAS as Partial County Alerting (PCA).

The implementation of PCA for a county must first be agreed to by local officials, emergency managers, and broadcasters.

If PCA is implemented, NWR listeners with Specific Area Message Encoding (SAME)-equipped receivers carrying the Public Alert™ logo can easily select a unique, six digit location code for their local area and receive automated notifications of WFO-issued warnings.

In addition, based on WFO decisions with local officials and emergency managers, PCA may be used for NWEMs.

When WFOs implement PCA, a Service Change Notice will first be issued to specify if PCA will be used for weather warnings, only, or for weather warnings and NWEMs. Maps will be posted on WFO web pages detailing partition boundaries and associated SAME location codes.

The operational implementation of PCA is an opt-in service for those who wish to receive warnings more applicable to their local area. If NWR listeners using Public Alert™ receivers wish to continue receiving all warnings for their county, they do not need to make any SAME location code changes.

Here is a graphical depiction of PCA for a county “before” and “after.” 

More Information

The NWS’s proposed national expansion of PCA includes the following enhancements:

+1. Expansion of this capability to other WFOs for select counties with the following NWR service improvements

+2. Expansion of the capability for optional EAS implementation by broadcasters

+3. Enhancements for the Weather Enterprise and Alerting Authorities

  • supporting emergency managers and civil alerting authorities by expanding PCA to include Non-Weather Emergency Messages (NWEMs) such as the Civil Emergency Message (CEM) and Evacuation Immediate (EVI)
  • documenting PCA in World Meteorological Organization (WMO)-formatted products for weather warnings and NWEMs using a Partition Tag Line located below the double ampersand (&&) symbol.
  • documenting PCA in Common Alerting Protocol version 1.2 (CAP v1.2) messages for weather warnings (Note: The NWS does not disseminate CAP messages for NWEMs.)
  • documenting NWS’ use of PCA in a new AWIPS shapefile PCA database 


Feedback method 

Please submit any comments, suggestions or questions to:
Mr. Timothy Schott
National Weather Service Headquarters
1325 East-West Highway, Station 14440
Silver Spring, Maryland 20910