NWS Partial County Alerting information

One way NWS meets its missions to protect the public is to send weather warnings via NOAA Weather Radio (NWR). Users of NWR receivers equipped with Specific Area Message Encoding can program their radios with a 6-digit county code to receive alerts for one or more counties. The NWS also sends warnings to the Emergency Alert System (EAS). Broadcasters use EAS to interrupt programming for vital NWS warnings.

NWR is county based. Even if a warning is issued for a small part of a county, the entire county is alerted. This issue is most prevalent with large or uniquely-shaped (e.g., panhandle); or configured (e.g., islands) counties. The NWS has received complaints about receiving "too many EAS alerts" for a county and "too many warnings not applicable to my area of the county." Similarly, broadcasters have expressed concerns about sending EAS activations that do not apply to their broadcast service area.

Both NWR and EAS allow for a county to be divided into two to nine partitions, each having a unique 6-digit code. This division of a county into multiple partitions is referred to as Partial County Alerting. More than 10 years ago, four NWS offices (Duluth, MN; Glasgow, MT, Rapid City, SD,  and Tucson, AZ) successfully implemented partial county codes. Most SAME-equipped NWR receivers can read these codes. By using the SAME partial county location codes, these WFOs have successfully issued warnings for predefined parts of a county, substantially reducing the “False Alarm Area” and “listener fatigue.” Despite the success of these four partitioning efforts, Partial County Alerting is underused. Check out our 1-page Partial County Alerting fact sheet.

NWS restarted this program with Clark County, Nevada in 2021. The Las Vegas Forecast Office coordinated with Emergency Managers, the Nevada State Emergency Communications Committee, broadcasters, state and local government officials, EAS encoder/decoder manufacturers, and NWR receiver manufacturers to use partitions for the following warnings:

• Dust Storm Warning (DSW)
• Flash Flood Warning (FFW)
• Severe Thunderstorm Warning (SVR)
• Tornado Warning (TOR)

More Information

• Overview
• Partial County Alerting Concept
• PCA Example: Flash Flood Warning
• WFOs using PCA
• Programming your NWR Receiver: Q&A
• SAME Location Codes for Counties
• SAME Location Code with a non-zero first digit
• Information for broadcasters
• Outreach Resources and Contacts

Previous NWR and EAS dissemination:

 Flash Flood Warning

This Warning, (depicted in green), currently activates NWR Specific Area Message Encoding (SAME) and EAS for the hatched area.