Should Hennepin County use smaller severe weather warning zones?

Do you own a National Oceanic and Atmospheric Administration weather radio?

It could alert you of severe weather in smaller areas in Hennepin County in the future. The Twin Cities National Weather Service office is evaluating a process called partial county alerting.

Hennepin is the 60th largest of 87 counties in Minnesota. But it is the most populous county in Minnesota with more than 1 million people!

Hennepin is also the biggest county in the immediate Twin Cities metro area. Only Wright County (45th biggest in Minnesota) to the west is bigger.

Ramsey County to the east of Hennepin is the smallest county in Minnesota! Anoka, Scott, Carver, Chisago, and Washington counties all rank in the seven smallest counties of Minnesota.

So it makes sense that the National Weather Service would look at breaking up larger Hennepin County in multiple warning zones.

Here is what the Twin Cities NWS office is looking at:

NWS Weather Forecast Office (WFO) Twin Cities, MN and Hennepin County Emergency Management are proposing a change in the dissemination of warnings via NOAA Weather Radio All Hazards (NWR) and the Emergency Alert System (EAS) for Hennepin County. This change would target the delivery of weather warnings to populations to a more targeted threat area and minimize or eliminate unnecessary delivery of weather and water warnings to residents located far from the threat area. 

Current SAME Location Code for Hennepin County: 027053

Proposed SAME Location Codes:

Northwest Hennepin: 127053

Northeast Hennepin: 327053

West Central Hennepin: 427053

Central Hennepin: 527053

East Central Hennepin: 627053

Southern Hennepin: 827053

 NWR listeners who wish to continue receiving SAME weather alerts for all Hennepin County partitions should make no changes and continue using SAME Code 027053.

NWR listeners who wish to receive SAME weather alerts specific to their local area should add the appropriate, partition-specific SAME Code and delete SAME Code 027053.

Note that if WFO Twin Cities issues a weather alert applicable to the entire county, you will continue to receive these alerts. You will also continue to receive all Civil Emergency Messages issued for Hennepin County.

Here is how the new warning process would affect NOAA weather radio:

NOAA Weather Radio All Hazards (NWR) uses Specific Area Message Encoding (SAME) when the following warnings are issued by WFO Twin Cities:

Dust Storm Warning (DSW)

Flash Flood Warning (FFW)

Severe Thunderstorm Warning (SVR)

Snow Squall Warning (SQW)

Tornado Warning (TOR)

Although NWS meteorologists specify latitude and longitude points (i.e., polygons) to identify the threat area, the warnings from Hennepin County are currently conveyed via NWR and the Emergency Alert System (EAS) to the whole county. This means that even if a very small part of Hennepin County is included in a warning, all of Hennepin County receives the warning via SAME. Because of Hennepin County's population is heavily weighted to the eastern half of the county, residents are unnecessarily receiving EAS and NWR notifications for warnings in areas located up to 30 miles from the actual threat area.

To address the issue of SAME and EAS over alerting for large counties when only a portion of the county is, in fact, affected, five WFOs (Duluth, Glasgow, Rapid City, Tucson, and Las Vegas) assigned partial county NWR and EAS codes to sections of large counties within their area of responsibility.  This partitioning has worked very well for them for many years. By using the SAME partial county location codes, these WFOs have successfully issued warnings for predefined parts of a county, which substantially reduces the “False Alarm Area” and “listener fatigue” via NWR and EAS.

You can submit your comments submit your comments by email to the Twin Cities NWS office through July 31.