What is PCA?

In addition to whole county alerting some NWS offices are looking to sub-divide the County by what we call Partial County Alerting (PCA). This will be most noticeable via alerts issued with the Emergency Alert System (EAS) and NOAA Weather Radio (NWR). Alerting via EAS and NWR are based on the Federal Information Processing Series (FIPS) and Specific Area Message Encoding (SAME), which tells the alert where to go.

PCA for Arapahoe County is being proposed, in addition to the entire County alerting, to separate residents into three distinct geographical areas. This proposed change is annotated by the leading digit of the SAME code. The SAME code is the FIPS codes plus a digit at the beginning. FIPS for Arapahoe County is 08005 with the SAME code being 008005. SAME codes that are Partial County Alerting will change the first zero (0) to a digit between one (1) and nine (9). See the maps linked on this page to find out what the leading digit changes to for your city, x08005, where x is a number between 1-9.

PCA Explanation

What Are The Proposed Changes

NWS Weather Forecast Office (WFO) Boulder, CO, is proposing to change the dissemination of warnings via NOAA Weather Radio All Hazards (NWR) and the Emergency Alert System (EAS) for Arapahoe County, Colorado. The proposed change targets 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.

WFO Boulder worked with Arapahoe County Emergency Managers and Communicatons, the Colorado State Emergency Communications Committee, broadcasters, state and local government officials, EAS encoder/decoder manufacturers, and NWR receiver manufacturers to propose these changes.

The proposed change will be configured, if approved, for those receiving weather information and alerts from the following Weather Radio Transmitters

• Denver, KEC76 transmitting on frequency 162.550
• Deer Trail, WXJ45 transmitting on frequency 162.500
• Franktown, WNG550 transmitting on frequency 162.450

Current SAME Location Code for All of Arapahoe County: 008005

Proposed Paritioned SAME Location Codes

• Western Arapahoe: 408005
• Central Arapahoe: 508005
• Eastern Arapahoe: 608005

See map below for a more detailed, interactive sampling of cities and their proposed SAME codes.

NWR listeners who wish to continue receiving SAME weather alerts for all of Arapahoe county partitions should make no changes and continue using SAME Code 008005

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 008005.

Note that if WFO Boulder 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 Arapahoe County.

NOAA Weather Radio

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

• 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 for Arapahoe 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 Arapahoe County is included in a warning, all of Arapahoe County receives the warning via SAME. Because of Arapahoe County's shape and population bases concentrated in much of the central and western third of the county, residents are unnecessarily receiving EAS and NWR notifications for warnings in areas located more than 50 miles from the actual threat area.

Additional Information

• PCA fact sheet
• 5 Weather Forecast Offices Using PCA
• Programming Your NWR Receiver: Q&A
• SAME Location Codes for Counties
• SAME Location Code Information for Using PCA
• Information fore Broadcasters
• Reference: see how our friends in Clark County, NV implemented PCA