National Weather Service Seattle - Public Zone Reform

National Weather Service will implement a reconfiguration to the public zones for western Washington, which is scheduled for March 18, 2025.

Overview

The NWS Weather Forecast Office (WFO) in Seattle, Washington is responsible for issuing weather forecasts and plain text products for the majority of western Washington. This includes the following counties: Clallam, Grays Harbor, Island, Jefferson, King, Kitsap, Lewis, Mason, Pierce, San Juan, Skagit, Snohomish, Thurston, and Whatcom. The counties listed above make up NWS Seattle's County Warning Area (CWA), which is considered their geographic area of responsibility.

A wide variety of text products are issued for the public and NWS core partners to raise awareness on upcoming weather hazards and associated impacts with the goal of saving lives, protecting property, and enhancing the national economy. These text products currently include Watches, Warnings, Advisories, and Special Weather Statements. NWS meteorologists often refer to these text products as their current headlines, as these products are widely distributed over television, radio, internet, social media, various smartphone applications, etc. For this reason, it is imperative that these products are issued in a manner that is as accurate, clear, and concise as possible.

Current Public Zones

While headlines can be issued by county, this is typically not an ideal approach for NWS Seattle's CWA. This is because each county within the CWA features complex terrain and a wide array of localized weather effects. At times, NWS Seattle's current public zone configuration has proven to be challenging leading up to and during a wide variety of weather scenarios, some of which can be high-impact events. The map below shows NWS Seattle's current public zone configuration. This configuration can result in considerable over- or under-warning of communities due to their size and climatological diversity contained within each zone. For instance, an entire zone may be alerted when only a small portion of the zone is expected to experience the weather hazard OR a decision is made not to issue an alert altogether for the same reason. These limitations can cause confusion when trying to relay hazardous weather messages to our partners and the public.

Current NWS Seattle Public Zones (click the map for zone names)

Current Public Zones WAZ001: San Juan County WAZ503: Western Whatcom County WAZ504: Southwest Interior WAZ506: Western Skagit County WAZ507: Everett and Vicinity WAZ509: Tacoma Area WAZ510: Admiralty Inlet Area WAZ511: Hood Canal Area WAZ512: Lower Chehalis Valley Area WAZ513: Olympics WAZ514: Eastern Strait of Juan de Fuca WAZ515: Western Strait of Juan de Fuca WAZ516: North Coast WAZ517: Central Coast WAZ555: East Puget Sound Lowlands WAZ556: Bellevue and Vicinity WAZ558: Seattle and Vicinity WAZ559: Bremerton and Vicinity WAZ567: West Slopes North Cascades and Passes WAZ568: West Slopes North Central Cascades and Passes WAZ569: West Slopes South Central Cascades and Passes


New Public Zones

To help address a number of issues associated with the current suite of public forecast zones, NWS Seattle is reconfiguring their zones using carefully selected elevation thresholds, local climatology, major transportation routes, and main population centers to help improve the accuracy of their watches, warnings, and advisories for a wide variety of weather hazards. These changes will be most beneficial during the following scenarios:

  • Puget Sound Convergence Zone snowfall events
  • Snowfall events where mountain valley communities are not impacted
  • Coastal flooding events
  • Tsunami events

These changes will allow WFO Seattle to explore transitioning to zone-based hydrologic services in the future. The reconfiguration will allow NWS Seattle to provide a much better service for the public and their core partners as any headlines in effect would generally be more representative of the true weather conditions within a given zone.

New Public Zones (as of June 17)

New Public Zones WAZ001: San Juan County WAZ301: Cascades of Whatcom and Skagit Counties WAZ302: Cascades of Snohomish and Northern King Counties WAZ303: Cascades of Southern King County WAZ304: Cascades of Pierce and Lewis Counties WAZ305: Foothills and Valleys of the North Cascades WAZ306: Foothills and Valleys of Snohomish and Northern King Counties WAZ307: Foothills and Valleys of Central King County WAZ308: Foothills and Valleys of Pierce and Southern King Counties WAZ309: Foothills and Valleys of Thurston and Lewis Counties WAZ310: Lowlands of Western Whatcom County WAZ311: Lowlands of Western Skagit and Northwestern Snohomish Counties WAZ312: Downtown Everett / Marysville Area WAZ313: Shoreline / Lynnwood / South Everett Area WAZ314: Eastside WAZ315: City of Seattle WAZ316: Lowlands of Pierce and Southern King Counties WAZ317: Olympia and Southern Puget Sound WAZ318: Lowlands of Lewis and Southern Thurston Counties WAZ319: Middle Chehalis River Valley WAZ320: Willapa and Black Hills WAZ321: Southern Hood Canal WAZ322: Northern Hood Canal WAZ323: Eastern Kitsap County WAZ324: Port Townsend Area WAZ325: Eastern Strait of Juan de Fuca WAZ326: Western Strait of Juan de Fuca WAZ327: Lake Crescent Area including US 101 WAZ328: Olympics WAZ329: Foothills of the Western and Southern Olympic Peninsula WAZ330: Northern Washington Coast WAZ331: Grays Harbor County Coast WAZ332: Lower Chehalis River Valley WAZ333: Island County


Based on local experience and the climatology of western Washington, the following considerations were a priority during the zone update:

  • Climatology: Updated public zones were created to reflect the climatology of western Washington hazards to the greatest extent possible. The hazards considered include the following:
    • Winter (snow & freezing rain)
    • Extreme temperatures
    • Wind
    • Coastal (flooding & high surf)
    • Tsunami
    • Hydrologic
  • Lewis County: In the existing configuration, zone 504 includes portions of Lewis and Thurston counties, which creates a situation where Lewis County receives alerts for tsunami and coastal hazards. The new public zones were designed to remove Lewis County as a coastal zone.
  • Eastern Puget Sound Lowlands: Zone 555 (in the map above) is a large Cascade Foothills zone that spans Pierce, King, and Snohomish counties which very often leads to over- or under-alerting. The new segments this zone into several climatologically distinct areas to provide greater local detail.
  • Grays Harbor County: Adjustments were made to Grays Harbor County, including both interior and coastal regions, to account for recent tsunami modeling results as well as to better align with meteorological events.
  • Cascade and Olympic Valleys: Communities in the valleys of the Cascades and Olympics in the current public zones are included in the mountains, often resulting in over-alerting within these valleys during winter events. These communities will be separated into new public zones to provide greater detail.
  • NWS Portland Public Zones: NWS Portland are in the process of updating their public zones, which will go into effect in March 2024. The new zones strongly matches NWS Portland, particularly with the segmentation of the Willapa Hills.
  • Hydrology: Current hydrology watches are issued county-based. Considerations were made allow for the flexibility in issuing zone based hydrologic watches, dependent on future decisions.
  • Other Considerations included city, county, and tribal boundaries; population density; major transportation routes, and recent zone changes by neighboring NWS offices.

Slide the vertical bar to view Current (left) and New (right) Public Zones. Use controls in lower right to zoom in.

NWS Seattle is eager to improve the services they provide, and we hope you share our enthusiasm regarding this much-needed change. The new Public zones are scheduled to be implemented March 18, 2025.

Public Zone Reform

NWS Seattle

weather.gov/sew