Wyoming Zone Forecast Boundary Changes - Effective October 5, 2009

Effective Monday, October 5, 2009 at 2:00 p.m. MDT, the Riverton and Cheyenne NWS offices will be modifying forecast zone boundaries throughout southeast Wyoming and in a few locations across central Wyoming.  The realignment of these boundaries will allow both offices to provide improved weather forecast services, especially during hazardous weather conditions, by better accounting for terrain and climatological differences.

The changes for the Cheyenne NWS office are quite comprehensive and involve most forecast zone boundaries in southeast Wyoming and adjacent portions of the Nebraska Panhandle.  Click here to view a complete description and map of the new Cheyenne forecast zones.  Again, the purpose of these changes is to improve public forecast and warning prodcuts and services by better accounting for climatological and topographic differences in complex mountainous terrain.  The full service change notice (SCN) is also available online.

Forecast zone boundaries in southern Natrona County have been altered slightly by the Riverton NWS office to align with the changes initiated from the Cheyenne NWS office.  The new boundaries in this region will also better depict frequent differences in snowfall and wind speeds in this area.  Two additional changes were made to better account for topographic differences around Togwotee Pass and South Pass.  The new boundaries shift Togwotee Pass to the Teton and Gros Ventre Ranges where westerly flow predominates in winter.  South Pass is now grouped with the southwest flow dominated forecast zone of the Wind River Mountains West.  A series of maps to illustrate the areas being altered is available below.  Just click on the thumbnail image for a larger view.  The full SCN is available here.

Public Forecast Zone Boundary Changes
Effective October 5, 2009 - 2:00 p.m.

 Map of New Riverton Public Forecast Zones  Map of the Togwotee Pass Area with New Public Forecast Zone Boundaries  Map of the South Pass Area with New Public Forecast Zone Boundaries  Map of Southern Natrona County with New Public Forecast Zone Boundaries
Map of new NWS Riverton
Public Forecast Zone
Boundaries - Effective
October 5, 2009

Map of the Togwotee
Pass Area with New
Public Forecast Zone
Boundaries

Map of the South Pass
Area with New Public
Forecast Zone
Boundaries
Map of Southern
Natrona County with
New Public Forecast
Zone Boundaries


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