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Public Information Statement
National Weather Service Rapid City SD
846 AM MST Thu Jan 24 2019

To:       Family of Services (FOS) subscribers, NOAA Weather Wire 
          Service (NWWS) subscribers, Emergency Managers Weather
          Information Network (EMWIN) subscribers, NOAAPort
          subscribers, National Weather Service (NWS) partners
          and other users, and NWS employees.

From:     Melissa Smith
          Service Hydrologist
          Rapid City, SD

Subject:  Revisions of Flood Category Stages for the Cheyenne River 
          near Wasta (WASS2) and the Cheyenne River near Plainview 
          (PLNS2). 

Effective February 13, 2019, the National Weather Service (NWS) in 
Rapid City, SD will change the flood category stages for the 
Cheyenne River near Wasta (WASS2) and the Cheyenne River near 
Plainview (PLNS2). 

All NWS flood warnings, flood statements, flood advisories, flood 
watches, probability outlooks, and NWS hydrographs on the Advanced 
Hydrologic Prediction Service (AHPS) will reference the new category 
levels. This change is part of a recent evaluation of the levels 
based on high water, flood events, and impacts over the past 10 
years. 

The new flood categories will be as follows (all values at level 
above gage zero datum).

Cheyenne River near Wasta (levels were lowered): 
Gage zero datum: 2260.78 ft above MSL NGVD29

    New Flood Categories                Previous Flood Categories   
    ------------------                  ------------------------- 
    Action Stage: 11.0 ft               Action Stage: 11.0 ft  
    Flood Stage: 13.0 ft                Flood Stage: 14.0 ft 
    Moderate Flood Stage: 15.0 ft       Moderate Flood Stage: 16.0 ft  
    Major Flood Stage: 16.0 ft          Major Flood Stage: 17.0 ft

Cheyenne River near Plainview (levels were raised):
Gage zero datum: 1848.7 ft above MSL NAVD88

    New Flood Categories                Previous Flood Categories
    --------------------                -------------------------
    Action Stage: 15.0 ft               Action Stage: 14.0 ft   
    Flood Stage: 17.0 ft                Flood Stage: 16.0 ft
    Moderate Flood Stage: 19.0 ft       Moderate Flood Stage: 17.0 ft
    Major Flood Stage: 20.0 ft          Major Flood Stage: 19.0 ft


The National Weather Service welcomes public feedback. If you have 
any questions or comments on this change, please contact:

    Melissa Smith
    Service Hydrologist
    (605) 341-9271 ext 493
    melissa.smith@noaa.gov

    National Weather Service
    300 East Signal Drive
    Rapid City SD 57701

$$