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Public Information Statement
National Weather Service Grand Forks ND
209 PM CDT Mon Jul 16 2018

To:      Subscribers:
         -Family of Services
         -NOAA Weather Wire Service
         -Emergency Managers Weather Information Network
         Other NWS partners, users, and employees

From:    Ryan Knutsvig         
         Meteorologist in Charge 
         National Weather Service Grand Forks, ND

Subject: Changes in Gage Reporting and Flood Categories for Stream 
         Gage on the Sheyenne River at Harwood (HWDN8)

Effective Monday, October 1, 2018, the National Weather Service 
(NWS) Advanced Hydrologic Prediction Service (AHPS) webpage will 
change the reporting of observations for the stream gage at Harwood 
on the Sheyenne River from an elevation height above mean sea level 
to a stage value in feet above Gage Zero/Gage Datum. The gage datum 
has been established by the United States Geological Survey (USGS) 
as 801.16 feet above the North American Vertical Datum of 1988 
(NAVD88).

Following this change, observations at this site will be posted
800.00 feet less than the previous method (see items 1-3 below). 
This change has been coordinated with local partners, customers, 
and gage cooperators.

Changing the reporting of observations to a stage value rather than 
elevation will require new stages to be assigned to NWS flood 
categories to ensure consistency in NWS forecast and warning 
services. The new flood categories will be as follows:

 1. New flood stage is 84.00 feet above Gage Zero. Previous flood 
    stage was 884.00 feet above mean sea level.

 2. New moderate flood stage is 86.00 feet above Gage Zero. Previous 
    moderate flood stage was 886.00 feet above mean sea level.

 3. New major flood stage is 91.00 feet above Gage Zero. Previous 
    major flood stage was 891.00 feet above mean sea level.

Associated impact statements and historical crest information 
available on the NWS AHPS webpage will also be adjusted accordingly.

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

    Ryan Knutsvig
    Meteorologist in Charge
    NWS Grand Forks, ND
    Phone: 701-772-0720 x642    
    E-mail: ryan.knutsvig@noaa.gov

    or

    Amanda Lee
    Service Hydrologist
    NWS Grand Forks, ND
    Phone: 701-772-0720 x493
    E-mail: amanda.lee@noaa.gov

$$