NOUS41 KWBC 271241 



Service Change Notice 18-46

National Weather Service Headquarters Silver Spring MD

841 AM EDT Fri April 27 2018


To:       Subscribers:

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS Partners and Employees


From:     Allison Allen

          Chief, Marine, Tropical and Tsunami Services Branch


Subject:  Use of Above Ground Level in the Coastal Hazard

          Message Effective On or Around May 31, 2018


Effective on or around May 31, 2018, coastal Weather Forecast

Offices (WFOs), except in the Alaska Region, will reference

water levels for coastal flooding to ground level (inundation)

in the Coastal Hazard Message (CFW) when issuing coastal flood

hazards.  If a coastal WFO issues a CFW for coastal flooding and

tropical cyclone watches/warnings are in effect, a range of

water levels above ground will be used to convey the inherent

uncertainty in the forecast.


This change will enable coastal WFOs to provide a consistent

message for referencing water levels for coastal flooding due to

any meteorological cause. WFOs may additionally use other

vertical datum references (e.g., Mean Lower Low Water (MLLW),

etc.), but this information will follow any references to water

levels above ground and be enclosed in parenthesis (e.g., 8 feet

above ground (10 feet MLLW)).


An example of the language that may be used when coastal flood

hazards are issued in the CFW is provided below:


*COASTAL FLOODING...2 to 3 feet of water above ground can be

expected through Wednesday morning then 3 to 4 feet through

early Thursday afternoon along low lying areas along the coast,

especially around the time of high tide Wednesday and Thursday.


The affected CFW hazards and their VTEC are:


Hazard                     VTEC

------                     ----

Coastal Flood Statement    CF.S

Coastal Flood Advisory     CF.Y

Coastal Flood Watch        CF.A

Coastal Flood Warning      CF.W


There will be no changes to AWIPS IDS or WMO headers.


The NWS policy and procedures regarding this change in the CFW

can be found in NWS Instructions 10-320 Surf Zone Forecast and

Coastal/Lakeshore Hazard Services and 10-601 Weather Forecast

Office Tropical Cyclone Products.  The Instructions can be found



If you have questions or comments please contact:


John Kuhn

Meteorologist, Marine, Tropical and Tsunami Services Branch

NWS Headquarters

Silver spring, MD



National Service Change Notices are online at: