NOUS41 KWBC 211915 AAA



Service Change Notice 17-46: Updated

National Weather Service Headquarters, Silver Spring, MD

315 PM EST Thu Dec 21 2017


To:       Subscribers:

          -NOAA Weather Wire Service

          -Emergency Managers Weather Information Network


          Other NWS Partners and NWS Employees


From:     Michelle Hawkins, Chief

          Severe, Fire, Public, and Winter Weather

            Services Branch


Subject:  Updated: Delayed Implementation of Impact Based   

          Warnings (IBW) at NWS Alaska Region Offices until

          February 21, 2018


Updated to delay implementation of IBW at NWS Alaska Region

offices until February 21, 2018


The NWS Alaska Region WFOs will transition to the IBW format

effective February 21, 2018. The contiguous United States NWS

WFOs, transitioned operationally to the IBW format on May 10,

2017 and NWS Pacific Region Weather Forecast Offices (WFOs) and

Weather Service Office Pago Pago, American Samoa, transitioned

on October 2, 2017.


The NWS had been experimenting with the IBW format from 2013 to

2016 at a variety of WFOs and received positive feedback from

the public, partners and social scientists. Severe Thunderstorm

Warning (SVR), Tornado Warning (TOR), and Severe Weather

Statement (SVS) products will be stratified into categories

distinguishing extreme cases from base convective warnings.

Additional enhanced wording will be included to convey

information about associated impacts, specific hazards expected,

and recommended actions, both within the bullet statements and

as part of the tag line codes.


Additional information and product examples are online at:


A Product Description Document (PDD) outlining the products is

online at:


For more information, please contact:


Noelle Runyan

NWS Acting Severe Weather Program Leader

Bohemia, NY



Greg Schoor

NWS Severe Weather Program Coordinator

Norman, OK 73072



National Service Change Notices are online at: