NOUS41 KWBC 201530



Service Change Notice 17-46

National Weather Service Headquarters Washington DC

1130 AM EDT Mon Apr 10 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



Subject:   Impact Based Warnings (IBW) to become operational at

           all Contiguous United States (CONUS) NWS Weather

           Forecast Offices (WFO) effective May 10, 2017.


The NWS will go operational with the IBW format at all the CONUS

WFOs on May 10, 2017. OCONUS sites will transition to the IBW

format no later than December 31, 2017. The NWS has been

experimenting with the IBW format since 2013 at a variety of

WFOs. Successes with this format along with comments received

from the public, partners and social scientists have all been



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

on-line at:


For more information, please contact:

  Jim Keeney

  Acting NWS Severe Storms Program Lead

  Kansas City, MO 64153



National Service Change Notices are online at: