NOUS41 KWBC 071125 CCA



Service Change Notice 12-29: Corrected

National Weather Service Headquarters Washington DC

725 AM EDT Fri Sep 7 2012


To:        Subscribers:

           -Family of Services

           -NOAA Weather Wire Service

           -Emergency Managers Weather Information Network


           Other NWS partners and employees


From:      Eli Jacks

           Chief, Fire and Public Weather Services Branch


Subject:   Corrected: Transition of NWS Storm Prediction Center

           (SPC) Thunderstorm Outlook (CONUS Only) from

           Experimental to Operational Status Effective

           September 26, 2012


Corrected to change the fourth issuance time of the day from

2030Z to 2100Z.


Effective Wednesday, September 26, 2012, at 1700 Coordinated

Universal Time (UTC), the SPC Thunderstorm Outlook becomes

operational. This product is issued only for the CONUS.


The SPC Thunderstorm Outlook depicts the expected geographic

areas of thunderstorms including 10, 40 and 70 percent

probabilities in 4 or 8 hour time periods. A 40 percent

probability means given similar environmental conditions, a

thunderstorm would be observed at any one location (in either a

county or city) within the 40 percent thunder probability area

four times out of ten, or 40 percent of the time.


Forecasts of thunderstorms are critical for the protection of

life and property since every thunderstorm contains lightning

that is a potential killer. The high temporal and spatial

resolution of the SPC Thunderstorm Outlook will aid both NWS

forecasters and NWS partners in time-sensitive decisions related

to thunderstorms and ultimately provide greater safety for the

U.S. public. 


SPC Thunderstorm Outlook issuance and valid times are:


Issue Time (UTC)     Valid Periods (UTC)

----------           -------------------

  0600Z              1200-1600, 1600-2000, 2000-0000

  1300Z              1600-2000, 2000-0000, 0000-0400

  1700Z              2000-0000, 0000-0400, 0400-1200

  2100Z              0000-0400, 0400-1200

  0130Z              0400-1200


The SPC Thunderstorm Outlooks web-based graphic is online at:


If you have any questions, please contact:


   John Ferree

   NWS Severe Storms Services

   Norman, OK  73072



National Service Change Notices are online at: