[nws-changes] 20080505: postpone issuance of sev thunderstorm and flash flood warnings

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NOUS41 KWBC 051835 AAA
PNSWSH

SERVICE CHANGE NOTICE 08-35...AMENDED
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
235 XM EDT MON MAY 5 2008

TO:       SUBSCRIBERS:
         -FAMILY OF SERVICES
         -NOAA WEATHER WIRE SERVICE
         -EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
         OTHER NWS PARTNERS...AND NWS EMPLOYEES

FROM:     THOMAS GRAZIANO
         CHIEF...HYDROLOGIC SERVICES BRANCH

SUBJECT:  AMENDED: TO POSTPONE INDEFINITELY THE ISSUANCE OF
         COMBINED SEVERE THUNDERSTORM AND FLASH FLOOD
WARNINGS IN THE WESTERN UNITED STATES BASED UPON FEEDBACK FROM OUR PARTNERS AND USERS...THE NWS HAS DECIDED TO POSTPONE INDEFINITELY THE ISSUANCE OF COMBINED SEVERE THUNDERSTORM AND FLASH FLOOD WARNINGS.
THIS SERVICE CHANGE NOTICE /SCN/ WAS ORIGINALLY TO BE EFFECTIVE
TUESDAY JULY 1 2008 AT 1200 COORDINATED UNIVERSAL TIME /UTC/.

THE TEXT OF THE ORIGINAL SCN FOLLOWS:

NWS WEATHER FORECAST OFFICES /WFO/ IN THE WEST WILL ISSUE COMBINED SEVERE THUNDERSTORM AND FLASH FLOOD WARNINGS WHEN CONDITIONS MEETING CRITERIA FOR BOTH TYPES OF WARNINGS RESULT FROM THE SAME THUNDERSTORM. ALL NWS WEATHER FORECAST OFFICES IN WASHINGTON...OREGON...IDAHO...MONTANA...CALIFORNIA...NEVADA... UTAH AND ARIZONA MAY ISSUE THE COMBINED WARNING. HOWEVER... ISSUANCE OF THE COMBINED WARNING IS EXPECTED TO BE A VERY RARE OCCURRENCE OUTSIDE OF THE SOUTHWESTERN STATES CALIFORNIA... NEVADA...UTAH AND ARIZONA/ DURING THE SOUTHWEST MONSOON SEASON.

THE COMBINED WARNINGS AND FOLLOW-UP STATEMENTS WILL BE ISSUED USING THE FLASH FLOOD WARNING /FFW/ AND FLASH FLOOD STATEMENT /FFS/ AWIPS IDENTIFIERS.

THE COMBINED PRODUCT WILL BE IMPLEMENTED AS A MEANS OF PROVIDING WARNINGS FOR THUNDERSTORMS WITH BOTH FLASH FLOODING AND SEVERE CHARACTERISTICS /LARGE HAIL AND/OR DAMAGING WINDS/. PREVIOUS TESTS OF COMBINED WARNINGS WERE SUCCESSFUL WITH IMPLEMENTATION PENDING OPERATIONAL USE OF VALID TIME EVENT CODE /VTEC/ IN FLASH FLOOD PRODUCTS. NOW THAT VTEC IS PROVIDED IN FLASH FLOOD PRODUCTS...COMBINED WARNINGS ARE POSSIBLE AND PREFERRED BY LOCAL DISSEMINATION PARTNERS WHERE THESE TYPES OF STORMS OCCUR.

DUE TO THE INDEFINITE POSTPONEMENT OF THIS SCN...PRODUCT EXAMPLES
ARE NO LONGER ON-LINE.

TRADITIONAL FLASH FLOOD WARNINGS WILL CONTAIN A SINGLE PRIMARY VTEC LINE...WHILE COMBINED WARNINGS WILL CONTAIN TWO PRIMARY VTEC LINES...ONE FOR THE FLASH FLOOD WARNING AND ONE FOR THE SEVERE THUNDERSTORM WARNING. NO SEPARATE SEVERE THUNDERSTORM WARNING TEXT PRODUCT /SVR/ WILL BE ISSUED IN THESE CASES. FURTHER DETAILS ON THE USE OF VTEC CODE CAN BE FOUND AT THE FOLLOWING WEB SITE /USE LOWER CASE/:

 HTTP://WWW.NWS.NOAA.GOV/OM/VTEC/

PARTNERS AND USERS WHO ALREADY RECEIVE NWS FLASH FLOOD WARNINGS DO NOT HAVE TO MAKE ANY CHANGES TO RECEIVE THE COMBINED WARNINGS. IF YOU HAVE QUESTIONS REGARDING THESE PRODUCTS...PLEASE CONTACT:
CRAIG SCHMIDT
CHIEF METEOROLOGICAL SERVICES DIVISION NATIONAL WEATHER SERVICE WESTERN REGION HEADQUARTERS
125 SOUTH STATE STREET ROOM 1311
SALT LAKE CITY UT 84138
PHONE: 801-524-4000 X266
E-MAIL: CRAIG.SCHMIDT@xxxxxxxx

NWS SERVICE CHANGE NOTICES ARE ONLINE AT /USE LOWER CASE/:

 HTTP://WWW.NWS.NOAA.GOV/OM/NOTIF.HTM

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