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-------- Original Message --------001 NOUS41 KWBC 061146
PNSWSH
SERVICE CHANGE NOTICE 09-36
NATIONAL WEATHER SERVICE HEADQUARTERS WASHINGTON DC
746 AM EDT WED MAY 6 2009
TO: SUBSCRIBERS:
-FAMILY OF SERVICES
-NOAA WEATHER WIRE SERVICE
-EMERGENCY MANAGERS WEATHER INFORMATION NETWORK
OTHER NWS PARTNERS...AND NWS EMPLOYEES
FROM: CRAIG SCHMIDT
CHIEF...METEOROLOGICAL SERVICES DIVISION
WESTERN REGION HEADQUARTERS SALT LAKE CITY UT
SUBJECT: EXPERIMENTAL CRITERION CHANGE FOR HAIL SIZE IN SEVERE
THUNDERSTORM WARNING DETERMINATION AT ALL WESTERN
REGION WEATHER FORECAST OFFICES FROM THREE-QUARTER
/0.75/ INCH TO ONE /1/ INCH IN DIAMETER OR LARGER
EFFECTIVE JUNE 1 2009
ON JUNE 1 2009...ALL WESTERN REGION /WR/ WEATHER FORECAST OFFICES /WFOS/ WILL BEGIN USING A NEW EXPERIMENTAL HAIL CRITERION FOR DETERMINING WHEN TO ISSUE SEVERE THUNDERSTORM WARNINGS /SVR/. IN AN EFFORT TO BETTER REPRESENT HAIL WHICH PRODUCES DAMAGE AND TO REDUCE USER COMPLACENCY TO NUMEROUS SEVERE THUNDERSTORM WARNINGS FOR THREE-QUARTER /0.75/ INCH DIAMETER HAIL...THE WFOS IN WR WILL USE HAIL CRITERION OF ONE /1/ INCH IN DIAMETER OR LARGER AS OPPOSED TO THE REFERENCED /0.75/ INCH CRITERION. THERE IS NO CHANGE IN HAIL CRITERION FOR AVIATION THUNDERSTORM WARNINGS /I.E. CONVECTIVE SIGMETS/ OR FOR SPECIAL MARINE WARNINGS /SMW/. A SERVICE CHANGE NOTICE /SCN/ ANNOUNCING THE NWS CENTRAL REGION/S /CR/ SIMILAR EXPERIMENT IS AVAILABLE ONLINE AT /USE LOWER CASE LETTERS/:
HTTP://WWW.WEATHER.GOV/OS/NOTIFICATION/SCN09-19HAIL_CHANGE.TXTA PRODUCT DESCRIPTION DOCUMENT /PDD/ FOR THIS WR EXPERIMENT IS AVAILABLE ONLINE AT /USE LOWER CASE LETTERS/:
HTTP://PRODUCTS.WEATHER.GOV/THIS EXPERIMENT WILL BE IMPLEMENTED FOR ALL AREAS IN EIGHT WESTERN STATES: ARIZONA...CALIFORNIA...IDAHO...MONTANA... NEVADA...OREGON...UTAH AND WASHINGTON.
NO CHANGE WILL OCCUR WITH RESPECT TO WIND SPEED IN SEVERE THUNDERSTORM WARNINGS. WINDS EQUAL TO OR IN EXCESS OF 50 KNOTS /58 MPH/ WILL REMAIN THE CRITERION. FOR THUNDERSTORMS EXPECTED TO PRODUCE AROUND 3/4 INCH TO 7/8 INCH DIAMETER HAIL BUT REMAIN BELOW SEVERE WIND LIMITS...WR WFOS ARE EXPECTED TO USE THE SPECIAL WEATHER STATEMENT /SPS/... HEADLINED AS A SIGNIFICANT WEATHER ADVISORY. WFOS WILL ALSO CONTINUE TO COLLECT AND DISTRIBUTE HAIL REPORTS THAT ARE THREE- QUARTERS /0.75/ INCH IN DIAMETER OR GREATER BY WAY OF THE LOCAL STORM REPORT /LSR/ AS USUAL.
IF YOU HAVE QUESTIONS...PLEASE CONTACT: CRAIG SCHMIDT NATIONAL WEATHER SERVICE WESTERN REGION HEADQUARTERS 125 SOUTH STATE STREET ROOM 1311 SALT LAKE CITY UT 84138 801-524-4000 CRAIG.SCHMIDT@xxxxxxxx NATIONAL SERVICE CHANGE NOTICES ARE ONLINE AT /USE LOWER CASE LETTERS/: HTTP://WWW.WEATHER.GOV/OM/NOTIF.HTM $$ NNNN
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