[ARRL-OK] HWO Supplemental Issued 1610L

Wed, 11 Jun 2003 19:23:33 EDT

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE NORMAN OK
410 PM CDT WED JUN 11 2003

THIS HAZARDOUS WEATHER OUTLOOK COVERS NORTHERN...WESTERN...CENTRAL...AND 
SOUTHERN OKLAHOMA...AND WESTERN NORTH TEXAS..
DAY ONE...
THIS AFTERNOON AND TONIGHT...
THUNDERSTORM OUTLOOK...
THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS ACROSS EXTREME SOUTHWESTERN 
OKLAHOMA AND ALL OF WESTERN NORTH TEXAS. THERE IS A SLIGHT RISK OF SEVERE 
THUNDERSTORMS ACROSS THE REST OF THE FORECAST AREA.LOCATIONS...THE MODERATE RISK 
AREA IS LOCATED SOUTH AND WEST OF A LINE FROM HOLLIS...TO ALTUS...TO 
WALTERS...TO HENRIETTA. THE SLIGHT RISK AREA INCLUDES THE REST OF THE FORECAST AREA.

TIMING...
THE MOST LIKELY TIME FOR SEVERE THUNDERSTORMS WILL BE FROM 5 PM THROUGH 
OVERNIGHT. 

IMPACTS...
THE PRIMARY THREAT WILL BE EXTREMELY LARGE HAIL... POSSIBLY BASEBALL SIZED OR 
LARGER... AND DAMAGING WINDS IN EXCES OF 70 MPH WITH THE STRONGEST SUPERCELLS 
THIS EVENING. THE PRIMARY THREAT OVERNIGHT WILL BE DAMAGING WINDS... WITH THE 
LARGE HAIL THREAT DECREASING WITH TIME. SUPERCELLS THIS EVENING WILL BE 
CAPABLE OF PRODUCING MINORSTRUCTURAL DAMAGE.RECOMMENDED ACTIONS...STORM SPOTTER 
GROUPS AND EMERGENCY MANAGEMENT PERSONNEL ACROSS THE ENTIRE FORECAST AREA SHOULD 
LISTEN FOR UPDATED FORECAST INFORMATION THROUGHOUT THE DAY...AND PLAN FOR 
POSSIBLE SEVERE WEATHER OPERATIONS LATE THIS AFTERNOON THROUGH TONIGHT.  

DISCUSSION...A SURFACE LOW HAS DEVELOPED TO THE NORTHWEST OF CHILDRESS THIS 
AFTERNOON...WITH A WEAK SURFACE BOUNDARY...GENERATED BY THUNDERSTORMS LAST 
NIGHT AND THIS MORNING...EXTENDING FROM THIS LOW ALONG THE RED RIVER. A DRYLINE 
WAS LOCATED FROM EAST OF AMARILLO...TO JUST WEST OF CHILDRESS...TO EAST OF 
MIDLAND. THE DRYLINE IS EXPECTED TO CONTINUE TO SHARPEN THIS AFTERNOON. WARM MOIST 
AND VERY UNSTABLE AIR IS IN PLACE EAST OF THE DRYLINE.THE CAP WHICH DEVELOPED 
OVER THE AREA DUE TO THE SUBSIDENCE BEHIND THE UPPER LEVEL SYSTEM THAT MOVED 
THROUGH LAST NIGHT CONTINUES TO WEAKEN. THE SURFACE BOUNDARY AND THE DRY LINE 
WILL BE POTENTIAL FOCUSING MECHANISMS FOR THUNDERSTORMS LATE THIS AFTERNOON. IN 
PARTICULAR...THE AREA WHERE THESE TWO BOUNDARIES INTERSECT WILL BE A FAVORED 
LOCATION FOR DEVELOPMENT. SURFACE TEMPERATURES CLIMBED INTO THE MID 80S TO MID 
90S ACROSS THE AREA...WITH DEWPOINTS RANGING FROM THE MID 60S TO MID 70S. 
THIS VERY UNSTABLE AIRMASS HAS ALLOWED CAPE VALUES OF 3500 TO 6000 TO DEVELOP 
ACROSS MUCH OF THE AREA. WINDS ALOFT ARE NOT EXPECTED TO BE PARTICULARLY 
STRONG...BUT GIVEN THE VERY UNSTABLE CONDITIONS... VERTICAL WIND SHEAR WILL BE 
SUFFICIENT TO ALLOW STORMS TO QUICKLY BECOME SEVERE. THE COMBINATION OF EXTREME 
INSTABILITY AND MODEST VERTICAL WIND SHEAR WILL BE FAVORABLE FOR HIGH PRECIPITATION 
SUPERCELLS CAPABLE OF EXTREMELY LARGE HAIL... DAMAGING WINDS AND TORRENTIAL 
RAINFALL.  THE PROBABILITY OF TORNADOES WILL BE VERY LOW.STORMS THAT FORM LATE 
THIS AFTERNOON OR EARLY THIS EVENING WILL LIKELY ORGANIZE INTO ANOTHER LINE OR 
LARGE CLUSTER BY LATE EVENING AND TRACK ACROSS MUCH OF THE AREA. LARGE 
HAIL...STRONG WINDS AND HEAVY RAIN WILL BE THE MAIN CONCERNS AFTER DARK. 

PROBABILITY TABLE...
VALID THROUGH 700 AM CDT THURSDAY JUN 12.
PROBABILITY OF THUNDERSTORMS OCCURRING IN THENWS NORMAN COUNTY WARNING 
AREA...100 PERCENT.PROBABILITY OF SEVERE STORMS IF STORMS OCCUR...100 PERCENT.

OTHER HAZARDOUS WEATHER...
THUNDERSTORMS LATE THIS AFTERNOON THROUGH TONIGHT WILL LIKELY PRODUCE HEAVY 
RAIN WHICH COULD PRODUCE LOCAL FLOODING. .

DAYS TWO THROUGH SEVEN...
THURSDAY THROUGH TUESDAY...
THUNDERSTORM OUTLOOK...
THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THURSDAY THROUGH FRIDAY NIGHT 
OVER THE ENTIRE FORECAST AREA. THUNDERSTORM CHANCES WILL CONTINUE AREAWIDE 
EACH DAY THROUGH EARLY NEXT WEEK.    

OTHER HAZARDOUS WEATHER...NONE IS EXPECTED.     

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