Hail and Damaging Wind in South Dakota, August 1, 2011

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
908 AM MDT MON AUG 1 2011

.DISCUSSION...CURRENT SURFACE MAP SHOWS TROF MOVING THROUGH
WESTERN SOUTH DAKOTA...WITH WEAK LOW ALONG TROF OVER NORTHWEST
SOUTH DAKOTA. WATER VAPOR IMAGERY HAS SHORTWAVE OVER NRN UT/SW WY IN
MONSOON FLOW. SHORTWAVE MOVES INTO WESTERN DAKOTAS THIS
AFTERNOON/EVENING. SCATTERED THUNDERSTORMS EXPECTED. STRONGEST
SHEAR OVER NORTHWEST/CENTRAL SOUTH DAKOTA. INVERTED-V SOUNDINGS
INDICATE THAT BIGGEST THREAT WILL BE WIND GUSTS.

&&

.AVIATION...COLD FRONT WILL CROSS THE AREA LATE TODAY...PRODUCING
SCT TSTMS THIS AFTN AND EVENING. SKIES WILL BE VFR...WITH IFR/MVFR
VCNTY TSTMS. WINDS WILL BECOME NW...WITH SPEEDS REACHING 20-25 KT
ACRS WRN SD PLAINS.

&&

.PREV DISCUSSION... /ISSUED 300 AM MDT MON AUG 01 2011/

DISCUSSION...CURRENT SURFACE ANALYSIS PLACES TROF STRETCHING DOWN
FROM SOUTHERN SASKATCHEWAN INTO EASTERN MONTANA/WYOMING...WHILE HIGH
REMAINS OVER THE MIDWEST. UPPER LEVEL ANALYSIS PLACES PERSISTENT
HIGH OVER THE SOUTHERN PLAINS WITH MONSOONAL FLOW PUSHING INTO OUR
AREA. MOST OF THE OVERNIGHT CONVECTION HAS PUSHED TO THE
NORTHEAST...THOUGH A FEW LITTLE STRAY STORMS CONTINUE TO SLIDE
ACROSS THE CWA.

FOR TODAY...UNSETTLED PATTERN CONTINUES AS NEXT SHORT WAVE
APPROACHES THE AREA WHILE AFFILIATED COLD FRONT STARTS TO SLIDE
IN...BRINGING ANOTHER ROUND OF THUNDERSTORMS. STRONGEST INSTABILITY
REMAINS MAINLY OVER THE NRN/ERN CWFA WHICH...COMBINED WITH AMPLE
SHEAR...WILL POSSIBLY BRING ANOTHER ROUND OF SEVER WEATHER. EXPECT
STORMS TO BE TAMER ELSEWHERE...THOUGH A STRAY SEVERE STORM OR TWO
WILL NOT BE OUT OF THE QUESTION. TEMPERATURES WILL REMAIN HOT AND
HUMID AHEAD OF THE FRONT TOWARDS CNTRL/SRN SODAK...SO WILL KEEP HEAT
ADVISORY GOING. STORMS WILL TAPER OFF BY LATE TONIGHT AS FRONT
PUSHES OUT OF THE AREA.

ON TUESDAY...A QUIETER AND COOLER DAY IS ON TAP IN THE WAKE OF THE
FRONT AS A COOLER/DRIER AIRMASS SETTLES IN. WITH LIMITED INSTABILITY
ALONG WITH WEAK FORCING...EXPECT ANY ISOLD CONVECTION SHOULD BE
LIMITED TO HIGHER ELEVATIONS OF NERN WYO INTO THE BLKHLS VICINITY.
EXPECT CONVECTION COVERAGE TO INCREASE OVERNIGHT AS LOW LEVEL JET
INCREASES AND STRONG THETA-E ADVECTION DEVELOPS OVER THE AREA.

FOR WEDNESDAY...MONSOONAL FLOW RETURNS TO THE AREA BRINGING CHANCES
FOR THUNDERSTORMS THROUGH THE DAY INTO THE EVENING. TEMPERATURES
WILL REMAIN NEAR AVERAGE.

EXTENDED...ZONAL FLOW CARRYING SHORT WAVES WILL REMAIN OVER THE AREA
THROUGH FRIDAY. LONG WAVE TROF ALONG PACIFIC COAST WILL SEND A
STRONGER SHORT WAVE NORTHEASTWARD TOWARD THE PLAINS...THEN MOVES
ALONG NORTHERN US BORDER FRIDAY NIGHT INTO SATURDAY...WITH COLD
FRONT CROSSING THE PLAINS...WILL GIVE NWRN SD A HIGHER CHANCE OF
THUNDERSTORMS. AS WAVE MOVES TOWARD THE GREAT LAKES... UPPER RIDGE
BUILDS OVER THE ROCKIES...BUT WILL CONTINUE TO BRING SHORT WAVES
THROUGH THE FLOW. TEMPERATURES WILL REMAIN NEAR AVERAGE... SLIGHTLY
COOLER SAT AND SUN BEHIND THE FRONT...THEN WARM AGAIN AT THE
BEGINNING OF THE WEEK.

AVIATION...COLD FRONT WILL CROSS THE AREA TODAY...PRODUCING SCT
TSTMS THIS AFTN AND EVEN. SKIES WILL BE VFR...WITH IFR/MVFR VCNTY
TSTMS. WINDS WILL BECOME NW...WITH SPEEDS REACHING 20-25 KT ACRS WRN
SD PLAINS.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...HEAT ADVISORY UNTIL 7 PM MDT /8 PM CDT/ THIS EVENING FOR BENNETT-
     HAAKON-JACKSON-MELLETTE-SHANNON-TODD-TRIPP-ZIEBACH.

WY...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
515 AM MDT MON AUG 1 2011

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-021300-
BENNETT-BUTTE-CENTRAL BLACK HILLS-CUSTER CO PLAINS-FALL RIVER-HAAKON-
HARDING-HERMOSA FOOT HILLS-JACKSON-MELLETTE-NORTHEASTERN CROOK-
NORTHERN BLACK HILLS-NORTHERN CAMPBELL-NORTHERN FOOT HILLS-
NORTHERN MEADE CO PLAINS-PENNINGTON CO PLAINS-PERKINS-RAPID CITY-
SHANNON-SOUTHERN BLACK HILLS-SOUTHERN CAMPBELL-SOUTHERN FOOT HILLS-
SOUTHERN MEADE CO PLAINS-STURGIS/PIEDMONT FOOT HILLS-TODD-TRIPP-
WESTERN CROOK-WESTON-WYOMING BLACK HILLS-ZIEBACH-
515 AM MDT (615 AM CDT) MON AUG 1 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR WESTERN SOUTH DAKOTA AND
NORTHEASTERN WYOMING.

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT RISK FOR SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING OVER NORTHWEST INTO PARTS OF CENTRAL SOUTH DAKOTA...
PARTICULARLY NORTH AND EAST OF A LINE FROM BUFFALO TO PHILIP. LARGE
HAIL AND DAMAGING WIND GUSTS WILL BE THE MAIN THREATS.

A HEAT ADVISORY IS IN EFFECT TODAY FOR CENTRAL SOUTH DAKOTA. HEAT
INDEX VALUES WILL REACH 100 TO 110 DEGREES.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

CHANCES FOR THUNDERSTORMS WILL CONTINUE EACH DAY THROUGH THE UPCOMING
WEEKEND. ALTHOUGH WIDESPREAD SEVERE THUNDERSTORMS ARE NOT EXPECTED AT
THIS TIME...AN OCCASIONAL SEVERE STORM WITH LARGE HAIL OR DAMAGING
WIND GUSTS REMAINS POSSIBLE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY.

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE RAPID CITY SD
828 AM MDT MON AUG 01 2011

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0430 PM     HAIL             3 NNW DOWNTOWN SPEARFIS 44.54N 103.87W
07/31/2011  E1.00 INCH       LAWRENCE           SD   PUBLIC

&&

SMITH