Tornado Warning 18, NWS Rapid City, SD

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
300 PM MDT FRI AUG 3 2007

.DISCUSSION...WATER VAPOR IMAGERY SHOWING A WEAK RIDGE ACROSS THE
NORTHERN PLAINS WITH SEVERAL EMBEDDED SHORTWAVES MOVING THROUGH
TODAY. LATEST OBS SHOW A SURFACE TROUGH EXTENDING FROM SE MT ACROSS
THE SD/WY BORDER INTO SE WY. STRONG RETURN FLOW CONTINUES ACROSS
MUCH OF THE SD PLAINS...ESPECIALLY ACROSS SOUTH CENTRAL
ZONES...BRINGING AMPLE MOISTURE NORTH. THOUGH HEATING HAS BEEN
LIMITED WITH EXTENSIVE CLOUD COVER TODAY...DEWPOINTS IN THE UPPER
60S HAS COMPENSATED ENOUGH TO BRING CAPE VALUES IN THE 1000 TO 2000
J/KG RANGE. THE LOW LEVEL JET WILL STRENGTHEN ACROSS CENTRAL
NEBRASKA AND SOUTH CENTRAL SOUTH DAKOTA THIS AFTERNOON INCREASING
THE 0-1 KM SHEAR TO 15 TO 25 KT. THE STRONG LOW LEVEL SHEAR AND LOW
LCL HEIGHTS HAVE PRODUCED A DECENT THREAT FOR TORNADOES LATE THIS
AFTERNOON INTO THE EARLY EVENING HOURS. THUS TORNADO WATCH 561 HAS
BEEN ISSUED FOR SOUTH CENTRAL SD UNTIL 10 PM MDT. ANOTHER SHORTWAVE
WAS MOVING INTO SE MT AND CENTRAL WY ATTM. AHEAD OF THIS WAVE...MORE
STORMS WERE FIRING IN SE MT AND VIS SAT SHOWING TOWERING CU ALONG A
BOUNDARY EXTENDING THROUGH THE NORTHERN HILLS. COULD HAVE ADDITIONAL
SEVERE STORMS DEVELOPMENT IN THE NEXT FEW HOURS BEFORE SLIDING
EASTWARD. HEAVY RAINFALL AMOUNTS ARE POSSIBLE WITH ANY STORM THAT
DEVELOPS. SOME AREAS HAVE ALREADY SEEN 2 TO 4 INCHES OF QPF ACROSS
JACKSON AND MELLETTE COUNTIES FROM THE STORMS THIS MORNING. THIS
EVENING THE STORMS ARE EXPECTED TO CONSOLIDATE INTO AN MCS AND SLIDE
THROUGH CENTRAL SD AHEAD OF A DEEPENING SURFACE LOW.

THE WEAK UPPER LEVEL RIDGE WILL PERSIST THROUGH THE REST OF THE
SHORT TERM. THE WEAK SOUTHWEST FLOW ALOFT WILL CONTINUE TO BRING
SHORTWAVES ACROSS THE AREA WITH AFTERNOON/EVENING STORMS FIRING.
HIGHS WILL BE IN THE UPPER 80S TO MID 90S.

EXTENDED...ZONAL ORIENTED FLOW WILL DOMINATE THE WEATHER NEXT WEEK
OVER THE NORTHERN PLAINS. SEVERAL WAVES WILL CROSS THE AREA...WITH
THE BEST CHANCE OF SHOWERS AND THUNDERSTORMS ON MONDAY. MID-WEEK
SHOULD BE MAINLY DRY. HAVE LEFT THE END OF THE WEEK DRY FOR NOW BUT
BASED ON THE TIMING OF THE WAVES...MAY HAVE TO RAISE POPS FOR THE
END OF THE WEEK IN LATER FORECASTS. TEMPERATURES WILL BE ABOVE
NORMAL.

&&

.AVIATION...SCT -SHRA/-TSRA BE FOUND ACROSS THE FORECAST AREA
THROUGH THIS EVENING. MVFR CIGS/VSBYS WITH SOME AREAS OF IFR
CONDITIONS ARE EXPECTED TO DEVELOP OVER WESTERN AND CENTRAL SOUTH
DAKOTA OVERNIGHT. VFR CONDITIONS ARE EXPECTED ACROSS THE REST OF THE
AREA.

&&

.UNR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
WY...NONE.

&&

CALDERON/RICHARDS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
630 AM MDT FRI AUG 3 2007

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-041300-
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-
630 AM MDT (730 AM CDT) FRI AUG 3 2007

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE EXPECTED TODAY INTO THIS EVENING BEFORE TAPERING
OFF LATER TONIGHT. THERE IS A SLIGHT RISK THAT SOME OF THESE STORMS
MAY BECOME SEVERE OVER NORTHEAST WYOMING ALONG WITH WESTERN AND SOUTH
CENTRAL SOUTH DAKOTA. LARGE HAIL AND STRONG WIND GUSTS WILL BE THE
MAIN THREATS. ALSO...SOME OF THE THUNDERSTORMS ARE EXPECTED TO BE
SLOW MOVING WHICH MAY RESULT IN LOCALLY HEAVY RAINFALL.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THERE IS A CHANCE FOR THUNDERSTORMS OVER VARIOUS PARTS OF THE AREA
FROM SATURDAY AFTERNOON THROUGH MONDAY. AT THIS TIME SEVERE WEATHER
IS NOT EXPECTED.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY.