Severe Thunderstorm Warning 102, NWS Rapid City, SD

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
250 PM MDT WED AUG 7 2002

MODELS ARE CONSISTENT ENOUGH FOR THIS PACKAGE...WITH THE ETA
TRENDING A LITTLE SLOWER MOVEMENT WITH THE PACIFIC SHORT WAVE
CROSSING THE NORTHERN ROCKIES THU NIGHT.

CONVECTION IS ALREADY FIRING ALONG AND BEHIND AN OLD BOUNDARY
EXTENDING FROM THE CENTRAL BLACK HILLS NORTHEAST TO NEAR HEI.
WINDSHEAR IN THE AREA IS MOSTLY MINIMAL...EXCEPT FOR POSSIBLY A
LITTLE MORE NEAR THE BOUNDARY. MONSOON PLUME THROUGH EASTERN
WY...JUST EDGING INTO WRN SD WILL PROVIDE PLENTY OF MOISTURE FOR
TSTMS TONIGHT...BUT CAPES WILL REMAIN IN THE MODERATE
RANGE...1000-1500.

TONIGHT...CONVECTION HAS ALREADY FORMED OVER THE BLACK HILLS AND THE
HIGHER TERRAIN OF EASTERN WYOMING THIS AFTERNOON.  THIS IS EXPECTED
TO CONTINUE AND EXPAND IN AREAL COVERAGE TO INCLUDE NERN WY AND THE
PLAINS OF WRN SD THIS EVENING AS WEAK MID LEVEL IMPULSSES CROSS THE
NORTHERN HIGH PLAINS THIS EVENING. SHEAR IS NOT EXPECTED TO SUPPORT
A LOT OF SEVERE STMS WITH RATHER WEAK SW FLOW ALOFT.

THURSDAY...SIMILAR AMOUNTS OF MOISTURE AND CAPE ARE EXPECTED TO
DEVELOP AHEAD OF THE PACIFIC SHORT WAVE...BUT SHEAR SHOULD BE MORE
SUPPORTIVE OF LONG LIVED SEVERE STORMS AS MID LEVEL FLOW
INCREASES...AND LCLS SHOULD BE LOWER.

THURSDAY NIGHT AND FRIDAY...MID LEVEL SUPPORT AND COOL ADVECTION
ALOFT WILL PLAY A LARGER ROLE IN TSTM DEVELOPMENT. FRIDAY WILL
LIKELY BE THE COLDEST DAY OUT OF THE NEXT 7.

SATURDAY...COOL ADVECTION AND A LITTLE MOISTURE IN THE NLY FLOW
WRAPPING AROUND THE MID LEVEL LOW WILL PROBABLY PRODUCE A SMALL
AMOUNT OF STRATIFORM PCPN DURING THE DAY SATURDAY.

SATURDAY NIGHT THROUGH SUNDAY NIGHT...A TRANSIENT SHORT WAVE RIDGE
WILL KEEP A CAP ON CONVECTION FOR THE SECOND HALF OF THE WEEKEND.

MONDAY...A PACIFIC COLD FRONT WILL SWEEP THROUGH THE
REGION...BRINGING AN REINFORCING SHOT OF COOL AIR TO KEEP
TEMPERATURES TO BELOW SEASONAL NORMALS.  THE MRF INDICATES MOST OF
THE PRECIPITATION WILL ACCOMPANY THE FRONT...OCCURRING EARLY IN THE
DAY IN THE WEST AND ENDING BY EARLY AFTERNOON IN THE EAST.

TUESDAY AND WEDNESDAY...WEAK COOL ADVECTION AT MID LEVELS SHOULD
KEEP THE AMS UNSTABLE ENOUGH FOR SCT AFTERNOON CONVECTION...BUT DON
EXPECT ANYTHING SIGNIFICANT...WITH LITTLE LOW LEVEL FLOW AND
MODERATE WLY FLOW ALOFT.

.UNR...NONE.

CARPENTER