Hail and Damaging Winds in Wyoming, August 5, 2008

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
140 PM MDT TUE AUG 5 2008

.DISCUSSION...WATER VAPOR SHOWS STRONG SHORT WAVE MOVING SEWD ACRS
SRN SASK EARLY THIS AFTN...WHICH IS HELPING DRAW THE MONSOONAL
MOISTURE PLUME NORTHWARD THRU ID/WY. AT THE SFC...BROAD HIGH IS
LOCATED OVER THE NRN PLAINS WITH RETURN FLOW ACRS ERN WY AND FAR WRN
SD. MAIN FCST CONCERN WILL PCPN CHANCES TONIGHT AS UPR WAVE MOVES
THRU THE NRN PLAINS.

THRU TONIGHT...SELY BL FLOW WILL RESULT IN MLCAPES APPROACHING
2000J/KG ACRS FAR SWRN SD AND NERN WY BY LATE THIS AFTN. AS
AFOREMENTIONED SHORT WAVE MOVES INTO ERN MT...LARGE SCALE ASCENT
WILL PROVIDE LIFT NECESSARY FOR TSTMS TO DEVELOP ACRS OUR FAR WRN
ZONES LATE THIS AFTN. AS SELY BL FLOW INCREASES EVEN MORE INTO THE
EVE HOURS...SHEAR WILL BE QUITE SUFFICIENT FOR SUPERCELLS GENERALLY
WEST OF THE BLKHLS. AS SHORT WAVE CONTINUES ITS SEWD MOVEMENT INTO
THE WRN DAKOTAS OVERNIGHT...EXPECT A CLUSTER OF STORMS POSSIBLE
FORMING INTO AN MCS TO MOVE ACRS WRN SD. PRECIPITABLE WATERS
GENERALLY ABOVE 125% OF NORMAL COULD LEAD TO LOCALLY HEAVY RAINS IN
SPOTS.

WED...CONVECTION COULD STILL BE ONGOING IN THE MRNG ACRS SCNTRL SD
BEFORE SHORT WAVE EXITS THE AREA. CDFNT SINKING SWD INTO THE NRN
PLAINS BEHIND THE WAVE WILL ALLOW COOLER AIR TO FILTER IN. BEST
CHANCE FOR STORMS WILL BE ACRS THE SRN HALF OF ZONES WHERE BEST
INSTABILITY LIES...BUT ENTIRE AREA SHOULD DRY OUT WED EVE AS SFC
HIGH SETTLES INTO THE NRN PLAINS.

THU...SFC HIGH WILL SHIFT EWD INTO THE UPR MIDWEST WITH RETURN FLOW
ACRS OUR WRN ZONES...WHERE BEST CHC FOR AFTN/EVE CONVECTION WILL
ALSO PREVAIL.

EXTENDED...AN UPPER LEVEL RIDGE FRIDAY OVER THE EAST SLOPES OF THE
ROCKIES WILL SHIFT INTO THE CENTRAL US FOR THE WEEKEND...AND THEN
FLATTEN EARLY NEXT WEEK. IT HAD LOOKED LIKE THE WEEKEND COULD BE
MAINLY DRY...BUT NOW RMOP/ECMWF/GFS SUGGEST WEAKNESSES ROTATING
THROUGH RIDGE WILL BE ENOUGH TO SUPPORT SMALL CHANCES FOR TSRA EACH
DAY. TEMPERATURES WILL BE NEAR NORMAL.

&&

.AVIATION...VFR CONDITIONS LATE THIS AFTERNOON WILL GIVE WAY TO
CONVECTIVE ACTIVITY OVER MT/WY THIS EVENING...WHICH MAY TURN INTO A
COMPLEX TONIGHT AS IT MOVES ACROSS PORTIONS OF THE DAKOTAS.
LOCALIZED MVFR CIGS/VSBYS DUE TO THE STORMS ARE EXPECTED...WITH A
POTENTIAL MVFR SC DECK BEHIND THE OUTFLOW IN SD THAT DEVELOPS AND
MOVES EAST OF THE CWA.

&&

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

&&

JOHNSON/HELGESON

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
1148 AM MDT TUE AUG 5 2008

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-061300-
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-
1148 AM MDT (1248 PM CDT) TUE AUG 5 2008

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

.DAY ONE...TODAY AND TONIGHT

A STRONG UPPER LEVEL DISTURBANCE WILL APPROACH NORTHEASTERN WYOMING
LATE THIS AFTERNOON AND EVENING...THEN MOVE ACROSS WESTERN SOUTH
DAKOTA TONIGHT. THERE IS A SLIGHT CHANCE THAT SOME OF THESE STORMS
COULD BE SEVERE LATE THIS AFTERNOON AND EVENING...PRIMARILY ACROSS
NORTHEASTERN WYOMING. LARGE HAIL AND DAMAGING WIND GUSTS WILL BE THE
MAIN THREATS. THESE STORMS WILL ALSO HAVE THE POTENTIAL TO PRODUCE
LOCALLY HEAVY RAINFALL...ESPECIALLY AS THE STORMS MOVE ACROSS THE
BLACK HILLS REGION LATER THIS EVENING AND OVERNIGHT.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THERE IS A SLIGHT CHANCE FOR THUNDERSTORMS WEDNESDAY AFTERNOON AND
EVENING FOR NORTHEAST WYOMING...AND MUCH OF WESTERN AND SOUTH
CENTRAL SOUTH DAKOTA. THERE IS A SLIGHT RISK THAT SOME OF THESE
STORMS MAY BECOME SEVERE...PARTICULARLY OVER FAR SOUTHWEST SOUTH
DAKOTA NEAR THE NEBRASKA BORDER. LARGE HAIL AND DAMAGING WIND GUSTS
WILL BE THE MAIN THREATS.

A SLIGHT CHANCE OF THUNDERSTORMS WILL REMAIN IN THE FORECAST FOR
VARIOUS PARTS OF THE AREA FROM THURSDAY THROUGH SATURDAY. WIDESPREAD
SEVERE WEATHER IS NOT EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT EXPECTED TODAY.