Tornado and Hail in Wyoming, May 28, 2007

AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NATIONAL WEATHER SERVICE RAPID CITY SD
245 PM MDT MON MAY 28 2007

.DISCUSSION...20Z SFC ANALYSIS SHOWS FRONTAL BOUNDARY EXTENDING FROM
NEAR KMBG TO KCDR WITH SFC CAPE >2500J/KG SOUTHEAST OF THE FRONT
OVER CENTRAL SOUTH DAKOTA. AREA SPECIAL SOUNDINGS STILL SHOW A
PRETTY GOOD CAP OVER MUCH OF THE REGION...BUT WITH UPPER TROUGH
APPROACHING EXPECT TO SEE CAP ERRODE OVER SOUTHWESTERN SOUTH DAKOTA
DURING THE NEXT FEW HOURS. LINE OF THUNDERSTORMS CURRENTLY
APPROACHING NORTHEASTERN WYOMING LOCATED OUT AHEAD OF THE SURFACE
LOW. NAM INDICATES THAT THOSE STORMS MAY DEVELOP INTO A CONVECTIVE
CLUSTER AND HEAD NORTHEAST ACROSS OUR CWA OVERNIGHT.

TUESDAY/WEDNESDAY...MODELS ARE COMING INTO CLOSER AGREEMENT SHOWING
UPPER LOW STALLING OVER THE NORTHERN PLAINS LEADING TO UNSETTLED AND
COOLER WEATHER...SO HAVE RAISED POPS AND COOLED TEMPS.

EXTENDED...WITH MODELS QUICKLY SHIFTING TO A WETTER SOLUTION AS A
CUT OFF LOW STALLS ACROSS THE NORTHERN PLAINS...HAVE ADDED CHANCE
POPS TO THURSDAY. LOW BEGINS PHASING IN WITH AN UPPER TROUGH AND
SHIFTS EAST BY LATER FRIDAY WITH BULK OF PRECIP MOVING INTO EASTERN
SD. ALSO BUMPED DOWN TEMPS WITH COLDER AIR ALOFT AND MORE CLOUDS IN
THE AREA. UPPER RIDGE DEVELOPS BEHIND THE DEPARTING LOW BRINGING
BACK DRY WEATHER FOR THE WEEKEND INTO THE BEGINNING OF THE WORK
WEEK.

&&

.AVIATION...SHOWERS AND STORMS WILL AFFECT ALL TAF SITES/TWEB ROUTES
THROUGH THIS AFTERNOON AND EVENING. SOME STORMS COULD HAVE LARGE
HAIL AND DAMAGING WINDS...PARTICULARLY THROUGH THE KRAP-KPIR AND
KRAP-KBIS TWEB ROUTES. OTHERWISE MORE WIDESPREAD RAIN WITH PERHAPS
SOME THUNDERSTORMS WILL MOVE ACROSS THE AREA LATE THIS EVENING INTO
THE EARLY MORNING HOURS. MVFR CIGS ARE ALSO EXPECTED TO MOVE INTO
THE AREA LATE TONIGHT AND PERHAPS PERSIST THROUGH TOMORROW MORNING.

&&

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

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE RAPID CITY SD
1215 PM MDT MON MAY 28 2007

SDZ001-002-012>014-024>032-041>044-046-047-049-072>074-WYZ054>058-
071-291300-
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-
1215 PM MDT (115 PM CDT) MON MAY 28 2007

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

.DAY ONE...TODAY AND TONIGHT

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER MOST OF
WESTERN SOUTH DAKOTA AND NORTHEASTERN WYOMING THIS AFTERNOON AND
THIS EVENING.

A COLD FRONT WILL STALL OVER WESTERN SOUTH DAKOTA TODAY. LOW
PRESSURE WILL DEEPEN ALONG THE FRONT IN EAST CENTRAL WY. THE LOW
WILL BRING MOIST AND UNSTABLE AIR INTO THE REGION. SUBSTANTIAL
INSTABILITY WILL COMBINE WITH FAVORABLE WINDS TO PRODUCE SEVERE
THUNDERSTORMS THIS AFTERNOON AND TONIGHT.

ACTIVITY WILL BEGIN OVER THE HIGHER TERRAIN OF THE BLACK HILLS AND
NORTHEASTERN WYOMING AROUND 200 PM...AND THEN SPREAD OVER THE
SOUTH DAKOTA PLAINS THIS EVENING. THE BEST CHANCE FOR SEVERE WEATHER
WILL BE EAST OF A LINE FROM LEMMON TO RAPID CITY TO PINE RIDGE.
BETWEEN 500 PM AND 900 PM...THERE IS AN ISOLATED TORNADO THREAT EAST
OF A LINE FROM FAITH TO PHILIP.

THE MAJORITY OF THE SEVERE THUNDERSTORMS WILL PUSH AWAY FROM THE
AREA BY MIDNIGHT. SHOWERS AND THUNDERSTORMS WILL AFFECT MOST OF THE
REGION OVERNIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

ISOLATED THUNDERSTORMS MAY OCCUR TUESDAY AND SATURDAY NIGHT...BUT
ORGANIZED SEVERE THUNDERSTORMS ARE NOT EXPECTED.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED TODAY.