Severe Thunderstorm Warning 54, NWS Aberdeen, SD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
345 PM CDT MON JUN 6 2005

.SHORT TERM...TODAY THROUGH THURSDAY NIGHT
ACTIVE NIGHT EXPECTED ACROSS THE CWA. WARM FRONT NOW EXTENDS FROM
SOUTH OF PIERRE TO SOUTH OF WATERTOWN. 18Z KABR SOUNDING THAT THE
ATMOSPHERE IS WELL CAPPED AHEAD OF THE BOUNDARY ACROSS MUCH OF THE
CWA. HOWEVER...AS STRONG LOW LEVEL JET DEVELOPS OVERNIGHT AND WAVE
CURRENTLY IN THE CENTRAL ROCKIES MOVES TO THE NORTH TOWARD WESTERN
SOUTH DAKOTA. THE INTERACTION OF THE WAVE WITH THE FRONT SHOULD
RESULT IN THE RAPID DEVELOPMENT OF CONVECTION ACROSS NW SD OR SW ND
THIS EVENING WITH STORM SLIDING EAST SOUTH DAKOT TOWARD THE MBG AREA
LATER THIS EVENING.  AMPLE SHEAR...INSTABILITY AND SHEAR AVAILABLE
THIS EVENING FOR ANY CONVECTIONS THAT DEVELOPS WILL BE SUPERCELLULAR
INITIALLY. ONLY QUESTION BECOMES IS HOW QUICKLY BOUNDARY LAYER
STABILIZES TOWARD SUNSET. CURRENT THINKING IS THAT BOUNDARY LAYER
WILL STABILIZE QUICKLY ENOUGH SO THAT ONLY AN ISOLATED TORNADO
THREAT EXISTS THIS EVEING WEST OF MOBRIDGE. AFTER THE EVENING...
EXPECT THAT AN MCS WILL PROCEED ALONG THE ND/SD BORDER.  INITIAL
STORMS WILL BE SUPERCELLULAR AND LIKELY TO PRODUCE LARGE HAIL AS IT
PROCEEDS THROUGH THE AREA.  AS THE NIGHT GOES ON AND LLJ CONTINUES
TO FEED STORMS...THERE IS EXPECTED TO BE SOME HEAVY RAIN.  THE
GREATEST RISK OF HEAVY RAIN WILL BE ALONG AND NORTH OF HIGHWAY 12.
THE MCS SHOULD EXIT THROUGH NRN MN LATE TONIGHT OR EARLY TUESDAY
MORNING. WITH THE STRONG WINDS AND EXPECTED CLOUDS COVER...LOWS
OVERNIGHT WILL BE IN THE MID 60S.

WENT A LITTLE CLOSER TO GFS FOR SURFACE LOW/FRONTAL TIMING LATER
TUESDAY THROUGH WEDNESDAY...SHOWING A SECONDARY LOW CENTER
REDEVELOPING TOWARD SOUTH CENTRAL SOUTH DAKOTA IN THE AFTERNOON AS
NEXT SHORTWAVE APPROACHES THE AREA. FRONT MOVES SLOWLY EAST TO NEAR
EASTERN EDGE OF CWA TUESDAY NIGHT...THEN SHIFTS BACK TO THE WEST IN
RESPONSE TO STRONGER UPPER FORCING REMAINING WEST OF THE AREA.

WHAT THIS MEANS FOR PRECIP CHANCES IS WE SHOULD SEE A BREAK IN
PRECIP BEHIND EXITING MCS TUESDAY...BUT THEN COULD GET INTERESTING
AGAIN BY LATE TUESDAY AFTERNOON...AND MORESO OVERNIGHT TUESDAY
NIGHT. DEVELOPMENT DURING THE LATE AFTERNOON WILL REALLY DEPEND ON
CAPPING...AND WILL GO WITH HIGHEST POPS IN WESTERN CWA NEAR THE
FRONT...WITH JUST A SLIGHT CHANCE IN EASTERN AREAS. CHANCE OF SEVERE
TSRA STILL LOOKING GOOD FOR TOMORROW NIGHT /AND LATE AFTERNOON IF
ANYTHING DEVELOPS/...AND WILL CONTINUE MENTION OF POSSIBLE SEVERE IN
THE FORECAST. HAVE ENOUGH CONFIDENCE IN PRECIP CHANCES TO BUMP POPS
UP TO LIKELY MOST AREAS. HOWEVER...PLACEMENT OF HIGHEST POPS TRICKY
WITH SOME UNCERTAINTY OF WHERE BOUNDARIES FROM MORNING ACTIVITY WILL
LIE. FOR NOW...LEANING TOWARD POSSIBLE OUTFLOW OVER SOUTHERN CWA...
AND HAVE HIGHEST POPS FROM CENTRAL INTO NORTHEAST SECTIONS OF SD...
WITH CHANCE POPS IN THE NORTH CENTRAL PARTS OF THE STATE.

ANY MCS WHICH DEVELOPS TUESDAY NIGHT SHOULD EXIT EASTERN AREAS EARLY
WEDNESDAY MORNING...BUT WITH FRONT LINGERING IN/SHIFTING BACK INTO
EASTERN CWA DURING THE AFTERNOON...WILL CONTINUE WITH CHANCE OF TSRA
IN THE EAST AND SLIGHT CHANCE ELSEWHERE WEDNESDAY AFTERNOON AND
EARLY EVENING. BOTH ETA AND GFS SHOWING ANOTHER WAVE COMING INTO THE
AREA THURSDAY...ALTHOUGH AGAIN SOME DIFFERENCE IN PLACEMENT. MORE
UNCERTAINTY IN THIS...BUT FEEL AT LEAST SMALL CHANCE POPS WARRANTED
WITH THIS DURING THE DAY THURSDAY.

.LONG TERM...FRIDAY THROUGH MONDAY
LONGER RANGE MODELS SHOW PERSISTANCE OF WESTERN CONUS TROUGH/EASTERN
RIDGE THROUGH THE END OF THE WEEK...WITH WHAT APPEARS TO BE SOME
TRANSITION TO A MORE ZONAL PATTERN BY EARLY NEXT WEEK. HOWEVER...AS
HAS BEEN THE CASE IN RECENT DAYS...DIFFERENCES WITH SMALL SCALE
FEATURES ROTATING AROUND THE BASE OF THE UPPER TROUGH STILL MAKE
CONFIDENCE IN LONGER RANGE FORECAST SOMEWHAT LOW. FOR NOW...WILL GO
WITH DRY FORECAST FOR DAYTIME HOURS FRIDAY...WITH SLIGHT CHANCE OF
THUNDERSTORMS FRIDAY NIGHT AND SATURDAY AS ECMWF SHOWING FAIRLY
STRONG WAVE SLIDING ACROSS THE AREA. SOMEWHAT BETTER CHANCES DURING
LATTER HALF OF THE WEEKEND...WITH A CHANCE LINGERING ACROSS EASTERN
AREAS INTO THE DAY ON MONDAY. TEMPS COULD BE VERY DEPENDENT ON CLOUD
COVER IF WE HAVE NIGHTTIME RAINS LINGERING INTO THE DAY FOR ANY
LENGTH OF TIME...BUT WITH ENSEMBLES NOT SHOWING MUCH SPREAD IN
TEMPS...WILL GO FAIRLY CLOSE TO GFS GUIDANCE NUMBERS FOR NOW.

&&
.ABR WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
&&

 PS/JH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
ISSUED BY NATIONAL WEATHER SERVICE SIOUX FALLS SD
1150 AM AM CDT MON JUN 6 2005

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-071000-
BIG STONE-BROWN-BUFFALO-CAMPBELL-CLARK-CODINGTON-CORSON-DAY-DEUEL-
DEWEY-EDMUNDS-FAULK-GRANT-HAMLIN-HAND-HUGHES-HYDE-JONES-LYMAN-
MARSHALL-MCPHERSON-POTTER-ROBERTS-SPINK-STANLEY-SULLY-TRAVERSE-
WALWORTH-
1150 AM CDT MON JUN 6 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PARTS OF CENTRAL...NORTH
CENTRAL AND NORTHEAST SOUTH DAKOTA...AS WELL AS BIG STONE
AND TRAVERSE COUNTIES IN MINNESOTA.

.DAY ONE...TODAY AND TONIGHT

A MODERATE RISK OF SEVERE THUNDERSTORMS EXISTS FOR LATE THIS
AFTERNOON AND OVERNIGHT WEST OF THE MISSOURI RIVER AND NORTH OF
HIGHWAY 212. A SLIGHT RISK OF SEVERE THUNDERSTORMS EXISTS OVER THE
REMAINDER OF CENTRAL AND EASTERN SOUTH DAKOTA AS WELL AS WEST
CENTRAL MINNESOTA. THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE
WESTERN DAKOTAS LATE THIS AFTERNOON.  THESE STORMS WILL MOVE TOWARD
THE MISSOURI RIVER THIS EVENING...REACHING ABERDEEN...WATERTOWN AND
WHEATON AFTER MIDNIGHT.  WHILE AN ISOLATED TORNADO IS POSSIBLE WEST
OF MOBRIDGE THIS EVENING...THE PRIMARY THREAT WILL BE VERY LARGE
HAIL AND DAMAGING WINDS.  AS THE STORMS MOVE EAST OF THE JAMES RIVER
TOWARD MIDNIGHT...LARGE HAIL WILL BE THE PRIMARY THREAT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

A MODERATE RISK OF SEVERE THUNDERSTORMS EXISTS FOR TUESDAY AFTERNOON
AND EVENING ACROSS EASTERN SOUTH DAKOTA AND WEST CENTRAL MINNESOTA.
THIS COULD BE A SIGNIFICANT SEVERE WEATHER OUTBREAK WITH POTENTIAL
OF VERY LARGE HAIL...DAMAGING WINDS...AND ISOLATED TORNADOES.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED TONIGHT.

SCHUMACHER