Hail and Damaging Winds in South Dakota, June 6, 2007

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
335 PM CDT WED JUN 6 2007

.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT
FOCUS CONTINUES TO BE ON THUNDERSTORM/SEVERE THUNDERSTORM
POTENTIAL ACROSS THE CWA TONIGHT INTO EARLY THURSDAY MORNING.
POTENT UPPER LEVEL SYSTEM CONTINUES TO TRACK THROUGH THE
CENTRAL/NORTHERN ROCKIES...WITH A LEADING ASSOCIATED SHORTWAVE
PUSHING INTO CENTRAL WYOMING. LOW PRESSURE AT THE SURFACE
CURRENTLY CENTERED ACROSS WESTERN SOUTH DAKOTA/WESTERN NEBRASKA.
STRONG SOUTHERLY/SOUTHEASTERLY FLOW CONTINUES TO SEND WARM AND
MOIST AIR NORTHWARD INTO THE CENTRAL AND EASTERN DAKOTAS. AN UPPER
LEVEL 100KT JET WILL EJECT NORTHEASTWARD THIS EVENING INTO
TONIGHT...WITH THE LEFT-EXIT QUADRANT NOSING INTO THE CENTRAL
DAKOTAS BY 00-03Z AND INTO THE EASTERN DAKOTAS BY 06Z
TONIGHT HELPING ENHANCE THE UVM THROUGH THE NIGHT. AS THE SFC LOW
TRACKS EASTWARD THROUGH THE NIGHT...IT WILL DEEPEN WHICH WILL
ALLOW FOR STRONG FLOW AT THE SURFACE THROUGH THE NIGHT. RUC ALSO
ADVERTISING CLOSE TO 50-70KT LLJ DEVELOPING ACROSS THE EASTERN
DAKOTAS BY LATE EVENING INTO THE OVERNIGHT HOURS. WITH THE STRONG
FLOW IN THE LOWER AND MID LEVELS...0-6 KM SHEAR VALUES WILL HOVER
AROUND 40KT...WITH SOME LOCATIONS ACROSS CENTRAL SD APPROACHING
60KT BY 06Z TONIGHT. ONLY DRAWBACK TO THUNDERSTORM POTENTIAL IS
STRONG CAP CURRENTLY IN PLACE ACROSS THE CWA. 18Z SOUNDINGS FROM
KABR AND KUNR INDICATED AROUND 300-500 J/KG OF CINH...AS THE
LATE AFTERNOON/EVENING PROGRESSES CAA IN THE MID LEVELS IS
EXPECTED TO REDUCE THE STRENGTH OF THE CAP. ALSO...ANY REMAINING
CAP SHOULD BE ABLE TO BE ERODED DUE TO THE STRENGTH OF THE UPWARD
MOTION EXPECTED WITH THIS SYSTEM.

AS THE EXPECTED THUNDERSTORMS PROGRESS ACROSS THE CWA...A
TRANSITION TO MORE OF SQUALL LINE TYPE FEATURE IS EXPECTED WITH
DAMAGING WINDS BECOMING AN INCREASING THREAT TOWARD LATE EVENING
INTO THE OVERNIGHT HOURS. DECENT VEERING IN THE LOW LEVEL WIND
PROFILE ALONG WITH STRONG 0-1KM SHEAR SHOW THE THREAT FOR
TORNADOES DOES EXIST ACROSS THE ENTIRE CWA...HOWEVER IT IS THE
GREATEST ACROSS CENTRAL AND NORTH CENTRAL SOUTH DAKOTA WHERE MORE
SUPERCELLULAR TYPE THUNDERSTORMS ARE POSSIBLE.

AS FOR THE REMAINDER OF THE SHORT TERM...THE UPPER LEVEL SYSTEM
CURRENTLY OVER THE ROCKIES WILL CONTINUE TO PUSH THROUGH THE
NORTHERN PLAINS...WITH AN ASSOCIATED COLD FRONT SLIDING THROUGH
DURING THE DAY. STRONG NORTHWEST WINDS ARE EXPECTED BEHIND THIS
FRONT...WITH A POSSIBLE WIND ADVISORY NEEDED FOR THE AFTERNOON
INTO THE EARLY EVENING HOURS. H85 WINDS OF 45-50 KT MAY TRANSLATE
DOWN TO THE SURFACE GIVING SUSTAINED WINDS OF 25 TO 35 MPH OR
HIGHER. LATEST MODEL RUNS ADVERTISE SYSTEM EXITING SLIGHTLY
QUICKER THAN PREVIOUSLY THOUGHT...SO DID END POPS EARLIER.
OTHERWISE HIGH PRESSURE BUILDS INTO THE REGION FOR FRIDAY INTO
FRIDAY NIGHT.

.LONG TERM...SATURDAY THROUGH WEDNESDAY

THE PRIMARY FORECAST CHALLENGES IN THE LONG TERM REVOLVE MOSTLY
AROUND PRECIPITATION CHANCES AND TEMPERATURES.

SATURDAY MORNING...500MB FLOW PATTERN IS PRIMARILY ZONAL OVER THE
CWA...WITH SPLIT FLOW OVER THE WEST COAST INVOLVING A SLIGHT RIDGE
OVER WESTERN CANADA AND A CUTOFF LOW OFF THE SOUTHERN CALIFORNIA
COAST. AT THE SURFACE...SURFACE HIGH PRESSURE HAS MOVED EAST AND
THE CWA IS IN LIGHT SOUTHERLY SURFACE FLOW WITH A SUBTLE TROUGH
THROUGHOUT THE AREA. THE GFS/ECMWF AGREE ON BRINGING AN UPPER LOW
JUST OFFSHORE THE QUEEN CHARLOTTE ISLANDS OFF THE BRITISH COLUMBIA
COAST SATURDAY AND SATURDAY NIGHT...BEFORE DIVING THE LOW INTO THE
PACIFIC NORTHWEST MONDAY INTO TUESDAY. THE ECMWF IS A BIT STRONGER
AND FURTHER EAST WITH THIS TROUGH...WITH A 500MB LOW OVER
NORTHWEST MONTANA WHILE THE GFS KEEPS THE TROUGH CENTER MORE OVER
SOUTHEAST CANADA AT THE SAME TIME. THIS IS PRETTY DIVERGENT FROM
THE 06Z GFS RUN...IN WHICH THE GFS WAS MOVING THE TROUGH THROUGH
FASTER THAN THE 00Z ECMWF. IN THE MEANTIME...A LONG WAVE TROUGH
DEVELOPS OVER THE WESTERN UNITED STATES WITH THIS CWA PRIMARILY IN
WEST/SOUTHWEST FLOW BECOMING MORE SOUTHWESTERLY BY TUESDAY
MORNING. LEE SURFACE PRESSURE DEVELOPS SUNDAY OVER THE WESTERN
PLAINS IN RESPONSE TO THIS LONG WAVE TROUGH. WITH CURRENT PROJECTED
SLOW/STATIONARY MOVEMENT OF THE TROUGH...SURFACE LOW PRESSURE
REMAINS VIRTUALLY PARKED OVER THE CENTRAL THIRD OF THE COUNTRY
THROUGHOUT THE WEEK...LEAVING EXTENDED CHANCES OF RAIN AND
THUNDERSTORMS THROUGHOUT THE WEEK. THE GFS DEPICTS SEVERAL WAVES
MOVING NORTH DURING THE TIME PERIOD...WHILE KEEPING THE GENERAL
AREA OF LOW PRESSURE OVER THE PLAINS. THIS SETUP WILL HAVE TO BE
MONITORED IN LATER FORECAST PACKAGES AS THIS COULD BE A SETUP FOR
HEAVY RAIN CHANCES OVER AREAS OF THE PLAINS.

TEMPERATURE WISE...AS SOUTHERLY FLOW SETS UP SATURDAY/SUNDAY ON
THE BACKSIDE OF THE EXITING HIGH PRESSURE AND IN ADVANCE OF THE
LOW PRESSURE IN THE WESTERN PLAINS...WARM AND HUMID AIR IS SET TO
ADVANCE NORTHWARD INTO THE AREA. NEW 12Z GFS MODEL 850MB
TEMPERATURE PROGS/MEX GUIDANCE SUGGEST A MUCH WARMER SETUP THAN
PREVIOUS RUNS...HOWEVER...SINCE THIS RUN IS MUCH SLOWER AND NOW MORE
IN LINE WITH THE 00Z ECMWF AND 00Z/12Z CANADIAN MODEL RUNS ON THE
TROUGH DIGGING INTO THE NORTHWEST...THIS POTENTIAL COULD BE
REALIZED. RAISED TEMPERATURES INTO NEXT WEEK BUT DID NOT GO NEARLY
AS HIGH AS THE NEW 12Z MEX GUIDANCE...WHICH IS INDICATING HIGHS
90-95F ACROSS THE AREA BY MONDAY WITH 850MB TEMPERATURES HOVERING
AROUND 24-26C LATE SUNDAY THROUGH LATE TUESDAY.

&&
.AVIATION...
THUNDERSTORMS ARE EXPECTED TO DEVELOP IN THE EARLY EVENING HOURS
WEST OF THE MISSOURI RIVER...AND THEN TRACK EASTWARD ACROSS THE
REST OF THE CWA DURING THE LATE EVENING AND OVERNIGHT HOURS.
SEVERE WEATHER IS ANTICIPATED ACROSS MUCH OF THE REGION AFTER 00Z.
AREAS OUTSIDE OF THUNDERSTORMS WILL REMAIN VFR...HOWEVER...STRONG
WINDS ARE EXPECTED TO CONTINUE THROUGHOUT THE NIGHT...WELL INTO
THURSDAY FOR THE ENTIRE REGION.

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

SHORT TERM...ALBRECHT
LONG TERM...ECKSTEIN
AVIATION...ECKSTEIN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
438 AM CDT WED JUN 6 2007

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-070945-
TRAVERSE-BIG STONE-CORSON-CAMPBELL-MCPHERSON-BROWN-MARSHALL-
ROBERTS-WALWORTH-EDMUNDS-DAY-DEWEY-POTTER-FAULK-SPINK-CLARK-
CODINGTON-GRANT-HAMLIN-DEUEL-STANLEY-SULLY-HUGHES-HYDE-HAND-JONES-
LYMAN-BUFFALO-
438 AM CDT WED JUN 6 2007 /338 AM MDT WED JUN 6 2007/

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF WEST CENTRAL
MINNESOTA...CENTRAL SOUTH DAKOTA...NORTH CENTRAL SOUTH DAKOTA AND
NORTHEAST SOUTH DAKOTA.

.DAY ONE...TODAY AND TONIGHT

A STRONG STORM SYSTEM WILL MOVE EAST ACROSS THE DAKOTAS THIS
EVENING AND OVERNIGHT. SEVERE THUNDERSTORMS ARE LIKELY ACROSS
WESTERN SOUTH DAKOTA LATE THIS AFTERNOON...MOVING INTO PARTS OF
CENTRAL SOUTH DAKOTA THIS EVENING. LARGE HAIL AND STRONG WINDS
ARE POSSIBLE...ALONG WITH A FEW TORNADOES. THE SEVERE THREAT WILL
SHIFT EAST OVERNIGHT TOWARDS THE JAMES RIVER VALLEY AND POINTS
EAST. STRONG WINDS AND LARGE HAIL WILL BE THE PRIMARY
THREATS...ALTHOUGH AN ISOLATED TORNADO OR TWO CANNOT BE RULED OUT.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS ARE POSSIBLE THURSDAY AFTERNOON BUT SEVERE WEATHER
IS NOT ANTICIPATED AT THIS TIME. CHANCES FOR THUNDERSTORMS ALSO
EXIST LATE THIS WEEKEND AND INTO EARLY NEXT WEEK.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL LIKELY BE NEEDED ACROSS CENTRAL SOUTH
DAKOTA LATE THIS AFTERNOON AND EVENING.

SPOTTER ACTIVATION MAY BE NECESSARY ACROSS EASTERN SOUTH DAKOTA
AND WEST CENTRAL MINNESOTA AFTER SUNSET AND CONTINUING THROUGH THE
OVERNIGHT HOURS.

TT