Hail and Damaging Winds in South Dakota, August 3, 2010

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
340 PM CDT TUE AUG 3 2010

.SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT
THE MAIN FORECAST CHALLENGE IS THE TIMING OF THE COOLER AND DRIER
THAT WILL INVADE THE REGION FROM NORTHERN CANADA. MODEL PREFERENCE WAS
A BLEND OF 0Z ECMWF/9Z SREF/12Z NAM. THE 12Z GFS WAS OVERLY
AGGRESSIVE WITH RETURN FLOW DEVELOPING AS EARLY AS 0Z FRIDAY AND
WAS THEREFOR REJECTED.

AS OF 19Z SHOWERS AND THUNDERSTORMS...SOME OF WHICH ARE
SEVERE...ARE ONGOING ACROSS WESTERN SOUTH DAKOTA. THE STRONGEST
STORMS ARE SLOWLY BUILDING SOUTHEAST OF THE LINE...OR TOWARDS
BETTER INSTABILITY. A SURFACE HIGH PRESSURE AND WEAK NORTHEAST
WINDS SHOULD KEEP MOST OF THE SEVERE WEATHER ACROSS SW AND SOUTH
CENTRAL SOUTH DAKOTA THIS AFTERNOON/EVENING. WILL MAINTAIN HIGH
POPS THROUGH MOST OF THE TONIGHT PERIOD AS DRIER AIR FILTERS INTO
THE REGION FROM THE NORTHWEST.

WEDNESDAY WILL FEATURE THE CONTINUATION OF THE INFLUX OF COOLER
DRIER AIR WITH BOUNDARY LAYER DEW POINTS DROPPING FROM THE MID
60S...TO THE MID 50S BY 0Z THURSDAY. WITH THE ATMOSPHERE BECOMING
INCREASINGLY MORE STABLE DURING THE AFTERNOON HOURS...HAVE REDUCED
POPS TO SCHC CWA WIDE.

THE NEXT POSSIBILITY FOR WEATHER COULD BE THURSDAY NIGHT ACROSS THE
SW CWA...OR ALONG I90. BOTH THE SREF AND NAM SHOW A LLJ DEVELOPING
AFTER 06Z FRIDAY ACROSS WESTERN SOUTH DAKOTA. WHILE THE OVERALL
AMOUNT OF AVAILABLE MOISTURE APPEARS PRETTY LOW...WILL INTRODUCE
SCHC POPS FOR NOW WITH THE BELIEF THAT MORNING ACCAS COULD
DEVELOP.

.LONG TERM...FRIDAY THROUGH TUESDAY
THE MODELS AND GFS ENSEMBLES AGREE REAL WELL THROUGH THE LONG TERM
WITH THE UPPER LEVEL FLOW ACROSS OUR REGION. A 50H UPPER LEVEL
RIDGE AXIS OUT WEST EARLY ON WILL BUILD EAST AND PARK ACROSS THE
CENTRAL PART OF THE US BY SATURDAY AND REMAIN THROUGH TUESDAY.
THE MODELS AND ENSEMBLES ALSO SHOW 50H UPPER LEVEL TROUGHING
ACROSS THE WESTERN US THROUGH THIS TIME PERIOD. SEVERAL SHORT
WAVES WILL COME OFF THIS TROUGH AND UP AND OVER THE RIDGE AXIS IN
THE CENTRAL PART OF THE US BRINGING SEVERAL CHANCES OF SHRAS/TSRAS
TO THE REGION. WITH THIS UPPER LEVEL RIDGING AND PLENTY OF
SUNSHINE...TEMPERATURES WILL BE NEAR TO SLIGHTLY ABOVE NORMAL FOR
THIS TIME OF YEAR WITH HIGH HUMIDITY REMAINING.

&&

.AVIATION...
TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS

VFR CONDITIONS ARE EXPECTED FOR ALL TAF LOCATIONS THROUGH TONIGHT
AND WEDNESDAY MORNING. A SHORT WAVE TROUGH SLIDING ACROSS THE
REGION THROUGH TONIGHT WILL BRING SCT SHRAS/TSRAS TO THE AREA. SOME
OF THESE MAY AFFECT THE TAF LOCATIONS. WILL WATCH DEVELOPMENT AND
AMEND IF NECESSARY.

&&

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

SHORT TERM...SD
LONG TERM...MOHR
AVIATION...MOHR

WEATHER.GOV/ABERDEEN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
353 AM CDT TUE AUG 3 2010

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-040900-
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-
353 AM CDT TUE AUG 3 2010 /253 AM MDT TUE AUG 3 2010/

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

AFTERNOON THUNDERSTORMS...PRIMARILY ACROSS WESTERN SOUTH
DAKOTA...WILL TRANSITION EAST THROUGH THE COURSE OF THE AFTERNOON
AND EVENING. THE SEVERE RISK SHOULD BE CONFINED WEST OF THE
MISSOURI RIVER WITH THE MAIN THREATS BEING LARGE HAIL AND DAMAGING
WINDS. FURTHER EAST...AN ISOLATED STORM OR TWO COULD FORM...WITH
THE MAIN THREAT BEING LIGHTNING. THUNDERSTORMS WILL CONTINUE EAST
OVERNIGHT...BUT THE RISK FOR SEVERE WEATHER WILL HAVE DIMINISHED
GREATLY BY THE LATE EVENING.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

THUNDERSTORM CHANCES CONTINUE IN THE FORECAST FOR WEDNESDAY AND
THE UPCOMING WEEKEND. THE RISK FOR SEVERE WEATHER IS EXPECTED TO
BE LIMITED DURING THIS TIME PERIOD.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE REQUIRED LATE THIS AFTERNOON FOR WEST
RIVER COMMUNITIES.

CONNELLY