Severe Thunderstorm Warning 69, NWS Aberdeen, SD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
222 PM CDT TUE JUL 7 2009

.SHORT TERM...TONIGHT
FORECAST CHALLENGE IS SEVERE CONVECTION.

CURRENTLY...A SURFACE LOW IS POSITIONED OVER CENTRAL SOUTH
DAKOTA...WITH A WARM FRONT EXTENDING OVER INTO PORTIONS OF EAST
CENTRAL AND SOUTHEASTERN SOUTH DAKOTA. GOOD DIABATIC HEATING NOTED
IN SURFACE OBS AND SATELLITE IMAGERY ALONG AND SOUTH OF THIS WARM
FRONTAL BOUNDARY. MOSTLY SUB-SEVERE CONVECTION HAS BEEN RUMBLING
THROUGH THE CWA TODAY.

THROUGH LATE THIS EVENING...SEVERE THUNDERSTORM CHANCES EXIST
ALONG THE WARM FRONT...AS WELL AS TRAILING OFF INTO SOUTH CENTRAL
SOUTH DAKOTA ALONG A SURFACE TROF EXTENDING DOWN FROM THE SURFACE
LOW. 0-6KM SHEAR IS MARGINAL FOR SUPPORTING LONG LIVED
SUPERCELLULAR THUNDERSTORMS. HOWEVER 0-1KM AND 0-3KM
SHEAR...COMBINED WITH THE AVAILABLE INSTABILITY SUGGESTS THAT A
SMALL POTENTIAL FOR TORNADOES TO DEVELOP EXISTS WITH INITIAL
THUNDERSTORMS LATE THIS AFTERNOON AND EARLY THIS EVENING...ALONG
WITH LARGE HAIL. DURING THE EVENING HOURS...WILL HAVE TO MONITOR
FOR THE POTENTIAL TO SEE THUNDERSTORMS ORGANIZING INTO MORE OF A
BOWING LINE SEGMENT OR TWO GIVEN THE MODEST 0-3KM SHEAR
ENVIRONMENT. SEVERE THUNDERSTORM WATCH 560 HAS BEEN ISSUED FOR
PORTIONS OF THE SOUTH AND SOUTHEASTERN FORECAST ZONES UNTIL 03Z
THIS EVENING.

OVERNIGHT LOWS WILL BE HIGHLY DEPENDENT UPON DURATION OF
CONVECTIVE DEBRIS CLOUD COVER. LOW TEMPERATURES SHOULD DROP INTO
THE 50S AND 60S.

.LONG TERM...WEDNESDAY THROUGH TUESDAY
FORECAST CHALLENGE MAINLY EVOLVES AROUND SEVERE POTENTIAL ON
WEDNESDAY NIGHT.

THE PERIOD BEGINS WITH A MID/UPPER LEVEL RIDGE OVER THE NORTHERN
PLAINS. AT THE SFC MODELS SHOW A FRONTAL BOUNDARY ALONG THE
NE/SD BORDER WITH A LOW FORMING OVER CENTRAL MONTANA. THE FRONTAL
BOUNDARY WILL LIFT NORTHWARD AS A WARM FRONT DURING THE DAY ON
WEDNESDAY. AS IT DOES MOISTURE WILL SURGE NORTHWARD ALONG WITH
INCREASING SOUTHERLY WINDS. BY WEDNESDAY NIGHT...TEMPS AT H7 WARM
TO +10C IN THE NORTHEAST TO +14 ALONG THE MISSOURI RIVER. THE CAP
WILL BE WEAKER ACROSS SOUTHWEST NORTHERN DAKOTA. THE
DESTABILIZATION WILL BE DUE TO AN IMPRESSIVE SHORT WAVE TROF THAT
MOVE INTO THE AREA. THE NOSE OF A 60 KNOT LLJ ALSO POINTS INTO
THAT LOCATION. THE 0-6KM BULK SHEAR VALUES INCREASE TO +60 KNOTS
OVER THE EXTREME NW CWA WITH 0-1KM BULK SHEAR VALUES OVER 45
KNOTS. THE DAY TWO OUTLOOK FOR SPC IS SHOWING A HIGH END SLIGHT
RISK FOR SEVERE STORMS ALONG THE ND/SD BORDER. RAPID THUNDERSTORM
DEVELOPMENT IS EXPECTED WITH SOME CAPABLE OF PRODUCING TORNADOES.

BEHIND THIS SYSTEM...HIGH PRESSURE BUILDS INTO THE REGION WITH THE
BOUNDARY LAYER STABILIZING. BY START OF THE NEXT WORK WEEK...GFS
ENSEMBLES BEGIN TO DIVERGE AS A SERIES OF SHORT WAVES TRAVERSE
ACROSS THE REGION.

&&

.AVIATION...
VFR CONDITIONS ARE EXPECTED TONIGHT. HOWEVER ISOLATED/SCT THUNDERSTORMS
COULD PRODUCE A BRIEF PERIOD OF HEAVY RAIN AND IFR CONDITIONS FOR
THE KATY TERMINAL THIS EVENING. BY TOMORROW MORNING...SOME
TERMINALS MAY SEE VISIBILITIES FALL TO 4SM WITH BR. GOOD VFR
CONDITIONS ARE EXPECTED THROUGHOUT THE DAY ON WEDNESDAY.

&&

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

SHORT TERM...DORN
LONG TERM...SD
AVIATION...SD

WEATHER.GOV/ABERDEEN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
331 AM CDT TUE JUL 7 2009

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-080845-
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-
331 AM CDT TUE JUL 7 2009 /231 AM MDT TUE JUL 7 2009/

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

.DAY ONE...TONIGHT

A FRONT SITUATED ACROSS THE REGION...ALONG WITH BOUNDARIES FROM
MORNING CONVECTION...WILL PROVIDE THE FOCUS FOR AFTERNOON
THUNDERSTORM DEVELOPMENT. THE ENVIRONMENT THESE STORMS WILL FORM
UNDER IS SUPPORTIVE FOR SUPERCELL DEVELOPMENT WITH THE MAIN
RISK BEING FOR HAIL AND HIGH WINDS...AND POSSIBLY AN ISOLATED
TORNADO.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THUNDERSTORM ACTIVITY IS POSSIBLE AGAIN WEDNESDAY NIGHT...WITH
MODELS INDICATING A FAST MOVING THUNDERSTORM COMPLEX EFFECTING THE
NORTHERN TIER OF THE STATE. THE MAIN THREAT FROM THIS COMPLEX IS
FOR HIGH WINDS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND EVENING.

CONNELLY

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ABERDEEN SD
1245 PM CDT TUE JUL 7 2009

SDZ010-017-018-071845-
EDMUNDS-FAULK-SPINK-
1245 PM CDT TUE JUL 7 2009

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED FOR EASTERN
FAULK...NORTHWESTERN SPINK AND SOUTHEASTERN EDMUNDS COUNTIES UNTIL
145 PM CDT...

AT 1243 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR CRESBARD...OR 17 MILES NORTHEAST OF
FAULKTON...MOVING SOUTHEAST AT 30 MPH.

A FEW LOCATIONS IN THE ADVISORY INCLUDE DEVOE...CHELSEA...MIRANDA...
NORTHVILLE...ROCKHAM...MELLETTE...ATHOL AND ASHTON.

PENNY TO NICKEL SIZE HAIL...AND WINDS AROUND 40 TO 50 MPH ARE
EXPECTED WITH THIS STORM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS. IF YOU CAN HEAR
THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

&&

FOWLE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ABERDEEN SD
116 PM CDT TUE JUL 7 2009

SDZ010-017-018-071820-
EDMUNDS-FAULK-SPINK-
116 PM CDT TUE JUL 7 2009

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED FOR EASTERN
FAULK...NORTHWESTERN SPINK AND SOUTHEASTERN EDMUNDS COUNTIES UNTIL
145 PM CDT...

AT 1243 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR CRESBARD...OR 17 MILES NORTHEAST OF
FAULKTON...MOVING SOUTHEAST AT 30 MPH.

A FEW LOCATIONS IN THE ADVISORY INCLUDE DEVOE...CHELSEA...MIRANDA...
NORTHVILLE...ROCKHAM...MELLETTE...ATHOL AND ASHTON.

PENNY TO NICKEL SIZE HAIL...AND WINDS AROUND 40 TO 50 MPH ARE
EXPECTED WITH THIS STORM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS. IF YOU CAN HEAR
THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

&&

FOWLE

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE ABERDEEN SD
122 PM CDT TUE JUL 7 2009

SDZ018-019-071845-
CLARK-SPINK-
122 PM CDT TUE JUL 7 2009

...A SIGNIFICANT WEATHER ADVISORY HAS BEEN ISSUED FOR CENTRAL SPINK
AND NORTHWESTERN CLARK COUNTIES UNTIL 145 PM CDT...

AT 121 PM CDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM NEAR MELLETTE...OR 19 MILES NORTH OF REDFIELD...
MOVING SOUTHEAST AT 25 MPH.

A FEW LOCATIONS IN THE ADVISORY INCLUDE ASHTON...REDFIELD...TURTON...
FRANKFORT...AND DOLAND.

PENNY TO NICKEL SIZE HAIL...AND WINDS AROUND 40 TO 50 MPH ARE
EXPECTED WITH THIS STORM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

LIGHTNING IS ONE OF NATURES NUMBER ONE KILLERS. IF YOU CAN HEAR
THUNDER...YOU ARE CLOSE ENOUGH TO BE STRUCK BY LIGHTNING.

&&

FOWLE

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