Severe Thunderstorm Warning 193, NWS Aberdeen, SD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
300 PM CDT MON JUL 28 2008

.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT
A TOUGH FORECAST FOR THE INITIAL PERIOD. MODELS ARE HIGHLY
DIFFERENT ON EVOLUTION OF POTENTIAL CONVECTION LATE THIS AFTERNOON
AND TNT. GFS KEEPS IT CAPPED WITH MOST CONVECTION OVER NORTH
DAKOTA. MEANWHILE NAM/LOCAL WRF STILL MAINTAIN DECENT CHC OF
STORMS OVER CWA. 18Z SOUNDING WAS STILL CAPPED BUT THAT CAP SHOULD
BE OVERCOME WITH SLIGHT HEIGHT FALLS ALOFT AND CONTINUED SURFACE
HEATING. OUTFLOW BOUNDARY FROM EARLIER CONVECTION OVER NORTH
DAKOTA HAS SLID WELL SOUTH INTO THE CWA. PER SAT PIX AND OBS...IT
APPEARS TO EXTEND FROM JUST SOUTH OF GROTON SOUTHWEST TO NORTH OF
PIR. IT IS PROBABLY GOING THROUGH SOME FRONTOLYSIS BUT IS STILL
THE PRIME SPOT FOR ANY SPIN-UPS THAT MIGHT OCCUR THIS EVENING.
OTHERWISE WIDESPREAD INSTABILITY/HIGH MOISTURE AND DECENT SHEAR
PROFILES SUGGEST WE SHOULD GET SOME STRONG/SEVERE STORMS LATE THIS
AFTERNOON AND EVENING. WET BULBS AND FREEZING LEVELS ARE HIGH SO
WIND MIGHT BE THE MAIN THREAT WITH ACTIVITY ONCE IT CONGEALS INTO
A POTENTIAL MCS. BY 6Z MOST OF THE ACTIVITY SHOULD HAVE SHIFTED OFF
TO THE EAST AND SOUTH OF THE CWA. BEHIND THIS SYSTEM SURFACE HIGH
BUILDS IN ON TUESDAY FOR A REFRESHING BREAK FROM HUMIDITY OF PAST
COUPLE DAYS. HOWEVER IT WILL STILL REMAIN RATHER WARM. FOR LATE
TUESDAY NIGHT THROUGH WEDNESDAY NIGHT RETURN FLOW SETS UP WITH
SOME POTENTIAL FOR TSRAS. HOWEVER BUILDING RIDGE ALOFT OVER THE
REGION AHEAD OF PACIFIC NORTHWEST S/W WILL PROBABLY LIMIT COVERAGE
OF STORMS...SO FOR NOW NOTHING MORE THAN A SLIGHT CHANCE IS
WARRANTED. CONCERNING TEMPERATURES...ONCE AGAIN MAV APPEARS TO BE
TOO MUCH AFFECTED BY CLIMO. MUCH OF THE CWA IS STILL PRETTY GREEN
AND THIS IS KEEPING TEMPERATURES FROM CLIMBING AS MUCH AS THEY
MIGHT OTHERWISE HAVE...ESPECIALLY OVER WESTERN PORTIONS OF THE
CWA.

.LONG TERM...WEDNESDAY THROUGH MONDAY
THE MAIN CHALLENGE IN THE EXTENDED CENTERS AROUND PRECIPITATION
CHANCES THROUGHOUT THE PERIOD. THE PERIOD BEGINS WITH VIRTUALLY
ZONAL FLOW/SLIGHTLY RIDGED ALOFT ACROSS THE NORTHERN HIGH PLAINS.
FAIRLY DEEP TROF SETS UP ACROSS THE EASTERN CONUS...WHICH DOES NOT
TELECONNECT WELL WITH THE WEAK RIDGE. SEVERAL MID LEVEL WAVES RIDE
ACROSS THE NORTHERN PLAINS...AND DOWN INTO THE TROF. HAVE KEPT
SLIGHT POPS OVER THE EASTERN CWA...WERE THE WEAKER CAPE WILL BE.
TURNING TOWARDS THE WEEKEND...THE GFS SHOWS A MORE PRONOUNCED MID
LEVEL TROF MOVING ACROSS THE REGION...WITH A SURFACE FRONTAL
BOUNDARY BOUNCING BACK AND FORTH. RATHER DIFFICULT TO PINPOINT
TIMING OF POP/WX...SO HAVE GONE MOSTLY DRY FOR THE EXTENDED. THE
BEST CHANCES LOOK TO BE SATURDAY NIGHT ACROSS THE EAST...THEN
SUNDAY NIGHT ACROSS THE WEST. FOR SATURDAY NIGHT...THE LLJ IS
SHOWN TO BE 40-50KTS...HOWEVER H7 TEMPS ARE +16 TO +18C. FAIRLY
STRONG COLD FRONT MOVES ACROSS THE CWA ON SUNDAY...HOWEVER EXPECT
THE FRONT TO PASS DRY.

&&
.AVIATION...
BKN-OVC IFR LEVEL CLOUDS WILL CONTINUE TO POSE AS A PROBLEM THIS
EVENING ACROSS THE CWA. SHOWERS AND THUNDERSTORM ARE EXPECTED ACROSS
THE REGION THIS EVENING. RATHER DIFFICULT TO PINPOINT THE OVERALL
TIMING AND LOCATION OF THUNDERSTORMS SO ALL SITES HAVE VCTS. WITH
CLEARING SKIES FOR ANTICIPATED TOMORROW MORNING AND LIGHT
WINDS...HAVE MENTIONED A TEMPO PERIOD OF 4-5SM BR IN KMBG AND
KPIR. EXPECT VFR CONDITIONS ON TUESDAY.
&&

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

SHORT TERM...TDK
LONG TERM...SD
AVIATION...SD

WEATHER.GOV/ABERDEEN

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE ABERDEEN SD
850 AM CDT MON JUL 28 2008

MNZ039-046-SDZ003>011-015>023-033>037-045-048-051-291400-
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-
850 AM CDT MON JUL 28 2008 /750 AM MDT MON JUL 28 2008/

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

SEVERE THUNDERSTORMS ARE POSSIBLE THROUGHOUT THE FORECAST AREA THIS
AFTERNOON INTO TONIGHT. LARGE HAIL...DAMAGING THUNDERSTORM WIND
GUSTS AND POSSIBLY EVEN ISOLATED TORNADOES POSE THE MAIN THREATS
WITH STORMS TODAY AND TONIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

THUNDERSTORMS...SOME POSSIBLY SEVERE...ARE EXPECTED AGAIN ON
WEDNESDAY AND WEDNESDAY NIGHT.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON AND TONIGHT.

TDK