Hail in South Dakota, August 26, 2008

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
322 PM CDT TUE AUG 26 2008

.SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT
MAIN FORECAST CHALLENGE IS THUNDERSTORM CHANCES TONIGHT AND WHERE
AND IF ANY OF THE STORMS WILL BE SEVERE. A FAIRLY STRONG SHORTWAVE
ASSOCIATED WITH AN UPPER LEVEL TROUGH CURRENTLY OVER THE
NORTHWESTERN PART OF THE COUNTRY WILL EJECT FROM EASTERN MONTANA
ACROSS NORTH DAKOTA TONIGHT. A SURFACE COLD FRONT CURRENTLY OVER
WESTERN SOUTH DAKOTA WILL STEADILY TRACK EASTWARD OVERNIGHT...AND
LOOKS TO BE THE FOCUS FOR THUNDERSTORM DEVELOPMENT. THE REGION HAS
BEEN UNDER A DECENT CAP ALL DAY...BUT SHOULD SEE IT BEGIN TO BREAK
DOWN ACROSS THE WESTERN CWA DURING THE REMAINDER OF THE AFTERNOON
AND INTO THE EARLY EVENING HOURS. AN AXIS OF
INSTABILITY...1000-2000 J/KG OF CAPE AND -2 TO -4 LIS...DEVELOPS
ALONG THE FRONT AS IT PUSHES TO THE WESTERN CWA THIS
EVENING...MAKING THAT AREA THE FOCUS OF THE BEST POTENTIAL FOR
SEVERE STORMS TO DEVELOP. WILL KEEP A MENTION OF T+ GOING OVER
PORTIONS OF THE WESTERN CWA DURING THE EVENING HOURS...AND EXPECT
LARGE HAIL TO BE THE MAIN THREAT. BY 06Z...THE INSTABILITY BEGINS
TO WANE. HOWEVER...AS A 30 TO 40 KNOT LLJ DEVELOPS OVER THE
EASTERN CWA AND THE CAP BEGINS TO WEAKEN IN THAT AREA...EXPECT TO
SEE AN AREA OF RAIN WITH EMBEDDED NON-SEVERE THUNDERSTORMS PUSH
ACROSS THE CENTRAL AND EASTERN CWA OVERNIGHT. MAY SEE A FEW
LINGERING SHOWERS OVER THE EXTREME EASTERN CWA EARLY WEDNESDAY
MORNING...THEN AN AREA OF WEAK HIGH PRESSURE SLIDES OVER THE
NORTHERN PLAINS. ANOTHER SURFACE TROUGH APPROACHES THE REGION
WEDNESDAY NIGHT...BUT MODELS ARE NOT IN GOOD AGREEMENT WITH
TIMING...SO HAVE OPTED TO STICK WITH PERSISTENCE AND LEAVE
WEDNESDAY NIGHT DRY FOR NOW.

BIGGEST STORY WITH TEMPERATURES WILL BE SIGNIFICANTLY COOLER AIR
MOVING IN BEHIND THE EXITING FRONT ON WEDNESDAY. H85 TEMPS FALL
INTO THE +8 TO +14 RANGE...RESULTING IN HIGH TEMPERATURES IN THE
70S CWA WIDE.

.LONG TERM...THURSDAY THROUGH TUESDAY
MODELS STILL IN GOOD AGREEMENT WITH UPPER FLOW THROUGH THE
WEEKEND...AND BEGIN TO DIVERGE ON HOW BEST TO HANDLE UPPER TROUGH
PASSING ACROSS THE NORTHERN CONUS FOR THE START OF NEXT WEEK.
ECMWF SEEMS TO HAVE BEST RUN TO RUN CONTINUITY WITH THIS
FEATURE...WHICH WILL BRING THE BEST CHANCE FOR PRECIPITATION...BUT
BETWEEN HERE AND THERE WE WILL HAVE TO DEAL WITH TWO OTHER SYSTEMS
DURING THIS PERIOD.

WILL BEGIN PERIOD WITH BROAD UPPER TROUGH OVERHEAD...AND EMBEDDED
SECONDARY SHORTWAVE MOVING ACROSS THE CWA. THIS REFLECTS DOWN TO
THE SURFACE AS A WEAK TROUGH BEHIND DOWNSTREAM COLD FRONT. PROFILE
MOISTURE MARGINAL FOR DIURNALLY DRIVEN CONVECTION...HOWEVER STEEP
MID LEVEL LAPSE RATES WARRANT INCLUSION OF SLIGHT CHANCE FOR
NORTHEAST COUNTIES THROUGH THE EARLY AFTERNOON AFTER WHICH FEATURE
WILL HAVE MOVED OUT OF THE CWA. GFS IS FASTER WITH THIS SYSTEM
OVER NAM GUIDANCE.

SECOND FEATURE TO DISCUSS WILL BE NORTHWEST FLOW SHORTWAVE MOVING
ACROSS NORTH DAKOTA/MINNESOTA FRIDAY. RESULTING SURFACE
REFLECTION...A WEAK COLD FRONT...IS ALSO MOISTURE STARVED WITH
BEST MID LEVEL FORCING/MOISTURE INTO MINNESOTA DURING PEAK HEATING.

TEMPERATURES THIS PERIOD...WITH SEE COOL NW FLOW FOR THE FIRST
PART TO START OFF...WITH GRADUAL WARMING TREND LASTING INTO THE
WEEKEND. TEMPERATURES COOL OFF FOR THE START OF NEXT WEEK AS UPPER
TROUGH MOVES INTO THE REGION.

&&

.AVIATION...
VFR CONDITIONS WILL PREVAIL THROUGH THE EARLY EVENING HOURS
ACROSS THE CWA. SCT MID TO HIGH CLOUDS AOA 10K FEET WILL TRACK
FROM THE WESTERN CWA TO THE EASTERN CWA. VSBYS WILL BE UNRESTRICTED.
SOUTHERLY SURFACE WINDS WILL BE IN THE 20 TO 35 KNOT RANGE AT ALL
TAF SITES THROUGH EARLY EVENING...THEN WILL DIMINISH INTO THE 15
TO 20 MPH RANGE AFTER SUNSET. WITH THE APPROACH OF A COLD
FRONT...THUNDERSTORMS ARE EXPECTED TO DEVELOP AT OR NEAR THE KPIR
AND KMBG TAF SITES AFTER 00Z...WITH A BROAD AREA OF RAIN AND
EMBEDDED THUNDERSTORMS TRACKING EASTWARD OVERNIGHT...LIKELY
AFFECTING KABR BY 03Z AND KATY BY 04Z. CIGS AND VSBYS WILL
POTENTIALLY FALL INTO THE MVFR OR HIGH IFR CATEGORY WITH THE
STRONGER STORMS. WINDS WILL ALSO SHIFT AROUND TO THE NORTHWEST AS
THE FRONT PASSES.

&&

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

SHORT TERM...PARKIN
LONG TERM...CONNELLY
AVIATION...PARKIN

WEATHER.GOV/ABERDEEN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
503 AM CDT TUE AUG 26 2008

SDZ003>006-009-010-015>018-033>037-045-048-051-271015-
CORSON-CAMPBELL-MCPHERSON-BROWN-WALWORTH-EDMUNDS-DEWEY-POTTER-
FAULK-SPINK-STANLEY-SULLY-HUGHES-HYDE-HAND-JONES-LYMAN-BUFFALO-
503 AM CDT TUE AUG 26 2008 /403 AM MDT TUE AUG 26 2008/

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

.DAY ONE...TODAY AND TONIGHT

A COLD FRONT WILL APPROACH CENTRAL SOUTH DAKOTA DURING THE LATE
AFTERNOON AND EARLY EVENING HOURS. SCATTERED THUNDERSTORMS ARE
EXPECTED ALONG THIS FRONT...SOME OF WHICH COULD BECOME STRONG TO
SEVERE WITH LARGE HAIL AND GUSTY WINDS IN EXCESS OF 55 MPH. THESE
STORMS WILL MOVE EAST THROUGH THE EVENING...APPROACHING THE JAMES
VALLEY AFTER DARK WHILE LOSING THEIR INTENSITY.

STRONG SOUTH WINDS FROM 20 TO 35 MPH WILL BE FOUND TODAY ACROSS
CENTRAL AND EASTERN SOUTH DAKOTA. GUSTS WILL REACH 40 TO 45 MPH.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY AFTER 5 PM CDT /4 PM MDT/ FOR
COUNTIES BORDERING THE MISSOURI RIVER ACROSS NORTH CENTRAL SOUTH
DAKOTA.

MNZ039-046-SDZ007-008-011-019>023-271015-
TRAVERSE-BIG STONE-MARSHALL-ROBERTS-DAY-CLARK-CODINGTON-GRANT-
HAMLIN-DEUEL-
503 AM CDT TUE AUG 26 2008

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE POSSIBLE AFTER DARK AS A COLD FRONT TRACKS
EASTWARD ACROSS THE AREA. STORMS ARE NOT EXPECTED TO BE SEVERE BUT
A FEW COULD BE ON THE STRONG SIDE WITH SMALL HAIL AND WIND GUSTS
NEAR 45 MPH.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

A SLIGHT CHANCE FOR THUNDERSTORMS EXISTS ACROSS NORTHEASTERN SOUTH
DAKOTA AND WEST CENTRAL MINNESOTA THURSDAY AFTERNOON AS A WEAK
DISTURBANCE SLIDES THROUGH THE AREA. THESE STORMS ARE NOT EXPECTED
TO HAVE THE POTENTIAL TO BECOME SEVERE AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY OR TONIGHT.

TMT