Severe Thunderstorm Warning 154, NWS Aberdeen, SD

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE ABERDEEN SD
348 PM CDT MON AUG 6 2007

.SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT
FORECAST CHALLENGES INCLUDE AREAL COVERAGE OF THUNDERSTORMS THIS
EVENING AND AGAIN TUESDAY NIGHT...ALONG WITH TEMPERATURES.

PRESENTLY...ELEVATED SHOWERS AND THUNDERSTORMS ARE MOVING EAST-
NORTHEAST ACROSS FAR NORTHEAST SOUTH DAKOTA AND WEST CENTRAL
MINNESOTA. TWO BOUNDARIES FOR FORCING WORTH NOTING THIS EVENING
INCLUDE THE STALLED OUT FRONTAL BOUNDARY RUNNING MAINLY FROM KBKX
WESTWARD THROUGH KPIR AND TRAILING BACK TOWARD KIEN...ALONG WITH
AN INVERTED SURFACE TROF SLOWLY MOVING EASTWARD THROUGH THE
NORTHERN HIGH PLAINS. PLENTIFUL LOW LEVEL MOISTURE AROUND FOR
THUNDERSTORM DEVELOPMENT THIS EVENING...PROVIDED AN ADEQUATE
SOURCE OF LIFT SHOWS UP /PROLLY THE JET-LET INFERRED BY THE
MID/HIGH CLOUDS STREAMING NORTH OUT OF NEBRASKA THIS AFTERNOON/.
THE ATMOSPHERE IS ALREADY SHOWING A CONSIDERABLE AMOUNT OF
INSTABILITY ACROSS WESTERN AND SOUTHERN SOUTH DAKOTA.

ONCE THE SHOWERS AND THUNDERSTORMS DEPART THE FAR NORTHEASTERN
CORNER OF THE FORECAST AREA EARLY THIS EVENING...AND ANY
CONVECTION THAT DEVELOPS ACROSS CENTRAL OR SOUTH CENTRAL SOUTH
DAKOTA DISSIPATES...EXPECTING SURFACE HIGH PRESSURE TO BUILD INTO
THE FORECAST AREA FOR THE REMAINDER OF THE NIGHT AND INTO
TUESDAY...PUSHING THE MOIST AIR SOUTH INTO NEBRASKA TEMPORARILY
AND ALLOWING FOR MORE STABLE...AND LESS CLOUDY CONDITIONS ON
TUESDAY. AS THE HIGH REPOSITIONS TO THE SOUTH AND EAST TUESDAY
NIGHT...RETURN FLOW SETS BACK UP AGAIN. AN UPPER LEVEL SHORT WAVE
MAKES ITS WAY NORTH-NORTHEAST ACROSS WESTERN NEBRASKA AND WESTERN
SOUTH DAKOTA TUESDAY NIGHT WHILE 850-700HPA WAA AND MOISTURE
ADVECTION IS AT A PREMIUM. ELEVATED NIGHT-TIME SHOWERS AND
THUNDERSTORMS LIFTING INTO THE WESTERN THIRD OF THE FORECAST AREA
TUESDAY NIGHT STILL LOOKS ON TRACK. EAST AND SOUTHEAST SURFACE
WINDS ON TUESDAY WILL LIKELY KEEP TEMPERATURES FROM ACHIEVING
THEIR FULL POTENTIAL. NEVERTHELESS...925HPA AND 850HPA THERMAL
PROGS INDICATE TEMPERATURES SHOULD WARM INTO THE MID 80S TO MID
90S ON TUESDAY.

.LONG TERM...WEDNESDAY THROUGH SUNDAY
BROAD SOUTHWEST FLOW LOOKS TO CONTINUE INTO THE WEEKEND. MODELS
SHOWING SERIES OF SHORTWAVES TO PASS THROUGH AREA DURING PERIOD.
IT WILL BE TOUGH TO PINPOINT EXACT PRECIP TIMES THIS FAR OUT...SO
A BROADBRUSH APPROACH WILL BE CONTINUED. BEST CHANCES LOOK TO BE
WEDNESDAY AND AGAIN THURSDAY EVENING...BUT ENTIRE PERIOD WILL BE
UNSETTLED.

RIDGE WILL SLOWLY BUILD INTO AREA THROUGH THE PERIOD RAISING
HEIGHTS. THE SOUTHWEST PORTION OF THE FORECAST AREA LOOKS TO
REALLY HEAT UP THIS WEEKEND. IT WILL DEPEND SOME ON CLOUDS AND
CONVECTION AS RIDGE RUNNING THUNDERSTORMS LOOK LIKE A GOOD BET.
FORECAST AREA WILL BE ON EDGE OF THE CAP AS H7 TEMPS HOVER AROUND
+10C THROUGH THE PERIOD...WARMING ON THE WEEKEND.

&&

.AVIATION...
ALL TAF SITES HAVE BEEN BATTLING PERIODIC IFR OR MVFR CIGS AND/OR
VISBY REDUCTION IN FOG MUCH LATER INTO THE DAY THAN IS TYPICAL FOR
EARLY AUGUST. PLENTIFUL LOW LEVEL MOISTURE AND RAIN-COOLED
BOUNDARY LAYER AIR ARE LIKELY THE CULPRITS. NEVERTHELESS THE WARM
AUGUST SUNSHINE IS RAPIDLY ERODING THESE UNFAVORABLE FLYING
CONDITIONS THIS AFTERNOON...WITH ALL FOUR TERMINALS EXPECTED TO BE
INTO GOOD VFR FLYING WEATHER BY 23Z THIS AFTERNOON.

ANOTHER ROUND OF SHOWERS AND THUNDERSTORMS IS STILL POSSIBLE BY
EARLY THIS EVENING...MAINLY AT THE KPIR TERMINAL WHERE THE GREATEST
AMOUNT OF INSTABILITY FOR THUNDERSTORMS CURRENTLY EXISTS. AGAIN
THIS IS MAINLY A CONCERN AT THE KPIR TERMINAL BETWEEN 00Z AND 06Z
THIS EVENING. CONFIDENCE IS TOO LOW AT THIS TIME TO MENTION
THUNDER IN THE TAF...HOWEVER INSERTION OF TSRA INTO THE KPIR TAF
WILL FOLLOW LATER THIS EVENING AS NEEDED. OTHERWISE...HIGH
PRESSURE WILL BUILD INTO ALL FOUR TERMINALS TONIGHT AND
TUESDAY...WHICH SHOULD RESULT IN VFR CONDITIONS LATE TONIGHT
THROUGH TUESDAY AFTERNOON.

&&

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

SHORT TERM...DORN
LONG TERM...SCARLETT
AVIATION...DORN

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE ABERDEEN SD
458 AM CDT MON AUG 6 2007

SDZ003>006-009>011-016>020-022-034>037-048-051-071000-
CORSON-CAMPBELL-MCPHERSON-BROWN-WALWORTH-EDMUNDS-DAY-POTTER-FAULK-
SPINK-CLARK-CODINGTON-HAMLIN-SULLY-HUGHES-HYDE-HAND-LYMAN-BUFFALO-
458 AM CDT MON AUG 6 2007 /358 AM MDT MON AUG 6 2007/

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE POSSIBLE TODAY ACROSS PORTIONS OF CENTRAL AND
EASTERN SOUTH DAKOTA. A FEW STORMS COULD BECOME SEVERE WITH LARGE
HAIL AND STRONG WINDS BEING THE MAIN THREATS.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

OFF AND ON CHANCES FOR THUNDERSTORMS EXIST THROUGH MUCH OF THE
WEEK AS THE WEATHER PATTERN REMAINS A BIT MORE ACTIVE THAN RECENT
WEEKS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY THIS AFTERNOON ACROSS PORTIONS
OF CENTRAL SOUTH DAKOTA.

MNZ039-046-SDZ007-008-021-023-071000-
TRAVERSE-BIG STONE-MARSHALL-ROBERTS-GRANT-DEUEL-
458 AM CDT MON AUG 6 2007

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

.DAY ONE...TODAY AND TONIGHT

AREAS OF DENSE FOG WILL OCCUR THROUGH SUNRISE ACROSS EXTREME
NORTHEASTERN SOUTH DAKOTA AS WELL AS BIG STONE AND TRAVERSE
COUNTIES IN MINNESOTA. VISIBILITIES MAY BE REDUCED TO LESS THAN
ONE QUARTER MILE AT TIMES.

THUNDERSTORMS ARE POSSIBLE THIS AFTERNOON BUT THE SEVERE THREAT
APPEARS TO BE LIMITED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

OFF AND ON CHANCES FOR THUNDERSTORMS EXIST THROUGH MUCH OF THE
WEEK AS THE WEATHER PATTERN REMAINS A BIT MORE ACTIVE THAN RECENT
WEEKS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED TODAY OR TONIGHT.

SDZ015-033-045-071000-
DEWEY-STANLEY-JONES-
458 AM CDT MON AUG 6 2007 /358 AM MDT MON AUG 6 2007/

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS ARE POSSIBLE TODAY ACROSS PORTIONS OF CENTRAL SOUTH
DAKOTA. A FEW STORMS COULD BECOME SEVERE WITH LARGE HAIL AND
STRONG WINDS BEING THE MAIN THREATS.

THE GRASSLAND FIRE DANGER WILL REACH THE HIGH TO VERY HIGH
CATEGORY THIS AFTERNOON.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

OFF AND ON CHANCES FOR THUNDERSTORMS EXIST THROUGH MUCH OF THE
WEEK AS THE WEATHER PATTERN REMAINS A BIT MORE ACTIVE THAN RECENT
WEEKS.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NECESSARY THIS AFTERNOON ACROSS PORTIONS
OF CENTRAL SOUTH DAKOTA.

TMT