Severe Thunderstorm Warning 159, NWS Aberdeen, SD

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE ABERDEEN SD
1227 PM CDT SAT AUG 12 2006

.UPDATE...LOTS GOING ON IN THE NEXT 12 TO 24 HOURS. UPDATED
FORECAST THIS MORNING FOR STRONGER SOUTH WINDS AND TO REDRAW THE
WEATHER AND POP GRIDS FOR BETTER ALIGNMENT WITH ONGOING TSRA OUT
WEST AND OUT EAST...AS WELL AS TO ISSUE A FLOOD WATCH FOR SEVERAL
COUNTIES IN CENTRAL FA FROM 23Z TODAY TO 17Z SUNDAY WITH TRAINING
STORMS POSSIBLE AND PWATS IN THE 12Z HI-RES NAM SHOWING BETWEEN 2
AND 2.5 INCHES THIS EVENING. THE EXCESSIVE RAINFALL DISCUSSION
ALSO HIGHLIGHTS NORTHEAST SOUTH DAKOTA FOR TONIGHT.

THE POTENTIAL FOR TORNADIC SUPERCELLS IN AND EAST OF THE JAMES
RIVER VALLEY IS INCREASED WITH THE 12Z HI- RES NAM AND LATEST RUC
SOLUTIONS POINTING TO LCL HEIGHTS LESS THAN 1500FT AGL AND STRONG
0-1KM EHI OF OVER 2.5 WHICH IS FAVORABLE FOR STRONG LOW LEVEL
MESOCYCLONES. MU CAPES THIS EVENING OUT EAST ARE OVER 3000J/KG AND
THE ML TO 3KM CAPE PARAMETER FOR ENHANCED LOW LEVEL UPWARD MOTION
IS OVER 100J/KG. WILL WATCH THIS AREA CLOSELY. UPDATED THE GRIDS
AND SENT OUT A NEW PFMABR...ZFPABR...HWOABR.

DORN

&&

.PREV DISCUSSION... (ISSUED 350 AM CDT SAT AUG 12 2006)

SHORT TERM...TODAY THROUGH 12Z TUESDAY.
BIGGEST CHALLENGE IN THE NEAR TERM DEALS WITH PCPN CHCS FOR THE
WEEKEND.

LLJ INDUCED CONVECTION MOVING THROUGH SOUTHERN CWA ATTM...WITH
STRONGER CELLS LOCATED IN FSD CWA. WILL CANCEL WATCH FOR OUR CWA
WITH NEW ZONE ISSUANCE. OTW WAITING FOR NEXT WAVE TO EJECT OUT OF
WRN TROF INTO CWA. WITH COLD FRONT MOVING EVER SO SLOWLY EAST ACROSS
CWA...OUTFLOW BOUNDARIES FROM THIS MORNINGS CONVECTION AND JET MAX
ALOFT...SHOULD HAVE NO PROBLEM FIRING OFF STORMS LATER THIS
AFTERNOON. PWATS AHEAD OF FRONT APPROACH 2 INCHES...COMBINED WITH
IMPRESSIVE LONG LIVED 7H AND 85H THETA-E FORCING. MENTIONED HEAVY
RAIN ACROSS SERN CWA FOR THE EVENING HOURS...AND DAY SHIFT MAY HAVE
TO EXPAND THE AREAL COVERAGE FOR THAT LATER TODAY. ALSO OF INTEREST
WAS THAT THE NAM AND GFS BOTH SHOW 85H FRONT STALLING ACROSS NRN CWA
THIS EVENING...WITH GOOD CONVERGENCE ZONE ACROSS NE CWA. UPPER
DIVERGENCE ZONE COINCIDES WITH THIS...LENDING CREDANCE TO HEAVY RAIN
FORECAST. WILL ALSO HOLD OFF ON ANY HYDROLOGIC HEADLINES IN THE
ZONES...BUT WILL COVER IN HWO. FIRST WAVE LIFTS THROUGH
OVERNIGHT...WITH PCPN CHCS DECREASING SLIGHTLY...ONLY TO RAMP BACK
UP FOR THE DAY SUNDAY WITH PASSAGE OF UPPER TROF AND NEXT EMBEDDED
7H/5H WAVES. GIVEN SHEAR AND MOISTURE AVAILABLE...SCT SVR NOT OUT OF
THE QUESTION LATER THIS AFTERNOON INTO THE EVENING...AND WILL COVER
IN THE HWO. FRONT CLEARS CWA BY SUNDAY EVENING WITH STRONG DOWNGLIDE
ON 7H THETA-E SFC AND GOOD DRYING TAKING PLACE 7H-5H LAYER. SFC
WINDS ALSO PICKUP ON BACKSIDE OF FEATURE. MONDAY AND MONDAY NIGHT
SHOULD BE UNEVENTFUL WITH PLEASANT TEMPS AS CANADIAN HIGH PRESSURE
RULES THE ROOST.

INHERITED MAX/MIN T GRIDS LOOKED GOOD WITH ONLY COSMETIC TWEAKING
NECESSARY. UPPED SKY COVER GRIDS FOR TONIGHT AND SUNDAY GIVEN
EXPECTED PCPN

LONG TERM...TUESDAY THROUGH FRIDAY
MODELS AGREE THAT UPPER RIDGING WILL BE TAKING PLACE ACROSS THE
NORTHERN PLAINS AT THE START OF THE EXTENDED PERIOD. FLOW THEN
BECOMES SW TOWARDS THE END OF THE WEEK WITH UNSETTLED WEATHER
DEVELOPING. MODELS STILL ON TRACK WITH BRINGING A LOW PRESSURE INTO
THE DAKOTAS BY THURSDAY AND INTO FRIDAY. AS USUAL...THERE ARE SOME
DIFFERENCES IN TIMING AND STRENGTH...BUT PREVIOUS WX/POP GRIDS LOOK
FINE FOR RIGHT NOW. TEMPERATURES WERE CHANGED LITTLE AND SHOULD BE
NEAR NORMAL FOR MOST OF THE PERIOD.

&&

.ABR WATCHES/WARNINGS/ADVISORIES...
SD...FLOOD WATCH FROM 6 PM CDT THIS EVENING THROUGH SUNDAY MORNING
     FOR CLARK-CODINGTON-DAY-HAMLIN-HAND-MARSHALL-SPINK.

MN...NONE.
&&

HINTZ/TARVER

HAZARDOUS WEATHER OUTLOOK...CORRECTED
NATIONAL WEATHER SERVICE ABERDEEN SD
1133 AM CDT SAT AUG 12 2006

SDZ003>005-009-010-015>017-033>036-045-131645-
CORSON-CAMPBELL-MCPHERSON-WALWORTH-EDMUNDS-DEWEY-POTTER-FAULK-
STANLEY-SULLY-HUGHES-HYDE-JONES-
1133 AM CDT SAT AUG 12 2006 /1033 AM MDT SAT AUG 12 2006/

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

.DAY ONE...THIS AFTERNOON AND TONIGHT
THUNDERSTORMS WILL DEVELOP BY EARLY AFTERNOON AND CONTINUE INTO THE
EVENING. THERE IS A CHANCE THAT SOME OF THE STORMS MAY BECOME
SEVERE...WITH LARGE HAIL THE MAIN THREAT.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
THUNDERSTORMS WILL CONTINUE THROUGH THE MORNING SUNDAY.
THUNDERSTORM DEVELOPMENT IS ALSO POSSIBLE THURSDAY AND FRIDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION MAY BE NEEDED THIS AFTERNOON BY 2PM CDT.

SDZ006-007-011-018>020-022-037-131645-
BROWN-MARSHALL-DAY-SPINK-CLARK-CODINGTON-HAMLIN-HAND-
1133 AM CDT SAT AUG 12 2006

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

.DAY ONE...THIS AFTERNOON AND TONIGHT
THUNDERSTORMS WILL DEVELOP LATER THIS AFTERNOON ALONG AND EAST OF A
SLOW MOVING COLD FRONT DRAPED ACROSS THE REGION. THUNDERSTORMS WILL
CONTINUE INTO THE OVERNIGHT HOURS. SOME OF THE STORMS THIS AFTERNOON
AND THIS EVENING ALONG AND EAST OF A LINE FROM KENNEBEC TO MILLER TO
HECLA WILL DEVELOP IN A VERY MOISTURE RICH...FAVORABLE SHEAR...AND
VERY UNSTABLE ENVIRONMENT...RESULTING IN SEVERE HAIL AND
THUNDERSTORM WINDS. AN ISOLATED TORNADO IS POSSIBLE THIS EVENING
AS WELL. VERY HEAVY RAIN IS ALSO POSSIBLE WITH THESE STORMS FROM
LATE THIS AFTERNOON THROUGH SUNDAY MORNING...CREATING THE
POTENTIAL FOR FLOODING. A FLOOD WATCH IS IN EFFECT FROM 6 PM CDT
TODAY TO NOON CDT ON SUNDAY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
THUNDERSTORMS WILL CONTINUE THROUGH THE DAY SUNDAY. THUNDERSTORM
DEVELOPMENT IS ALSO POSSIBLE THURSDAY AND FRIDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL BE NEEDED THIS AFTERNOON AFTER 4 PM CDT.

MNZ039-046-SDZ008-021-023-048-051-131645-
TRAVERSE-BIG STONE-ROBERTS-GRANT-DEUEL-LYMAN-BUFFALO-
1133 AM CDT SAT AUG 12 2006

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

.DAY ONE...THIS AFTERNOON AND TONIGHT
THUNDERSTORMS WILL DEVELOP LATER THIS AFTERNOON ALONG AND EAST OF A
SLOW MOVING COLD FRONT DRAPED ACROSS THE REGION. THUNDERSTORMS WILL
CONTINUE INTO THE OVERNIGHT HOURS. SOME OF THE STORMS THIS AFTERNOON
AND THIS EVENING ALONG AND EAST OF A LINE FROM KENNEBEC TO MILLER TO
HECLA WILL DEVELOP IN A VERY MOISTURE RICH...FAVORABLE SHEAR...AND
VERY UNSTABLE ENVIRONMENT...RESULTING IN SEVERE HAIL AND
THUNDERSTORM WINDS. AN ISOLATED TORNADO IS POSSIBLE THIS EVENING
AS WELL. VERY HEAVY RAIN IS ALSO POSSIBLE WITH THESE STORMS FROM
LATE THIS AFTERNOON THROUGH SUNDAY MORNING...CREATING THE
POTENTIAL FOR FLOODING.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY
THUNDERSTORMS WILL CONTINUE THROUGH THE DAY SUNDAY. THUNDERSTORM
DEVELOPMENT IS ALSO POSSIBLE THURSDAY AND FRIDAY.

.SPOTTER INFORMATION STATEMENT...
SPOTTER ACTIVATION WILL BE NEEDED THIS AFTERNOON AFTER 4 PM CDT.

DORN

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE ABERDEEN SD
1051 AM CDT SAT AUG 12 2006

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

1010 PM     TSTM WND GST     11 SSW TIMBER LAKE      45.28N 101.16W
08/11/2006  E60 MPH          DEWEY              SD   PUBLIC

            BRANCHES DOWN

&&

DMOHR