Severe Thunderstorm Warning 251, NWS Sioux Falls, SD

897 
WWUS53 KFSD 280930
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
430 AM CDT SUN AUG 28 2011

SDC003-015-043-281000-
/O.CON.KFSD.SV.W.0251.000000T0000Z-110828T1000Z/
DOUGLAS SD-BRULE SD-AURORA SD-
430 AM CDT SUN AUG 28 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHERN
AURORA...SOUTHEASTERN BRULE AND NORTHWESTERN DOUGLAS COUNTIES UNTIL
500 AM CDT...

AT 430 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING WALNUT SIZE HAIL.  THIS
STORM WAS LOCATED 9 MILES SOUTHEAST OF GRASS RANCH COLONY...OR 16
MILES SOUTHEAST OF KIMBALL...MOVING SOUTHEAST AT 35 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  STICKNEY AROUND 450 AM CDT...
  HARRISON AROUND 455 AM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 4375 9892 4357 9833 4355 9833 4333 9850
      4345 9871 4350 9871 4350 9879 4363 9902
TIME...MOT...LOC 0930Z 305DEG 29KT 4355 9876
WIND...HAIL <58MPH 1.50IN

$$

HANKO

619 
WWUS53 KFSD 280944
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
444 AM CDT SUN AUG 28 2011

SDC003-015-043-281000-
/O.CON.KFSD.SV.W.0251.000000T0000Z-110828T1000Z/
DOUGLAS SD-BRULE SD-AURORA SD-
444 AM CDT SUN AUG 28 2011

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT FOR SOUTHWESTERN
AURORA...SOUTHEASTERN BRULE AND NORTHWESTERN DOUGLAS COUNTIES UNTIL
500 AM CDT...

AT 444 AM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS WERE TRACKING
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING WALNUT SIZE HAIL.  THIS
STORM WAS LOCATED 8 MILES NORTHWEST OF HARRISON...OR 18 MILES
SOUTHWEST OF PLANKINTON...MOVING SOUTHEAST AT 30 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  HARRISON AROUND 500 AM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

SEVERE THUNDERSTORMS PRODUCE DAMAGING WIND IN EXCESS OF 60 MILES PER
HOUR...DESTRUCTIVE HAIL...DEADLY LIGHTNING...AND VERY HEAVY RAIN. FOR
YOUR PROTECTION MOVE TO AN INTERIOR ROOM ON THE LOWEST FLOOR OF YOUR
HOME OR BUSINESS. HEAVY RAINS FLOOD ROADS QUICKLY SO DO NOT DRIVE
INTO AREAS WHERE WATER COVERS THE ROAD.

&&

LAT...LON 4363 9902 4366 9892 4349 9837 4333 9850
      4345 9870 4350 9871 4350 9879
TIME...MOT...LOC 0944Z 308DEG 24KT 4349 9867
WIND...HAIL <58MPH 1.50IN

$$

HANKO

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
900 PM CDT FRI AUG 26 2011

.DISCUSSION...
SHORT WAVE MOVING INTO WESTERN NORTH DAKOTA WILL CONTINUE TO MOVE
SOUTHEAST OVERNIGHT AND SHOULD BEGIN TO INTERACT WITH BOUNDARY
ACROSS SOUTHWEST SD INTO SOUTHCENTRAL SD. LLJ SHOULD GRADUALLY
INCREASE AFTER 06Z AND WITH H850 CAPES IN THE 1500-2500
RANGE...WOULD EXPECT TO SEE SOME ELEVATED STORMS TO BEGIN DEVELOPING
AFTER 07 OR 08Z ACROSS NORTHWESTERN CWA AND THEN SPREAD EAST
SOUTHEAST OVERNIGHT. DID DELAY DEVELOPMENT BY A FEW HOURS FROM
PREVIOUS FORECAST AS HRRR IS ALSO NOW A TAD SLOWER CLOSER TO 18Z NAM
SOLUTION. OTHERWISE TEMPERATURE FORECAST LOOKS GOOD AND ONLY CHANGES
WERE TO TIMING OF THUNDERSTORM DEVELOPMENT. MARGINAL SEVERE HAIL
WOULD BE THE MAIN THREAT WITH THESE STORMS.

&&

.AVIATION...
LIGHT SOUTHEASTERLY SURFACE WINDS TO REMAIN IN PLACE THROUGH SUNDAY
AFTERNOON. THE ONLY EXCEPTION WILL BE WITH SCATTERED THUNDERSTORMS
WHICH ARE EXPECTED TO MOVE ACROSS THE AREA SUNDAY MORNING. THE MAIN
FOCUS FOR THUNDERSTORMS WILL BE ACROSS SOUTHEAST SOUTH DAKOTA...INTO
NORTHWEST IOWA. /97

&&

.PREVIOUS DISCUSSION...
A SUBTLE SHORT WAVE IS THE MAIN FEATURE TO WATCH TONIGHT...WHICH MAY
EVENTUALLY BRING NOT SO SUBTLE WEATHER. AT THE MOMENT...IT IS HARD
TO DECIPHER ACTUALLY WHERE IT IS ON WATER VAPOR...BUT IS PROBABLY
ASSOCIATED WITH A JET STREAK CURRENTLY IN SW MT. THE STRENGTH OF THE
WAVE INCREASES AFTER EVENING TONIGHT MAINLY IN CENTRAL SD ALONG THE
850MB-700MB THERMAL RIDGE AXIS AND ASSOCIATED MODEST LOW LEVEL JET.
AFTER MIDNIGHT...MID LEVEL TEMPERATURES THEN COOL WITH ML CAPES
INCREASING TO ABOUT 1000 TO 1500 J/KG ALONG AND WEST OF THE JAMES
RIVER VALLEY. COUPLED WITH THIS CAPE IS A ML CIN MINIMUM BY 09Z
SUNDAY WITH VERY HIGH CINS FROM GREGORY COUNTY AND POINTS WESTWARD.
THEREFORE LATEST THOUGHTS ARE IS THAT SCATTERED CONVECTION SHOULD
DEVELOP AFTER MIDNIGHT WEST OF THE JAMES. AS IT PRESSES EAST TO
SOUTHEASTWARD LATE TONIGHT...RAIN CHANCES MAY BECOME QUITE LIKELY IN
A SWATH AROUND MITCHELL TO YANKTON IN THE PRE DAWN HOURS. THESE
AREAS HAVE STEEP MID LEVEL LAPSE RATES FROM 700MB TO 500MB AND GOOD
DIRECTIONAL WIND SHEAR FROM 850MB UPWARD. IT IS DOUBTFUL WHETHER ANY
OF OUR ATMOSPHERE BELOW 900MB TO 850MB WILL BE TAPPED...SO AM
IGNORING THE WIND SHEAR IN THE LOWEST LEVELS. SCATTERED CONVECTION
WILL ENCIRCLE THE LIKELY POPS. BUT HEADING EASTWARD INTO SW MN AND
NW IA...RAIN CHANCES WANE EAST OF THE I 29 CORRIDOR WHERE CONDITIONS
ARE MUCH MORE STABLE COUPLED WITH ANEMIC WIND SHEAR. IN THE STRONGER
CELLS...SOME SEVERE HAIL COULD BE A THREAT LATE TONIGHT...ESPECIALLY
FROM YANKTON TO CHAMBERLAIN. CONCERNING TEMPERATURES...KEPT THE
READINGS ON THE WARMER SIDE OF GUIDANCE WITH CLOUD COVER ANTICIPATED
AFTER MIDNIGHT.

THUNDERSTORMS WILL MOST LIKELY BE ONGOING ON SUNDAY MORNING...WITH
THE BETTER CHANCE SITUATED ALONG THE MIDDLE AND LOWER MISSOURI RIVER
CORRIDOR WHERE THE INSTABILITY AXIS/LOW LEVEL CONVERGENCE/AND BEST
PV ADVECTION COINCIDE AS THE SHORTWAVE SLIDES TO THE SOUTHEAST.
EXPECT ACTIVITY TO DIMINISH LATER IN THE MORNING AND EARLY AFTERNOON
AS FORCING WEAKENS. HIGHS ON SUNDAY WILL BE IN THE LOWER TO MID 80S
IN THE WEST...TO THE MID AND UPPER 70S EAST WHERE CLOUDS MAY HANG
AROUND LONGER. SUNDAY NIGHT AND MUCH OF MONDAY SHOULD BE DRY IN
BETWEEN SYSTEMS...AS UPPER LEVEL RIDGING BUILDS INTO THE
REGION...AND LOWS ON SUNDAY NIGHT WILL BE UPPER 50S TO LOWER
60S...AND HIGHS ON MONDAY RIGHT AROUND NORMAL...IN THE LOWER TO MID
80S.

NEXT SHORTWAVE BEGINS TO ENCROACH ON THE AREA ON MONDAY NIGHT WITH
INCREASING 850 MB THETA E ADVECTION INTO OUR WEST...BRINGING ANOTHER
CHANCE OF SHOWERS AND THUNDERSTORMS TO THAT AREA DURING THE
NIGHT...THEN LIFTING OFF TO THE NORTHEAST ON TUESDAY AS THE WAVE
TRACKS INTO THE UPPER MIDWEST...THOUGH MODELS NOT IN THE BEST OF
AGREEMENT ON PLACEMENT OF CONVECTION ON TUESDAY.

BY WEDNESDAY THE UPPER LEVEL RIDGE AXIS SHIFTS TO OUR EAST IN AN
EVOLVING SOUTHWESTERLY UPPER LEVEL FLOW. WITH THIS...WILL HAVE
MOSTLY DRY CONDITIONS WITH WARMING TEMPERATURES...REACHING THE UPPER
80S TO LOWER 90S ACROSS THE AREA BY THURSDAY. NEXT POSSIBILITY OF
SHOWERS AND THUNDERSTORMS LOOKS TO COME IN ON THURSDAY NIGHT AND
FRIDAY AS A DECENT UPPER LEVEL SHORTWAVE TRACKING TO OUR NORTH PULLS
A COLD FRONT THROUGH OUR AREA DURING THIS TIME FRAME...BRINGING
COOLER TEMPERATURES FOR THE END OF THE WEEK.

&&

&&

.FSD WATCHES/WARNINGS/ADVISORIES...
SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1132 AM CDT SAT AUG 27 2011

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-281200-
AURORA-BEADLE-BON HOMME-BROOKINGS-BRULE-BUENA VISTA IA-
CHARLES MIX-CHEROKEE IA-CLAY-CLAY IA-COTTONWOOD MN-DAKOTA NE-
DAVISON-DICKINSON IA-DIXON NE-DOUGLAS-GREGORY-HANSON-HUTCHINSON-
IDA IA-JACKSON MN-JERAULD-KINGSBURY-LAKE-LINCOLN-LINCOLN MN-
LYON IA-LYON MN-MCCOOK-MINER-MINNEHAHA-MOODY-MURRAY MN-NOBLES MN-
OBRIEN IA-OSCEOLA IA-PIPESTONE MN-PLYMOUTH IA-ROCK MN-SANBORN-
SIOUX IA-TURNER-UNION-WOODBURY IA-YANKTON-
1132 AM CDT SAT AUG 27 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR SOUTHEAST SOUTH DAKOTA...
SOUTHWEST MINNESOTA...NORTHWEST IOWA...AND NORTHEAST NEBRASKA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
A CHANCE FOR THUNDERSTORMS WILL START BY LATE EVENING IN SOUTH
CENTRAL SOUTH DAKOTA...AND SPREAD SLOWLY EAST AND SOUTHEAST LATE
INTO THE NIGHT. SEVERE WEATHER IS NOT EXPECTED...ALTHOUGH THERE
WILL BE A MINIMAL THREAT FOR AN ISOLATED LARGE HAIL PRODUCING
STORM LATE TONIGHT OR EARLY SUNDAY MORNING ACROSS THE LOWER BRULE
AREAS.

FLOODING...
MINOR TO MODERATE FLOODING ON PARTS OF THE JAMES RIVER WILL
CONTINUE OVER THE NEXT COUPLE OF WEEKS...BUT RIVER LEVELS WILL
SEE A SLOW BUT STEADY DROP. BARRING HEAVY RAINS...THE JAMES RIVER
IS EXPECTED TO BE LARGELY BELOW FLOOD STAGE DURING THE FIRST HALF
OF SEPTEMBER.

FLOODING WILL CONTINUE ALONG THE MISSOURI RIVER BETWEEN FORT
RANDALL DAM AND NEAR PONCA NEBRASKA...WITH RIVER LEVELS
CONTINUING TO DROP VERY SLOWLY.

.DAYS TWO THROUGH SEVEN...SUNDAY THROUGH FRIDAY

SCATTERED THUNDERSTORMS WILL PERSIST THROUGH SUNDAY MORNING
ACROSS SOUTHEAST SOUTH DAKOTA...NORTHEAST NEBRASKA...NORTHWEST
IOWA AND POSSIBLY EXTREME SOUTHWEST MINNESOTA. A LESSER THREAT
WILL CONTINUE ON SUNDAY AFTERNOON AND EVENING AS THE FOCUS FOR
STORMS DROPS SOUTH AND EAST. NO SEVERE STORMS ARE
ANTICIPATED...WITH ONLY A RISK FOR AN ISOLATED HAIL PRODUCING
STORM SUNDAY MORNING THROUGH THE MISSOURI VALLEY.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL NOT BE NEEDED TODAY AND TONIGHT.

&&

FOR MORE INFORMATION PLEASE VISIT OUR WEBSITE AT
WWW.WEATHER.GOV/SIOUXFALLS. THIS INCLUDES THE GRAPHICAL HAZARDOUS
WEATHER OUTLOOK.