Severe Thunderstorm Warning 47, NWS Sioux Falls, SD

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
518 AM CDT TUE JUN 1 2010

.DISCUSSION...
PATTERN LOOKS TO REMAIN ACTIVE THROUGH THE NEXT SEVERAL DAYS WITH
CONFLUENT ZONAL FLOW FEATURING NUMEROUS WAVES...DIFFICULT TO TIME
AND DIFFICULT TO TRACK...MAKING FOR A CHALLENGING FCST. STRONGEST
TROUGHING EARLY THIS MORNING THRU CANADA WITH SECONDARY MAIN TROUGH
BACK THRU NV...WITH A COUPLE EMBEDDED SMALLER WAVES IN WSW FLOW INTO
NRN PLAINS. ONE SUCH WAVE LIFTING FROM WY/CO INTO WRN SD...AND
ANOTHER BACK IN UT. LLJ INCREASING THRU CNTRL PLAINS 88D VWP AND HBR
PROFILER...BUT LACK OF PLAINS PROFILERS ACRS NRN NEBRASKA DOES NOT
MAKE IT ANY EASIER TO DIAGNOSE LLJ.  LOW LVL FRONTAL BNDRY FM SERN
ND TO NWRN SD...WITH SECONDARY WMFNT WELL TO S IN NRN KS. MAIN LO
LVL MOISTURE TRANSPORT BACK THRU CNTRL NEBRASKA WITH RETREATING SFC
RIDGE HOLDING DRIER AIR IN THRU ERN CWA.

NOTING DEVELOPING ACC FIELD OVR WRN NEBRASKA/SRN SD...EXTENDING TO
STRONGER CONVECTION IN NWRN KS/SWRN NEBRASKA...AS EFFECTS OF LEADING
SHORTWAVE MOVE INTO PLAINS AND INTERACT WITH LLJ. EML PUSHING INTO
PLAINS ALSO CONTRIBUTING TO INCREASING POTENTIAL INSTABILITY AXIS
THRU CNTRL NEBRASKA/SD THIS MORNING. OVERALL...LIKE IDEA SHOWN IN
THE HRRR AND IN SOME FORM THE NAM/GFS WITH INCREASING PCPN AREA
EXPECTED TO EVOLVE OVER NEXT 2-3H ACRS WRN/SRN CWA IN WAA WING...
SPREADING AND BECOMING MORE WIDESPREAD TO THE NORTHEAST THRU MID TO
LATE MORNING. MOST SOUNDINGS INDICATE LITTLE RESISTANCE TO THIS
ELEVATED CONVECTION /PRIOR TO INITIATION/ AND THUS CONCERN THAT WL
JUST GO WITHOUT CESSATION...WHICH WOULD NOT ONLY LIMIT SVR THREAT
TO THE N AND W...BUT EVEN MORE TO THE S THRU THE AFTN. HOWEVER...
0-6KM BULK SHEAR INCREASES TO 40 TO 50 KTS BY AFTN ACRS THE AREA...
USING SOME CREATIVE NON CONVECTIVE PROFILES. THIS MORE THAN
SUFFICIENT TO ORGANIZE STORMS WHICH DEVELOP EITHER ON EDGE OF THE
ELEVATED CONVECTIVE AREAS BY EARLY AFTN AS DESTABILIZATION WITH
L80S/L60S T/TD COMBO...OR ON MAIN FRONTAL BNDRY WITH ELEVATED
INSTABILITY. THREAT FOR SVR CERTAINLY FAVORS SERN HALF OF AREA...
AND CHOSE EXEPECT GRADIENT IN SHEAR/INSTABILITY IN DEEPER FRONTAL
CONVERGENCE AREA FOR DEVELOPMENT.  WOULD EXPECT BULK OF THREAT WOULD
BE HAIL TO WIND TRANSITION AS STORMS GROW UPSCALE INTO MCS...BUT MORE
DISCRETE SUPERCELLS LATER AFTN MAY BRING A NOMINAL TOR THREAT WITH
LOWEST ATM SHEAR FROM NON-CONVECTED AREAS JUST ON THE SHY SIDE OF
FAVORABLE.  CONCERN FOR HEAVY RAINFALL IN PLACE...BUT WITH FORWARD
PROPOGATION EXPECTED TO GENERALLY REIGN...EXPECT ANY PROBLEMS WOULD
BE MORE PROPERLY HANDLED ON THE STORM SCALE...HENCE NOT A WIDESPREAD
THREAT FOR FLASH FLOODING.

TEMPERATURES YET ANOTHER CHALLENGE...AND IF PCPN FAILS TO
MATERIALIZE IN TIMELY MANNER DURING THE MORNING...A WARM AIRMASS
COULD EASILY YIELD MUCH WARMER MAXES BEFORE FROPA SINKS SWRD THRU
THE AFTN. SOMEWHERE FROM LOWER 70S IN EARLIER RAIN AREAS THRU ERN SD
TO MID 80S IN SRN PORTIONS OF NW IA AHEAD OF BNDRY/PCPN.

PUSHED OUT PCPN JUST A BIT FASTER TONIGHT AS JET ENTRANCE REGION
AIDS IN BRINGING DRIER NLY FLOW IN AT LOW LVLS...AND DRIVES THE
LOWER LVL FRONTAL BNDRY INTO KS/MO BY EARLY WED. HOWEVER...WL
CONTINUE TO FIND A FAIRLY STRONG WAVE ALFT RIDING ALONG LINGERING
MID LVL BNDRY INTO WED MORNING...SO DIFFICULT TO FULLY REMOVE POPS
THRU SERN 2/3 OR SO OF AREA. YET ANOTHER IMPULSE LOOKS TO COME OUT
OF THE WRN HIGH PLAINS BY LTR WED...BUT AS MAIN BAROCLINICITY ALSO
WORKS SWRD...KEPT ONLY SOME CHC LVL POPS ALG FAR S/SE CWA. CLOUDS
AND COOLER TMPS SHUD KNOCK QUITE A BIT OFF SRN HIGHS WED...WITH ONLY
UPR 60S TO LOWER 70S MOST AREAS.

SFC RIDGE BRINGS PARTIAL CLEARING WED NIGHT INTO THU AS SETTLE SE
ACRS THE AREA. CONTINUE TO FAVOR A BIT SLOWER PROGRESSION PER
ECMWF...AS SEEMS CONVECTION HAVING ITS WAY WITH ESPLY GFS.

NEXT BETTER THREAT IN THE SHORT RANGE FOR PCPN LOOKS TO START UP BY
LATER THU AFTN ALG WRN FLANK...AND SPREADS EWRD THU NIGHT AND
FRIDAY. WAA PCPN EXPECTED TO START UP LTR THU CNTRL SD...AND PUSH
EWRD THU NIGHT BECOMING MORE WIDESPREAD. ENOUGH CONFIDENCE IN
DYNAMIC STRENGTH AND INSTABILITY TO PUSH MENTION TO SCT.

DID VERY LITTLE TO FCST AGAIN BEYOND FRI...AS INCREASING UNCERTAINTY
IN FLOW MAKES FOR POTENTIALLY UNNECESSARY FLIP FLOPS.  DID LOOK LIKE
COULD BE A DECENTLY MIXY DAY BY SATURDAY...FEATURING A BIT MORE WLY
COMPONENT THAN EARLIER FCST...LEADING TO A SMALL RAISING OF TMPS
THRU WRN/SRN CWA MORE LKLY TO BE OUT OF PCPN/CLDS EARLIER. /CHAPMAN

&&

.AVIATION...
SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BECOME POSSIBLE
EARLY THIS MORNING OVER CENTRAL SD...WITH THIS ACTIVITY SPREADING
TOWARDS I29 AND SW MN BY LATE MORNING. MAINLY VFR CEILINGS AND
VISIBILITIES ARE EXPECTED DURING THIS TIME. BY AFTERNOON...STRONGER
THUNDERSTORMS WILL BECOME POSSIBLE WITH A FEW MVFR CEILINGS AND
VISIBILITIES. SOME OF THESE THUNDERSTORMS MAY ALSO PRODUCE HEAVY
RAIN AND SEVERE WEATHER. THE MORE ORGANIZED THUNDERSTORM THREAT
SHOULD BE AROUND THE FSD AREA FROM ABOUT 19Z THROUGH 0Z WHILE SUX
SEES THE BETTER CHANCE FROM ABOUT 23Z TO 5Z. /08

&&

.FSD WATCHES/WARNINGS/ADVISORIES...

SD...NONE.
MN...NONE.
IA...NONE.
NE...NONE.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
1141 AM CDT TUE JUN 01 2010

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-021200-
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-
1141 AM CDT TUE JUN 01 2010

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
ELEVATED THUNDERSTORMS WILL CONTINUE FROM SOUTHEAST SOUTH
DAKOTA...INTO SOUTHWEST MINNESOTA AND EXTREME NORTHWEST IOWA INTO
THE EARLY AFTERNOON. ISOLATED SEVERE STORMS PRODUCING HAIL UP TO
QUARTER SIZE AND LOCALLY HEAVY RAIN WILL BE POSSIBLE WITH THESE
STORMS... EXTENDING FROM LAKE ANDES TO SIOUX FALLS SOUTH
DAKOTA...AND INTO SOUTHWEST MINNESOTA.

ADDITIONAL THUNDERSTORM DEVELOPMENT WILL BECOME MORE LIKELY AFTER
2 PM FARTHER TO THE SOUTHEAST...ESPECIALLY ALONG AND SOUTHEAST OF
A LINE FROM YANKTON SOUTH DAKOTA...TO ROCK VALLEY AND SPIRIT LAKE
IOWA DURING THE AFTERNOON HOURS. STORMS IN THESE AREAS WILL BE
CAPABLE OF PRODUCING LARGE HAIL UP TO 2 INCHES IN DIAMETER...AND
DAMAGING WINDS WILL BE AN INCREASING THREAT AS STORMS SPREAD TO
THE SOUTHEAST. ISOLATED TORNADOES WILL ALSO BE
POSSIBLE...ESPECIALLY NEAR ANY LOW LEVEL BOUNDARIES RESULTING
FROM THE MORNING CONVECTION TO THE NORTH.  THE SEVERE THREAT
SHOULD END BY 9 PM AS THE COLD POOL ASSOCIATED WITH THE STORMS
PUSHES FORWARD AWAY FROM THE FORECAST AREA.

FLOODING...
AREAS OF HEAVY RAIN CAN BE EXPECTED FROM THUNDERSTORMS MOVING
ACROSS THE AREA THIS AFTERNOON AND EARLY EVENING. LOCALIZED FLASH
FLOODING WILL BE POSSIBLE...MAINLY ALONG AND SOUTHEAST OF A LINE
FROM WAGNER SOUTH DAKOTA...TO SIOUX FALLS TO WINDOM MINNESOTA.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

ISOLATED THUNDERSTORMS ARE POSSIBLE ON WEDNESDAY INTO EARLY
WEDNESDAY MORNING...GENERALLY SOUTH OF A LINE FROM CHAMBERLAIN TO
SPENCER IOWA. THESE STORMS WILL NOT BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE LIKELY BETWEEN 2 PM AND 9 PM CDT...
ESPECIALLY ALONG AND SOUTHEAST OF A LINE FROM YANKTON SOUTH
DAKOTA TO SPIRIT LAKE IOWA.

&&

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

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PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
151 PM CDT TUE JUN 01 2010

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

0145 PM     HAIL             HARTLEY                 43.18N 95.48W
06/01/2010  E1.75 INCH       O'BRIEN            IA   BROADCAST MEDIA

0148 PM     HAIL             MONETA                  43.13N 95.39W
06/01/2010  E1.75 INCH       CLAY               IA   AMATEUR RADIO

&&

MDB

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
153 PM CDT TUE JUN 01 2010

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

0122 PM     TORNADO          4 WNW SANBORN           43.20N 95.73W
06/01/2010                   O'BRIEN            IA   TRAINED SPOTTER

            BRIEF TOUCHDOWN

&&

RRYRHOLM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
155 PM CDT TUE JUN 01 2010

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

0151 PM     HAIL             2 ENE HARTLEY           43.19N 95.44W
06/01/2010  E2.50 INCH       O'BRIEN            IA   TRAINED SPOTTER

            DAMAGE TO TREES AND CARS

&&

RRYRHOLM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
159 PM CDT TUE JUN 01 2010

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

0150 PM     HAIL             3 WNW EVERLY            43.18N 95.38W
06/01/2010  M1.75 INCH       CLAY               IA   CO-OP OBSERVER

&&

RRYRHOLM