Severe Thunderstorm Warning 251, NWS Sioux Falls, SD

000 
WWUS53 KFSD 180244
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
943 PM CDT MON SEP 17 2007

SDC087-099-180253-
/O.CAN.KFSD.SV.W.0251.000000T0000Z-070918T0300Z/
MINNEHAHA SD-MCCOOK SD-
943 PM CDT MON SEP 17 2007

...THE SEVERE THUNDERSTORM WARNING FOR SOUTHEASTERN MCCOOK AND 
NORTHWESTERN MINNEHAHA COUNTIES IS CANCELLED...

THE STORM HAS WEAKENED AND IS NO LONGER SEVERE. HOWEVER...PEA SIZE 
HAIL AND BRIEF HEAVY RAINS CAN BE STILL BE EXPECTED AS SCATTERED 
THUNDERSTORMS MOVE ACROSS THE AREA.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 100 AM CDT
TUESDAY MORNING FOR NORTHWEST IOWA AND SOUTHWEST MINNESOTA AND
SOUTHEASTERN SOUTH DAKOTA.

LAT...LON 4384 9707 4370 9690 4352 9721 4359 9731
TIME...MOT...LOC 0243Z 226DEG 34KT 4371 9702

$$

CJ

AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NATIONAL WEATHER SERVICE SIOUX FALLS SD
345 PM CDT MON SEP 17 2007

.DISCUSSION...
FRONTAL ZONE HAS PUSHED INTO FAR WRN CWA PASSING K9V9 PRIOR TO 20Z.
CURRENTLY IN WAKE OF WAVE WHICH LIFTED INTO SRN ND...WITH CONVECTION
WANED OVR CWA.  HAS ALLOWED AMPLE SUN TO BRING STRONG MIXING WITHIN
LLJ AXIS...WITH TMPS IN MID 80S TO ARND 90 MOST AREAS. EVEN THEN...
MOST RECENT TAMDAR RAOB FROM KSUX AREA ARND 18Z STILL SHOWS A MLCIN
OF ARND 200 J/KG WITH 88/65 T/TD.  CRITICAL ISSUE FOR TONIGHT IS
DETERMINING CONVECTIVE POTENTIAL...TIMING...SEVERITY...AND COVERAGE.

NOW NOTING SEVERAL LINES OF CU DEVELOPING ALG VARIOUS BNDRYS IN
NEBRASKA...WITH SOME CONVECTION TAKING OFF IN NWRN KS ALG PREFRONTAL
WIND SHIFT.  WOULD THINK FEATURE ON WV IN ERN CO AND NE PANHANDLE
IS CRITICAL FEATURE FOR GETTING PCPN TO REALLY TAKE OFF...AND THIS
FAVORS BNDRY WHICH WOULD BE MORE WWRD...OR MOST RECENT CU DEVELOPMENT
AXIS FROM ERN GREGORY CTY SWRD TOWARD KLBF. MRR PROFILER HAS SHOWN
DRASTIC INCRS IN MID LVL WNDS OVER THE LAST 3H...AS WAVE STARTS TO
HAVE INFLUENCE SPREADING EWRD.  ACTIVITY SHUD BE FAIRLY MINIMAL INTO
EARLY EVENING...AS CAP SHUD RULE THE ROOST. EXPECT ISOLD/SCT
CONVECTION TO DEVELOP WITHIN 22Z-00Z WINDOW NR SFC CONVERGENCE AXIS
CLOSING ON JAMES VLY. SHEAR OFF NLG PROFILER IS HARDLY IMPRESSIVE...
AND LIKENED MORE TOWARD A DEEP DISTRIBUTED SPEED SHEAR...FAVORING
MULTICELL DEVELOPMENT.  TORNADO THREAT WOULD APPEAR TO BE MINIMAL AT
THIS TIME...ESPLY BY THE TIME ENHANCED LIFT WL START TO INFLUENCE
THE BNDRY.  LOOKS LIKE 03Z ARND THE CRITICAL TIME TO GET ACTIVITY TO
REALLY INCREASE IN COVERAGE...AND WOULD THINK IT IS MUCH MORE TOWARD
A MARGINAL WIND/HAIL EVENT DURING THE EARLY TO MID EVENING HOURS...
CENTERED ON AN AXIS FROM MARSHALL TO SIOUX FALLS...TO YANKTON.

MAIN BNDRY SHUD SLOW TO A SCREECHING HALT TONIGHT...OUTSIDE
CONVECTIVE OUTFLOW INFLUENCE...IN WAIT FOR MAIN WAVE TO EMERGE
DURING TUESDAY.  LIKEWISE...RESPONSE COULD RESULT IN A MARKED
DECREASE IN CONVECTION LATE TONIGHT AS WELL.

FRONT WILL MOVE SLOWLY EAST THROUGH THE CWA ON TUESDAY...HOLDING
NEARLY STEADY BETWEEN JAMES VALLEY AND I-29 IN THE MORNING WHILE
MAIN UPPER WAVE LIFTS NORTHEAST INTO THE AREA. WOULD EXPECT LATE
NIGHT PRECIP TO EXPAND BACK TO THE WEST IN THE MORNING AS THE UPPER
WAVE APPROACHES...WITH PRECIP SHIELD SCALING BACK FROM THE SOUTHWEST
THROUGH THE AFTERNOON AS THE WAVE LIFTS NORTHEAST. MORE ABUNDANT
CLOUD COVER AND PRECIP SHOULD HOLD TEMPS MUCH COOLER THAN WE HAVE
SEEN ACROSS THE AREA TODAY. SEVERE POTENTIAL WILL BE LIMITED IN
BROAD CLOUD/PRECIP SHIELD...THOUGH CANNOT RULE OUT SOME ELEVATED
MARGINALLY SEVERE STORMS AS THE WAVE ADDS DYNAMIC SUPPORT.

PRECIP SHOULD EXIT THE AREA TUESDAY EVENING AS THE WAVE LIFTS
NORTHEAST OF THE AREA...WITH DRY CONDITIONS AND SEASONABLE TEMPS
ACROSS THE AREA WEDNESDAY AS THE SURFACE RIDGE MOVES ACROSS THE
AREA. WILL KEEP CHANCE OF TSRA ACROSS MAINLY NORTHWEST PORTION OF
THE CWA...AS RETURN FLOW BRINGS INCREASED WARM ADVECTION AND LOW
LEVEL JET LATER WEDNESDAY NIGHT INTO THURSDAY.

DEEP UPPER LOW BECOMES CUTOFF OVER CALIFORNAI BY MID-LATE WEEK...AND
SEEING QUITE A BIT OF VARIABILITY IN HANDLING THIS UPPER LOW THROUGH
THE LONGER RANGE. GFS SHOWS SOME RUN-TO-RUN CONSISTENCY...HOWEVER IT
IS A SIGNIFICANT OUTLIER AMONG THE REMAINDER OF THE GFS ENSEMBLE
MEMBERS...BRINGING A COLD FRONT THROUGH MUCH MORE QUICKLY/COMPLETELY
THROUGH THE CWA ON FRIDAY...WHILE HANGING THE UPPER CUTOFF WELL WEST
OF THE GREATER ENSEMBLE CONSENSUS. ON THE FLIP SIDE...00Z ECMWF
LIFTS UPPER LOW NORTHEAST THROUGH THE ROCKIES MUCH MORE QUICKLY...
AND PREFER COMPROMISE BETWEEN THESE SOLUTIONS WHICH MATCHES 00Z GFS
ENSEMBLE...AND TO SOME DEGREE THE 06Z OPERATIONAL GFS RU...FAIRLY
WELL. THIS IDEA WILL HANG THE FRONT UP ACROSS THE NORTHERN PORTION
OF THE CWA FRIDAY...LIFTING IT BACK NORTH OF THE AREA THROUGH THE
WEEKEND. WILL LINGER A SMALL CHANCE OF PRECIP IN THE NORTHERN CWA
FRIDAY...THOUGH BETTER CHANCE LOOKS TO BE NORTH OF OUR AREA. THEN
DRY AND SEASONABLY WARM FOR THE WEEKEND BEFORE NEXT FRONT NEARS THE
AREA FROM THE NORTHWEST. TIMING OF THIS BOUNDARY QUITE UNCERTAIN AT
THIS TIME...BUT LOOKS TO BE NEAR ENOUGH TO CWA TO WARRANT COOLER
TEMPS AND MENTION OF PRECIP FOR MONDAY.

&&

.AVIATION...
MVFR CIGS/VSBYS WL BE FOUND OUTSIDE AREAS WHICH EXPERIENCE
CONVECTION OVERNIGHT AND INTO TUESDAY MORNING...WITH EXCEPTION OF
SOME POST CONVECTIVE MVFR CIGS ANRD KSUX AFT 11Z.  MVFR CIGS/VSBYS
WILL BE ASSOCIATED WITH MORE INTENSE CONVECTION...MAINLY 01Z-07Z
AT KHON...03Z-08Z AT KFSD...AND 04Z-11Z AT KSUX.

&&

.FSD WATCHES/WARNINGS/ADVISORIES...

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

&&

 CHAPMAN/JH

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
357 PM CDT MON SEP 17 2007

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-181200-
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-
357 PM CDT MON SEP 17 2007

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

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS...
SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP BETWEEN 5 PM AND
7 PM THROUGH THE LOWER JAMES VALLEY.  THESE STORMS WILL BE
CAPABLE OF PRODUCING DAMAGING WINDS TO AROUND 60 MPH AND HAIL TO
HALF DOLLAR SIZE.  THE STORMS WILL WORK EASTWARD TOWARD A
MARSHALL...SIOUX FALLS...VERMILLION LINE BY LATE EVENING.  THE
HAIL THREAT SHOULD DIMINISH AS STORMS BECOME MORE WIDESPREAD
ALONG THE LINE BY LATE EVENING...WITH A MARGINAL DAMAGING WIND
THREAT CONTINUING THROUGH SOUTHWEST MINNESOTA AND WESTERN
PORTIONS OF NORTHWEST IOWA THROUGH AROUND MIDNIGHT.

.DAYS TWO THROUGH SEVEN...TUESDAY THROUGH SUNDAY

HEAVY RAINFALL IS POSSIBLE ON TUESDAY ALONG AND EAST OF A LINE
FROM YANKTON TO BROOKINGS SOUTH DAKOTA...WITH THE GREATEST THREAT
EAST OF A LINE FROM TRACY MINNESOTA TO SIOUX CITY IOWA.

THUNDERSTORMS WILL BE POSSIBLE AGAIN ON FRIDAY...MAINLY FROM
SOUTH CENTRAL SOUTH DAKOTA INTO SOUTHWEST MINNESOTA. A FEW OF
THESE STORMS MAY BE SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 5 PM AROUND THE LOWER
JAMES VALLEY...AND AFTER 7 PM ALONG THE I 29 CORRIDOR.

&&

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