Severe Thunderstorm Warning 82, NWS Sioux Falls, SD

272 
WWUS53 KFSD 021402
SVSFSD

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SIOUX FALLS SD
902 AM CDT FRI AUG 2 2013

SDC023-053-021412-
/O.CAN.KFSD.SV.W.0082.000000T0000Z-130802T1430Z/
GREGORY SD-CHARLES MIX SD-
902 AM CDT FRI AUG 2 2013

...THE SEVERE THUNDERSTORM WARNING FOR WEST CENTRAL CHARLES MIX AND
CENTRAL GREGORY COUNTIES IS CANCELLED...

THE STORM WHICH PROMPTED THE WARNING HAS WEAKENED BELOW SEVERE
LIMITS...AND NO LONGER POSES AN IMMEDIATE THREAT TO LIFE OR PROPERTY.
HOWEVER...HEAVY RAIN IS STILL POSSIBLE WITH THIS THUNDERSTORM AS IT
MOVES THROUGH AREAS FROM SOUTH OF PLATTE TOWARD GEDDES THROUGH 945 
AM CDT.

LAT...LON 4332 9871 4316 9882 4333 9928 4344 9923
TIME...MOT...LOC 1402Z 291DEG 21KT 4332 9900

$$

CHAPMAN

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SIOUX FALLS SD
608 AM CDT FRI AUG 2 2013

.SHORT TERM...(TODAY AND TONIGHT)
ISSUED AT 341 AM CDT FRI AUG 2 2013

CONFIDENCE ON CONVECTIVE DEVELOPMENT/EVOLUTION IS EXTREMELY LOW FOR
TODAY WITH NOT A SINGLE MODEL HANDLING OVERNIGHT CONVECTION WELL.
CURRENT RADAR SHOWING CONVECTION DEVELOPING OVER WESTERN SOUTH
DAKOTA VERY EARLY THIS MORNING...THOUGH NOT SURE IF ANY OF THIS
ACTIVITY WILL MAKE IT INTO OUR WESTERN ZONES WITH STORM MOTION TO
THE SOUTHEAST AND A MORE STABLE/DRIER ATMOSPHERE OVER OUR AREA. A
STATIONARY BOUNDARY IS SITUATED SOMEWHERE ACROSS THE AREA...THOUGH
VERY HARD TO DEFINE WITH SURFACE OBS...WITH ASSORTED OUTFLOW
BOUNDARIES AROUND THE REGION. THE ASSUMPTION AT THIS POINT IS THAT
MOST CONVECTIVE DEVELOPMENT WILL BE FOCUSED IN THE VICINITY OF THIS
BOUNDARY TODAY...WHERE EVER IT MAY END UP. IT IS PROGGED TO BE
DRAPED ACROSS OUR FAR SOUTH THIS AFTERNOON...SO KEPT THE HIGHER POPS
OVER THAT AREA AND UP THROUGH THE MISSOURI RIVER VALLEY WHERE
PROGGED INSTABILITY WILL BE GREATER. MODELS DO INDICATE THE
ATMOSPHERE BECOMING MORE STABLE THROUGH THE DAY AS BETTER
INSTABILITY IS SHUNTED TO THE SOUTH...SO THINK THAT THE BETTER
CHANCE OF ANY SEVERE WEATHER MAY BE TO THE SOUTH OF OUR CWA. THAT
BEING SAID...THE BEST CHANCE OF SEVERE STORM DEVELOPMENT IF IT WERE
TO OCCUR WOULD BE IN THE AFTERNOON THROUGH OUR LOWER SOUTH
CENTRAL/MISSOURI RIVER ZONES WHERE LINGERING INSTABILITY/STRONG
DIRECTIONAL SHEAR MAY EXIST. MODELS CONTINUE TO COME IN COOLER THAN
PREVIOUS RUNS WITH REGARD TO HIGHS TODAY UNDER AN EASTERLY LOW LEVEL
FLOW...SO DROPPED HIGHS A COUPLE MORE DEGREES...RUNNING GENERALLY
MID AND UPPER 70S...TO AROUND 80 TROUGH OUR SOUTHERN MOST IOWA ZONES.

BY TONIGHT...EXPECT ANY LINGERING THUNDERSTORM ACTIVITY IN OUR SOUTH
TO DIMINISH AS DRIER AIR CONTINUES TO FILTER INTO THE REGION AND THE
STATIONARY BOUNDARY PULLS OUT OF OUR AREA. 925 MB TEMPERATURES COOL
SLIGHTLY OVERNIGHT UNDER A NORTHEASTERLY LOW LEVEL FLOW...WITH LOWS
DROPPING INTO THE MID 50S TO NEAR 60.

.LONG TERM...(SATURDAY THROUGH THURSDAY)
ISSUED AT 341 AM CDT FRI AUG 2 2013

FSD FORECAST AREA WILL BE UNDER THE INFLUENCE OF COOL CANADIAN HIGH
PRESSURE AND EASTERLY LOW LEVEL FLOW...MAKING FOR A COOL EARLY
AUGUST WEEKEND WITH HIGH TEMPS ONLY IN THE 70S. RETURN FLOW SETS UP
ACROSS WESTERN SODAK FOR SATURDAY NIGHT IN RESPONSE TO PAC NW VORT
MAX TRAVERSING THE UPPER RIDGE. MODELS NOW MOSTLY IN AGREEMENT WITH
INSTABILITY AXIS REMAINING SOUTH AND WEST...WITH A 850MB BOUNDARY
SITTING JUST SOUTH OF MO RIVER. HAVE CONCENTRATED HIGHEST CHANCE POPS
ACROSS THE MO RIVER VALLEY AREA AND WEST OF THE JAMES RIVER
ACCORDINGLY...BUT OVERALL HAVE LOWERED POPS FOR SUNDAY/SUNDAY
NIGHT. MUCAPES REMAIN BELOW 1000 J/KG AS WELL FOR SUNDAY SO SEVERE
WEATHER THREAT IS VERY LOW. ASSOCIATED LOW LEVEL COLD FRONT PUSHES
THROUGH SUNDAY OVERNIGHT AND FOR THE FIRST PART OF MONDAY WITH
SOME SCT CONVECTION STILL POSSIBLE.

CONTINUED FAST NORTHWEST FLOW ALOFT BETWEEN CANADIAN CLOSED LOW AND
SOUTHERN CONUS RIDGE WILL CONTINUE TO MAKE CONVECTIVE FORECASTING
VERY CHALLENGING. MODELS PICKING UP ON MORE SIGNIFICANT SHORT
WAVE/FRONT FROM CANADIAN LOW THAT SWINGS THROUGH ON MONDAY NIGHT
THROUGH TUESDAY OR TUESDAY NIGHT PER THE GFS OR ECMWF. LOOKS LIKE
SOME DECENT RETURN FLOW WITH GFS ADVERTISING VERY HIGH MUCAPES FOR
TUESDAY AFTERNOON ACROSS MUCH OF THE FORECAST AREA. DEEP LAYER
SHEAR 50 KTS TUESDAY AFTERNOON MAKES ORGANIZED CONVECTION A
POSSIBILITY. HOWEVER...WITH TIMING AND PLACEMENT ISSUES IN THE
MODELS AS OF LATE...CONFIDENCE OF ANY SEVERE THREAT IS LOW. WILL
MONITOR FOR CONSISTENCY IN SUBSEQUENT MODEL RUNS.

OTHERWISE RETROGRADING UPPER CANADIAN LOW WILL BRING EVEN COOLER
TEMPS FOR THE LATTER HALF OF THE WEEK...ALTHOUGH THE LATEST ECMWF IS
NOT QUITE AS BULLISH WITH THE COLD AIR ADVECTION AS IT WAS
YESTERDAY.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING)
ISSUED AT 602 AM CDT FRI AUG 2 2013

SCATTERED SHOWERS AND THUNDERSTORMS WILL DEVELOP ACROSS THE WEST
AND SOUTH TODAY...THOUGH CONFIDENCE IN TIMING AND EVOLUTION IS LOW
WITH MODELS HANDLING THE CONVECTION POORLY. CONVECTION MORE LIKELY
TO BRIEFLY AFFECT KHON AND KSUX THAN KFSD...AND ANY HEAVIER
THUNDERSTORM ACTIVITY COULD RESULT IN SHORT LIVED LOWERING OF
CONDITIONS. THERE WILL BE A POSSIBILITY OF MVFR CEILINGS AROUND
KSUX LATER TONIGHT.

&&

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

SHORT TERM...JM
LONG TERM...
AVIATION...JM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SIOUX FALLS SD
741 AM CDT FRI AUG 02 2013

SDZ038>040-050-052>071-MNZ071-072-080-081-089-090-097-098-
IAZ001>003-012>014-020>022-031-032-NEZ013-014-031200-
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-
741 AM CDT FRI AUG 02 2013

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 THIS MORNING INTO MID
AFTERNOON MAINLY SOUTHWEST OF A LINE FROM HURON TO SIOUX FALLS TO
STORM LAKE. STRONGEST STORMS WILL BE LOCATED SOUTH OF A
CHAMBERLAIN TO FREEMAN TO SIOUX CITY LINE...AND A FEW OF THESE
STORMS COULD BE SEVERE.  THE MAIN THREATS WOULD BE HAIL TO THE
SIZE OF QUARTERS AND WIND GUSTS TO 60 MPH.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

THERE WILL BE A CHANCE OF THUNDERSTORMS ACROSS THE AREA ON
SATURDAY NIGHT AND SUNDAY. THESE STORMS ARE NOT EXPECTED TO BE
SEVERE.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION WILL BE POSSIBLE AFTER 10 AM CDT.

&&

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