MESO: Mesoscale Discussion 1934

ACUS11 KWNS 042220
SWOMCD
SPC MCD 042220
IAZ000-MOZ000-NEZ000-SDZ000-042345-

MESOSCALE DISCUSSION 1934
NWS STORM PREDICTION CENTER NORMAN OK
0520 PM CDT FRI OCT 04 2013

AREAS AFFECTED...ERN NEB...SE SD AND WRN IA

CONCERNING...TORNADO WATCH 539...

VALID 042220Z - 042345Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 539 CONTINUES.

SUMMARY...THE TORNADO THREAT APPEARS LIKELY TO CONTINUE ACROSS NE
NEB INTO THE EARLY EVENING AND MAY SPREAD NWD INTO SE SD AND
POSSIBLY EWD INTO NW IA. ISOLATED LARGE HAIL AND WIND DAMAGE WILL
ALSO BE POSSIBLE WITH THE MORE INTENSE STORMS. A LOCAL EXTENSION HAS
BEEN DONE ACROSS SERN SD FROM WEST OF YANKTON SD EWD INTO NW IA.

DISCUSSION...THE LATEST SFC ANALYSIS SHOWS A 1001 MB LOW IN NERN NEB
WITH A MOIST AXIS EXTENDING FROM NEAR THE SFC LOW SEWD ACROSS THE
OMAHA AREA WHERE SFC DEWPOINTS ARE IN THE MID 60S TO LOWER 70S F.
THIS IS CONTRIBUTING TO MLCAPE IN THE 2000 TO 2500 J/KG RANGE AS
ESTIMATED BY MESOSCALE ANALYSIS. IN ADDITION...THE OMAHA AND SIOUX
FALLS WSR-88D VWPS SHOW DEEP LAYER SHEAR AROUND 60 KT WITH 0-1 KM
SHEAR OF 25 TO 30 KT. THIS MAGNITUDE OF INSTABILITY AND SHEAR SHOULD
CONTINUE TO SUPPORT SUPERCELL DEVELOPMENT AND TORNADOES WILL BE
POSSIBLE WITH THE MORE DOMINANT ROTATING STORMS. THE CELLS IN NERN
NEB JUST TO THE SOUTH OF THE SD BORDER ARE SFC-BASED AND SHOULD
REMAIN SO FOR SEVERAL MORE HOURS BEFORE MOVING INTO THE COOLER AIR
IN THE SIOUX FALLS AREA. FOR THIS REASON...THE STORMS SHOULD
CONTINUE TO HAVE A TORNADO THREAT INTO EARLY THIS EVENING. IN
ADDITION TO THE TORNADO THREAT...ISOLATED LARGE HAIL WILL BE
POSSIBLE DUE TO THE COLD TEMPS ALOFT AND MODERATE INSTABILITY IN
PLACE. AS THE STORMS CONTINUE TO EXPAND IN COVERAGE...LINEAR
DEVELOPMENT WILL BE POSSIBLE ALONG THE FRONT SUGGESTING THE WIND
DAMAGE THREAT COULD INCREASE EARLY THIS EVENING.

..BROYLES/WEISS.. 10/04/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...DMX...EAX...FSD...OAX...LBF...

LAT...LON 43619736 43499818 43379840 43049851 42789819 42449757
41879677 41079607 40589580 40419541 40599463 40929427
41899424 43039522 43459635 43619736

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