MESO: Mesoscale Discussion 1271

ACUS11 KWNS 272038
SWOMCD
SPC MCD 272037
MOZ000-KSZ000-OKZ000-NEZ000-272200-

MESOSCALE DISCUSSION 1271
NWS STORM PREDICTION CENTER NORMAN OK
0337 PM CDT THU JUN 27 2013

AREAS AFFECTED...PORTIONS KS...EXTREME SERN NEB...WRN/CENTRAL
MO...NRN OK.

CONCERNING...SEVERE THUNDERSTORM WATCH 376...378...

VALID 272037Z - 272200Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
376...378...CONTINUES.

SUMMARY...SVR THREAT SHOULD INCREASE ACROSS WW AREAS...PARTICULARLY
KS PORTION...DURING REMAINDER MID-LATE AFTN. MIXTURE OF
QUASI-LINEAR AND CLUSTERED MODES IS POSSIBLE...WITH SOME
SUPERCELL-FAVORABLE CONDITIONS OVER ERN KS. THREAT FOR LARGE AND
OCCASIONALLY SIGNIFICANT/DAMAGING HAIL WILL EXIST...TRANSITIONING TO
DAMAGING WIND...WITH SOME OVERLAP POSSIBLE. ADDITIONAL WW MAY BE
REQUIRED WITHIN NEXT 2-3 HOURS FOR PORTIONS NRN OK.

DISCUSSION...SFC MESOANALYSIS SHOWED HEAT-AIDED FRONTAL-WAVE LOW
BETWEEN HLC-CNK...WITH COLD FRONT SWWD ACROSS W-CENTRAL KS TO LAA
AREA IN SERN CO. COLD FRONT SHOULD CONTINUE MOVING SEWD ACROSS
CENTRAL/SERN KS...PRECEDED BY INCREASINGLY WELL-DEFINED CONVECTIVE
BOUNDARY ARISING FROM TSTMS THAT HAVE INITIATED INVOF FRONT. SFC
MAP ALSO SHOWED TWO PRIMARY OUTFLOW FEATURES...

1. BLENDED OUTFLOW/DIFFERENTIAL-HEATING BOUNDARY EXTENDING FROM
DECAYING CONVECTION OVER S-CENTRAL MO...NWWD ACROSS ERN KS NEAR
EMP...TO BETWEEN SLN-MHK. BOUNDARY HAS DECELERATED AND IS MOVING
SLOWLY SWWD...AND ALSO HAS MODIFIED WITH FAVORABLY MOIST/BUOYANT AIR
TO ITS IMMEDIATE NE.
2. FRESHER OUTFLOW BOUNDARY EXTENDING FROM S-CENTRAL NEB NEAR
HDE...SEWD ACROSS MHK AREA...THEN BECOMING DIFFUSE ENEWD TOWARD STJ.
THIS BOUNDARY WAS PRODUCED LARGELY BY CONVECTION NOW WEAKENING NEAR
MHK...IS MOVING SWWD 15-20 KT ACROSS KS/NEB BORDER AND TOWARD
SLN...AND INTERSECTS FRONTAL ZONE INVOF NEWER CONVECTION OVER
SMITH/OSBORNE COUNTIES KS.

AIR MASS S OF FRONT AND OUTFLOWS TRANSITIONS FROM VERY HIGH-MOISTURE
CONTENT AND ADEQUATELY HEATED INVOF MO BOUNDARY TO VERY HOT...WITH
MODERATE MOISTURE CONTENT AND DEEP MIXED LAYER OVER WRN KS.
MODIFIED FCST SOUNDINGS SUGGEST MLCAPE RANGES FROM AROUND 1500 J/KG
OVER SWRN KS TO 4000 J/KG IN S-CENTRAL KS AND EXTREME N-CENTRAL
OK...TO NARROW CORRIDOR OF 5000-6000 J/KG ON E SIDE OF FIRST OUTFLOW
BOUNDARY OVER SRN/WRN MO. SHARP DECREASE IN BUOYANCY IS NOTED WITH
NEWD EXTENT OVER CENTRAL/SRN MO. RELATED INSTABILITY GRADIENT
SHOULD FORM EFFECTIVE ERN BOUND FOR SUBSTANTIAL SVR
POTENTIAL...WHILE AREA OF TSTMS EXPANDS/INTENSIFIES ACROSS KS AND
EVENTUALLY INTO PORTIONS NRN OK. DIFLUENT MID-UPPER FLOW STILL IS
STRONG ENOUGH TO SUPPORT 30-40 KT EFFECTIVE SHEAR MAGNITUDES OVER
MUCH OF THIS REGION.

..EDWARDS.. 06/27/2013

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

ATTN...WFO...LSX...SGF...EAX...TSA...OAX...TOP...ICT...OUN...
GID...DDC...GLD...AMA...

LAT...LON 38070167 38340128 38990016 40079859 39559734 39579659
40319621 40499462 39209296 38099261 37529195 37139398
37009482 36409870 37020167 38070167

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