DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 231253
SWODY1
SPC AC 231251

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0751 AM CDT WED MAY 23 2012

VALID 231300Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS SWRN MN/WRN IA/SERN
SD/SRN AND ERN NEB/NWRN AND N-CNTRL KS...

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
CAROLINAS AND FAR SERN VA...

...SYNOPSIS...
A LARGE TROUGH OVER THE WRN HALF OF THE CONUS WILL DIG SEWD AS
MID-LEVEL HEIGHT FALLS OVERSPREAD THE CNTRL/SRN ROCKIES AND CNTRL
PLAINS...WITH A BELT OF STRONG MID-LEVEL FLOW WITHIN THE BROAD BASE
OF THE TROUGH. AN ASSOCIATED SFC COLD FRONT EXTENDING SSWWD FROM THE
ND/MN BORDER TO A LOW OVER THE KS/CO BORDER WILL GRADUALLY PROGRESS
EWD/SEWD. BROAD/MOSTLY WEAK MID/UPPER-LEVEL CYCLONIC FLOW WILL BE
FOUND FROM THE NRN GULF OF MEXICO EXTENDING NEWD ACROSS THE SERN
STATES INTO THE MID ATLANTIC.

...SWRN MN/WRN IA/SERN SD/SRN AND ERN NEB/NWRN AND N-CNTRL KS THIS
AFTERNOON INTO TONIGHT...
AS A PLUME OF THE ELEVATED MIXED LAYER IS ADVECTED INTO THE REGION
BY THE ENHANCED MID-LEVEL FLOW ACCOMPANYING THE AMPLIFYING
TROUGH...STEEP MID-LEVEL LAPSE RATES WILL OVERLAY A CORRIDOR OF
MODEST BOUNDARY-LAYER MOISTURE NEAR AND EAST OF THE COLD FRONT. WITH
WARM-SECTOR BOUNDARY-LAYER DEWPOINTS IN THE 50S TO PERHAPS AROUND
60F -- LIMITED BY VERTICAL MIXING AND DISTANCE FROM SUBSTANTIALLY
RICHER LOW-LEVEL MOISTURE -- 1000-2000 J/KG OF MLCAPE WILL LIKELY
DEVELOP THIS AFTERNOON. AND...WITH INCREASING LARGE-SCALE
ASCENT/DIURNAL HEATING CONTRIBUTING TO THE EROSION OF THE INITIALLY
STRONG EML CAP...SFC-BASED STORMS WILL LIKELY DEVELOP INVOF THE
FRONT BY LATE AFTERNOON.

THE COMBINATION OF MODERATE INSTABILITY AND MODERATE TO STRONG DEEP
SHEAR -- STRONGEST BEHIND THE FRONT -- WILL SUPPORT ORGANIZED STORMS
INCLUDING BOWING LINE SEGMENTS AND POSSIBLE SUPERCELLS. THIS
ACTIVITY WILL BE CAPABLE OF PRODUCING LARGE HAIL...ESPECIALLY WITH
SUSTAINED SUPERCELL STRUCTURES...ALONG WITH SVR WIND...PARTICULARLY
WITH SFC-BASED CONVECTION.

LOW-LEVEL SHEAR MAY BE SUFFICIENT TO SUPPORT THE THREAT FOR A
TORNADO OR TWO INTO THE EVENING...THOUGH LIMITED LOW-LEVEL MOISTURE
AND EVENTUAL FRONTAL UNDERCUTTING/UPSCALE CONVECTIVE GROWTH SHOULD
LIMIT THE OVERALL TORNADO THREAT.

...NERN CO THIS AFTERNOON INTO EARLY EVENING...
MODESTLY MOIST UPSLOPE FLOW BENEATH STRONG MID/HIGH-LEVEL FLOW WILL
SUPPORT ISOLATED TO SCATTERED THUNDERSTORMS WITH A THREAT FOR SVR
HAIL/WIND. ONLY MARGINAL DESTABILIZATION SHOULD PREVENT A MORE
SUBSTANTIAL SVR THREAT FROM EVOLVING.

...SOUTHEAST STATES/CAROLINAS/SERN VA THIS AFTERNOON INTO EARLY
EVENING...
A ZONE OF COOL MID-LEVEL TEMPERATURES /-14C TO -17C AT 500 MB/ WILL
OVERLAY AREAS OF STRONG SFC HEATING AND A NNE-SSW-ORIENTED WEAK SFC
FRONT. STEEP LAPSE RATES AND MODEST DEEP SHEAR WILL SUPPORT A THREAT
FOR MULTICELL STORMS CAPABLE OF SVR HAIL AND WIND...ESPECIALLY
ACROSS THE PIEDMONT/COASTAL AREAS OF THE CAROLINAS AND FAR SERN VA.

...SRN MS AND ERN LA THIS AFTERNOON...
STRONG HEATING AMIDST A NEWD-ADVANCING WARM FRONT WILL SUPPORT
ISOLATED TO WIDELY SCATTERED TSTMS. BOUNDARY-LAYER DEWPOINTS IN THE
LOWER 60S NEAR AND SW OF THE FRONT WILL SUPPORT MODERATE TO STRONG
DESTABILIZATION...WITH STEEP LOW-LEVEL LAPSE RATES LIKELY YIELDING
DCAPE VALUES IN EXCESS OF 1000 J/KG. VERY WEAK FLOW THROUGHOUT THE
TROPOSPHERE WILL SUPPORT A PULSE CONVECTIVE MODE...AND A LOW THREAT
FOR DMGG WIND GUSTS AND PERHAPS MARGINALLY SVR HAIL CANNOT BE RULED
OUT WITH THE STRONGEST STORMS.

..COHEN/CORFIDI.. 05/23/2012

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