DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 180559
SWODY1
SPC AC 180557

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1257 AM CDT SAT AUG 18 2012

VALID 181200Z - 191200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE
CENTRAL/SRN PLAINS INTO THE ARKLATEX...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE
MID-ATLANTIC/COASTAL CAROLINAS...

...SYNOPSIS...
A BROAD LONG WAVE TROUGH WILL CONTINUE ACROSS THE ERN TWO-THIRDS OF
THE CONUS ON SAT WITH AN UPPER LEVEL RIDGE REMAINING OVER THE WEST.
A SHORTWAVE TROUGH CURRENTLY ENTERING THE NRN PLAINS WILL MOVE S/SE
ALONG THE WRN PORTION OF THE UPPER TROUGH AND INTO THE MO RIVER
VALLEY. AN UPPER LEVEL TROUGH OVER THE NE PAC WILL MOVE INLAND OVER
THE PAC NW/NRN CA.

AT THE SURFACE...A COLD FRONT ACCOMPANYING THE CENTRAL U.S.
SHORTWAVE WILL MOVE SWD TO A POSITION FROM SERN NEB INTO THE TX
PANHANDLE BY 19/00Z...WHERE IT WILL INTERSECT A WARM FRONT EXTENDING
SEWD ALONG THE RED RIVER AND INTO THE MID MS RIVER VALLEY. A COLD
FRONT WILL MOVE EWD OFF THE EAST COAST.

...CENTRAL/SRN PLAINS EWD TO ARKLATEX...
A WARM FRONT IS EXPECTED TO BE IN THE GENERAL VICINITY OF THE RED
RIVER AT 12Z SAT...WITH THE WWD PORTION LIFTING NWD DURING THE DAY
IN RESPONSE TO THE APPROACHING SHORTWAVE TROUGH. THE POTENTIAL FOR
ON-GOING OR MORNING TSTM DEVELOPMENT ACROSS THE CENTRAL/SRN PLAINS
ADDS SOME UNCERTAINTY TO THE AMOUNT OF NWD MOVEMENT OF THE FRONT
DURING THE DAY. CURRENT INDICATIONS ARE THAT THE COLD FRONT-WARM
FRONT INTERSECTION WILL BE LOCATED ACROSS THE TX PANHANDLE BY 18Z
WITH THE WARM FRONT EXTENDING SEWD TOWARDS THE ARKLATEX.

TSTMS WILL LIKELY DEVELOP OR INTENSIFY NEAR THE COLD FRONT/WARM
FRONT INTERSECTION BY EARLY AFTN AND MOVE SEWD ALONG OR SOUTH OF THE
WARM FRONT. STRENGTHENING WIND FIELDS WILL LEAD TO DEEP LAYER SHEAR
OF 40-50 KTS OVER WRN PORTIONS OF THE SLIGHT RISK AREA WHICH WILL
SUPPORT SUPERCELL STRUCTURES INITIALLY... WITH TSTMS POTENTIALLY
EVOLVING INTO A SEWD-MOVING COMPLEX WITH TIME. OTHER SVR TSTMS MAY
DEVELOP FARTHER EAST ALONG THE WARM FRONT AND IN THE WARM SECTOR AIR
MASS TO THE SOUTH AS FORCING FOR ASCENT AND AREAS OF STRONG DIABATIC
HEATING ASSIST IN REMOVING CINH.

ADJUSTMENTS TO SVR PROBABILITIES ARE POSSIBLE WITH LATER OUTLOOKS AS
THE IMPACTS OF OVERNIGHT CONVECTION ARE ASSESSED.

...CAROLINAS/MID-ATLANTIC STATES...
DIURNAL HEATING SHOULD RESULT IN POCKETS OF MODERATE MLCAPE IN
ADVANCE OF THE COLD FRONT. ALTHOUGH STRONGER SHEAR WILL REMAIN WEST
OF THE HIGHEST INSTABILITY...IT SHOULD BE SUFFICIENT FOR MULTICELL
TSTMS PRODUCING DAMAGING WINDS AND ISOLATED LARGE HAIL. FORECAST
SOUNDINGS DEPICT MID-LEVEL DRY AIR WHICH MAY ENHANCE DOWNDRAFT
STRENGTH/DAMAGING WIND POTENTIAL WITH THE STRONGEST TSTMS.

...OR...
AS HEIGHT FALLS AND STRONGER FLOW ALOFT MOVE INLAND WITH THE UPPER
TROUGH...EXPECT ISOLATED/WIDELY SCT TSTMS TO DEVELOP WITHIN A DEEPLY
MIXED BOUNDARY LAYER. DAMAGING WINDS WILL BE POSSIBLE WITH THE
STRONGEST TSTMS.

..BUNTING/COHEN.. 08/18/2012

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