DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 191723
SWODY2
SPC AC 191721

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1121 AM CST THU DEC 19 2013

VALID 201200Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A PROGRESSIVE/SPLIT LARGE SCALE PATTERN WILL EXIST OVER THE CONUS ON
FRIDAY...HIGHLIGHTED BY EXTENSIVE CYCLONIC UPPER FLOW OVER MUCH OF
THE CONUS AND THE GENERAL EASTWARD ADVANCEMENT OF A POTENT UPPER
TROUGH/POLAR JET OVER NORTHWEST MEXICO. AIR MASS MODIFICATION WILL
STEADILY OCCUR ESPECIALLY OVER THE SOUTH-CENTRAL CONUS...WITH AN
INCREASING MOIST BOUNDARY LAYER BECOMING ESTABLISHED ALONG/SOUTH OF
A FRONTAL ZONE FROM PARTS OF TX/ARKLATEX NORTHEASTWARD INTO THE
LOWER OH RIVER VALLEY.

...PORTIONS OF TX/ARKLATEX...
AS SOUTHERN HIGH PLAINS CYCLOGENESIS GRADUALLY OCCURS FRIDAY...THE
PRIMARY SURFACE BOUNDARY WILL STALL/ORIENT SOUTHWEST-NORTHEASTWARD
FROM SOUTHWEST TX TO THE OH VALLEY...WITH A FRONTAL WAVE/SURFACE LOW
MOVING EASTWARD ACROSS THE MIDWEST/OH VALLEY. WITHIN THE NEARBY WARM
SECTOR...LOWER TO MIDDLE 60S F SURFACE DEWPOINTS WILL BECOME
INCREASING PREVALENT ACROSS THE SOUTHERN HALF OF TX AND ADJACENT
ARKLATEX/LOWER MS RIVER VALLEY.

IN SPITE OF INCREASING BOUNDARY LAYER MOISTURE...THE MAJORITY OF THE
REGION WILL BE INFLUENCED BY WEAK OVERALL FORCING AND SUBTLE HEIGHT
TENDENCIES /IF NOT WEAK HEIGHT RISES/...AT LEAST THROUGH THE
DAYLIGHT HOURS. THIS SCENARIO...WITH AN INCREASINGLY STOUT ELEVATED
MIXED LAYER ACROSS TX...SHOULD GENERALLY CAP THE WARM SECTOR WITH
THE POSSIBLE EXCEPTION OF FRIDAY NIGHT IMMEDIATELY NEAR THE FRONT.

AS GRADUAL HEIGHT FALLS BEGIN TO INFLUENCE TX FRIDAY NIGHT VIA THE
NORTHWEST MEXICO/SOUTHWEST STATES UPPER TROUGH...A STRENGTHENING LOW
LEVEL JET/ASSOCIATED ISENTROPIC UPLIFT FOCUSED NEAR/NORTH OF THE
REGIONAL SURFACE FRONTAL ZONE WILL RESULT IN A NOCTURNAL INCREASE OF
TSTMS. THIS INCLUDES A CORRIDOR FROM SOUTHWEST/CENTRAL TX
NORTHEASTWARD TO THE ARKLATEX/OZARKS. A COUPLE OF NEAR SURFACE-BASED
STORMS CANNOT BE ENTIRELY DISCOUNTED NEAR THE FRONT...BUT THE MOST
PROBABLE/DOMINANT SCENARIO WILL BE FOR STORMS TO DEVELOP/INCREASE ON
THE IMMEDIATE COOL SIDE OF THE SURFACE FRONT...WITH STORMS GENERALLY
ROOTED ABOVE A RELATIVELY COOL/STABLE BOUNDARY LAYER. STRONG SHEAR
THROUGH THE CLOUD LAYER/SUFFICIENT ELEVATED INSTABILITY SUGGEST THAT
MARGINALLY SEVERE HAIL MAY OCCUR WITH A FEW OF THE STORMS. IN SPITE
OF INCREASING DEEP LAYER SHEAR/LENGTHENING LOW-LEVEL
HODOGRAPHS...ANY SEVERE WIND GUST AND/OR BRIEF TORNADO POTENTIAL
WILL BE CONTINGENT UPON NEAR SURFACE-BASED DEVELOPMENT WITHIN THE
WARM SECTOR FRIDAY NIGHT...WHICH APPEARS RELATIVELY LOW/UNCERTAIN AT
THIS TIME.

..GUYER.. 12/19/2013

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