[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 130546
SWODY1
SPC AC 130544

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1144 PM CST FRI JAN 12 2007

VALID 131200Z - 141200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
IN MID-UPPER LEVELS...SYNOPTIC SCALE TROUGH IS FCST TO REMAIN OVER
WRN CONUS...AS EMBEDDED UPPER VORTEX NOW OVER NV/UT BORDER REGION
MOVES/REDEVELOPS NEWD OVER WY.  MEANWHILE...STRONG VORTICITY LOBE
PIVOTING THROUGH BASE OF TROUGH MAY EVOLVE INTO CLOSED OR NEARLY
CLOSED LOW FARTHER SW OVER 4-CORNERS AREA...BY 14/12Z.  ALTHOUGH
LATEST OPERATIONAL SPECTRAL/NAM AND VARIOUS SREF MEMBERS FROM 12/21Z
RUN DIFFER SOME ON GEOMETRY AND RELATIVE STRENGTH OF EACH
LOW...GENERAL SCENARIO IS IN GOOD AGREEMENT.  THIS FOMENTS HIGH
CONFIDENCE IN PRESENCE OF EXTENSIVE BELT OF MID-UPPER SWLYS FROM NRN
MEX ACROSS SRN/CENTRAL PLAINS TO OH VALLEY THROUGH MOST OF
PERIOD...JUXTAPOSED OVER BROAD REGIME OF LOW LEVEL WAA/MOISTURE
TRANSPORT.

AT SFC...INTENSE ARCTIC COLD FRONT -- NOW ANALYZED FROM SERN NM INTO
CENTRAL TX THEN NEWD ACROSS SRN IL -- IS EXPECTED TO MOVE SLOWLY SWD
ACROSS LOWER OH VALLEY...AR AND INTO S-CENTRAL TX.  WEAK LOW MAY
FORM AND MOVE NEWD ALONG FRONT...ACROSS AR...AS SRN STREAM MIDLEVEL
PERTURBATION NOW OVER BAJA/NERN MEX EJECT NEWD.  WRN SEGMENT OF
FRONT OVER SW TX AND SERN NM MAY STALL OR DECELERATE
CONSIDERABLY...WITH STRONG/PRIMARY SFC CYCLONE EXPECTED TO RE-FORM
OVER CENTRAL NM BY LATE IN PERIOD.

...SE TX TO SRN AR...
VERTICAL SHEAR PROFILES S OF FRONT WILL BE FAVORABLE FOR ANY
SUSTAINED/DISCRETE CONVECTION TO ROTATE...ESPECIALLY IF SFC WINDS
ARE BACKED SOMEWHAT BY WEAK FRONTAL-WAVE LOW DEVELOPMENT INDICATED
IN SPECTRAL/NAM GUIDANCE.  MAIN CONCERNS WILL BE CONVECTIVE MODE...
PLACEMENT RELATIVE TO SFC-BASED INFLOW...AND LACK OF DEEPER AND MORE
ROBUST BUOYANCY.  NUMEROUS SHOWERS WITH EMBEDDED TSTMS MAY DEVELOP
INVOF FRONT...LEAVING MOST PROBABLE AREA FOR DISCRETE DEVELOPMENT
ASSOCIATED WITH WEAK BOUNDARY LAYER FORCING TO ITS S...DURING
AFTERNOON.  FCST SOUNDINGS INDICATE VERY SIMILAR REGIME TO THAT OVER
CENTRAL TX PREVIOUS DAY...WITH MLCAPE PROFILES BELOW 500 J/KG IN
MAGNITUDE AND REMAINING MOSTLY BELOW LAYERS MOST SUITABLE FOR CG
LIGHTNING PRODUCTION.  BRIEF TORNADO CANNOT BE RULED OUT...BUT
PROBABILITIES APPEAR TOO LIMITED TO WARRANT CATEGORICAL SVR OUTLOOK
ATTM.

...S-CENTRAL/SW TX...
RELATIVE WEAKNESS IN LOW LEVEL VERTICAL SHEAR IS FCST OVER DEEP S TX
AND S-CENTRAL TX...MAINLY DUE TO DESTRUCTIVE INFLUENCE OF RELATIVELY
WEAK 1-3 KM AGL FLOW ON HODOGRAPH SIZE.  THESE WEAKNESSES ARE LESS
EVIDENT FARTHER NW TOWARD LOWEST PECOS VALLEY REGION...HOWEVER
AFTERNOON SBCINH MAY BE STRONGER.  REASONABLE PRESENCE OF SSELY-SELY
SFC WINDS AND 40-50 KT WINDS IN MIDDLE PORTION OF BUOYANT PROFILES
YIELDS FAVORABLE EFFECTIVE SHEARS OF 40-50 KT IN SUPPORT OF SOME
STORM ORGANIZATION EVEN WHERE WEAKNESSES ARE EVIDENT ATOP BOUNDARY
LAYER.

WITH ANAFRONTAL NET FLOW REGIME...ACTIVITY FORMING S OF FRONT
EFFECTIVELY MAY BE UNDERCUT BY FRONT...HOWEVER MRGL POTENTIAL FOR
SFC-BASED SVR IN WARM SECTOR IS EVIDENT AND WILL BE REFLECTED IN
UNCONDITIONAL PROBABILITIES.  ALTHOUGH CAPPING WILL INCREASE WITH
SWD EXTENT...HEATING MAY BE SUFFICIENT TO WEAKEN CINH AND SUPPORT
DEVELOPMENT NEAR AND S OF FRONT...AND ALSO ALONG ERN SLOPES OF
SERRANIAS DEL BURRO RANGE OF NRN MEX.  ANY ACTIVITY DEVELOPING OVER
MEX MOUNTAINS MAY MOVE NEWD ACROSS RIO GRANDE INTO S TX DURING LATE
AFTERNOON/EARLY EVENING...HOWEVER EXTENSIVE MID/HIGH CLOUD COVER MAY
RESTRICT HEATING OF HIGHER TERRAIN AND LIMIT OR PREVENT SUCH
DEVELOPMENT.  GIVEN THESE UNCERTAINTIES...SVR PROBABILITIES ARE KEPT
MRGL FOR THIS AREA AS WELL.

..EDWARDS.. 01/13/2007