[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 120550
SWODY1
SPC AC 120548

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1148 PM CST THU JAN 11 2007

VALID 121200Z - 131200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
SIGNIFICANT MID-UPPER LEVEL PATTERN SHIFT UNDERWAY AS HEIGHTS FALL
ACROSS WRN CONUS.  POSITIVELY TILTED TROUGH -- NOW EVIDENT IN
MOISTURE CHANNEL IMAGERY FROM SASK TO N-CENTRAL CA -- IS EXPECTED TO
STRENGTHEN IN SRN PORTION WITH CLOSED LOW EVOLVING OVER NV EARLY IN
PERIOD.  ASSORTED MESOSCALE VORTICITY LOBES WILL PIVOT AROUND
ASSOCIATED CIRCULATION...AS NET CYCLONE TRACK SLOWLY CURVES EWD OVER
UT BY END OF PERIOD.

AT SFC...INTENSE ARCTIC COLD FRONT NOW ANALYZED FROM ERN IA ACROSS
SERN KS TO CENTRAL TX PANHANDLE -- IS FCST TO MOVE SWD TO POSITION
OVER OH VALLEY..ARKLATEX...W-CENTRAL TX BY END OF PERIOD.  KINEMATIC
RESPONSES ASSOCIATED WITH LOW LEVEL CYCLOGENESIS OVER NWRN NM/SWRN
CO SHOULD IMPEDE SWWD PROGRESS OF FRONT ACROSS ERN NM...AND IN FACT
MAY CAUSE SOME NWD RETREAT THERE.

...SRN PLAINS...BIG BEND/PECOS VALLEY TO OZARKS...
MRGL SVR POTENTIAL MAY DEVELOP DURING AFTERNOON ACROSS PORTIONS
CENTRAL/NRN TX AHEAD OF FRONT...WHERE 50-60 KT MIDLEVEL SWLYS AND
SELY SFC WINDS WILL CONTRIBUTE TO FAVORABLY LARGE DEEP-LAYER SHEAR
VECTORS AND LOW LEVEL HODOGRAPHS.  MAIN CAVEATS WILL BE WEAKNESS OF
BOTH BUOYANCY AND LOW LEVEL FORCING FOR CONVECTION...IN ABSENCE OF
ANY SIGNIFICANT PREFRONTAL BOUNDARIES.  ALTHOUGH SHADED BY MID/UPPER
CLOUDS FOR MUCH OF DAY...SUFFICIENT SFC HEATING MAY DEVELOP TO
SUPPORT HORIZONTAL CONVECTIVE ROLLS...WITH SOME DEEPER DEVELOPMENT
POSSIBLE DURING AFTERNOON WHEN SBCINH IS SMALLEST.  WEAK LAPSE RATES
ALOFT SHOULD LIMIT MLCAPES TO BELOW 500 J/KG IN MOST AREAS...AND
ONLY SMALL PROPORTION OF CONVECTION MAY REACH OPTIMAL ICING LAYERS
FOR CG LIGHTNING PRODUCTION.  HOWEVER...GIVEN ENVIRONMENTAL SHEAR
PROFILES...STORM ROTATION IS POSSIBLE WITH NONZERO RISK OF A TORNADO
OR DAMAGING GUST.

THIS THREAT SHOULD SHIFT GRADUALLY TOWARD HAIL AND ISOLATED WIND
WITH WWD EXTENT -- ESPECIALLY INTO TRANS-PECOS...PERMIAN BASIN AND
BIG BEND REGION WHERE SOMEWHAT HIGHER LCL...STEEPER DEEP-LAYER LAPSE
RATES...AND LARGER BUOYANCY ARE EXPECTED.  AFTERNOON/EARLY EVENING
SHEAR PROFILES ALONG AND S OF FRONT SHOULD BE FAVORABLE FOR
SUPERCELLS...WITH 40-50 KT EFFECTIVE SHEAR EVIDENT IN NAM/NAM-KF
FCST SOUNDINGS...AND MLCAPE TO NEAR 700 J/KG.  CONVECTIVE COVERAGE
MAY BE LIMITED BY WEAK LOW LEVEL FORCING IN THIS REGION AS WELL.

SVR POTENTIAL IN ALL AREAS APPEARS TO BE TOO MRGL/CONDITIONAL TO
WARRANT CATEGORICAL OUTLOOK ATTM.

ALTHOUGH LAPSE RATES ALOFT WILL BE WEAK...ISOLATED/EPISODIC GEN
THUNDER POTENTIAL MAY EXIST AS FAR NE AS SWRN MO/WRN KY AND AS FAR N
AS ATOP FREEZING SFC TEMPS IN PORTIONS OK/KS OVERNIGHT...SUPPORTED
BY LOW LEVEL WAA REGIME...ASSOCIATED MOISTENING INVOF LLJ...AND
ISENTROPIC ASCENT TO LFC.

..EDWARDS.. 01/12/2007