[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 191725
SWODY2
SPC AC 191724

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1124 AM CST TUE DEC 19 2006

VALID 201200Z - 211200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
MODELS REMAIN CONSISTENT WITH LARGE/DEEP UPPER LOW TRACKING NEWD
FROM THE SRN ROCKIES INTO THE CENTRAL HIGH PLAINS REGION DURING DAY
2.  ALTHOUGH MODELS DIFFER SLIGHTLY WITH THE TIMING OF A
POSITIVELY-TILTED SRN STREAM IMPULSE...THIS FEATURE SHOULD TRACK
NEWD ACROSS THE TX COASTAL PLAIN AND LA DURING THE FIRST HALF OF THE
PERIOD.  SURFACE COLD FRONT IS EXPECTED TO SPREAD ESEWD THROUGH SRN/
ERN TX...REACHING DEEP S TX...TX COASTAL PLAIN TO WRN LA DURING
21/00-06Z.  SURFACE BOUNDARY...CURRENTLY EXTENDING EWD FROM DEEP S
TX INTO THE GULF OF MEXICO...IS EXPECTED TO MOVE NWD ON DAY 2
REACHING THE UPPER TX COAST REGION BY 21/00Z...AND THEN MAY SPREAD
JUST INLAND OVER SW LA WEDNESDAY NIGHT.

...S-CENTRAL/SE TX TO SW LA...
FORCING FOR ASCENT ASSOCIATED WITH THE LEAD SRN STREAM IMPULSE
SHOULD BE EXITING MUCH OF THE TX COASTAL PLAIN WEDNESDAY MORNING...
WITH RESULTANT TEMPORARY DECELERATION OF SWLY MID LEVEL FLOW. 
HOWEVER...HEIGHT GRADIENT SHOULD TIGHTEN SOME ALONG SERN PERIPHERY
OF UPPER LOW AS NEXT MID/UPPER LEVEL JET MAX TRANSLATES THROUGH THIS
PORTION OF UPPER SYSTEM...WEDNESDAY AFTERNOON TO WEDNESDAY NIGHT.

DESPITE SURFACE DEWPOINTS IN THE MID 60S IN ADVANCE OF THE COLD
FRONT...WEAK LAPSE RATES AND LIMITED SURFACE HEATING ARE EXPECTED TO
RESULT IN MARGINAL INSTABILITY WITHIN WARM SECTOR AIR MASS. 
ALTHOUGH ASCENT IS EXPECTED TO BE WEAK FROM DEEP S TX TO SW LA...AS
STRONGER HEIGHT FALLS OCCUR FARTHER N AHEAD OF THE UPPER LOW...
FRONTAL ASCENT SHOULD BE SUFFICIENT FOR SURFACE BASED TSTM
DEVELOPMENT.  WEAK INSTABILITY COMBINED WITH INCREASING DEEP LAYER
SHEAR SUGGESTS AT LEAST A MARGINAL/CONDITIONAL SEVERE POTENTIAL. 
SOME CONCERN FOR AN ISOLATED TORNADO THREAT MAY EXIST AT THE
INTERSECTION OF THE ADVANCING COLD FRONT AND NWD MOVING SURFACE
BOUNDARY WHERE FORECAST SOUNDINGS INDICATE LARGE LOW LEVEL
HODOGRAPHS.  THIS THREAT WOULD BE FROM PARTS OF THE MIDDLE TO UPPER
TX COAST WEDNESDAY AFTERNOON AND INTO SW LA WEDNESDAY NIGHT. 
HOWEVER...THIS OUTLOOK WILL MAINTAIN LOW PROBABILITIES FOR SEVERE
GIVEN WEAK INSTABILITY AND WEAK UPPER FORCING.

..PETERS.. 12/19/2006