[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 180543
SWODY1
SPC AC 180541

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1141 PM CST SUN DEC 17 2006

VALID 181200Z - 191200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
CLOSED UPPER LOW IS FORECAST TO DEVELOP/DRIFT EWD ACROSS THE SWRN
U.S. WITH TIME...WITH DOWNSTREAM RIDGE FORECAST OVER THE SERN HALF
OF THE CONUS.

MEANWHILE...MORE PROGRESSIVE FLOW REGIME IS EXPECTED ACROSS CANADA
AND THE NRN U.S. WITHIN FASTER NRN BRANCH OF THE WLYS.

AT THE SURFACE...MAIN FEATURE WILL BE AN ENE-WSW BAROCLINIC ZONE
INITIALLY EXTENDING FROM SRN NEW ENGLAND WSWWD TO W TX.  THIS
FEATURE WILL CONTINUE MOVING SSEWD WITH TIME AS 1035 MB HIGH DRIFTS
SLOWLY SWD ACROSS THE CONUS.

THOUGH MOST OF THE COUNTRY WILL REMAIN STABLE WITH RESPECT TO DEEP
MOIST CONVECTION...ISOLATED THUNDERSTORMS ARE FORECAST FROM THE FOUR
CORNERS INTO W TX IN ASSOCIATION WITH THE EVOLVING UPPER CLOSED LOW.


...PARTS OF AZ AND UT EWD INTO WRN TX...
AS UPPER LOW INTENSIFIES ACROSS THE SWRN STATES...STEEPENING
MID-LEVEL LAPSE RATES SHOULD RESULT IN SUFFICIENT INSTABILITY FOR
SHOWERS AND ISOLATED THUNDERSTORMS -- PARTICULARLY DURING THE SECOND
HALF OF THE PERIOD.  

OVERNIGHT...LOW-LEVEL JET IS FORECAST TO DEVELOP ACROSS W TX AND
INTO ERN NM IN RESPONSE TO SLOW EWD MOVEMENT OF THE UPPER FEATURE. 
RESULTING LOW-LEVEL WARM/MOIST ADVECTION MAY ALLOW A FEW
THUNDERSTORMS TO DEVELOP AS FAR E AS THE TX PANHANDLE/S
PLAINS/TRANSPECOS REGION THROUGH 19/12Z.

..GOSS.. 12/18/2006