[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 250436
SWODY1
SPC AC 250434

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1034 PM CST FRI NOV 24 2006

VALID 251200Z - 261200Z

...NO TSTM AREAS FORECAST...

A CYCLONIC UPPER FLOW CONTINUES TO EVOLVE FROM THE EASTERN PACIFIC
THROUGH THE PLAINS AND UPPER MISSISSIPPI VALLEY REGION.  MODELS
INDICATE THAT THIS REGIME WILL REMAIN COMPRISED OF A COUPLE OF
DISTINCT STRONGER BELTS...BUT THE PATTERN IS FORECAST TO BEGIN
AMPLIFYING TOWARD THE END OF THE FORECAST PERIOD.

THE MOST SIGNIFICANT EMBEDDED SHORT WAVE IMPULSES APPEAR LIKELY TO
BE DIGGING IN THE SOUTHERN BRANCH OF THE POLAR WESTERLIES...ONE OFF
THE PACIFIC NORTHWEST COAST...THE OTHER INTO THE BASE OF AN IN PHASE
SOUTHERN BRANCH/SUBTROPICAL STREAM TROUGH ACROSS BAJA. FARTHER
EAST...A MID-LEVEL SHORT WAVE TROUGH...EMBEDDED WITHIN THE NORTHERN
STREAM...IS PROGGED TO SHIFT EAST OF THE NORTHERN INTERMOUNTAIN
REGION INTO THE NORTHERN PLAINS BY 12Z SUNDAY. MEANWHILE...A COUPLE
OF ADDITIONAL SOUTHERN BRANCH IMPULSES ARE FORECAST TO ACCELERATE
NORTHEASTWARD AND WEAKEN WITHIN CONFLUENT REGIME EAST OF BROADER
SCALE TROUGH AXIS...INTO UPPER RIDGE OVER THE EASTERN STATES.  THE
INCREASINGLY SHEARED LEAD IMPULSE IS PROGGED TO LIFT ACROSS THE
CENTRAL PLAINS AND MID MISSOURI VALLEY INTO THE UPPER GREAT LAKES
REGION...WHILE THE UPSTREAM SYSTEM LIFTS ACROSS THE LOWER COLORADO
VALLEY INTO THE FOUR CORNERS REGION.

...EAST OF THE ROCKIES...
MOISTENING OF THE BOUNDARY LAYER OVER THE WESTERN GULF OF MEXICO HAS
BEEN INHIBITED BY AN ELONGATED SURFACE RIDGE EXTENDING FROM THE ST.
LAWRENCE VALLEY INTO THE GULF OF MEXICO.  WHILE A MORE RAPID
MODIFICATION MAY BEGIN TO OCCUR DURING THIS PERIOD...A SIGNIFICANT
RETURN FLOW OF MOISTURE INTO THE CENTRAL STATES APPEARS UNLIKELY TO
OCCUR.

ISENTROPIC ASCENT OF AN AIR MASS CHARACTERIZED BY 40S/LOWER 50S
SURFACE DEW POINTS COULD EVENTUALLY SATURATE LOWER LEVELS TO THE
WEST OF SURFACE RIDGE...ACROSS PARTS OF THE MID MISSOURI VALLEY INTO
THE LOWER GREAT LAKES...TOWARD THE END OF THE PERIOD. 
HOWEVER...MODEL FORECAST SOUNDINGS SUGGEST THAT AN INITIALLY WARM
AND DRY LOWER/MID TROPOSPHERE WILL PROBABLY INHIBIT DEEP CONVECTIVE
DEVELOPMENT THROUGH AT LEAST 12Z SUNDAY.

...WEST OF ROCKIES...
SOME MOISTENING IS OCCURRING ACROSS THE FOUR CORNERS WITH INITIAL
SOUTHERN BRANCH SHORT WAVE TROUGH.  AND...UPSTREAM SYSTEM MAY REMAIN
VIGOROUS ENOUGH TO SUPPORT SIGNIFICANT UPWARD VERTICAL MOTION. 
HOWEVER...THIS DOES NOT LOOK LIKELY TO SPREAD INTO THE MORE
FAVORABLE OROGRAPHY OF THE FOUR CORNERS REGION UNTIL AFTER
SUNSET...WHICH WILL PROBABLY MINIMIZE POTENTIAL FOR THUNDERSTORM
ACTIVITY.

FARTHER NORTH...HEATING ACROSS THE NORTHERN ROCKIES WILL CONTRIBUTE
TO AT LEAST MARGINAL DESTABILIZATION BENEATH VERY COLD MID-LEVEL AIR
MASS ASSOCIATED WITH THE NORTHERN BRANCH SHORT WAVE TROUGH. 
HOWEVER...SOUNDINGS ACROSS THESE AREAS ARE FORECAST TO REMAIN
LARGELY BELOW FREEZING.  WHILE SCATTERED LOW-TOPPED CONVECTION IS
PROBABLE...THUNDERSTORM ACTIVITY...IF ANY...SEEMS LIKELY TO BE VERY
ISOLATED OR SPARSE IN COVERAGE.

..KERR.. 11/25/2006