DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 090501
SWODY2
SPC AC 090500

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1200 AM CDT TUE OCT 09 2012

VALID 101200Z - 111200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
IT STILL APPEARS THAT EASTERN PACIFIC BLOCKING WILL CONTINUE TO
SLOWLY BREAK DOWN DURING THIS FORECAST PERIOD. WHILE THE CLOSED LOW
NEAR THE CALIFORNIA COAST IS EXPECTED TO REMAIN CUT OFF FROM THE
STRONGER WESTERLIES...MODELS DO SUGGEST THAT IT MAY BEGIN TO SLOWLY
TURN TOWARD THE SOUTHERN CALIFORNIA COAST...AFTER FURTHER DIGGING
OFFSHORE MUCH OF WEDNESDAY INTO WEDNESDAY NIGHT.
DOWNSTREAM...CONFLUENT BELTS OF WESTERLIES ACROSS THE ROCKIES INTO
THE ATLANTIC SEABOARD MAY GRADUALLY BEGIN TO BECOME MORE ZONAL...AS
A VIGOROUS IMPULSE WITHIN THE SOUTHERN PORTION OF A NORTHERN STREAM
SHORT WAVE TROUGH ACCELERATES IN NEGATIVELY TILTED FASHION EAST
NORTHEAST OF THE LOWER GREAT LAKES THROUGH MUCH OF NEW ENGLAND. AN
ASSOCIATED SURFACE COLD FRONT IS EXPECTED TO SURGE OFF THE NORTH
ATLANTIC COAST...WHILE STALLING AND WEAKENING ACROSS THE SOUTHEAST
STATES INTO THE SOUTHERN PLAINS. WHILE AN INFLUX OF MOISTURE WILL
CONTINUE ON SOUTHERLY FLOW OFF THE WESTERN GULF OF MEXICO...ANOTHER
SIGNIFICANT COLD FRONT IS EXPECTED TO NOSE SOUTHWARD TO THE LEE OF
THE NORTHERN ROCKIES.

...PARTS OF SRN ROCKIES/PLAINS INTO LWR/MID MS VALLEY...
SOME ADJUSTMENTS TO CATEGORICAL AND SEVERE PROBABILITY LINES HAVE
BEEN MADE BASED ON CURRENT ANTICIPATED FRONTAL POSITION...AND
INCREASING UNCERTAINTY CONCERNING POTENTIAL COVERAGE OF THUNDERSTORM
ACTIVITY...PARTICULARLY NORTH OF THE SURFACE FRONT WEDNESDAY NIGHT.
LARGE-SCALE FORCING FOR UPWARD VERTICAL MOTION BENEATH A BUILDING
SOUTHERN STREAM RIDGE APPEARS LIKELY TO REMAIN WEAK...AND REMNANT
ELEVATED MIXED LAYERS MAY RESULT IN CONSIDERABLE INHIBITION.

IT STILL APPEARS THAT THE MOISTENING BOUNDARY LAYER ALONG AND SOUTH
OF THE FRONT COULD BECOME CHARACTERIZED BY MODERATELY LARGE CAPE
WITH DAYTIME HEATING. AND A WEAKNESS IN MID-LEVEL INHIBITION MAY
ALLOW ISOLATED TO SCATTERED STORM DEVELOPMENT DURING THE DAY
WEDNESDAY ACROSS PARTS OF SOUTHEAST INTO NORTH CENTRAL TEXAS.
ADDITIONAL SCATTERED STORMS DO NOT APPEAR OUT OF THE QUESTION IN A
MOISTENING LOW-LEVEL UPSLOPE FLOW REGIME ACROSS SOUTHWEST TEXAS AND
SOUTHEASTERN NEW MEXICO. IF THIS OCCURS...LOW-LEVEL FLOW ACROSS
THESE AREAS IS GENERALLY NOT FORECAST TO BE PARTICULARLY
STRONG...BUT VEERING WITH HEIGHT...BENEATH WEAK TO MODEST WESTERLY
MID/UPPER FLOW...MAY CONTRIBUTE TO SUFFICIENT SHEAR TO SUPPORT LOW
PROBABILITIES FOR SEVERE HAIL/WIND DURING THE LATE AFTERNOON AND
EVENING.

...LWR COLORADO VALLEY INTO THE SRN GREAT BASIN...
NAM FORECAST SOUNDINGS SUGGEST SUFFICIENT MOISTENING AND
DESTABILIZATION TO SUPPORT THUNDERSTORM DEVELOPMENT WEDNESDAY NIGHT
AHEAD OF AN EASTWARD ADVANCING COLD FRONT ACROSS PARTS OF
SOUTHEASTERN CALIFORNIA INTO SOUTHERN NEVADA AND WESTERN ARIZONA.
LIFT MAY BE ENHANCED BY FORCING IN THE EXIT REGION OF AN APPROACHING
CYCLONIC MID/UPPER JET. ALTHOUGH PRE-FRONTAL SOUTHERLY LOW-LEVEL
FLOW IS EXPECTED TO REMAIN RELATIVELY WEAK... AND THE NOCTURNAL
BOUNDARY LAYER WILL BE IN THE PROCESS OF COOLING...SUB-CLOUD AIR MAY
STILL POSSESS SIZABLE ENOUGH TEMPERATURE/DEW POINT SPREADS FOR
EVAPORATIVE COOLING TO PROVIDE SOME RISK FOR STRONG WIND
GUSTS...WHEN COUPLED WITH PRECIPITATION LOADING.

..KERR.. 10/09/2012

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