DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 100503
SWODY2
SPC AC 100501

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1201 AM CDT WED OCT 10 2012

VALID 111200Z - 121200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A STRONG ZONAL BELT OF FLOW EXTENDING ACROSS THE MID LATITUDE
PACIFIC APPEARS LIKELY TO APPROACH THE PACIFIC NORTHWEST COAST
DURING THIS PERIOD. GUIDANCE HAS BEEN SUGGESTIVE THAT AN IMPULSE
EMERGING FROM THIS STREAM WILL SPLIT OFF INTO A LINGERING WEAKER
STREAM CURVING CYCLONICALLY INTO CALIFORNIA. AS THIS OCCURS...A
MUCH MORE SIGNIFICANT CLOSED LOW...EXPECTED NEAR SOUTHERN CALIFORNIA
COASTAL AREAS AT 12Z THURSDAY...IS FORECAST TO FINALLY TURN INLAND.
THIS LATTER FEATURE MAY SLOWLY ACCELERATE A BIT NORTH OF EAST...INTO
PORTIONS OF THE CENTRAL AND SOUTHERN GREAT BASIN BY LATE THURSDAY
NIGHT...AROUND THE NORTHWESTERN PERIPHERY OF A BUILDING SUBTROPICAL
HIGH CENTERED OVER THE WESTERN GULF OF MEXICO.

AT THE SAME TIME...WITHIN A SOMEWHAT LESS AMPLIFIED NORTHERN
STREAM...A SHORT WAVE TROUGH IS EXPECTED TO DIG ACROSS PARTS OF THE
GREAT LAKES REGION. THIS WILL BE ACCOMPANIED BY ANOTHER COLD
INTRUSION ACROSS THE NORTH CENTRAL STATES. WHILE THE ASSOCIATED
SURFACE COLD FRONT ADVANCES SOUTHWARD...REMNANTS OF A PREVIOUS FRONT
MAY LIFT NORTHWARD AS A WARM FRONT ACROSS THE OZARK PLATEAU.
CONSOLIDATION OF THESE BAROCLINIC ZONES IS EXPECTED ROUGHLY ACROSS
THE CENTRAL PLAINS/OZARK PLATEAU AND LOWER OHIO AND TENNESSEE
VALLEYS BY THE END OF THE PERIOD...WHILE A RETURN FLOW OF MOISTURE
FROM THE GULF OF MEXICO CONTINUES AROUND THE RIDGE...ACROSS THE
SOUTHERN HIGH PLAINS INTO AND ABOVE THE FRONTAL ZONE.

...SRN HIGH PLAINS INTO MIDDLE MISSISSIPPI VALLEY...
MID/UPPER FORCING FOR UPWARD VERTICAL MOTION APPEARS LIKELY TO
REMAIN RELATIVELY WEAK ACROSS THE REGION THROUGH THE PERIOD.
HOWEVER...AREAS OF ENHANCED LOW-LEVEL CONFLUENCE AND WARM ADVECTION
AROUND THE PERIPHERY OF THE LOW/MID-LEVEL RIDGING MAY CONTRIBUTE TO
THE RISK FOR THUNDERSTORM ACTIVITY ACROSS THE SOUTHERN HIGH
PLAINS...AND ALONG AND NORTH OF THE SURFACE FRONT...FROM PARTS OF
THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI VALLEY. MID-LEVEL
LAPSE RATES MAY BECOME STEEP ENOUGH TO SUPPORT MODEST CAPE...AND
SOME POTENTIAL FOR VIGOROUS CONVECTION. HOWEVER...LOW/MID-LEVEL
WIND FIELDS AND SHEAR PROBABLY WILL REMAIN A BIT MARGINAL FOR
ANYTHING MORE THAN LOW SEVERE PROBABILITIES...PARTICULARLY WITH THE
PRIMARY CONVECTIVE DEVELOPMENT EXPECTED TO FORM ABOVE A RELATIVELY
COOL/STABLE BOUNDARY LAYER.

...SOUTHERN PLATEAU...
MID-LEVEL COOLING AND STRONG LIFT ASSOCIATED WITH THE APPROACHING
CLOSED LOW ARE EXPECTED TO CONTRIBUTE TO SUFFICIENT INSTABILITY FOR
SCATTERED THUNDERSTORM ACTIVITY THURSDAY/THURSDAY NIGHT. ALTHOUGH
DESTABILIZATION MAY REMAIN WEAK...FORECAST SOUNDINGS SUGGEST IT MAY
BE BOUNDARY LAYER BASED...IN THE PRESENCE OF STRONG SHEAR FAVORABLE
FOR UPDRAFT ROTATION...AS A CYCLONIC 70-90 KT 500 MB JET STREAK
NOSES INTO CENTRAL ARIZONA. ONE OR TWO SUPERCELLS MAY NOT BE OUT OF
THE QUESTION...PERHAPS WITH A RISK FOR DAMAGING WIND GUSTS OR A
TORNADO.

..KERR.. 10/10/2012

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