SWODY2
SPC AC 221729
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1129 AM CST WED FEB 22 2012
VALID 231200Z - 241200Z
...THERE IS A SLGT RISK OF SVR TSTMS LATE THURSDAY/THURSDAY NIGHT
ACROSS PARTS OF THE LOWER OHIO AND TENNESSEE VALLEYS INTO THE GULF
STATES...
...SYNOPSIS...
MODELS MAY BE COMING IN BETTER AGREEMENT CONCERNING A STRONG
MID-LEVEL JET STREAK NOW DIGGING INLAND ACROSS THE PACIFIC
NORTHWEST...AND ITS INFLUENCE ON A CLOSED LOW CURRENTLY CUT-OFF FROM
THE STRONGER WESTERLIES...NEAR THE BAJA SPUR. IT NOW APPEARS MOST
PROBABLE THAT AN INITIAL SHORT WAVE TROUGH WILL TURN EAST SOUTHEAST
OF THE NORTHERN ROCKIES BY 12Z THURSDAY...AND CONTRIBUTE TO STRONG
SURFACE CYCLOGENESIS EAST OF THE MIDDLE MISSOURI VALLEY THROUGH THE
LOWER GREAT LAKES REGION BY 12Z FRIDAY...AS AN UPSTREAM IMPULSE DIGS
THROUGH THE CENTRAL ROCKIES. IT IS THIS LATTER FEATURE THAT MIGHT
FINALLY CONTRIBUTE TO A MORE RAPID EASTWARD ACCELERATION OF THE BAJA
LOW...BUT THE LOW STILL MIGHT NOT PROGRESS EAST OF THE GULF OF
CALIFORNIA INTO THE MEXICAN PLATEAU UNTIL LATE IN THE PERIOD.
DESPITE SOME GREATER CERTAINTY CONCERNING THE PATTERN EVOLUTION
...THE SEVERE POTENTIAL FOR THURSDAY REMAINS RATHER UNCERTAIN. THE
MOISTENING BOUNDARY LAYER OVER THE GULF OF MEXICO /WITH UPPER
60S...LOWER 70S SURFACE DEW POINTS/ CONTINUES TO DEEPEN...BUT
LOW-LEVEL FLOW ACROSS MUCH OF THE SOUTH CENTRAL AND SOUTHEAST HAS
DEVELOPED A SIGNIFICANT WESTERLY COMPONENT...AND LITTLE SIGNIFICANT
BACKING IS EXPECTED TO OCCUR THROUGH THIS PERIOD. A GRADUAL
NORTHWARD RETURN OF MID 50S TO NEAR 60S SURFACE DEW POINTS...NOW
PRESENT ACROSS EAST TEXAS INTO THE LOWER MISSISSIPPI VALLEY...MAY
OCCUR...BUT GENERALLY NOT BEFORE CAPPING ELEVATED MIXED LAYERS
OVERSPREAD WHAT WILL BECOME THE WARM SECTOR OF THE DEVELOPING
CYCLONE. WITH THE PRIMARY MID-LEVEL COLD CORE AND FORCING FOR
UPWARD VERTICAL MOTION EXPECTED TO REMAIN DISPLACED TO THE NORTHWEST
OF THE WARM SECTOR...WEAK CAPE AND THE LACK OF STRONGER DEEP LAYER
LIFT SEEM LIKELY TO SUBSTANTIALLY REDUCE THE OVERALL SEVERE STORM
POTENTIAL FROM WHAT IT COULD BE IF A POTENTIALLY UNSTABLE AIR MASS
WAS ALREADY PRESENT OVER THE MID SOUTH AND GULF STATES. STILL...THE
PRESENCE OF A SHEARED AND STRONG DEEP LAYER MEAN FLOW FIELD...AREAS
WITH RATHER LARGE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS...AND
POCKETS OF AT LEAST WEAK DESTABILIZATION SHOULD BE CONDUCIVE TO SOME
STRONG/SEVERE STORM DEVELOPMENT.
...LOWER OH/TN VALLEYS INTO GULF STATES...
THE INITIATION OF VIGOROUS STORM DEVELOPMENT CURRENTLY SEEMS MOST
PROBABLE LATE THURSDAY AFTERNOON...FROM THE NORTHEAST
ARKANSAS/MISSOURI BOOTHEEL/WESTERN TENNESSEE REGION INTO THE LOWER
OHIO VALLEY. WITHIN AN AXIS OF STRONGER WARM SECTOR/PRE-COLD
FRONTAL HEATING...MIXED LAYER CAPE ON THE ORDER OF 500 J/KG APPEARS
POSSIBLE...AS LIFT INCREASES ON THE SOUTHERN FRINGE OF STRONGER
MID-LEVEL FORCING. AIDED BY INCREASING FRONTAL FORCING BENEATH
STRONGLY DIFLUENT HIGH LEVEL FLOW...UPSCALE CONVECTIVE GROWTH INTO A
SQUALL LINE IS POSSIBLE...AS CONVECTION ADVANCES SOUTHEASTWARD
TOWARD THE CENTRAL/SOUTHERN APPALACHIANS AND UPPER TENNESSEE VALLEY
THROUGH THURSDAY NIGHT. ISOLATED SUPERCELLS MAY NOT BE OUT OF THE
QUESTION WITHIN AND JUST AHEAD OF THE LINE...ACCOMPANIED BY
POTENTIAL FOR LARGE HAIL AND TORNADOES...IN ADDITION TO THE RISK FOR
STRONG DAMAGING WIND GUSTS. ADDITIONAL STRONG/SEVERE STORM
DEVELOPMENT IS POSSIBLE ALONG THE FRONT AS IT ADVANCES SOUTHWARD
INTO THE LOWER MISSISSIPPI VALLEY AND UPPER TEXAS COASTAL
AREAS...PERHAPS DEEP SOUTH TEXAS...THURSDAY NIGHT.
..KERR.. 02/22/2012
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