DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 140732
SWODY3
SPC AC 140730

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CDT TUE AUG 14 2012

VALID 161200Z - 171200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE MIDWEST/MIDDLE MS
RIVER VALLEY/OZARKS...

...SYNOPSIS...
AN AMPLIFIED LONGWAVE FLOW REGIME WILL PERSIST OVER THE CONUS INTO
THURSDAY. THE PATTERN WILL BE HIGHLIGHTED BY A DEEP/EXTENSIVE
LONGWAVE TROUGH CENTERED OVER EAST-CENTRAL CANADA AND THE GREAT
LAKES REGION...TO THE NORTH AND EAST OF A BROAD UPPER RIDGE OVER THE
WESTERN/SOUTHERN CONUS.

...MIDWEST/GREAT LAKES REGION AND MIDDLE MS VALLEY/OZARKS...
THE SOUTHERN PART OF THE AFOREMENTIONED LONGWAVE TROUGH IS EXPECTED
TO CONTINUE TO AMPLIFY/DEVELOP EASTWARD OVER THE GREAT LAKES REGION
AND MIDWEST ON THURSDAY. AN ASSOCIATED COLD FRONT...POTENTIALLY
AUGMENTED BY EARLY DAY PRECIPITATION/CLOUD COVER ACROSS THE UPPER MS
VALLEY AND WESTERN GREAT LAKES VICINITY...WILL MAKE A STEADY
EASTWARD PROGRESSION ACROSS MUCH OF THE REGION...WITH A SLOWER/MORE
SOUTHEASTWARD MOVEMENT OF THE FRONT ACROSS THE OZARKS AND SOUTHERN
PLAINS.

IT SEEMS LIKELY THAT TSTMS WILL INCREASE/INTENSIFY THURSDAY
AFTERNOON ALONG OR /MORE SO/ AHEAD OF THE /EFFECTIVE/ COLD FRONT
WITHIN A RELATIVELY MOIST/MODERATELY UNSTABLE BOUNDARY LAYER.
CURRENT INDICATIONS ARE THAT THE RELATIVELY STRONGEST
DESTABILIZATION WILL OCCUR THURSDAY AFTERNOON ACROSS THE OZARKS INTO
DOWNSTATE IL AND PERHAPS INDIANA...WITH AS MUCH AS 1500-2500 J/KG
MLCAPE POSSIBLE. THE STRONGEST FORCING FOR ASCENT/VERTICAL SHEAR
WILL TEND TO LAG THE COLD FRONT EXCEPT FOR THE GREAT LAKES REGION
WHERE THE EXTENT OF DIURNAL DESTABILIZATION IS MORE QUESTIONABLE
OWING TO EARLY DAY CLOUD COVER/PRECIPITATION UNCERTAINTIES AND LOWER
OVERALL THETA-E. EVEN REMOVED FROM THE STRONGER FORCING/VERTICAL
SHEAR...STRONGER/MORE CERTAIN DESTABILIZATION FARTHER SOUTHWEST INTO
THE MIDDLE MS VALLEY/OZARKS WILL ACCOUNT FOR ORGANIZED/SUSTAINED
SEVERE TSTM POTENTIAL THURSDAY AFTERNOON INTO MID-EVENING. DAMAGING
WINDS AND BOUTS OF SEVERE HAIL WILL BE THE PRIMARY HAZARDS. TSTMS
SHOULD CONTINUE TO SPREAD EAST-SOUTHEASTWARD THURSDAY NIGHT ACROSS
THE OH VALLEY/LOWER GREAT LAKES/MID-SOUTH...BUT WITH A DIMINISHING
SEVERE THREAT BY THE LATE EVENING/OVERNIGHT HOURS.

...SOUTHERN PLAINS/MID-SOUTH...
ALTHOUGH WELL-REMOVED FROM THE STRONGER WESTERLIES ALOFT OVER THE
MIDWEST...ISOLATED TO SCATTERED TSTMS ARE EXPECTED TO DEVELOP
ALONG/AHEAD OF THE SOUTHEASTWARD MOVING COLD FRONT ACROSS THE
REGION. A HOT/DEEPLY MIXED BOUNDARY LAYER WILL ACCOUNT FOR ISOLATED
DOWNBURST POTENTIAL THURSDAY AFTERNOON/EARLY EVENING.

...SOUTHERN AZ...
MOISTURE SEEMS LIKELY TO STEADILY INCREASE INTO SOUTHERN AZ/LOWER CO
RIVER VALLEY BY THURSDAY...WITH A RESULTANT UPSWING IN TSTMS
PROBABLE ACROSS THE REGION. ESPECIALLY IF IT COINCIDES WITH A
MODESTLY INCREASING EASTERLY STEERING COMPONENT ON THE IMMEDIATE
PERIPHERY OF THE UPPER RIDGE...TSTMS MAY REACH THE SOUTHERN AZ
DESERT FLOOR WITH DOWNBURSTS AND STRONG/GUSTY WINDS POSSIBLE.

..GUYER.. 08/14/2012

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