Monday, September 12, 2011

DAY3SVR: Nws Storm Prediction Center Norman Ok

ACUS03 KWNS 120732
SWODY3
SPC AC 120731

DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0231 AM CDT MON SEP 12 2011

VALID 141200Z - 151200Z

...SYNOPSIS...
00Z/12TH-BASED NUMERICAL GUIDANCE ARE IN RELATIVELY GOOD AGREEMENT
WITH THE CONTINUED MID-WEEK AMPLIFICATION OF THE LONGWAVE TROUGH
OVER EASTERN CANADA AND THE GREAT LAKES REGION ON WEDNESDAY. AN
ASSOCIATED COLD FRONT IS EXPECTED TO GRADUALLY SPREAD EASTWARD
ACROSS THE MID-ATLANTIC/NORTHEAST SEABOARD...WHILE THIS SAME FRONT
OTHERWISE GENERALLY SETTLES SOUTH-SOUTHEASTWARD ACROSS A LARGE PART
OF THE SOUTH-CENTRAL/SOUTHEAST CONUS.

FARTHER WEST...WITHIN THE SOUTHERN PORTION OF A WESTERN STATES SPLIT
FLOW REGIME...THE PERSISTENT UPPER LOW OVER SOUTHERN CA IS EXPECTED
TO OPEN AND SPREAD EASTWARD ACROSS THE LOWER CO RIVER VALLEY/TOWARD
THE FOUR CORNERS AREA. OVERALL...A PARTICULARLY ACTIVE SEVERE
WEATHER SCENARIO IS NOT EXPECTED WEDNESDAY...BUT ISOLATED SEVERE
TSTMS MAY BE POSSIBLE IN A FEW AREAS.

...SOUTHERN HIGH PLAINS...
WHILE THE FRONTAL TIMING IS A BIT UNCERTAIN...SCATTERED TSTMS
/ESPECIALLY DIURNALLY/ SHOULD ACCOMPANY THE SOUTHWARD-MOVING COLD
FRONT /AND ASSOCIATED POST-FRONTAL HIGH PLAINS REGIME/ ACROSS THE
REGION INCLUDING NM AND THE OK/TX PANHANDLES. COINCIDENT WITH THE
FRONT...WEAK HEIGHT FALLS/MODESTLY STRENGTHENING FLOW ALOFT SHOULD
BEGIN TO OCCUR OWING TO THE INITIAL INFLUENCES OF THE SOUTHWEST
STATES UPPER TROUGH. IT IS NOT ENTIRELY CLEAR WHAT DEGREE OF
DESTABILIZATION WILL OCCUR OWING TO POTENTIAL CLOUD COVER/PERHAPS
EARLY DAY PRECIPITATION...BUT A NEAR-FRONTAL CORRIDOR OF MODEST
DESTABILIZATION /UP TO 1000-1500 J PER KG SBCAPE/ AND SUFFICIENT
VERTICAL SHEAR /EFFECTIVE BULK SHEAR 30-40 KT/ MAY YIELD ISOLATED
SEVERE WIND AND/OR HAIL WITH SOME OF THE MORE ROBUST STORMS MAINLY
WEDNESDAY AFTERNOON/EVENING.

...AR/ARKLAMISS...
LATEST NUMERICAL INDICATES THAT A MOIST/POTENTIALLY UNSTABLE
CORRIDOR MAY RESIDE ACROSS THE REGION NEAR THE SOUTHWARD-SAGGING
FRONT AND TO THE EAST OF A POSSIBLE SOUTHERN PLAINS/ARKLATEX SURFACE
FRONTAL WAVE...WITH THE POTENTIAL FOR A SPEED MAX TO THE INFLUENCE
THE REGION ON THE SOUTHERN PERIPHERY OF THE GREAT LAKES UPPER TROUGH
ASSOCIATED CYCLONIC FLOW ALOFT. WITH CURRENT EXPECTATIONS FOR AT
LEAST ISOLATED TO SCATTERED DIURNALLY-AIDED TSTMS...A FEW STORMS MAY
YIELD SEVERE WIND AND/OR HAIL PRIMARILY WEDNESDAY AFTERNOON/EVENING.


...NORTHEAST SEABOARD/SOUTHERN NEW ENGLAND...
A FEW STRONGER STORMS CANNOT BE RULED OUT AT THIS TIME ALONG THE
ADVANCING COLD FRONT...BUT UNCERTAIN DESTABILIZATION/POOR LAPSE
RATES ALOFT SUGGEST THAT SEVERE PROBABILITIES ARE NOT WARRANTED AT
THIS TIME.

..GUYER.. 09/12/2011

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