DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 210551
SWODY2
SPC AC 210549

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1249 AM CDT FRI SEP 21 2012

VALID 221200Z - 231200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NORTHEAST
AND MID-ATLANTIC REGIONS...

...SYNOPSIS...
A LARGE UPPER TROUGH OVER ERN CANADA AND THE ERN HALF OF THE U.S. IS
FORECAST TO SHIFT SLOWLY EWD WITH TIME...WHILE AN ACCOMPANYING COLD
FRONT ALSO PROGRESSES ACROSS THIS REGION. THIS FRONT SHOULD SHIFT
EWD ACROSS THE APPALACHIAN CREST THROUGH MIDDAY...AND THEN OFF THE
ATLANTIC COAST BY THE END OF THE PERIOD. UNTIL IT DOES...THIS FRONT
SHOULD FOCUS AN AREA OF PRIMARILY AFTERNOON AND EVENING CONVECTIVE
ACTIVITY.

MEANWHILE FARTHER W...LARGE-SCALE RIDGING WILL PREVAIL...THOUGH A
SMALL-SCALE LOW/TROUGH IS FORECAST TO DRIFT SEWD ACROSS THE PAC NW
REGION.

...PARTS OF THE NORTHEAST AND MID-ATLANTIC REGION...
AS MODEST DESTABILIZATION OCCURS AHEAD OF THE ADVANCING COLD
FRONT...DEVELOPMENT OF SHOWERS AND SCATTERED THUNDERSTORMS IS
FORECAST NEAR/AHEAD OF THE BOUNDARY. BY MID TO LATE AFTERNOON...A
BAND OF CONVECTION SHOULD EXTEND FROM ERN NY/WRN NEW ENGLAND SWWD
ALONG THE E SLOPES OF THE APPALACHIANS INTO GA/AL.

ATTM...IT APPEARS THAT A LACK OF ROBUST INSTABILITY SHOULD TEMPER
THE OVERALL SEVERE THREAT. HOWEVER...WITH THE ERN FRINGE OF THE
STRONGER BELT OF FLOW ALOFT EXTENDING ATOP THE WARM SECTOR...SOME
ORGANIZATION WITHIN THE CONVECTIVE BAND MAY OCCUR -- WHICH WOULD
SUGGEST LOCALLY GUSTY/DAMAGING WINDS MAY BE POSSIBLE. WHILE THE
THREAT SHOULD TAPER OFF THROUGH MID EVENING...THREAT APPEARS
SUFFICIENT ATTM TO MAINTAIN A FAIRLY NARROW SLIGHT RISK ACROSS PARTS
OF THE NORTHEAST AND MID-ATLANTIC REGIONS -- INCLUDING THE
ALBANY/NEW YORK CITY/PHILADELPHIA/BALTIMORE/WASHINGTON D.C. METRO
AREAS.

..GOSS.. 09/21/2012

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