Thursday, September 2, 2010

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 020513
SWODY2
SPC AC 020512

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1212 AM CDT THU SEP 02 2010

VALID 031200Z - 041200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
HURRICANE EARL STILL APPEARS LIKELY TO ACCELERATE NORTH
NORTHEASTWARD FRIDAY...JUST EAST OF THE MAJORITY OF MIDDLE AND
NORTHERN ATLANTIC COASTAL AREAS...TOWARD THE CANADIAN MARITIMES.
THIS IS EXPECTED TO OCCUR AS AN UPPER TROUGH WITHIN THE STRONGER
WESTERLIES AMPLIFIES UPSTREAM...FROM THE UPPER MIDWEST THROUGH THE
GREAT LAKES AND APPALACHIANS. THIS LATTER FEATURE WILL BE
ACCOMPANIED BY A SIGNIFICANT COLD FRONT...WHICH IS FORECAST TO SURGE
SOUTHEASTWARD THROUGH MUCH OF THE ATLANTIC SEABOARD AND GULF COAST
STATES BY 12Z SATURDAY.

ACROSS THE WEST...SUBTROPICAL RIDGING IS EXPECTED TO REMAIN
GENERALLY STRONG ACROSS MUCH OF CALIFORNIA AND THE SOUTHERN PLATEAU
INTO THE SOUTHERN ROCKIES. BUT AN UPPER RIDGE AXIS EXTENDING TO THE
NORTH MAY BEGIN TO WEAKEN AND SHIFT EAST OF THE NORTHERN
ROCKIES...AS ANOTHER VIGOROUS SHORT WAVE TROUGH ADVANCES INTO
BRITISH COLUMBIA AND THE PACIFIC NORTHWEST.

...LOWER GREAT LAKES SWWD THROUGH THE WESTERN GULF COAST...
MODELS SUGGEST THAT A BAND OF STRONGER FORCING MAY LINGER INTO EARLY
FRIDAY...SOUTH OF SOUTHERN ONTARIO INTO EASTERN OHIO... BEFORE
ADVANCING EASTWARD AND TENDING TO WEAKEN SOUTH OF THE INTERNATIONAL
BORDER...ACROSS WESTERN NEW YORK AND PENNSYLVANIA BY EARLY
AFTERNOON. THIS IS WHERE DEEP LAYER SOUTHWESTERLY MEAN FLOW FIELDS
AND SHEAR MAY ALSO REMAIN MODESTLY STRONG...BUT IT IS STILL NOT
CLEAR THAT SUFFICIENT DESTABILIZATION WILL OCCUR TO SUPPORT AN
APPRECIABLE RISK FOR STRONG/SEVERE THUNDERSTORMS.

OTHERWISE...AS THE FRONT ADVANCES EASTWARD OUT AHEAD OF THE MAIN
UPPER TROUGH...AND IN THE WAKE OF EARL...WEAKENING LOW-LEVEL
CONVERGENCE AND LIFT...COUPLED WITH LIMITED DESTABILIZATION DUE TO
WEAK MID-LEVEL LAPSE RATES...PROBABLY WILL MINIMIZE CONVECTIVE
POTENTIAL. HOWEVER...WIDELY SCATTERED THUNDERSTORMS WILL BE
POSSIBLE...MOSTLY DURING THE AFTERNOON...WEST OF THE APPALACHIANS
SOUTHWESTWARD THROUGH THE LOWER MISSISSIPPI VALLEY AND SOUTHEAST
TEXAS.

...SOUTHERN PLATEAU/ROCKIES...
A RETURN OF MONSOONAL MOISTURE...COUPLED WITH STRONG SURFACE
HEATING...MAY CONTRIBUTE TO SUFFICIENT DESTABILIZATION FOR WIDELY
SCATTERED THUNDERSTORMS FRIDAY AFTERNOON AND EVENING.

...NORTHERN INTERMOUNTAIN REGION...
STRONG PRE-FRONTAL SURFACE HEATING...COUPLED WITH INCREASING LIFT
AHEAD OF THE APPROACHING UPPER TROUGH...MAY CONTRIBUTE TO SUFFICIENT
DESTABILIZATION FOR ISOLATED TO WIDELY SCATTERED STORMS FROM NEAR
THE OREGON CASCADES INTO THE MOUNTAINS OF NORTHERN IDAHO AND WESTERN
MONTANA LATE FRIDAY AFTERNOON AND EVENING.

..KERR.. 09/02/2010

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