Tuesday, December 15, 2009

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 151703
SWODY2
SPC AC 151702

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1102 AM CST TUE DEC 15 2009

VALID 161200Z - 171200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...
A CLOSED LOW IS NOW IN THE PROCESS OF DEVELOPING NEAR JAMES BAY. AS
AN ASSOCIATED POLAR SHORT WAVE IMPULSE PIVOTS AROUND ITS SOUTHERN
AND EASTERN PERIPHERY...MODELS INDICATE THAT THE MID-LEVEL
CIRCULATION WILL DEVELOP SOUTHEASTWARD INTO THE CANADIAN MARITIMES
BY EARLY WEDNESDAY...BEFORE STALLING IN RESPONSE TO THE DOWNSTREAM
BLOCKING PATTERN. UPSTREAM...BROAD UPPER RIDGING WITHIN THE POLAR
WESTERLIES APPEARS LIKELY TO BEGIN TO BUILD ACROSS MUCH OF THE
REMAINDER OF CANADA AND THE NORTHERN/CENTRAL TIER STATES. BUT...AN
EMBEDDED SHORT WAVE IMPULSE IS PROGGED TO MIGRATE INLAND ACROSS THE
PACIFIC NORTHWEST. MEANWHILE...WITHIN A WEAK STREAM ACROSS THE
MEXICAN PLATEAU AND PARTS OF THE SOUTHERN TIER STATES...GUIDANCE
SUGGESTS THAT AN UPPER TROUGH AND EMBEDDED WEAK MID-LEVEL
CIRCULATION WILL CONTINUE TO SLOW SHIFT SOUTHEASTWARD ACROSS THE
LOWER RIO GRANDE VALLEY.

IT APPEARS THAT AT LEAST WEAK SURFACE CYCLOGENESIS MAY COMMENCE OVER
THE WESTERN GULF OF MEXICO WITH THE APPROACH OF THE SOUTHERN
IMPULSE. THIS IS EXPECTED TO OCCUR ALONG A STALLED LOW-LEVEL
BAROCLINIC ZONE ON THE SOUTHERN PERIPHERY OF THE COLD SURFACE RIDGE
WHICH HAS NOW ENCOMPASSED MUCH OF THE NATION EAST OF THE ROCKIES.
THE FRONT...EXTENDING EASTWARD ACROSS THE SOUTHERN GULF OF MEXICO
INTO THE WESTERN ATLANTIC...WILL LIKELY LINGER ACROSS THE FLORIDA
PENINSULA...AND PROBABLY WILL BECOME THE FOCUS FOR THE PRIMARY
CONVECTIVE DEVELOPMENT FOR THIS FORECAST PERIOD. HOWEVER...BOUNDARY
LAYER DESTABILIZATION AND HIGHER THUNDERSTORM PROBABILITIES ARE
EXPECTED TO REMAIN GENERALLY CONFINED TO OFFSHORE AREAS.

..KERR.. 12/15/2009

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