SWODY3
SPC AC 300830
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0230 AM CST FRI NOV 30 2007
VALID 021200Z - 031200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
MODELS SUGGEST THAT A SIGNIFICANT IMPULSE...ASSOCIATED WITH A STRONG
UPPER JET STREAK UNDERCUTTING THE HIGH LATITUDE BLOCKING
PATTERN...WILL LIFT NORTHEASTWARD TOWARD BRITISH COLUMBIA/PACIFIC
NORTHWEST COASTAL AREAS SUNDAY/SUNDAY NIGHT. AS THIS OCCURS...AN
UPPER RIDGE IS PROGGED TO BUILD DOWNSTREAM...ACROSS MUCH OF THE
INTERMOUNTAIN WEST AND ROCKIES...FORCING THE NORTHEASTWARD
ACCELERATION OF A SIGNIFICANT SHORT WAVE IMPULSE OUT OF THE SOUTH
CENTRAL HIGH PLAINS. THE LATTER FEATURE IS FORECAST TO REACH THE
UPPER OHIO VALLEY/CENTRAL APPALACHIANS BY EARLY SUNDAY EVENING...
BEFORE WEAKENING EAST OF THE AXIS OF AN EVOLVING BROADER SCALE
TROUGH OVER THE EASTERN STATES.
IN RESPONSE TO THE EVOLVING UPPER FLOW...A SIGNIFICANT SURFACE
CYCLONE IS FORECAST TO MIGRATE THROUGH THE GREAT LAKES REGION...
BEFORE WEAKENING AS NEW SURFACE CYCLOGENESIS TAKES PLACE ALONG THE
NEW ENGLAND COAST LATE SUNDAY NIGHT. ASSOCIATED COLD INTRUSION
APPEARS LIKELY TO REACH THE APPALACHIANS AND WESTERN/CENTRAL GULF
COAST BY LATE SUNDAY EVENING...BEFORE PROGRESSING THROUGH THE
REMAINDER OF THE EASTERN STATES EARLY MONDAY.
..MIDDLE MISSISSIPPI AND OHIO VALLEYS...
IN THE WARM SECTOR OF THE INITIAL SURFACE CYCLONE...MODELS FORECAST
LOW-LEVEL FLOW TO VEER TO A WESTERLY COMPONENT BY EARLY SUNDAY.
AND...IT APPEARS THAT STRONGER MID/UPPER FORCING FOR UPWARD VERTICAL
MOTION...ASSOCIATED WITH THE SHORT WAVE IMPULSE EMANATING FROM THE
PLAINS...WILL LIFT NORTHEAST OF THE BETTER LOW-LEVEL MOISTURE RETURN
BY SUNDAY AFTERNOON. WITH EVEN THE BEST MOISTURE RETURN LIKELY
LIMITED IN MAGNITUDE...DESTABILIZATION IS PROGGED TO BE QUITE WEAK.
AND...THERE IS STILL QUESTION AS TO WHETHER THERMODYNAMIC PROFILES
WILL BECOME SUPPORTIVE OF CHARGE SEPARATION/ CLOUD ELECTRIFICATION
EAST OF THE MIDDLE MISSISSIPPI VALLEY. HOWEVER...THE DEVELOPMENT OF
AT LEAST A LOW-TOPPED PRE-FRONTAL CONVECTIVE LINE APPEARS POSSIBLE
EARLY SUNDAY ACROSS PARTS OF EASTERN MISSOURI/CENTRAL AND SOUTHERN
ILLINOIS...WHICH MAY CONTINUE EASTWARD WITHIN 50+ KT MEAN CLOUD
BEARING LAYER FLOW ...THROUGH THE OHIO VALLEY BY EARLY SUNDAY
EVENING. THIS COULD BE ACCOMPANIED BY SPORADIC DAMAGING SURFACE
WIND GUSTS.
.KERR.. 11/30/2007
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