SWODY2
SPC AC 121715
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1115 AM CST WED NOV 12 2008
VALID 131200Z - 141200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
AMPLIFICATION WITHIN A STRONG BELT OF POLAR WESTERLIES ACROSS THE
NORTHERN PACIFIC IS UNDERWAY...AND MODELS INDICATE THAT THIS WILL
TRANSLATE DOWNSTREAM INTO THE U.S. DURING THIS FORECAST PERIOD. A
JET STREAK EMANATING FROM THE PACIFIC IS PROGGED TO CONTRIBUTE TO A
LARGE...DIGGING UPPER TROUGH TO THE LEE OF THE CANADIAN/NORTHERN
U.S. ROCKIES...AND STRONG SURFACE CYCLOGENESIS FROM THE LEE OF THE
CANADIAN ROCKIES...THROUGH THE CENTRAL INTERNATIONAL BORDER
AREA...INTO ONTARIO BY 12Z FRIDAY. AS THIS OCCURS...THE LAST COUPLE
IN A SERIES OF SIGNIFICANT SHORT WAVE IMPULSES ARE EXPECTED TO LIFT
OUT OF A LINGERING BROADER SCALE TROUGH OVER THE SOUTH CENTRAL
STATES. HOWEVER...CONSIDERABLE DISCREPANCIES EXIST AMONG THE MODEL
DATA CONCERNING THE MANNER IN WHICH THIS OCCURS...PARTICULARLY WITH
THE SECOND IMPULSE NOW STILL DIGGING TO THE SOUTHWEST OF THE TEXAS
BIG BEND REGION.
...CENTRAL APPALACHIANS INTO MID/SOUTH ATLANTIC SEABOARD...
THE INITIAL SOUTHERN STREAM IMPULSE APPEARS LIKELY TO BE IN THE
PROCESS OF LIFTING THROUGH THE LOWER OHIO VALLEY BY 12Z THURSDAY...
BEFORE CONTINUING TO ACCELERATE NORTHEASTWARD ACROSS NORTHERN MID
ATLANTIC COASTAL AREAS AND NEW ENGLAND LATE THURSDAY/THURSDAY NIGHT.
LOW-LEVEL MOISTURE ADVECTION AND ISENTROPIC ASCENT WITHIN A BROAD
FRONTAL ZONE...DEVELOPING IN THE WAKE OF A RETREATING COLD SURFACE
RIDGE OFF THE ATLANTIC COAST...MAY CONTRIBUTE TO SUFFICIENT
DESTABILIZATION FOR SCATTERED THUNDERSTORM ACTIVITY INLAND OF
EASTERN GULF AND SOUTHERN/MID ATLANTIC COASTAL AREAS.
HOWEVER...WEAK MID-LEVEL LAPSE RATES SHOULD MINIMIZE THE STRENGTH OF
THE UPDRAFTS...MOSTLY ROOTED ABOVE THE FRONTAL INVERSION LAYER.
TO VARYING DEGREES...GUIDANCE INDICATES THAT THE UPPER IMPULSE WILL
SUPPORT WEAK FRONTAL WAVE DEVELOPMENT ACROSS THE CAROLINAS. THIS
PROBABLY WILL OCCUR INLAND...ACCOMPANIED BY AN INFLUX OF BOUNDARY
LAYER MOISTURE AND DESTABILIZATION IN THE PRESENCE OF SUFFICIENT
DEEP LAYER SHEAR FOR ORGANIZED CONVECTIVE DEVELOPMENT...INCLUDING
SUPERCELLS. HOWEVER...WITH THE STRENGTH OF MID/UPPER FORCING FOR
UPWARD VERTICAL MOTION ACROSS THE WARM SECTOR STILL UNCLEAR...THE
RELATIVELY WARM MID-LEVEL ENVIRONMENT COULD ULTIMATELY SUPPRESS
CONVECTIVE POTENTIAL.
...WESTERN/CENTRAL GULF COAST REGION...
IT NOW SEEMS MOST PROBABLE THAT THE PRIMARY TRAILING SOUTHERN STREAM
IMPULSE WILL BE SLOWER TO LIFT NORTHEAST OF THE MEXICAN
PLATEAU/LOWER RIO GRANDE VALLEY REGION...MUCH AS HAS BEEN INDICATED
BY THE SREF/NAM AND MREF/GFS. AND...THE PRIMARY CONVECTIVE
DEVELOPMENT WITH THIS FEATURE IS EXPECTED TO REMAIN CONFINED TO
PARTS OF THE WESTERN/NORTHERN GULF OF MEXICO.
..KERR.. 11/12/2008
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