SWODY2
SPC AC 111723
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1123 AM CST TUE NOV 11 2008
VALID 121200Z - 131200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
MODELS INDICATE THAT A STRONG POLAR JET STREAK EMANATING FROM THE
NORTHERN PACIFIC WILL NOSE ACROSS THE SOUTHERN CANADIAN/NORTHERN
U.S. ROCKIES INTO THE NORTH CENTRAL PLAINS DURING THIS FORECAST
PERIOD...ACCOMPANIED BY STRONG SURFACE CYCLOGENESIS FROM THE LEE OF
THE CANADIAN ROCKIES INTO THE CENTRAL INTERNATIONAL BORDER AREA. AS
THIS OCCURS...AND DOWNSTREAM UPPER RIDGING STRENGTHENS ACROSS THE
EASTERN GULF OF MEXICO/CARIBBEAN AND WESTERN ATLANTIC...ANOTHER
SIGNIFICANT IMPULSE IS PROGGED TO LIFT OUT OF THE BASE OF AN
INCREASINGLY SHEARED POSITIVELY TILTED SOUTHERN BRANCH
TROUGH...ACROSS THE LOWER RIO GRANDE VALLEY...INTO THE LOWER OHIO
VALLEY BY WEDNESDAY NIGHT. THUS...WHILE MODIFICATION OF THE
BOUNDARY LAYER OVER THE WESTERN GULF CONTINUES...THE RETURN FLOW OF
MOISTURE IS EXPECTED TO BE DIRECTED INTO AREAS EAST OF THE
MISSISSIPPI VALLEY...MOSTLY ABOVE A LINGERING NEAR SURFACE STABLE
LAYER ASSOCIATED WITH A SLOWLY RETREATING/WEAKENING COLD SURFACE
RIDGE.
...WESTERN/CENTRAL GULF COAST...
A WINDOW OF OPPORTUNITY MAY EXIST FOR PRE-FRONTAL CONVECTIVE
DEVELOPMENT ACROSS PARTS OF DEEP SOUTH TEXAS WEDNESDAY MORNING...
BEFORE FORCING ASSOCIATED WITH THE UPPER IMPULSE LIFTS NORTHEAST OF
THE LOWER RIO GRANDE VALLEY. IF THIS OCCURS...LINGERING HIGH
MOISTURE LEVELS AND MODERATE INSTABILITY WILL PROVIDE A RISK FOR
SEVERE STORMS IN THE PRESENCE OF SUFFICIENT DEEP LAYER SHEAR FOR
SUPERCELLS...BENEATH 50+ KT SOUTHWESTERLY 500 MB FLOW.
OTHERWISE...CLOUD COVER/PRECIPITATION ASSOCIATED WITH WEAKENING
CONVECTION PROBABLY WILL LIMIT PRE-FRONTAL DESTABILIZATION FARTHER
TO THE NORTH...ACROSS WESTERN/CENTRAL GULF COASTAL AREAS INTO THE
LOWER MISSISSIPPI VALLEY. COUPLED WITH THE LIKELIHOOD OF ONLY VERY
WEAK WAVE DEVELOPMENT ALONG THE FRONTAL ZONE...POTENTIAL FOR SEVERE
STORM DEVELOPMENT WEDNESDAY/WEDNESDAY NIGHT SEEMS LOW.
...UPPER PORTIONS OF THE LWR MS VLY INTO THE LEE OF SRN APLCNS...
THE RISK FOR THUNDERSTORMS IS EXPECTED TO BE HAMPERED BY WEAK
MID-LEVEL LAPSE RATES. BUT...ZONES OF STEEPENING ISENTROPIC ASCENT
ABOVE THE COLD SURFACE-BASED LAYER ASSOCIATED WITH THE RETREATING
SURFACE RIDGE MAY BECOME SUFFICIENT FOR DEEP CONVECTIVE
DEVELOPMENT...AS LOW-LEVEL MOISTURE INCREASES AND CONTRIBUTES TO
DESTABILIZATION.
..KERR.. 11/11/2008
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