SWODY2
SPC AC 080646
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CST FRI FEB 08 2008
VALID 091200Z - 101200Z
..NO SVR TSTM AREAS FORECAST...
..SYNOPSIS...
WITHIN THE BELT OF STRONGER POLAR WESTERLIES EMANATING FROM THE
NORTHERN PACIFIC...MODELS INDICATE THAT A BROAD TROUGH WILL LINGER
OVER THE CENTRAL/EASTERN U.S. INTO 12Z SATURDAY...BEFORE BEGINNING
TO GRADUALLY LIFT NORTHEASTWARD...AS ANOTHER SIGNIFICANT TROUGH
BEGINS TO PROGRESS INTO THE CANADIAN ROCKIES/PACIFIC NORTHWEST. THE
PROGRESSION OF THE LARGER SCALE TROUGH IN THE EAST...HOWEVER...WILL
LIKELY BE SLOWED BY A VIGOROUS SHORT WAVE TROUGH DIGGING WITHIN A
STREAM EMANATING FROM THE NORTHWESTERN CANADIAN ARCTIC REGION. THIS
IMPULSE IS PROGGED TO BE ACCOMPANIED BY STRONG MID-LEVEL COOLING
/500 MB TEMPS OF -30 TO -40C/...ALONG AND NORTH OF AN INTENSIFYING
MID-LEVEL JET STREAK /120-140+ KT AT 500 MB/ NOSING ACROSS THE UPPER
MISSISSIPPI VALLEY THROUGH THE UPPER OHIO VALLEY AND NORTHERN MID
ATLANTIC COAST BY 12Z SUNDAY.
THE UPPER SYSTEM IS PROGGED TO SUPPORT SURFACE WAVE DEVELOPMENT
ALONG A BAROCLINIC ZONE ACROSS THE NORTHERN MID ATLANTIC COAST/
SOUTHERN NEW ENGLAND...AS A STRONG ARCTIC INTRUSION NOSES INTO THE
UPPER MIDWEST/GREAT LAKES AND UPPER OHIO VALLEY. AT THE SAME TIME
..MODELS INDICATE THAT A WEAKER PRECEDING SURFACE FRONT...OFF SOUTH
ATLANTIC COASTAL AREAS INTO THE SOUTHERN GULF OF MEXICO... WILL
FINALLY ADVANCE THROUGH THE REMAINDER OF THE FLORIDA PENINSULA.
..SOUTHERN FLORIDA PENINSULA...
A NARROW TONGUE OF HIGHER PRECIPITABLE WATER CONTENT AIR IN THE
VICINITY OF THE FRONTAL ZONE IS EXPECTED TO CONTRIBUTE TO WEAK TO
MODERATE DESTABILIZATION ACROSS SOUTHEAST COASTAL AREAS SATURDAY
AFTERNOON. AND...ENHANCED LOW-LEVEL CONVERGENCE NEAR THE FRONT AND
THE SEA BREEZE MAY PROVIDE THE FOCUS FOR THE INITIATION OF ISOLATED
THUNDERSTORMS...POSSIBLY ENHANCED BY FORCING ASSOCIATED WITH A WEAK
SUBTROPICAL IMPULSE. IF THIS OCCURS...FORECAST SOUNDINGS INDICATE
UNSATURATED LOWER/MID TROPOSPHERIC PROFILES SUPPORTIVE OF GUSTY
SURFACE WINDS. BUT...WEAK SHEAR/LIMITED INSTABILITY SEEM LIKELY TO
MINIMIZE THE SEVERE THREAT BEFORE ACTIVITY DIMINISHES AFTER DARK.
..LONG ISLAND INTO SOUTHERN NEW ENGLAND...
THE LOW-LEVEL ENVIRONMENT NEAR THE DEVELOPING FRONTAL WAVE IS
EXPECTED TO BE RATHER COOL...BUT FAIRLY SATURATED. AND...STRONG
MID-LEVEL COOLING PROGGED TO OVERSPREAD THE REGION DURING THE
EVENING HOURS SEEMS LIKELY TO STEEPEN LAPSE RATES SUFFICIENTLY FOR
LOW TOPPED CONVECTION...SOME OF WHICH MAY BE CAPABLE OF PRODUCING
CLOUD TO GROUND LIGHTNING.
..GREAT LAKES REGION...
LAKE EFFECT CONVECTIVE BANDS WILL BE POSSIBLE AS AN ARCTIC AIR MASS
OVERSPREADS THE REGION IN CYCLONIC FLOW TO THE SOUTHWEST OF THE
PRIMARY SURFACE CYCLONE. BUT...ANY ACTIVITY CAPABLE OF PRODUCING
LIGHTNING STRIKES WILL PROBABLY BE SHORT-LIVED...SPARSE IN COVERAGE
AND CONFINED TO THE OFFSHORE WATERS.
.KERR.. 02/08/2008
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