Sunday, October 7, 2007

DAY2SVR: Nws Storm Prediction Center Norman Ok

ACUS02 KWNS 071619
SWODY2
SPC AC 071618

DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1118 AM CDT SUN OCT 07 2007

VALID 081200Z - 091200Z

..NO SVR TSTM AREAS FORECAST...

..SYNOPSIS...

UPPER LOW INITIALLY OVER THE NRN PLAINS IS FORECAST TO INTENSIFY AS
IT LIFTS NEWD AS A NEGATIVELY-TILTED WAVE INTO THE UPPER GREAT
LAKES. IN THE LOW LEVELS...ATTENDANT SURFACE CYCLONE WILL DEEPEN
PRIOR TO OCCLUDING OVER NRN MN INTO WRN ONTARIO. TRAILING COLD
FRONT INITIALLY FROM THIS LOW SWD THROUGH THE MID MS VALLEY INTO SRN
PLAINS WILL PUSH EWD/SEWD THROUGH THE DAY. FARTHER E...BAROCLINIC
ZONE INITIALLY EXHIBITING WARM FRONTAL PROPERTIES OVER THE NERN
STATES IS EXPECTED TO TRANSITION INTO MORE OF A BACKDOOR COLD FRONT
WITH THIS FEATURE EVENTUALLY SAGGING SWD THROUGH THE REGION MONDAY
AFTERNOON AND NIGHT.

..UPPER GREAT LAKES...

AIR MASS IN ADVANCE OF COLD FRONT IS FORECAST TO BE QUITE MOIST WITH
DEWPOINTS IN THE MID/UPPER 60S...HOWEVER WEAK LAPSE RATES AND
CONSIDERABLE CLOUDINESS WILL LIMIT THE DEGREE OF DESTABILIZATION
WITH MLCAPES AOB 1000 J/KG. TSTMS ARE EXPECTED TO BE ONGOING MONDAY
MORNING ALONG FRONT WITHIN ZONE OF DEEP-LAYER FORCING FOR ASCENT IN
ADVANCE OF INTENSIFYING UPPER LOW. THESE STORMS WILL LIKELY PERSIST
THROUGH THE DAY ALONG FRONT OWING TO PERSISTENT FORCING FOR ASCENT
AND WEAK CAPPING...WITH A GRADUAL INCREASE IN INTENSITY THROUGH THE
AFTERNOON. LATEST MODEL GUIDANCE INDICATES THAT STRONGEST DEEP
LAYER VERTICAL SHEAR WILL LAG SYSTEM WARM SECTOR TO THE W...WITH
LARGELY UNIDIRECTIONAL SWLY FLOW ACROSS FRONTAL ZONE...CHARACTERIZED
BY 30-35 KT OF EFFECTIVE BULK SHEAR. THIS ENVIRONMENT MAY SUPPORT A
FEW ORGANIZED LINE SEGMENTS WITH THE POTENTIAL FOR MAINLY LOCALLY
DAMAGING WINDS THROUGH THE EVENING HOURS.

..NORTHEAST...

THERMODYNAMIC ENVIRONMENT WILL BE QUITE SIMILAR TO THAT ACROSS GREAT
LAKES REGION WITH BOUNDARY LAYER DEWPOINTS IN THE MID 60S...BUT WEAK
MID LEVEL LAPSE RATES LIMITING MLCAPES TO AOB 1000 J/KG. WEAK
PERTURBATIONS MOVING THROUGH DOWNSTREAM RIDGE POSITION COUPLED WITH
FRONTAL CONVERGENCE ARE EXPECTED TO CONTRIBUTE TO AN INCREASE IN
TSTM ACTIVITY ALONG AND S OF FRONTAL BOUNDARY MONDAY AFTERNOON.
FORECAST SOUNDINGS SHOW WLY LOW-LEVEL FLOW VEERING TO NWLY IN THE
MID TO UPPER-LEVELS WITH 35-40 KT OF EFFECTIVE BULK
SHEAR...SUPPORTIVE OF A FEW STRONG/SEVERE STORMS CAPABLE OF MAINLY
LOCALLY DAMAGING WINDS. CURRENTLY...IT APPEARS THAT THE MARGINAL
INSTABILITY/LAPSE RATES WILL LIMIT A MORE ORGANIZED SEVERE
THREAT...THEREFORE ONLY LOW PROBABILITIES WILL BE MAINTAINED.

.MEAD.. 10/07/2007

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