[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 080535
SWODY2
SPC AC 080534

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1234 AM CDT FRI SEP 08 2006

VALID 091200Z - 101200Z

...NO SVR TSTM AREAS FORECAST...

...SYNOPSIS...

SPLIT FLOW...LARGE-SCALE PATTERN IS FORECAST DURING THE DAY TWO
PERIOD...CHARACTERIZED BY OMEGA BLOCK ACROSS CANADA AND A WEAKER SRN
BRANCH FROM THE GREAT BASIN EWD TO INCREASINGLY CONFLUENT REGION
OVER THE OH VALLEY INTO THE NERN STATES.  IN THE
LOW-LEVELS...PRIMARY FEATURE WILL BE COLD FRONT WHICH WILL PUSH SEWD
THROUGH NEW ENGLAND AND THE OH VALLEY. THIS BOUNDARY WILL EXTEND
WWD TO LOW PRESSURE AREA DEVELOPING EWD ACROSS KS.

...NEW ENGLAND INTO THE UPPER OH VALLEY...

CURRENT SURFACE OBSERVATIONS AND MODEL FORECASTS SUGGEST THAT
BOUNDARY LAYER WILL NOT BE PARTICULARLY MOIST AHEAD OF SURFACE FRONT
WITH DEWPOINTS LIKELY IN THE 50S TO PERHAPS LOWER 60S. 
HOWEVER...DAYTIME HEATING COUPLED WITH HEIGHT FALLS/DYNAMIC COOLING
AHEAD OF SHORT WAVE TROUGHING DIGGING SEWD THROUGH QUEBEC SHOULD
SUPPORT SOME AIR MASS DESTABILIZATION SATURDAY WITH MLCAPES
INCREASING TO 500-1000 J/KG AT SOME LOCATIONS. WEAK CAPPING IN
CONJUNCTION WITH FRONTAL CONVERGENCE AND INCREASED LARGE-SCALE
FORCING FOR ASCENT AHEAD OF UPPER TROUGH WILL ALL CONTRIBUTE TO AN
INCREASE IN TSTM COVERAGE THROUGH THE AFTERNOON FROM NRN/CNTRL NEW
ENGLAND SWWD THROUGH NY INTO NRN AND CNTRL PARTS OF OH...IND 
AND IL.

FORECAST SOUNDINGS INDICATE THE STRONGEST MID-LEVEL FLOW AND
RESULTANT DEEP LAYER SHEAR /30-35 KTS IN THE LOWEST 6 KM AGL/ ACROSS
NEW ENGLAND INTO NY...IN CLOSEST PROXIMITY TO MID/UPPER-LEVEL JET
STREAKS OVER ERN QUEBEC INTO THE GULF OF ST. LAWRENCE. GIVEN THE
MODEST INSTABILITY AND VERTICAL SHEAR...POTENTIAL WILL EXIST FOR A
FEW ORGANIZED STORMS WITH A THREAT OF LOCALLY DAMAGING WINDS AND
PERHAPS SOME MARGINALLY SEVERE HAIL.

...CNTRL/SRN PLAINS...

FAIRLY WIDESPREAD CONVECTIVE DEVELOPMENT IS ANTICIPATED THROUGH THE
PERIOD AHEAD OF SRN BRANCH SHORT WAVE TROUGH WHICH WILL SLOWLY SHIFT
EWD THROUGH THE CNTRL PLAINS.  MODEL GUIDANCE /IN PARTICULAR THE GFS
AND SHORT-RANGE ENSEMBLE MEAN SOLUTIONS/ SUGGEST THAT SOME AIR MASS
DESTABILIZATION WILL OCCUR SATURDAY AFTERNOON FROM VICINITY OF
SURFACE LOW OVER WRN/CNTRL KS SWD ALONG WEAK DRY LINE OR LEE TROUGH
INTO WRN TX/WRN OK.  GIVEN THE RELATIVELY WEAK VERTICAL SHEAR
FORECAST...AND MODEL VARIABILITY IN THE EVOLUTION OF THIS SHORT WAVE
TROUGH AND ASSOCIATED CLOUDS/PRECIPITATION...NO SEVERE PROBABILITIES
WILL BE INCLUDED ATTM.

...WRN MT/ERN ID...

ISOLATED TSTMS WILL BE POSSIBLE AHEAD OF PACIFIC COLD FRONT SATURDAY
AFTERNOON INTO EVENING ALONG SRN FRINGE OF STRONG SHORT WAVE TROUGH
LIFTING NEWD THROUGH BRITISH COLUMBIA INTO ALBERTA.  BOTH VERTICAL
SHEAR AND INSTABILITY ARE FORECAST TO BE MARGINAL...THOUGH THE
PRESENCE OF STEEP LOW-LEVEL LAPSE RATES MAY SUPPORT A FEW STRONG
DOWNBURSTS WITH THE STRONGEST STORMS.

..MEAD.. 09/08/2006