[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 310540
SWODY1
SPC AC 310538

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1238 AM CDT MON JUL 31 2006

VALID 311200Z - 011200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE UPPER MS
VALLEY INTO UPPER GREAT LAKES...

...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF UPSTATE NY
INTO WRN NEW ENGLAND...

...SYNOPSIS...

PROGRESSIVE LARGE-SCALE PATTERN IS FORECAST FROM THE GREAT BASIN AND
PACIFIC NW EWD ACROSS SRN CANADA AND THE NRN TIER OF STATES INTO NEW
ENGLAND.  WITHIN THIS PATTERN...SHORT WAVE TROUGH NOW OVER FAR ERN
MT/WRN ND WILL LIFT NEWD ACROSS SRN MANITOBA INTO ONTARIO AHEAD OF
STRONGER IMPULSE SHIFTING EWD THROUGH THE PRAIRIE PROVINCES. 
MEANWHILE TO THE W...SHORT WAVE WILL MOVE EWD FROM THE ERN PACIFIC
INTO THE PACIFIC NW AND GREAT BASIN.

IN THE LOW-LEVELS...SURFACE COLD FRONT FROM THE RED RIVER VALLEY
SWWD INTO THE CNTRL HIGH PLAINS WILL SHIFT EWD THROUGH THE PERIOD
INTO THE UPPER GREAT LAKES...FOCUSING STRONG TO POTENTIALLY SEVERE
STORMS THIS AFTERNOON INTO TONIGHT.

...UPPER GREAT LAKES/UPPER MS VALLEY...

MCS CURRENTLY EVOLVING OVER NERN ND/NWRN MN IS EXPECTED TO BE
ONGOING AT THE ONSET OF THE FORECAST PERIOD OVER PORTIONS OF N-CNTRL
MN INTO THE ARROWHEAD REGION...DRIVEN LARGELY BY STRONG LOW-LEVEL
WAA ASSOCIATED WITH SWLY LLJ EXTENDING FROM THE CNTRL PLAINS INTO
UPPER GREAT LAKES.  LATEST MODEL GUIDANCE SUGGESTS THAT THE MAJORITY
OF THIS NOCTURNAL CONVECTION WILL MOVE/DEVELOP NEWD INTO SRN ONTARIO
TODAY WITH THE SRN FLANK POSSIBLY AFFECTING LOCATIONS AS FAR S AS
THE U.P. WITH THE PRIMARY THREAT BEING DAMAGING WINDS.

ADDITIONAL STORMS WILL BE POSSIBLE THIS AFTERNOON ALONG COLD FRONT
FROM NRN MN SWWD INTO ERN SD WHERE STEEP LAPSE RATES AND MOIST
BOUNDARY LAYER CONDITIONS /DEWPOINTS OF 65-75 F/ WILL CONTRIBUTE TO
MLCAPES OF 1500-3000 J/KG.  WHILE THE STRONGER LARGE-SCALE FORCING
WILL GRADUALLY SHIFT NEWD INTO ONTARIO...SUSTAINED LOW-LEVEL
CONVERGENCE AND DAYTIME HEATING SHOULD BE SUFFICIENT TO OVERCOME
CAP.  STRONGEST MID-LEVEL WIND FIELDS /45-55 KTS AT 500 MB/ AND
RESULTANT VERTICAL SHEAR ARE FORECAST ACROSS NRN MN...ALONG SRN
PERIPHERY OF SHORT WAVE TROUGH MOVING THROUGH MANITOBA/WRN ONTARIO
WHERE A FEW SUPERCELLS CAPABLE OF MAINLY DAMAGING WINDS AND LARGE
HAIL WILL BE POSSIBLE. FARTHER S INTO SD...BOTH SHEAR AND
INSTABILITY WILL BE WEAKER...THOUGH MULTICELLS WITH LOCALLY STRONG
WIND GUSTS AND SOME SEVERE HAIL WILL BE POSSIBLE.

...NY INTO WRN NEW ENGLAND...

PERSISTENT SWLY LLJ FROM THE CNTRL PLAINS THROUGH THE GREAT LAKES
INTO SWRN ONTARIO/SWRN QUEBEC IS FORECAST TO MAINTAIN A FEED OF A
MOIST AND MODERATELY UNSTABLE AIR INTO TSTM CLUSTERS/MCSS THAT ARE
EXPECTED TO PERSIST ACROSS SRN ONTARIO INTO SWRN QUEBEC.  THESE
STORMS MAY BEGIN TO TURN MORE SEWD LATE TONIGHT INTO PORTIONS OF
UPSTATE NY AND WRN NEW ENGLAND AS ACTIVITY SHIFTS E OF MEAN
MID-LEVEL RIDGE AXIS.  FORECAST SOUNDINGS INDICATE THAT INSTABILITY
WILL REMAIN MARGINAL...THOUGH RELATIVELY STRONG UNIDIRECTIONAL WIND
PROFILES WILL BE SUPPORTIVE OF DAMAGING WIND GUSTS.

...CNTRL/SRN HIGH PLAINS...

STEEP LAPSE RATES ARE FORECAST TO DEVELOP TODAY AHEAD OF COLD FRONT
MOVING SWD THROUGH THE CNTRL HIGH PLAINS...CONTRIBUTING TO MLCAPES
OF 1000-1500 J/KG.  VERTICAL SHEAR WILL REMAIN QUITE WEAK...THOUGH
THE STEEP LAPSE RATES /ESPECIALLY IN THE LOW-LEVELS/ WILL BE
SUPPORTIVE OF A FEW STRONG TO SEVERE STORMS CAPABLE OF MAINLY STRONG
WIND GUSTS.

...CNTRL/ERN NV...

ENVIRONMENT IS FORECAST TO BECOME INCREASINGLY SUPPORTIVE OF TSTMS
THIS AFTERNOON INTO EVENING AS FORCING FOR ASCENT ASSOCIATED WITH
APPROACHING MID-LEVEL TROUGH COUPLED WITH DAYTIME HEATING
CONTRIBUTES TO STEEP LAPSE RATES AND MARGINAL INSTABILITY.  DESPITE
THIS MARGINAL INSTABILITY...VERTICAL SHEAR WILL BE QUITE
STRONG...AND GIVEN THE INCREASED LARGE-SCALE FORCING...POTENTIAL
WILL EXIST FOR A FEW ORGANIZED STORMS CAPABLE OF SEVERE HAIL AND
LOCALLY DAMAGING WINDS.

..MEAD/GRAMS.. 07/31/2006