[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 291746
SWODY2
SPC AC 291745

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1245 PM CDT SAT JUL 29 2006

VALID 301200Z - 311200Z

...THERE IS A SLGT RISK OF SVR TSTMS EXTENDING FROM NRN ND/MN
THROUGH GREAT LAKES REGION TO PARTS OF SRN NY/PA/NWRN NJ...

...SYNOPSIS...
LONG WAVE TROUGH WILL DEVELOP SWD ALONG THE WEST COAST ON SUNDAY
RESULTING IN DOWNSTREAM RIDGE BUILDING EWD...AND EXTENDING FROM THE
MS VALLEY INTO ONTARIO/HUDSON BAY BY 12Z MONDAY.  STRONGER BELT OF
WLYS WILL REMAIN ALONG THE NRN TIER STATES...WITH THE PRIMARY ZONE
OF NWLY FLOW ALOFT EXTENDING FROM FAR NRN MN THROUGH THE GREAT LAKES
TO MID ATLANTIC/NERN STATES.  MODELS ARE IN GENERAL AGREEMENT WITH
EJECTING A PACIFIC SHORT WAVE TROUGH NEWD ACROSS THE NRN ROCKIES
SUNDAY INTO SRN ALBERTA/SASKATCHEWAN...WHILE A LOW AMPLITUDE TROUGH
PERSISTS ACROSS SERN CANADA AND NERN STATES.  POTENTIAL ALSO EXISTS
FOR SEVERAL SMALLER SCALE VORTICITY MAXIMA TO MOVE THROUGH THE BELT
OF STRONGER FLOW.

IN THE LOW-LEVELS...A COLD FRONT IS EXPECTED TO STALL FROM SRN NEW
ENGLAND INTO SRN NY...WITH THIS BOUNDARY EXTENDING WNWWD THROUGH THE
GREAT LAKES REGION TO A SURFACE LOW OVER THE DAKOTAS.  THE WRN
EXTENT OF THIS BOUNDARY WILL LIFT NWD AS A WARM FRONT ACROSS NRN
PLAINS/NRN MS VALLEY.

...NERN ND THROUGH NRN MN AND GREAT LAKES REGION...
RICH LOW LEVEL MOISTURE WILL PERSIST ALONG/S OF THE SURFACE FRONT
WHILE STRONGER BELT OF WLYS MAINTAINS A PLUME OF STEEP LAPSE RATES
INTO THE GREAT LAKES.  THESE FACTORS WILL CONTRIBUTE TO MODERATE TO
STRONG INSTABILITY FOR THUNDERSTORM DEVELOPMENT ALONG THE SURFACE
BOUNDARY AND/OR CONVECTIVE OUTFLOW BOUNDARIES FROM DAY 1 ACTIVITY AS
WEAK IMPULSES TRAVERSE THIS REGION.

THE FOLLOWING IS A LIKELY SCENARIO FOR DAY 2 SEVERE.  AN MCS...
POTENTIALLY SEVERE...SHOULD BE ONGOING AT 12Z SUNDAY ACROSS PARTS OF
THE NRN MS VALLEY/WRN GREAT LAKES REGION PER SPC DAY 1 CONVECTIVE
OUTLOOK.  THIS ACTIVITY MAY WEAKEN IN THE MORNING WITH THUNDERSTORM
REDEVELOPMENT DOWNSTREAM ACROSS THE GREAT LAKES SUNDAY AFTERNOON
INTO THE EVENING.  DEEP LAYER SHEAR WILL BE SUFFICIENT FOR SEVERE
STORM ORGANIZATION.  SEVERE THREAT SHOULD THEN SHIFT FARTHER NWWD AS
THE SURFACE FRONT MOVES NWD AND THE RIDGE BUILDS INTO THIS REGION. 
STRENGTHENING SSWLY PLAINS LLJ SHOULD FOCUS STRONGEST CONVERGENCE
ALONG THE U.S./CANADIAN BORDER FROM NRN ND/MN INTO THE UPPER GREAT
LAKES REGION WITH POTENTIAL FOR AN OVERNIGHT MCS OVER THIS REGION.

...LOWER GREAT LAKES TO MID ATLANTIC/SWRN NEW ENGLAND REGION...
AIR MASS IS ALSO EXPECTED TO BECOME MODERATELY UNSTABLE ALONG/S OF
SURFACE BOUNDARY...ESPECIALLY IN AREAS OF STRONGEST SURFACE HEATING.
MODELS DIFFER IN THE STRENGTH OF THE NWLY MID LEVEL FLOW/DEEP LAYER
SHEAR EXPECTED ACROSS THIS REGION ON DAY 2.  NONETHELESS...EVEN THE
WEAKER GFS SUGGESTS DEEP LAYER SHEAR WILL BE SUFFICIENT FOR
MULTICELLS /SFC-6 KM SHEAR 20-30 KT/.  ALTHOUGH MID LEVEL LAPSE
RATES WILL BE WEAK...MODERATE INSTABILITY AND THE EXPECTED SHEAR
SHOULD BE ADEQUATE FOR AT LEAST A FEW SEVERE STORMS WITH DAMAGING
WINDS/HAIL THE PRIMARY THREATS.  THUS...HAVE EXTENDED SLIGHT RISK
SEWD INTO THE LOWER GREAT LAKES AND PARTS OF THE MID ATLANTIC
REGION.

...CENTRAL/ERN MT TO WRN ND...
ASCENT AHEAD OF EJECTING PACIFIC SHORT WAVE THROUGH MAY PROMOTE
THUNDERSTORM DEVELOPMENT ACROSS THE HIGHER TERRAIN OF THE NRN
ROCKIES SUNDAY AFTERNOON...WITH ACTIVITY DEVELOPING NEWD INTO
CENTRAL/ERN MT AND WRN ND.  WEAK INSTABILITY IN THE VICINITY OF THE
INITIAL STORMS SHOULD PRECLUDE A SEVERE THREAT ACROSS WRN MT...BUT
GREATER INSTABILITY FARTHER EAST SUGGESTS A FEW STORMS MAY BECOME
SEVERE BY SUNDAY EVENING.  

...SWRN STATES...
ASCENT IN VICINITY OF WEAK UPPER CIRCULATION EXPECTED ACROSS ERN
AZ/WRN NM AND WITHIN MOIST AIR MASS SHOULD PROMOTE THUNDERSTORM
DEVELOPMENT ACROSS THE SWRN STATES ON DAY 2.  MARGINAL TO MODERATE
INSTABILITY AND GENERALLY WEAK DEEP LAYER SHEAR SUGGESTS STORM MODE
SHOULD BE PULSE WITH ISOLATED STRONG WIND GUSTS THE GREATEST THREAT.

..PETERS.. 07/29/2006