[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 281743
SWODY2
SPC AC 281741

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1241 PM CDT FRI JUL 28 2006

VALID 291200Z - 301200Z

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

...UPPER MS VALLEY THROUGH GREAT LAKES AREA...
ACTIVE SEVERE WEATHER DAY APPEARS LIKELY ON SATURDAY FROM THE UPPER
MS VALLEY INTO THE CENTRAL GREAT LAKES REGION WITH SEVERAL ROUNDS OF
SEVERE STORMS MOVING ESEWD ACROSS THIS REGION.

ONE POTENTIALLY SEVERE MCS IS EXPECTED TO BE ONGOING AT 12Z SATURDAY
ACROSS PARTS OF ERN ND INTO CENTRAL/NRN MN AS DISCUSSED IN THE SPC
DAY 1 CONVECTIVE OUTLOOK...WITH AN ATTENDANT THREAT OF HAIL AND
DAMAGING WINDS.  THIS MCS WILL BE ASSOCIATED WITH ASCENT AHEAD OF A
MID LEVEL SHORT WAVE TROUGH PROGGED TO TRACK ESEWD FROM NWRN MN INTO
THE CENTRAL GREAT LAKES BY 30/00Z...AND REACHING NEW ENGLAND BY 12Z
SUNDAY.  A SURFACE BOUNDARY IS EXPECTED TO REMAIN STATIONARY FROM
NRN MI WNWWD THROUGH NRN WI AND CENTRAL MN TO ALONG THE ND/SD BORDER
AND WILL BE THE FOCUS FOR STORMS TO TRACK ESEWD THROUGH THESE AREAS
DURING DAY 2 PERIOD.  AIR MASS ALONG/S OF THIS BOUNDARY IS EXPECTED
TO REMAIN VERY MOIST WITH SURFACE DEWPOINTS IN THE UPPER 60S TO
AROUND 70.  THIS COMBINED WITH SURFACE HEATING BENEATH ERN EXTENT OF
ELEVATED MIXED LAYER WILL RESULT IN AN AMPLE INFLOW...PER 30-35 KT
WSWLY LLJ...OF MODERATE INSTABILITY TO ONGOING MCS AS IT TRACKS INTO
NRN WI/WRN U.P. OF MI SATURDAY MORNING.  NAM POINT FORECAST
SOUNDINGS SUGGEST THE LIKELIHOOD FOR THIS MCS TO BECOME SURFACE
BASED AS SURFACE HEATING COMMENCES SATURDAY MORNING...WITH
INCREASING POTENTIAL FOR DAMAGING WINDS.  THIS INITIAL MCS SHOULD
REACH PARTS OF NRN LOWER MI SATURDAY AFTERNOON WITH THE CONTINUED
THREAT FOR DAMAGING WINDS AND HAIL.  GIVEN THE ENHANCED LOW LEVEL
SHEAR ALONG SURFACE BOUNDARY PER WSWLY LOW LEVEL WINDS BENEATH 50-60
KT WNWLY MID LEVEL AND HIGH SURFACE DEWPOINTS...THREAT FOR TORNADOES
WILL EXIST AS WELL.

MODELS SUGGEST A SECOND MCS SHOULD DEVELOP ACROSS PARTS OF NERN
MN/NWRN WI AREA BY LATE SATURDAY AFTERNOON/EARLY EVENING AS A SWLY
LLJ STRENGTHENS ACROSS THE UPPER MS VALLEY.  SUFFICIENT ELEVATED
INSTABILITY AND EFFECTIVE BULK SHEAR VALUES INDICATED THIS MCS MAY
BE SEVERE AS IT TRACKS ESEWD SATURDAY NIGHT THROUGH THE UPPER GREAT
LAKES. 

...LOWER GREAT LAKES TO NWRN ME...
A COLD FRONT WILL MOVE INTO THE NERN STATES SATURDAY EVENING AND
OVERNIGHT.  THE PRE-FRONTAL WARM SECTOR SHOULD BECOME MODERATELY
UNSTABLE DURING THE DAY.  THUNDERSTORMS THAT DEVELOP UPSTREAM ACROSS
CANADA AND ALONG LAKE BREEZES WITHIN THE PRE-FRONTAL WARM SECTOR MAY
SPREAD INTO PARTS OF NY AND NEW ENGLAND DURING THE AFTERNOON.  WEAK
LAPSE RATES SUGGEST SEVERE THREAT SHOULD BE MARGINAL.  HOWEVER...A
FEW STRONG TO SEVERE STORMS WILL BE POSSIBLE GIVEN EFFECTIVE BULK
SHEAR VALUES OF 25-30 KT RESULTING IN ISOLATED STRONG WIND GUSTS AND
HAIL IN THE STRONGER CORES.

...NRN HIGH PLAINS...
SHORTWAVE TROUGH WILL TRACK NEWD THROUGH THE NRN ROCKIES AND INTO
CANADA DURING THE DAY. LARGE SCALE ASCENT AND OROGRAPHIC FORCING MAY
BE SUFFICIENT TO INITIATE A FEW HIGH BASED STORMS OVER WRN MT. THIS
ACTIVITY MAY SUBSEQUENTLY SPREAD NEWD THROUGH PARTS OF NRN AND CNTRL
MT.  ADDITIONAL STORMS MAY DEVELOP ALONG FRONT EXTENDING FROM SERN
TO NORTH CENTRAL MT.  AT THIS TIME IT APPEARS THAT COVERAGE WILL BE
TOO ISOLATED AND MOISTURE/INSTABILITY TOO MARGINAL FOR A SLIGHT RISK
ACROSS CENTRAL MT.  ALTHOUGH INSTABILITY MAY BE GREATER ACROSS ERN
MT INTO ND SATURDAY AFTERNOON/NIGHT...MODEL UNCERTAINTIES IN THE
EVOLUTION OF THIS ACTIVITY PRECLUDES A SLIGHT RISK.

...SOUTHWESTERN STATES...
AN INVERTED SHORT WAVE TROUGH IS EXPECTED TO WEAKEN AS IT SPREADS
WWD ACROSS AZ ON SATURDAY...WHILE A MID LEVEL IMPULSE APPROACHES
SWRN NM/SERN AZ SATURDAY AFTERNOON/NIGHT.  AIR MASS IN THE LOWER
ELEVATIONS/DESERTS OF SRN/WRN AZ IS NOT EXPECTED TO BECOME AS
UNSTABLE AS EXPECTED DURING DAY 1.  NONETHELESS...THUNDERSTORMS
SHOULD DEVELOP OVER THE HIGHER TERRAIN OF NM AND AZ AND SUBSEQUENTLY
SPREAD SWWD.  ISOLATED DAMAGING WIND GUSTS AND HAIL WILL BE POSSIBLE
WITH THE STRONGER STORMS.

...PARTS OF THE CAROLINAS/SRN VA...
AIR MASS ACROSS THIS REGION IS EXPECTED TO BECOME MODERATELY
UNSTABLE SUPPORTING AFTERNOON/EVENING THUNDERSTORMS AS MID LEVEL
IMPULSE TRACKS SLOWLY EWD FROM THE SRN APPALACHIANS THROUGH NC/VA ON
SATURDAY.  GENERALLY WEAK DEEP LAYER SHEAR SHOULD RESULT IN
PULSE-TYPE STORMS WITH STEEP LOW LEVEL LAPSE RATES SUPPORTING
ISOLATED STRONG WIND GUSTS AND HAIL WITH THE STRONGER STORMS.

..PETERS.. 07/28/2006