[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 280555
SWODY2
SPC AC 280554

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1254 AM 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...

...SYNOPSIS...

BELT OF STRONGER FLOW WILL PERSIST ALONG THE NRN TIER OF THE U.S.
THIS PERIOD. SEVERAL IMPULSES WILL MOVE THROUGH THIS BAND OF FLOW.
ONE SUCH FEATURE NOW MOVING INTO THE PACIFIC NW IS FORECAST TO BE
OVER THE UPPER MS VALLEY EARLY SATURDAY. A STRONGER UPSTREAM
SHORTWAVE TROUGH IS FORECAST TO AMPLIFY INTO THE PACIFIC NW THEN
EJECT NEWD THROUGH THE NRN ROCKIES AND INTO SWRN CANADA DURING THE
DAY. A BAROCLINIC ZONE WILL EXTEND FROM A SURFACE LOW OVER THE
DAKOTAS EWD INTO THE GREAT LAKES AREA. A COLD FRONT WILL APPROACH
THE NERN STATES SATURDAY NIGHT.

...UPPER MS VALLEY THROUGH GREAT LAKES AREA...

THUNDERSTORMS ARE EXPECTED TO DEVELOP LATE FRIDAY NIGHT AND PERSIST
INTO EARLY SATURDAY OVER THE NRN PLAINS OR UPPER MS VALLEY AREA
WITHIN ZONE OF WARM ADVECTION AND ISENTROPIC ASCENT N OF SURFACE
FRONT. THE ATMOSPHERE IN VICINITY OF THE E-W BOUNDARY AND OUTSIDE OF
ONGOING CONVECTION IS EXPECTED TO BECOME MODERATELY UNSTABLE. LOW
LEVEL DEWPOINTS IN THE 60S...STEEP MID LEVEL LAPSE RATES AND SURFACE
HEATING SHOULD CONTRIBUTE TO MLCAPE AROUND 2000 J/KG. AS THE CAP
WEAKENS AND THE ATMOSPHERE DESTABILIZES...IT IS POSSIBLE THAT
ONGOING ELEVATED STORMS MAY EVENTUALLY BECOME FORWARD PROPAGATING IF
THEY CAN ROOT IN THE BOUNDARY LAYER. OTHER SURFACE BASED STORMS MAY
DEVELOP ALONG RESIDUAL OUTFLOW BOUNDARIES...ALONG LAKE BREEZE
BOUNDARIES OR IN VICINITY OF THE SURFACE FRONT. LARGE SCALE ASCENT
ASSOCIATED WITH EWD ADVANCING MID LEVEL IMPULSE MAY ENHANCE THE
POTENTIAL FOR THUNDERSTORM DEVELOPMENT...ESPECIALLY OVER THE GREAT
LAKES AREA. BELT OF 35 TO 40 KT MID LEVEL FLOW ABOVE SELY LOW LEVEL
FLOW NEAR SURFACE FRONT WILL CONTRIBUTE TO SUFFICIENT VERTICAL SHEAR
FOR ORGANIZED STORMS INCLUDING SUPERCELLS AND BOW ECHOES. LARGE HAIL
AND DAMAGING WIND WILL BE THE PRIMARY THREATS. OTHER MORE ELEVATED
STORMS MAY DEVELOP OVERNIGHT ACROSS THE UPPER MS VALLEY WITH
DEVELOPING WARM ADVECTION REGIME. LARGE HAIL SHOULD BE THE MAIN
THREAT WITH THAT ACTIVITY.


...NERN U.S...

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. LOW
LEVEL FLOW IS EXPECTED TO REMAIN WEAK...BUT WNWLY FLOW INCREASING TO
40-50 KT ABOVE 6 KM MAY RESULT IN SUFFICIENT UNIDIRECTIONAL SHEAR
FOR MID LEVEL UPDRAFT ROTATION. ISOLATED STRONG WIND GUSTS AND HAIL
COULD ACCOMPANY THE STRONGER STORMS.


...CNTRL AND NRN MT...

SHORTWAVE TROUGH WILL EJECT NEWD THROUGH THE NRN ROCKIES AND INTO
SWRN 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. AT THIS TIME IT APPEARS THAT COVERAGE WILL BE TOO
ISOLATED AND MOISTURE/INSTABILITY TOO MARGINAL FOR A SLIGHT RISK.


...SWRN U.S....

STORMS ARE EXPECTED TO DEVELOP OVER THE HIGHER TERRAIN OF NM AND AZ
AND SUBSEQUENTLY SPREAD SWWD DURING THE DAY. ISOLATED DAMAGING WIND
GUSTS AND HAIL WILL BE POSSIBLE WITH THE STRONGER STORMS.

..DIAL.. 07/28/2006