[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 110527
SWODY2
SPC AC 110526

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1226 AM CDT MON SEP 11 2006

VALID 121200Z - 131200Z

...THERE IS A SLGT RISK OF SVR TSTMS OVER PARTS OF THE LOWER OH
VALLEY AND MID SOUTH...

...SYNOPSIS...

UPPER TROUGH FROM THE UPPER GREAT LAKES INTO THE MIDDLE MS VALLEY
WILL AMPLIFY THROUGH THE DAY TWO PERIOD AS EMBEDDED VORTICITY MAXIMA
NOW OVER ERN ND/NWRN MN AND ERN MT PHASE AND DIG SEWD TOWARD THE
CNTRL AND LOWER MS VALLEY.  TO THE SW...VORTICITY MAXIMUM OVER
CNTRL/SRN CA IS FORECAST TO BECOME PROGRESSIVELY CUT OFF FROM MEAN
FLOW WITH THIS FEATURE REMAINING NEARLY STATIONARY OVER SRN PARTS OF
CA/AZ INTO BAJA AND THE NRN GULF OF CA.  

IN THE LOW-LEVELS...PRIMARY SURFACE LOW ASSOCIATED WITH CNTRL U.S.
TROUGH WILL DEVELOP NEWD FROM CNTRL OR SRN IL INTO LOWER MI BY
WEDNESDAY MORNING.  ATTENDANT COLD FRONT WILL SLOWLY PUSH EWD
THROUGH THE CNTRL/SRN MS VALLEY WITH A SECONDARY SURFACE LOW
DEVELOPING ON THIS BOUNDARY ALONG THE GULF COAST.

...LOWER OH VALLEY INTO MID SOUTH...

LATEST SHORT RANGE MODEL GUIDANCE REMAINS CONSISTENT IN INDICATING
THAT THE STRONGEST LARGE-SCALE FORCING FOR ASCENT /12-HR 500 MB
HEIGHT FALLS OF 30-60 M/ WILL OCCUR ACROSS SLIGHT RISK AREA LATE
TUESDAY AFTERNOON INTO TUESDAY NIGHT...FOCUSING STRONG TO SEVERE
STORMS ALONG AND AHEAD OF COLD FRONT.  IT APPEARS THAT CLUSTERS OF
TSTMS WILL PERSIST THROUGH MUCH OF THE PERIOD AHEAD OF SURFACE FRONT
FROM THE OH VALLEY SWD INTO THE MID SOUTH...DRIVEN BY DEEP-LAYER
FORCING AHEAD OF DIGGING TROUGH.  WHILE MID-LEVEL LAPSE RATES WILL
REMAIN RELATIVELY WEAK AND NEAR MOIST ADIABATIC...MOIST BOUNDARY
LAYER CONDITIONS AND DIURNAL HEATING WILL CONTRIBUTE TO POCKETS OF
MODERATE INSTABILITY WITH MLCAPES APPROACHING 1000-1500 J/KG.

THE MOST INTENSE STORM DEVELOPMENT WILL LIKELY OCCUR DURING THE MID
TO LATE AFTERNOON HOURS NEAR OR JUST W OF THE MS RIVER AS STRONGER
FORCING ASSOCIATED WITH ABOVEMENTIONED...DIGGING VORTICITY MAXIMA
BEGIN TO OVERSPREAD FRONTAL ZONE AND WRN EDGE OF INSTABILITY AXIS. 
INCREASING MID AND UPPER-LEVEL FLOW WILL RESULT IN 30-35 KTS OF
EFFECTIVE BULK SHEAR...SUFFICIENT FOR ORGANIZED MULTICELL CLUSTERS
AND MARGINAL SUPERCELL/BOW STRUCTURES CAPABLE OF MAINLY DAMAGING
WINDS AND SOME SEVERE HAIL.

AN ISOLATED TORNADO THREAT MAY EXIST NEAR THE GULF COAST ALONG TRACK
OF SECONDARY SURFACE LOW.  WHILE DEEP-LAYER SHEAR WILL NOT BE
PARTICULARLY STRONG...MODEST LOW-LEVEL SHEAR COUPLED WITH VERY MOIST
BOUNDARY LAYER CONDITIONS MAY SUPPORT PERIODIC UPDRAFT ROTATION WITH
A THREAT OF A BRIEF TORNADO OR TWO.  

...SRN AZ...

TSTMS ARE FORECAST TO BECOME INCREASINGLY WIDESPREAD TUESDAY
AFTERNOON INTO TUESDAY NIGHT ALONG THE NRN INFLUENCE OF
QUASI-STATIONARY UPPER LOW.  HERE...STEEP LAPSE RATES WILL COMBINE
WITH BOUNDARY LAYER DEWPOINTS IN THE 50S TO SUPPORT MLCAPES OF
AROUND 1000 J/KG.  FORECAST SOUNDINGS INDICATE ELY LOW-LEVEL FLOW
VEERING TO WLY IN THE UPPER TROPOSPHERE WITH GENERALLY 20-25 KTS OF
DEEP-LAYER SHEAR.  WHILE THIS SHEAR MAY LIMIT THE OVERALL SEVERE
WEATHER THREAT...THE STEEP LAPSE RATES AND DEEPLY MIXED BOUNDARY
LAYER CONDITIONS INDICATE THE POTENTIAL FOR LOCALLY STRONG WIND
GUSTS AND SOME MARGINALLY SEVERE HAIL WITH THE STRONGEST STORMS.

..MEAD.. 09/11/2006