[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 231634
SWODY1
SPC AC 231633

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1133 AM CDT WED AUG 23 2006

VALID 231630Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS NRN MS RIVER VALLEY INTO THE
CENTRAL GREAT LAKES...

...NRN MS RIVER VALLEY INTO THE CENTRAL GREAT LAKES...
FAVORABLE LOW LEVEL WAA REGIME WILL REMAIN IN PLACE TODAY ATOP
SURFACE OUTFLOW BOUNDARY/WARM FRONT WHICH EXTENDS FROM NERN IL/SERN
WI NWWD TO SURFACE LOW ALONG THE ND-SD BORDER THIS MORNING.  THIS
BOUNDARY WILL MOVE LITTLE THROUGH THE AFTERNOON...WHILE STRONG
HEATING AT THE SURFACE AND WARMING THROUGH H7 OCCURS ACROSS THE WARM
SECTOR.  APPEARS WSWLY H85 FLOW FROM 30-40 KT WILL PERSIST FOR MUCH
OF THE DAY INTO THE NRN MS RIVER VALLEY AND CONTINUE DEVELOPING
ELEVATED THUNDERSTORMS ALONG NERN EDGE OF MID LEVEL CAPPING ACROSS
WRN/CENTRAL WI.  MID LEVEL LAPSE RATES ARE QUITE STEEP AND FEED OF
MODERATE INSTABILITY WILL SUPPORT STRONG UPDRAFTS...FURTHER ENHANCED
BY 40-50 KT EFFECTIVE SHEAR...SUGGESTING ISOLATED LARGE HAIL MAY
OCCUR WITH THIS ACTIVITY.  

SEVERE THREAT MAY INCREASE LATER THIS AFTERNOON AS STRONG SURFACE
HEATING ALONG EDGE OF H7 THERMAL RIDGE OCCURS NEAR THE SURFACE FRONT
OVER THE NRN MS RIVER VALLEY.  FORECAST SOUNDINGS INDICATE CAP MAY
WEAKEN SUFFICIENTLY FOR SURFACE-BASED DEVELOPMENT WITHIN AN
ENVIRONMENT CHARACTERIZED BY 1500+ J/KG MLCAPE AND 40-50 KT DEEP
LAYER SHEAR.  THEREFORE...SUPERCELLS AND POSSIBLY ISOLATED
TORNADOES/VERY LARGE HAIL WOULD BE FAVORED SHOULD SURFACE-BASED
DEVELOPMENT OCCUR.  OTHERWISE...EXPECT EVOLUTION INTO ANOTHER
STRONG/SEVERE MCS WHICH WILL SPREAD ESEWD ACROSS THE CENTRAL GREAT
LAKES AHEAD OF SHORTWAVE TROUGH NOW SHIFTING EWD ACROSS NERN MT/SRN
SASK.  HAVE ADJUSTED SLGT RISK AREA INTO PORTIONS OF SWRN MI TO
ACCOUNT FOR THIS SCENARIO WHERE FORECAST SOUNDINGS LATER TONIGHT
YIELD MUCAPE AROUND 1500 J/KG AND SUFFICIENT CLOUD-LAYER SHEAR FOR
ROTATING UPDRAFTS.  AS WAS THE CASE LAST NIGHT...MCS COULD BOW INTO
A LINE THOUGH WIND DAMAGE POTENTIAL WILL DEPEND ON HOW STABLE THE
BOUNDARY LAYER REMAINS.  ATTM...EXPECT PRIMARY THREAT WILL BE FROM
LARGE HAIL.

..EVANS/TAYLOR.. 08/23/2006