[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 251250
SWODY1
SPC AC 251249

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0749 AM CDT FRI AUG 25 2006

VALID 251300Z - 261200Z

...THERE IS A SLGT RISK OF SVR TSTMS TODAY INTO EARLY TONIGHT FROM
KS NEWD TO WI...THEN ESEWD TO NRN PA...

...THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON/EVENING FOR NE
UT/NW CO/SW WY...

...ERN IA/NW IL/SRN WI THIS AFTERNOON...
A MID LEVEL TROUGH OVER THE CANADIAN PRAIRIES WILL PROGRESS EWD TO
ONTARIO...WHILE THE SRN EXTENT OF THIS TROUGH MOVES EWD FROM MN THIS
MORNING TO UPPER MI/LAKE SUPERIOR THIS EVENING WHILE GRADUALLY
WEAKENING.  AN ASSOCIATED SURFACE CYCLONE ACROSS SRN MN/NRN IA WILL
MOVE EWD ACROSS SRN WI TO LAKE MI AND WEAKEN IN CONJUNCTION WITH
DE-AMPLIFICATION OF THE MID LEVEL WAVE.  A TRAILING COLD FRONT
SHOULD CONTINUE SLOWLY SEWD ACROSS IA/NRN MO/KS THROUGH TONIGHT. 
FARTHER E...THE SURFACE PATTERN HAS BEEN COMPLICATED BY OUTFLOW FROM
OVERNIGHT STORMS ACROSS SRN WI/NERN IA.  AN OUTFLOW BOUNDARY EXTENDS
FROM E CENTRAL IA INTO SE WI AS OF 11Z...WHILE THE PRIMARY
BAROCLINIC ZONE IS LOCATED FARTHER N FROM CENTRAL WI ACROSS SRN
LOWER MI.

OVERNIGHT CONVECTION HAS EXHAUSTED MUCH OF THE STRONGER
INSTABILITY...AND THE RICHER BOUNDARY LAYER MOISTURE /MID 60S OR
GREATER/ IS CONFINED TO A NARROW CORRIDOR FROM ERN KS/WRN MO INTO
IA.  SOME RECOVERY WILL BE POSSIBLE THROUGH THIS AFTERNOON IN
ADVANCE OF THE SURFACE LOW/COLD FRONT AND IN THE WAKE OF THE MORNING
CONVECTION...AND A FEW THUNDERSTORMS MAY FORM FROM ERN IA INTO SRN
WI.  VERTICAL SHEAR AND LOW-MID LEVEL FLOW FIELDS ARE EXPECTED TO
WEAKEN SLOWLY THROUGH THIS EVENING IN THE WARM SECTOR...THOUGH
VERTICAL SHEAR MAY REMAIN AT LEAST MARGINALLY FAVORABLE FOR
SUPERCELLS ACROSS WI THIS AFTERNOON.

...LOWER MI TO PA AREA THROUGH THIS EVENING...
A BELT OF WEAK-MODERATE INSTABILITY IS EXPECTED TODAY ALONG A
LOW-LEVEL BAROCLINIC ZONE FROM SRN LOWER MI INTO CENTRAL PA.  DEBRIS
CLOUDS MAY LIMIT SURFACE HEATING ACROSS LOWER MI EARLY TODAY...BUT A
FEW THUNDERSTORM CLUSTERS ARE STILL EXPECTED INVOF THE SURFACE
BOUNDARY.  DEEP LAYER VERTICAL SHEAR WILL BE SUFFICIENT FOR BOTH
SUPERCELLS AND BOWING SEGMENTS...THE STRONGEST OF WHICH COULD
PRODUCE A FEW DAMAGING GUSTS AND MARGINALLY SEVERE HAIL.

...PLAINS AREA THIS AFTERNOON INTO EARLY TONIGHT...
A BROAD AREA OF THUNDERSTORMS ASSOCIATED WITH LOW-LEVEL WAA AND A
40-50 KT LLJ IS ONGOING ACROSS MO TO THE E OF THE
MOISTURE/INSTABILITY ACROSS FROM ERN OK INTO ERN KS.  SURFACE
HEATING AND BOUNDARY LAYER DEWPOINTS OF 65-70 F ALONG A SLOW MOVING
COLD FRONT IN KS WILL RESULT IN MODERATE INSTABILITY BY AFTERNOON
WHEN SURFACE-BASED THUNDERSTORM DEVELOPMENT IS EXPECTED.  STEEP
LOW-LEVEL LAPSE RATES AND MLCAPE VALUES OF 1500-2000 J/KG WILL
SUPPORT A THREAT FOR WIDELY SCATTERED DOWNBURSTS AND SOME HAIL THIS
AFTERNOON/EVENING ALONG AND S OF THE FRONT.  N OF THE
BOUNDARY...LOW-LEVEL NELY FLOW BENEATH 25-30 KT SWLY MID LEVEL FLOW
WILL RESULT IN SUFFICIENT DEEP LAYER SHEAR FOR SOME SUPERCELL
STRUCTURES FROM EXTREME SE CO ACROSS WRN/CENTRAL KS.  CONVECTION
WILL EVENTUALLY BECOME RATHER WIDESPREAD ALONG AND N OF THE
FRONT...THUS THE SEVERE STORM THREAT IS EXPECTED TO DIMINISH BY LATE
EVENING.

...NE UT/NW CO/SW WY AREA TODAY...
THE MID LEVEL TROUGH OVER ERN ORE/WA AND ID THIS MORNING WILL DIG
SLOWLY SEWD TOWARD NE NV/NW UT BY EARLY SATURDAY.  ASCENT IN ADVANCE
OF THE MID LEVEL TROUGH...ALONG WITH NW EDGE OF THE MONSOONAL
MOISTURE PLUME...WILL SUPPORT SCATTERED THUNDERSTORM DEVELOPMENT
FROM NE UT INTO SW WY AND NW CO TODAY INTO EARLY TONIGHT.  STEEP
L0W-MID LEVEL LAPSE RATES...LOW-LEVEL DEWPOINTS OF 45-50 F...AND
MODEST SWLY MID LEVEL FLOW SHOULD BE SUFFICIENT FOR A FEW STORMS
WITH STRONG/DAMAGING OUTFLOW WINDS AND MARGINALLY SEVERE HAIL.

..THOMPSON/GUYER.. 08/25/2006