[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 230547
SWODY1
SPC AC 230546

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1246 AM CDT WED AUG 23 2006

VALID 231200Z - 241200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE UPPER MS VLY...

...SYNOPSIS...
THE NRN STREAM WILL REMAIN ACTIVE ON WEDNESDAY.  SEVERAL SHORTWAVE
TROUGHS EMBEDDED WITHIN THIS FLOW WILL MOVE ACROSS THE NRN/HIGH
PLAINS AND BE THE IMPETUS FOR EPISODIC TSTM CLUSTERS.  LEAD SYSTEM
OVER THE DAKS WILL TRANSLATE SEWD INTO THE LWR GRTLKS REGION BY WED
EVE. AN UPSTREAM STRONGER TROUGH IS EXPECTED TO MOVE INLAND ACROSS
THE PAC NW EARLY WED...THEN MOVE INTO THE NRN INTERMOUNTAIN WEST WED
NIGHT. AHEAD OF THIS SYSTEM...A WEAKER IMPULSE SHOULD MOVE ACROSS
THE NRN DAKS AND THE CANADIAN PRAIRIES WED AFTN.

IN THE LWR-LVLS...TAIL END OF A FRONT WILL BE IN PLACE FROM THE
MIDWEST NWWD INTO THE UPPER MS VLY WHILE A LEE TROUGH EXISTS FROM
THE CNTRL DAKS SWD INTO THE CNTRL HIGH PLAINS THROUGH THE PERIOD.  A
NEW FRONT WILL GAIN STRENGTH ACROSS THE NRN INTERMOUNTAIN WEST AND
NRN ROCKIES BY EARLY THU.

...UPPER MS VLY...
SWLY LLJ AXIS IMPINGING ON THE NW-SE ORIENTED FRONT WILL BE FEEDING
A WED MORNING MCS ACROSS PORTIONS OF THE UPPER MS VLY. ASSOCD
OUTFLOW WILL REINFORCE THE BAROCLINIC ZONE THROUGH WED AFTN ACROSS
NRN IL NWWD INTO SWRN MN.  THE SHORTWAVE TROUGH/MCV WILL QUICKLY
MOVE SEWD AND LIKELY OUTRUN THE SUPPLY OF STEEP LAPSE RATES.  AS A
RESULT...THE MCS WILL LIKELY DIMINISH/WEAKEN AS IT MOVES SEWD TOWARD
THE MIDWEST/CNTRL GRTLKS REGION.

OUTFLOW BOUNDARY/FRONT WILL GRADUALLY RECOVER AND MOVE NEWD WED
AFTN.  AIR MASS SW OF THE FRONT WILL BECOME QUITE UNSTABLE AS STEEP
MID-LEVEL LAPSE RATES STREAM EWD FROM THE PLAINS AND SFC DEW POINTS
REMAIN IN THE UPPER 60S.  THERE IS A HIGH DEGREE OF UNCERTAINTY ON
WHETHER SFC-BASED TSTMS WILL DEVELOP ALONG THE FRONT GIVEN LACK OF
APPARENT LARGE SCALE ASCENT.  BUT...REGION WILL REMAIN ALONG NE EDGE
OF THE STRONGER CAP.  LOCAL CONVERGENCE ALONG THE FRONT AND STRONG
HEATING MAY CONTRIBUTE TO INITIATION FROM CNTRL/SRN MN INTO SWRN WI
AND NRN IL BY MID-AFTN.

GIVEN A STORM...THE 40-50 KT OF VERTICAL SHEAR WILL BE SUFFICIENT
FOR SUPERCELLS WITH LARGE HAIL...DAMAGING WINDS AND PERHAPS AN ISOLD
TORNADO.  LOW CONFIDENCE IN INITIATION ARGUES FOR LOW-END SLGT
RISK/LOW SVR PROBABILITIES ATTM.

...NRN DAKS INTO NRN MN...
ISOLD TSTMS MAY BACKBUILD/DEVELOP ACROSS SRN MANITOBA/SASK SWD INTO
THE NRN DAKS ALONG A LEE TROUGH WED AFTN.  CINH WILL BE AN
ISSUE...PARTICULARITY ACROSS SD...BUT WEAK HEIGHT FALLS ASSOCD WITH
A WEAK IMPULSE AND STRONG HEATING ALONG THE EDGE OF THE ELEVATED
MIXED LAYER WILL WEAKEN THE CAP.  MOST ACTIVITY SHOULD REMAIN N OF
THE INTERNATIONAL BORDER...BUT GIVEN A STORM...SUPERCELLS WILL BE
POSSIBLE WITH PRIMARILY LARGE HAIL.  AFTER DARK...ELEVATED BANDS OF
STORMS MAY EVOLVE/DEVELOP FARTHER NE INTO NRN MN WITH PERHAPS ISOLD
LARGE HAIL.  LOW PROBABILITIES WILL BE MAINTAINED AS COVERAGE IS
EXPECTED TO BE ISOLD.

...NRN HIGH PLAINS/ROCKIES...
STRONGER ASCENT WILL SPREAD NEWD ACROSS MT/WRN ND WED NIGHT AS
UPPER TROUGH AND HEIGHT FALLS DEVELOP ACROSS THE REGION. LINEAR
CONVECTIVE DEVELOPMENT MAY OCCUR ALONG THE LEADING EDGE OF THIS
ASCENT.  ISOLD DAMAGING WINDS MAY OCCUR WITH THE STRONGER
STORMS...BUT MOISTURE WILL BE QUITE LIMITED IN THE BOUNDARY LAYER.

..RACY/GUYER.. 08/23/2006