[SWODY2] SWODY2

[Severe Weather Outlook - Day 2]

ACUS02 KWNS 121649
SWODY2
SPC AC 121648

DAY 2 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
1148 AM CDT SAT AUG 12 2006

VALID 131200Z - 141200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE
CNTRL/NRN PLAINS AND UPPER MS VLY REGION...

...SYNOPSIS...
ACTIVE NRN STREAM WILL CONTINUE INTO SUNDAY AS A POTENT UPPER TROUGH
PROGRESSES EWD FROM THE NWRN STATES TODAY TO THE UPPER MS VLY BY
SUNDAY NIGHT.  ASSOCD COLD FRONT WILL REACH A MN...SD... NERN CO
LINE BY 00Z MON AND TO AN UPPER GRTLKS TO SRN HI PLAINS LINE BY 12Z
MON.  

...NRN PLAINS TO UPPER MS VALLEY...
SEVERAL AREAS OF CONVECTION SHOULD BE ONGOING ACROSS A LARGE PORTION
OF NWRN MN...THE DAKS AND NEB EARLY SUNDAY MORNING.  STRONGEST
STORMS SHOULD EXIST ACROSS MN ALONG THE NOSE OF THE WARM
SUB-TROPICAL CONVEYOR AHEAD OF THE APPROACHING MID-LEVEL TROUGH. 
THIS ACTIVITY SHOULD EITHER WEAKEN OR MOVE INTO NWRN ONT BY AFTN.

AIR MASS IN WAKE OF THE MORNING ACTIVITY AND AHEAD OF THE PRIMARY
COLD FRONT SHOULD BECOME INCREASINGLY UNSTABLE THROUGH SUNDAY AFTN
GIVEN RICH LOW-LEVEL MOISTURE AND MODEST HEATING.  BUT...SUB-
TROPICAL CONVEYOR AND POTENTIAL FOR CLOUD SUGGEST THAT LAPSE RATES
MAY SUFFER AND BE LOWER THAN RECENT DAYS.  NONETHELESS...TSTMS
SHOULD INTENSIFY/DEVELOP ALONG SERN EDGE OF MORNING CLOUD/TSTM
CLUSTERS ACROSS PORTIONS OF MN AND IA BY MID-AFTN AS CINH IS
WEAKENED VIA FRONTAL CIRCULATION AND LARGE SCALE HEIGHT FALLS. SHEAR
AND FORCING WILL BE STRONGEST WEST OF THE FRONT AND GIVEN
ORIENTATION OF THE DEEP LAYER SHEAR VECTORS...TSTMS WILL TEND TO
EVOLVE QUICKLY INTO LINE SEGMENTS WITH PERHAPS EMBEDDED SUPERCELLS. 
DAMAGING WINDS WILL BE THE PRIMARY SEVERE THREAT...BUT HAIL AND AN
ISOLD TORNADO CANNOT BE RULED OUT. BY EVE...A FAIRLY EXTENSIVE
SQUALL LINE WILL LIKELY EXIST ACROSS THE UPPER MS VLY THAT WILL MOVE
EWD AND WEAKEN OVERNIGHT.  

...CNTRL PLAINS...
THOUGH STRONGEST DEEP LAYER SHEAR AND ASCENT ARE EXPECTED ACROSS THE
NRN PLAINS...AIR MASS IS FORECAST TO BE MUCH MORE UNSTABLE ACROSS
PARTS OF THE MO VLY AND ADJACENT PLAINS.  HERE...MID-LEVEL LAPSE
RATES WILL BE STEEPER AND BOUNDARY LAYER CAPPED FOR MOST OF THE
AFTN.  RESULTANT STRONGER LOW-LEVEL HEATING SHOULD WEAKEN THE CAP
AND GIVEN WEAK LARGE SCALE FORCING AHEAD OF THE SEWD MOVING COLD
FRONT...TSTMS SHOULD DEVELOP LATE IN THE AFTN FROM SERN NEB SWWD
INTO WRN KS.  MAGNITUDE OF BUOYANCY MAY COMPENSATE FOR THE WEAKER
VERTICAL SHEAR AND ORGANIZED MULTICELL STORMS WILL BE POSSIBLE. 
MORE VIGOROUS STORMS WILL PRODUCE DAMAGING WINDS AND HAIL.  AN MCS
OR TWO IS LIKELY TO EVOLVE OVERNIGHT ACROSS PARTS OF IA SWWD INTO
KS...THOUGH THE SEVERE THREATS WILL LIKELY DIMINISH DURING SUNDAY
EVE.

..RACY.. 08/12/2006