[SWODY1] SWODY1

[Severe Weather Outlook Day 1]

ACUS01 KWNS 180054
SWODY1
SPC AC 180053

DAY 1 CONVECTIVE OUTLOOK  
NWS STORM PREDICTION CENTER NORMAN OK
0753 PM CDT THU AUG 17 2006

VALID 180100Z - 181200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE NORTHERN
PLAINS....

...NORTHERN PLAINS...
AN UPPER TROUGH IS BECOMING INCREASINGLY SHEARED AS IT ACCELERATES
EASTWARD OUT OF THE NORTHERN INTERMOUNTAIN REGION.  THIS IS
OCCURRING AS A MORE SIGNIFICANT SHORT WAVE TROUGH...EMBEDDED WITHIN
THE MAIN BELT OF WESTERLIES ACROSS CANADA...PROGRESSES EASTWARD INTO
HUDSON BAY/ONTARIO.  SURFACE FRONT ASSOCIATED WITH THE LATTER
FEATURE IS ADVANCING INTO THE UPPER MISSISSIPPI VALLEY...BUT THE
BOUNDARY HAS STALLED ACROSS PARTS OF NORTHERN SOUTH DAKOTA INTO
NORTHEAST WYOMING...AWAITING THE APPROACH OF UPSTREAM SYSTEM.  AS
LARGE-SCALE UPWARD VERTICAL MOTION FIELD STRENGTHENS ALONG/JUST
NORTH OF FRONT ACROSS NORTHWESTERN SOUTH DAKOTA THIS
EVENING...POTENTIAL STILL EXISTS FOR THE DEVELOPMENT OF AN
ORGANIZING MESOSCALE CONVECTION SYSTEM WITH RISK FOR DAMAGING
WINDS/LARGE HAIL.

VERTICAL SHEAR PROFILES ALONG FRONT ARE STRONG...VEERING FROM
EASTERLY AT LOW-LEVELS TO MODERATELY STRONG WESTERLY AT MID/UPPER
LEVELS...AND STEEP MID-LEVEL LAPSE RATES WILL MAINTAIN MOST UNSTABLE
CAPE ON THE ORDER OF 1000-2000 J/KG.  THIS MAY BE SUPPORTIVE OF
SUPERCELL STRUCTURES BEFORE CONVECTION CONSOLIDATES LATER THIS
EVENING/OVERNIGHT...GRADUALLY SPREADING EASTWARD ALONG FRONT ACROSS
NORTHERN/CENTRAL SOUTH DAKOTA.

...CENTRAL PLAINS INTO MIDDLE MISSISSIPPI VALLEY...
REMNANT BOUNDARY LEFT IN THE WAKE OF A SUBTROPICAL SHORT WAVE
TROUGH... WHICH HAS SHIFTED EAST OF UPPER PORTIONS OF THE MIDDLE
MISSISSIPPI VALLEY INTO THE SOUTHERN GREAT LAKES REGION...IS
BECOMING A FOCUS FOR INCREASING CONVECTIVE DEVELOPMENT ACROSS
NORTHERN KANSAS...NEAR INTERSTATE 70.  ACTIVITY SEEMS LIKELY TO
PERSIST TONIGHT...PERHAPS AIDED BY FORCING ASSOCIATED WITH ANOTHER
WEAK IMPULSE MIGRATING AROUND WESTERN/NORTHWESTERN PERIPHERY OF MID
SOUTH SUBTROPICAL RIDGE.  AND...DEVELOPMENT IS EXPECTED TO GRADUALLY
SHIFT EAST NORTHEASTWARD THROUGH PARTS OF NORTHERN MISSOURI/SOUTHERN
IOWA BY LATE TONIGHT...AS SOUTHERLY CENTRAL PLAINS LOW-LEVEL JET
GRADUALLY VEERS.  ALTHOUGH TIMING IS NOT OPTIMAL WITH THE ONSET OF
DIURNAL BOUNDARY LAYER COOLING...UNSATURATED LOWER/MID-LEVEL
PROFILES WILL ALLOW SUBSTANTIAL EVAPORATIVE COOLING NEAR HEAVY
PRECIPITATION CORES...CONTRIBUTING TO POTENTIAL FOR DOWNBURSTS AND
AT LEAST A LOCALIZED DAMAGING WIND THREAT.

..KERR.. 08/18/2006