SWODY1
SPC AC 190054
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0754 PM CDT WED AUG 18 2010
VALID 190100Z - 191200Z
...THERE IS A SLGT RISK OF SVR TSTMS TONIGHT ACROSS PARTS THE NRN
PLAINS INTO THE UPPER MS VALLEY...
...NORTHERN PLAINS INTO THE GREAT LAKES...
WITHIN THE STRONGER BELT OF WESTERLIES...BROAD UPPER TROUGHING
CONTINUES TO SLOWLY DEVELOP EASTWARD THROUGH THE HUDSON BAY REGION
AND ADJACENT EASTERN CANADIAN PROVINCES. ON THE SOUTHERN PERIPHERY
OF THIS CYCLONIC REGIME...A SHORT WAVE IMPULSE IS PROGRESSING
EASTWARD ACROSS WISCONSIN...ACCOMPANIED BY WEAK MID-LEVEL HEIGHT
FALLS WHICH APPEAR LIKELY TO SPREAD ACROSS LOWER MICHIGAN LATER
TONIGHT. ANOTHER IMPULSE IS EXPECTED TO CONTINUE DIGGING OUT OF
MANITOBA THROUGH NORTHWESTERN ONTARIO...BUT WEAK MID-LEVEL HEIGHT
RISES ARE PROGGED TO SPREAD ACROSS THE DAKOTAS INTO THE UPPER
MISSISSIPPI VALLEY OVERNIGHT...DOWNSTREAM OF AN UPPER TROUGH
MIGRATING ACROSS THE NORTHERN INTERMOUNTAIN REGION...WITHIN A WEAKER
BELT OF WESTERLIES ACROSS THE NORTHERN TIER STATES.
GIVEN THIS SCENARIO...CONVECTIVE POTENTIAL ACROSS THE REGION THROUGH
THE REMAINDER OF THE PERIOD REMAINS UNCLEAR. SOUTH OF A COLD FRONT
ADVANCING SOUTHWARD THROUGH THE UPPER GREAT LAKES/UPPER MISSISSIPPI
VALLEY AND NORTHERN PLAINS...CAPE IS MAXIMIZED NORTH AND EAST OF A
THERMAL LOW OVER SOUTH CENTRAL SOUTH DAKOTA...ON THE NOSE OF
ELEVATED MIXED LAYER AIR AS FAR EAST AS WESTERN/SOUTHERN MINNESOTA.
STRONGEST LOW-LEVEL CONVERGENCE THIS EVENING APPEARS LIKELY TO
BECOME FOCUSED ON THE NOSE OF A NOCTURNALLY STRENGTHENING LOW-LEVEL
JET...ACROSS EASTERN SOUTH DAKOTA...WHERE THE 19/00Z RAOB FROM
ABERDEEN SUGGESTS MID-LEVEL INHIBITION REMAINS LARGE. IT MAY VERY
WELL BE THAT ANY APPRECIABLE INCREASE IN CONVECTIVE DEVELOPMENT...IF
AT ALL...AWAITS LOW-LEVEL JET VEERING LATER THIS EVENING/
OVERNIGHT...WHEN STRONGER LOW-LEVEL FORCING DEVELOPS EAST OF
STRONGER MID-LEVEL INHIBITION...ACROSS SOUTHERN MINNESOTA AND
ADJACENT NORTHERN IOWA...PERHAPS INTO WESTERN WISCONSIN. IF FORCING
IS STRONG ENOUGH TO OVERCOME CAP...THE ENVIRONMENT APPEARS FAVORABLE
FOR THE DEVELOPMENT OF A MESOSCALE CONVECTIVE SYSTEM CAPABLE OF
PRODUCING DAMAGING WINDS AND LARGE HAIL.
OTHERWISE...HIGHER THUNDERSTORM PROBABILITIES TONIGHT SEEM TO EXIST
ALONG THE FRONTAL ZONE FARTHER TO THE NORTH/EAST...ACROSS PARTS OF
NORTHERN/CENTRAL WISCONSIN...THE UPPER PENINSULA OF MICHIGAN AND
NORTHWESTERN LOWER MICHIGAN. WHILE SEVERE POTENTIAL APPEARS MORE
LIMITED DUE TO MUCH MORE MODEST INSTABILITY... THERMODYNAMIC AND
KINEMATIC PARAMETERS MAY STILL BECOME SUFFICIENT FOR VIGOROUS
CONVECTION WITH GUSTY WINDS AND SOME HAIL.
..KERR.. 08/19/2010
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