DAY1SVR: Day 1 Convective Outlook

ACUS01 KWNS 151252
SWODY1
SPC AC 151250

DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0750 AM CDT WED SEP 15 2010

VALID 151300Z - 161200Z

...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE CENTRAL
PLAINS AND MID MS VALLEY...

WATER VAPOR LOOPS SHOW A RATHER STRONG SHORTWAVE TROUGH MOVING
ACROSS THE NORTHERN ROCKIES INTO THE DAKOTAS THIS MORNING. MODEL
GUIDANCE INDICATES THAT THIS TROUGH WILL AMPLIFY TODAY AS IT
PROGRESSES EASTWARD INTO THE UPPER MIDWEST REGION. THE LARGE AREA
OF LOW SURFACE PRESSURE CURRENTLY EXTENDING FROM KS INTO SD WILL
DEEPEN FURTHER AND MOVE INTO MN/IA/MO BY EVENING. STRENGTHENING
SOUTHERLY LOW LEVEL WINDS AHEAD OF THE SURFACE LOW WILL HELP TO
TRANSPORT RICH LOW LEVEL MOISTURE NORTHWARD INTO THE CENTRAL PLAINS
AND MID MS VALLEY.

THE PRIMARY FORECAST UNCERTAINTY TODAY INVOLVES LARGE AREA OF
ONGOING THUNDERSTORMS THIS MORNING OVER KS. THESE STORMS ARE LIKELY
TO PERSIST THROUGH MUCH OF THE DAY AND POSSIBLY RE-INTENSIFY THIS
AFTERNOON OVER MO WITH A MINOR SEVERE THREAT. IT IS UNCLEAR HOW
MUCH DESTABILIZATION WILL OCCUR IN THE WAKE OF THESE STORMS...BUT
PRESENT INDICATIONS ARE THAT THIS IS THE MOST LIKELY SCENARIO FOR
SEVERE THUNDERSTORM ACTIVITY TODAY. POCKETS OF STRONG AFTERNOON
INSTABILITY /MLCAPE OVER 2500 J/KG/ ARE POSSIBLE...ESPECIALLY OVER
PORTIONS OF EASTERN KS/WESTERN MO/NORTHEAST OK. NEW THUNDERSTORM
ACTIVITY WILL LIKELY DEVELOP ALONG THE COLD FRONT OVER EASTERN KS
LATE THIS AFTERNOON AND SPREAD EAST-SOUTHEASTWARD INTO MO/NORTHEAST
OK DURING THE EVENING. DAMAGING WINDS AND HAIL WILL BE THE MAIN
THREATS.

FARTHER NORTH OVER IA/MN...DESTABILIZATION AND HEATING ARE ALSO IN
QUESTION. HOWEVER...STRONGER LARGE SCALE FORCING AND PROXIMITY TO
SURFACE LOW MAY RESULT IN A FEW ORGANIZED STORMS DESPITE ONLY
MARGINAL CAPE VALUES. EFFECTIVE SHEAR VALUES OF 35-45 KNOTS AND
VEERING/INCREASING WINDS WITH HEIGHT SUGGEST A RISK OF ISOLATED
SUPERCELLS/BOWS CAPABLE OF LOCALLY DAMAGING WINDS AND HAIL.

..HART/STOPPKOTTE.. 09/15/2010

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