SWODY1
SPC AC 081615
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1115 AM CDT MON OCT 08 2007
VALID 081630Z - 091200Z
..NO SVR TSTM AREAS FORECAST...
..MI/WI...
UPPER TROUGH OVER THE NORTHERN AND CENTRAL PLAINS HAS BECOME
NEGATIVELY TILTED THIS MORNING...AND WILL ROTATE NORTHEASTWARD INTO
THE WESTERN GREAT LAKES REGION THROUGH TONIGHT. MAIN SURFACE COLD
FRONT CURRENTLY EXTENDS FROM WESTERN WI INTO CENTRAL MO AND WILL
ALSO RACE EASTWARD ACROSS PARTS OF WI/MI/IL TODAY. RATHER STRONG
SOUTHWESTERLY MID/UPPER LEVEL WINDS ARE EXPECTED TO OVERSPREAD THE
WARM SECTOR OVER WI/MI THIS AFTERNOON PROVIDING STRONG DEEP LAYER
EFFECTIVE SHEAR AND LARGE SCALE ASCENT FOR THUNDERSTORM
ORGANIZATION. ALSO...SOUTHERLY TO SOUTHEASTERLY LOW LEVEL WINDS
WILL LIKELY BE MAINTAINED THROUGH THE DAY YIELDING SUFFICIENT LOW
LEVEL SHEAR FOR A RISK OF SUPERCELLS AND PERHAPS A TORNADO. DESPITE
THESE POSITIVE FACTORS FOR SEVERE STORMS...THERE ARE ALSO SEVERAL
LIMITING FACTORS. SOUTHEASTERLY LOW LEVEL WINDS WILL TRANSPORT AIR
OFF LAKE MI INTO THREAT AREA LESSENING THETAE AND INSTABILITY.
ALSO...TIMING OF LEADING EDGE OF PRECIPITATION/CLOUDS INDICATE A
NARROW RISK ZONE OVER SOUTHWEST UPPER MI AND NORTHEAST WI. WILL
MAINTAIN AN AREA OF LOW SEVERE PROBABILITIES OVER THIS REGION FOR
CONDITIONAL RISK. HOWEVER...OVERALL THREAT APPEARS LIMITED.
..NY/MA/CT...
MORNING SURFACE ANALYSIS SHOWS SURFACE QUASI-STATIONARY BOUNDARY
EXTENDING ACROSS CENTRAL NY INTO SOUTHERN NEW ENGLAND. GENERALLY
CLEAR SKIES ARE PRESENT ALONG AND SOUTH OF BOUNDARY WHERE
TEMPERATURES WILL WARM INTO THE 80S AND YIELD MLCAPE VALUES AROUND
1000 J/KG. MID LEVEL LAPSE RATES ARE RATHER WEAK...SUGGESTING THAT
UPDRAFTS STRENGTH AND HAIL POTENTIAL WILL BE LIMITED.
HOWEVER...25-35 KNOT NORTHWEST FLOW AT MID LEVELS AND WEAK
CONVERGENCE ALONG BOUNDARY MAY BE SUFFICIENT FOR A RISK OF ISOLATED
STRONG STORMS CAPABLE OF GUSTY WINDS. THREAT SHOULD END QUICKLY
AFTER DARK.
.HART/JEWELL.. 10/08/2007
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