SWODY1
SPC AC 051616
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1116 AM CDT FRI OCT 05 2007
VALID 051630Z - 061200Z
..THERE IS A SLGT RISK OF SVR TSTMS THIS AFTERNOON AND EVENING OVER
PARTS OF EASTERN MN AND WESTERN WI...
..MN/WI...
BROAD POSITIVELY TILTED UPPER TROUGH IS PRESENT THIS MORNING OVER
THE WESTERN STATES...WITH UPPER RIDGE BEGINNING TO BUILD OVER THE
CENTRAL/EASTERN U.S. A COUPLE OF WEAK SHORTWAVE TROUGHS ARE
EMBEDDED IN THE SOUTHWESTERLY FLOW OVER THE CENTRAL/NORTHERN PLAINS.
ONE OF THESE FEATURES IS NOW OVER CENTRAL MN AND WILL TRACK INTO
WESTERN LAKE SUPERIOR THIS EVENING. FORCING FOR ASCENT AHEAD OF
THIS TROUGH IS AIDING IN THE MAINTENANCE OF SHOWERS AND
THUNDERSTORMS OVER PARTS OF MN/WI/UPPER MI. ELEVATED CAPE IN THIS
AREA IS WEAK...SUGGESTING THAT SEVERE THREAT THROUGH THE EARLY
AFTERNOON WILL BE QUITE LIMITED.
LATER THIS AFTERNOON...THINNING CLOUDS ARE EXPECTED OVER PARTS OF
MN/WI IN WAKE OF UPPER TROUGH. THIS WILL ALLOW AIR MASS TO SLOWLY
DESTABILIZE. FORECAST SOUNDINGS SUGGEST THAT MID LEVEL CAP WILL
STRENGTHEN AS UPPER RIDGE BUILDS BY EVENING. HOWEVER...THERE MAY BE
A TIME WINDOW FROM 20-03Z IN WHICH ISOLATED NEAR SURFACE-BASED
STORMS WILL BE POSSIBLE FROM EASTERN MN INTO WESTERN WI. IF STORMS
CAN DEVELOP...VERTICAL SHEAR AND INSTABILITY WILL BE FAVORABLE FOR
SUPERCELLS CAPABLE OF DAMAGING WINDS...LARGE HAIL...AND PERHAPS A
TORNADO. WE DO NOT HAVE HIGH CONFIDENCE IN THIS SCENARIO...BUT WILL
MAINTAIN SLIGHT RISK DUE TO CONDITIONAL THREAT.
..UT/CO INTO EASTERN MT...
BAND OF STRONG SOUTHWESTERLY FLOW ALOFT EXTENDS FROM THE SOUTHERN
GREAT BASIN INTO EASTERN MT. POCKETS OF STRONG HEATING WILL YIELD
STEEP LOW LEVEL LAPSE RATES AND MARGINAL INSTABILITY ALONG THIS SAME
AXIS. SCATTERED THUNDERSTORMS WILL BE POSSIBLE OVER THIS REGION
THIS AFTERNOON AND EARLY EVENING. THOSE STORMS THAT CAN BECOME
SUSTAINED IN HIGH-SHEAR ENVIRONMENT WILL HAVE THE POTENTIAL FOR
LOCALLY GUSTY WINDS AND HAIL. ORGANIZED SEVERE STORMS ARE NOT
ANTICIPATED.
.HART/JEWELL.. 10/05/2007
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