SWODY3
SPC AC 080746
DAY 3 CONVECTIVE OUTLOOK CORR 1
NWS STORM PREDICTION CENTER NORMAN OK
0246 AM CDT FRI APR 08 2011
VALID 101200Z - 111200Z
...THERE IS A MDT RISK OF SVR TSTMS ACROSS PARTS OF SE
MN...WI...ECNTRL IA...NW IL AND FAR NE MO...
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE UPPER MS
VALLEY...MID-MS VALLEY...OZARKS AND SRN PLAINS...
CORRECTED TO EXTEND MDT RISK AREA FURTHER INTO SE MN AND NRN IA TO
MATCH PROBABILITIES
...UPPER MS VALLEY/WRN GREAT LAKES...
AN IMPRESSIVE UPPER-LEVEL TROUGH IS FORECAST TO MOVE INTO THE CNTRL
PLAINS SUNDAY WITH AN UPPER-LEVEL LOW CLOSING OFF OVER THE NRN
PLAINS. AHEAD OF THE SYSTEM...A POWERFUL 55 TO 70 KT JET WILL
TRANSPORT LOW-LEVEL MOISTURE QUICKLY NWD INTO THE UPPER MS VALLEY
WHERE SFC DEWPOINTS SHOULD REACH THE LOWER TO MID 60S F. THIS SHOULD
ALLOW MODERATE INSTABILITY TO DEVELOP ACROSS MUCH OF THE UPPER
MIDWEST BY SUNDAY AFTERNOON WHERE NUMEROUS THUNDERSTORMS APPEAR
LIKELY TO DEVELOP AS LARGE-SCALE ASCENT INCREASES DURING THE
AFTERNOON. THUNDERSTORMS SHOULD FIRST DEVELOP DURING THE AFTERNOON
ALONG A WARM FRONT ACROSS IA...WI AND SRN MN WITH ADDITIONAL
CONVECTION INITIATING ALONG THE COLD FRONT DURING THE EARLY EVENING
EXTENDING SWD INTO NW MO. THIS IS EXPECTED AS THE EXIT REGION OF THE
AN IMPRESSIVE 80 TO 100 KT MID-LEVEL JET SPREADS ACROSS THE
UPPER-MIDWEST CREATING STRONG DEEP LAYER SHEAR AND VERY FAVORABLE
CONDITIONS FOR SEVERE STORMS. THIS COMBINED WITH STRONG LOW-LEVEL
SHEAR PROFILES SHOULD BE FAVORABLE FOR SUPERCELLS AND TORNADOES
ESPECIALLY IN ERN IA...NW IL...SE MN AND SW WI WHERE A MODERATE RISK
HAS BEEN PLACED. A FEW STRONG TORNADOES COULD OCCUR EITHER NEAR THE
WARM FRONT IN THE AFTERNOON OR ALONG THE COLD FRONT AS THE LOW-LEVEL
JET STRENGTHENS DURING THE EARLY EVENING.
AT THIS POINT...THE MODELS APPEAR TO BE IN GOOD AGREEMENT CONCERNING
THE TIMING AND STRENGTH OF THE SYSTEM. ALTHOUGH THIS IS THE
CASE...AM EXPECTING THE UPPER-LEVEL TROUGH TO BE A BIT SLOWER INTO
THE PLAINS SO HAVE NUDGED THE MODERATE RISK A BIT SWWD TO ACCOUNT
FOR THIS.
...SRN AND CNTRL PLAINS...
AN IMPRESSIVE UPPER-LEVEL TROUGH WILL MOVE INTO THE GREAT PLAINS
SUNDAY. THUNDERSTORM DEVELOPMENT WILL BE PROBABLE AHEAD OF THE
TROUGH ALONG A COLD FRONT FROM ERN KS SWD INTO ERN OK AND ECNTRL TX
WHERE MODERATE INSTABILITY AND STRONG DEEP LAYER SHEAR IS FORECAST.
DUE THE POTENTIAL FOR SUPERCELL DEVELOPMENT...AN ENHANCED THREAT FOR
TORNADOES...LARGE HAIL AND WIND DAMAGE COULD OCCUR DURING THE EARLY
EVENING FROM WCNTRL MO SWD INTO NW AR AND NE OK. THE THREAT SHOULD
BE MORE ISOLATED IN SE OK AND ECNTRL TX BUT THE ENVIRONMENT SHOULD
STILL SUPPORT HAIL AND WIND DAMAGE.
...UPPER OH VALLEY AND CNTRL APPALACHIAN MTNS...
ISOLATED THUNDERSTORM DEVELOPMENT ALSO MAY OCCUR JUST TO THE EAST OF
AN UPPER-LEVEL RIDGE IN THE UPPER OH VALLEY AND CNTRL APPALACHIAN
MTNS. IN THIS REGION...MODELS FORECAST AN AXIS OF MODERATE
INSTABILITY WITH ENOUGH DEEP LAYER SHEAR FOR A MARGINAL SEVERE
THREAT MAINLY SUNDAY AFTERNOON.
..BROYLES.. 04/08/2011
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