SWODY1
SPC AC 251943
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0243 PM CDT TUE OCT 25 2011
VALID 252000Z - 261200Z
...NO SVR TSTM AREAS FORECAST...
FEW CHANGES HAVE BEEN MADE TO EARLIER FORECAST WITH ONLY A SLIGHT
NWD SHIFT TO THE CONVECTIVE LINE OVER WI/LOWER MI TO ACCOUNT FOR
WARM ADVECTION TSTM ACTIVITY.
REGARDING THE SEVERE POTENTIAL ACROSS IL/IND...LOW LEVEL LAPSE RATES
ARE STEEPENING AHEAD OF COLD FRONT BUT INSTABILITY IS VERY WEAK
ACROSS THIS REGION. A FEW ROBUST STORMS MAY YET DEVELOP IN THE WAKE
OF WARM ADVECTION CLOUDINESS BUT OVERALL SEVERE THREAT APPEARS QUITE
LIMITED.
..DARROW.. 10/25/2011
.PREV DISCUSSION... /ISSUED 1106 AM CDT TUE OCT 25 2011/
...KS/NRN OK ENE INTO MO/IL/IND/OH...
CHANGES TO PREVIOUS OUTLOOK INCLUDE: 1/REDUCING COVERAGE OF MRGL SVR
WIND PROBABILITIES OVER THE MIDWEST. 2/ SPLITTING LOW-END SVR HAIL
RISKS WITH ONE AREA OVER THE MIDWEST AND ANOTHER CONFINED TO THE SRN
PLAINS.
WEAK LOW-LEVEL LAPSE RATES AND MEAGER MOISTURE RETURN ALONG A SEWD
MOVING CDFNT WILL LIMIT SVR PROBABILITIES...BUT BE SUFFICIENT FOR
SPORADIC TSTMS...PARTICULARLY OVER THE MIDWEST THIS EVENING. 12Z
SOUNDINGS SUGGEST SUBSTANTIAL WARM/DRY LAYER JUST ABOVE 900 MB
FARTHER SW INTO THE OZARKS...WHICH WILL LIKELY BE MITIGATING FACTOR
IN SUSTAINED CONVECTION OVER THAT REGION.
OVER THE MIDWEST...NEAR SFC-BASED STORMS WILL FORM EARLY THIS EVE
OVER CNTRL AND NRN IL IN ZONE OF STRONGEST LOW LVL ASCENT NEAR SFC
LOW. RELATIVELY COOL MID LVL TEMPS AND STRONG...UNIDIRECTIONAL
CLOUD LAYER FLOW MAY YIELD SMALL TO MARGINALLY SVR HAIL IN SOME
STORMS. 40 KT MEAN LWR TROPOSPHERIC WINDS ALSO COULD POSE A THREAT
FOR ISOLD STRONG SFC GUSTS. THE TSTMS SHOULD MOVE/DEVELOP EWD INTO
IND AND OH OVERNIGHT...WITH A CONTINUED LOW PROBABILISTIC SVR
THREAT.
FARTHER SW...WEAK MID LVL COOLING/ASCENT ASSOCIATED WITH ADDITIONAL
SHORTWAVE DISTURBANCES...ESPECIALLY TNGT...MAY SUPPORT A SMALL
CLUSTER OR TWO OF ELEVATED STORMS WITH HAIL FROM NRN OK INTO PARTS
OF KS.
...NRN AZ...
NO CHANGES NEEDED TO ONGOING FCST.
MODERATELY STRONG WSW UPR FLOW AND FAIRLY STEEP MID LVL LAPSE RATES
WILL OVERSPREAD AZ LATER TODAY AHEAD OF AMPLIFYING TROUGH. LOW LVL
SWLY UPSLOPE FLOW MAY FOSTER SCTD AFTN TSTMS ON THE RIM...AND
PERHAPS A FEW INSTANCES OF MAINLY SUB-SVR HAIL.
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