SWODY1
SPC AC 050554
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1154 PM CST TUE NOV 04 2008
VALID 051200Z - 061200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PARTS OF THE GREAT
PLAINS...WRN OZARKS AND MID-MO VALLEY......
...SRN AND CNTRL PLAINS/WRN OZARKS...
A LARGE UPPER-LEVEL TROUGH OVER THE ROCKIES TONIGHT IS FORECAST TO
CONTINUE AMPLIFYING AND CLOSE OFF OVER THE CNTRL HIGH PLAINS TODAY.
AHEAD OF THE APPROACHING SYSTEM...A WELL-DEVELOPED 60 TO 70 KT
LOW-LEVEL JET OVER THE GREAT PLAINS WILL QUICKLY TRANSPORT LOW-LEVEL
MOISTURE NWD AHEAD OF A FAST MOVING COLD FRONT IN THE CNTRL PLAINS.
SFC DEWPOINTS SHOULD REACH THE LOWER TO MID 60S F ACROSS MUCH OF OK
AND SE KS. MODEL FORECASTS INITIATE CONVECTION ALONG THE MOIST AXIS
JUST AHEAD OF THE FRONT DURING THE LATE AFTERNOON. THIS CONVECTION
SHOULD GRADUALLY ORGANIZE INTO A SQUALL-LINE DURING THE EARLY
EVENING MOVING INTO ERN PARTS OF THE SLIGHT RISK AREA. THIS SCENARIO
IS SUPPORTED BY A WIDE RANGE OF MODEL SOLUTIONS INCLUDING THE
NAM...GFS...NAMKF AND WRF.
CONCERNING THE SEVERE POTENTIAL...A POWERFUL MID-LEVEL JET IS
FORECAST TO ROUND THE BASE OF THE UPPER-LEVEL LOW AND EJECT NEWD
ACROSS THE SRN AND CNTRL PLAINS THIS AFTERNOON. THIS WILL MAKE
VERTICAL SHEAR PROFILES FAVORABLE FOR SEVERE STORMS ACROSS THE
SLIGHT RISK AREA WITH FORECAST SOUNDINGS INCREASING 0-6 KM SHEAR
VALUES INTO THE 50 TO 60 KT RANGE IN MUCH OF ERN KS AND OK BY 00Z.
THIS SHOULD EASILY SUPPORT SUPERCELL DEVELOPMENT AS STORMS INITIATE
ALONG A NARROW AXIS OF MODERATE INSTABILITY MOSTLY LIKELY STARTING
IN ECNTRL KS AND EXPANDING SWD INTO CNTRL OK DURING THE LATE
AFTERNOON. SUPERCELLS MAY HAVE TORNADO POTENTIAL ESPECIALLY IN SE KS
AND ECNTRL OK WHERE LOW-LEVEL SHEAR...LOW-LEVEL MOISTURE AND
INSTABILITY ARE FORECAST TO BE MAXIMIZED. HOWEVER...MODEL CONSENSUS
SUGGESTS THE STORMS WILL NOT REMAIN DISCRETE FOR VERY LONG AS STRONG
LOW-LEVEL CONVERGENCE AND VERY STRONG LARGE-SCALE ASCENT FORCES
SQUALL-LINE DEVELOPMENT. THIS SCENARIO WOULD FAVOR A DECREASING
TORNADO POTENTIAL AND INCREASING POTENTIAL FOR LARGE HAIL AND
DAMAGING WINDS WITH TIME.
...NRN PLAINS/MID-MO VALLEY...
AN UPPER-LEVEL LOW WILL CLOSE OFF TODAY IN THE CNTRL HIGH PLAINS AS
A POWERFUL MID-LEVEL JET EJECTS NEWD INTO THE CNTRL PLAINS. A REGION
OF STRONG UPPER-LEVEL DIVERGENCE ALONG WITH THE EXIT REGION OF THE
MID-LEVEL JET WILL ENHANCE LIFT. THIS COMBINED WITH INCREASING
LOW-LEVEL MOISTURE AND LIFT ASSOCIATED WITH A STRONG LOW-LEVEL JET
WILL BE FAVORABLE FOR CONVECTIVE DEVELOPMENT THIS MORNING INTO THE
AFTERNOON. THUNDERSTORMS SHOULD MOVE QUICKLY NNEWD ACROSS THE REGION
WITH THE GREATEST CONVECTIVE COVERAGE LIKELY IN THE LATE AFTERNOON
NEAR A SFC LOW IN ERN SD...AHEAD OF THE COLD FRONT IN ERN NEB AND
ALONG A WARM FRONT IN MN.
CONCERNING THE SEVERE POTENTIAL...FORECAST SOUNDINGS MAINTAIN STRONG
VERTICAL SHEAR PROFILES ACROSS THE REGION ASSOCIATED WITH THE EXIT
REGION OF THE MID-LEVEL JET. WITH 0-6 KM SHEAR VALUES IN THE 45 TO
55 KT RANGE AND MUCAPE VALUES APPROACHING 1000 J/KG...CONDITIONS
SHOULD BE FAVORABLE FOR ISOLATED SEVERE STORMS. HOWEVER...BEFORE 00Z
INSTABILITY SHOULD REMAIN MOSTLY ABOVE 700 MB SUGGESTING STORMS WILL
BE ELEVATED IN NATURE. THIS SHOULD KEEP THE PRIMARY THREAT HAIL
ACROSS ERN SD AND WRN MN. FURTHER SOUTH ACROSS ERN NEB AND WRN
IA...SOME SFC-BASED THUNDERSTORM DEVELOPMENT ALONG WITH WIND DAMAGE
POTENTIAL WILL BE POSSIBLE BY EARLY EVENING AS FORECAST SOUNDINGS
SHOW THE CAP DIMINISHING.
..BROYLES/HURLBUT.. 11/05/2008
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