SWODY3
SPC AC 190731
DAY 3 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
0231 AM CDT SAT APR 19 2008
VALID 211200Z - 221200Z
...THERE IS A SLGT RISK OF SVR TSTMS FROM PARTS ERN PARTS OF THE
CNTRL PLAINS INTO THE MID-UPPER MS VALLEY...
...SYNOPSIS...
MODEL CONSENSUS IS THAT AN UPPER JET MAX WILL EJECT NWD ALONG THE
ERN PERIPHERY OF WRN U.S. UPPER THROUGH THE DAKOTAS MONDAY...WHILE
ANOTHER SHORTWAVE TROUGH EJECTS NEWD INTO THE CNTRL PLAINS MONDAY
EVENING REACHING THE UPPER MS VALLEY LATE MONDAY NIGHT. IN WAKE OF
THE LEAD IMPULSE A COLD FRONT WILL MOVE EWD AND SWD INTO THE UPPER
MS VALLEY AND THROUGH THE CNTRL PLAINS. BY MONDAY EVENING THE FRONT
IS FORECAST TO EXTEND FROM MN SWWD THROUGH SWRN KS...AND FROM WRN WI
SWWD INTO NRN OK BY THE END OF THIS PERIOD. DRYLINE WILL EXTEND FROM
NEAR THE BIG BEND AREA OF TX NWD THROUGH CNTRL OK AND SRN KS WHERE
IT WILL INTERSECT THE FRONT.
...NERN KS AND ERN NEB THROUGH IA AND MN SRN MN...
RICHER LOW LEVEL MOISTURE WITH MID 60S ACROSS ERN KS AND MO TO THE
UPPER 50S FARTHER NORTH INTO MN WILL ADVECT NWD INTO THE PRE-FRONTAL
WARM SECTOR. SWLY MID LEVEL FLOW WILL MAINTAIN AN EML OVER MUCH OF
THIS REGION. THESE PROCESSES WILL RESULT IN MODERATE INSTABILITY
FROM ERN KS INTO THE MID MS VALLEY WITH MARGINAL INSTABILITY LIKELY
FARTHER NORTH ACROSS THE UPPER MS VALLEY. HOWEVER...CURRENT
INDICATIONS ARE THAT THE EML WILL LIKELY CONTRIBUTE TO A STRONG CAP
OVER MUCH OF THE WARM SECTOR. THE CAP AND POTENTIAL FOR LARGE SCALE
SUBSIDENCE IN WAKE OF THE LEAD WAVE SUGGEST IT MAY BE DIFFICULT TO
INITIATE SURFACE BASED STORMS DURING THE DAY. INITIAL STORMS MAY
DEVELOP ALONG THE COLD FRONT ACROSS PARTS OF MN WHERE CAP WILL BE
WEAKER ON NRN PERIPHERY OF THE EML. INCREASING LARGE SCALE ASCENT
ASSOCIATED WITH EJECTING SHORTWAVE TROUGH AND STRENGTHENING LOW
LEVEL JET SHOULD RESULT IN SUFFICIENT LIFT FOR STORMS TO INITIATE
MAINLY ALONG AND NORTH OF THE FRONT DURING THE EVENING AND OVERNIGHT
FROM PARTS OF ERN NEB INTO IA. ACTIVITY COULD DEVELOP AS FAR SW AS
NERN KS. EFFECTIVE SHEAR FROM 30 TO 40 KT...STEEP MID LAPSE RATES
AND MODERATE INSTABILITY SUGGEST A FEW OF THE STORMS COULD PRODUCE
ISOLATED LARGE HAIL AND STRONG WIND GUSTS.
...OK AND TX...
THE ATMOSPHERE WILL LIKELY BECOME MODERATELY TO STRONGLY UNSTABLE AS
RICHER LOW LEVEL MOISTURE RETURNS NWD BENEATH STEEP MID LEVEL LAPSE
RATES. HOWEVER...EXPECTATION OF A STRONG CAP AND TENDENCY FOR DEEPER
FORCING FOR ASCENT TO REMAIN NW OF THIS REGION SUGGEST THE DRYLINE
WILL PROBABLY REMAIN INACTIVE.
..DIAL.. 04/19/2008
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