SWODY2
SPC AC 301701
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1201 PM CDT WED SEP 30 2009
VALID 011200Z - 021200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS PORTIONS OF THE OZARK
PLATEAU/ERN SRN PLNS EWD INTO THE MID-MS RVR VLY/MID-SOUTH...
...SYNOPSIS...
STRONG WRN STATES MID-LVL WAVE WILL TRANSLATE EWD INTO THE PLNS AND
CLOSE INTO A LOW OVER THE CORN BELT BY THU EVE. A 70-90 KT H5 JET
WILL EVOLVE FROM THE GRT BASIN INTO THE SRN PLNS/OZARKS DURING THE
PD. IN THE LWR-LVLS...A LOW OVER THE MID-MO RVR VLY WILL DEEPEN
OVER NWRN IA/SWRN MN THU AFTN/NIGHT. A STRONG CDFNT TRAILING THIS
LOW WILL SWEEP ESE ACROSS THE CNTRL/SRN PLNS AND THE OZARKS REGION
DURING THE DAY AND EVENTUALLY INTO THE LWR OH RVR VLY...MID-SOUTH
AND CNTRL TX BY THE END OF THE PD. THE FRONT WILL SERVE AS A FOCUS
FOR PSBL SVR TSTMS THU AFTN/NIGHT.
...LWR MO/MID-MS RVR VLYS SWD TO THE WRN GULF CSTL AREA...
STRONG LOW/MID-LVL THETA-E ADVECTION COURTESY OF A 40-50 KT SSWLY
LLJ WILL LIKELY DRIVE A CONSIDERABLE AMOUNT OF CLOUDS AND ELEVATED
CONVECTION EARLY THU MORNING FROM SWRN MN SWD INTO THE OZARK
PLATEAU. THIS ACTIVITY WILL TRANSLATE ENE DURING THE AFTN INTO THE
UPR MS VLY AND MIDWEST.
ATTENTION WILL THEN FOCUS FARTHER W FOR SVR POTENTIAL AFT 18Z.
STRONG WARM ADVECTION WILL PROBABLY DRIVE A CONSIDERABLE AMOUNT OF
MULTI-LAYERED CLOUDS EAST OF THE CDFNT...ESP FROM THE OZARKS NWD.
THIS WILL LIMIT DESTABILIZATION ACROSS IA AND NRN MO WITH STRONGER
INSTABILITY FROM CNTRL/SRN MO SWWD INTO ERN OK...AR AND NERN TX. BY
MID-AFTN...MLCAPES SHOULD RANGE FROM A FEW HUNDRED J/KG IN SRN IA TO
2000 J/KG OVER ERN OK...WRN AR AND NERN TX.
SFC-BASED TSTM INITIATION IS LIKELY ALONG AND IMMEDIATELY AHEAD OF
THE CDFNT EARLY IN THE AFTN FROM SRN IA INTO NRN MO. A SUBSEQUENT
BACKBUILDING/AND OR NEW DEVELOPMENT IS EXPECTED SW INTO THE WRN
OZARK PLATEAU AND CNTRL OK 18-21Z AS THE SRN PERIPHERY OF LARGER
SCALE HEIGHT FALLS SPREADS EWD. WHILE STORMS ALONG THE NRN PORTIONS
OF THE FRONT MAY PRODUCE ISOLD HAIL/DMGG WINDS...HIGHEST SVR
POTENTIAL WILL EVOLVE FROM SRN MO SWWD INTO AR...ERN OK AND NERN TX.
HERE...MORE ROBUST SFC-BASED INSTABILITY AND DECENT MID-LVL LAPSE
RATES COUPLED WITH INCREASING DEEP-LAYER SHEAR /40-50 KTS/ WILL BE
FAVORABLE FOR ORGANIZED SVR STORMS. INITIAL STORMS MAY BE
SUPERCELLS WITH LARGE HAIL AND ISOLD TORNADOES...BUT ANTICIPATED
SPEED OF FRONT...THE TEMPORAL BACKING OF THE MID-LVL FLOW AND
MAGNITUDE OF FORCING WILL RESULT IN A TRANSITION TO A COMPLEX LINEAR
MCS AS STORMS MATURE. DMGG WINDS WILL BECOME MORE OF A THREAT WITH
TIME DURING THE EVENING ACROSS THE MID-SOUTH AS MAIN PORTIONS OF THE
70-90 KT WLY MID-LVL JET PUNCHES EWD ACROSS THE FRONT.
SVR THREATS SHOULD GRADUALLY DECREASE OVERNIGHT. INSTABILITY WILL
BECOME LESS WITH EWD EXTENT. LLVL MOISTURE RETURN WILL BE STRONGEST
ACROSS ERN TX INTO THE MS DELTA REGION. BUT...SURGING NATURE TO THE
CDFNT AND THE FACT THAT STRONGER LARGE SCALE ASCENT WILL BEGIN TO
TURN MORE NE TOWARD THE LWR OH VLY ARGUE THAT STORMS ALONG WRN
PORTIONS OF THE FRONT MAY BECOME UNDERCUT AND LIMIT SVR THREATS TO
ISOLD HAIL AND/OR DMGG WIND GUSTS.
..RACY.. 09/30/2009
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