SPC AC 201636
DAY 1 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1036 AM CST TUE FEB 20 2007
VALID 201630Z - 211200Z
...THERE IS A SLGT RISK OF SVR TSTMS OVER PORTIONS OF THE LOWER MS
VALLEY...
...SYNOPSIS...
A STRONG/POSITIVE TILT SRN STREAM JET WILL SHIFT EWD ACROSS THE
LOWER MS VALLEY/GULF COAST REGION TODAY WITH WEAK SURFACE
TROUGH/COLD FRONT EXTENDING FROM THE RED RIVER ACROSS CNTRL AR INTO
THE OH VALLEY THIS AFTERNOON. SOUTH OF THIS FRONT...SLY WINDS WILL
MAINTAIN MOIST ADVECTION WITH INCREASING INSTABILITY BENEATH STEEP
LAPSE RATES ALOFT. FARTHER N...A POTENT SHORTWAVE TROUGH WILL
CONTINUE EWD ACROSS THE GREAT LAKES/OH VALLEY WITH ELEVATED THUNDER
EXPECTED AS FAR N AS OH.
...NERN AR/SERN MO/WRN TN/WRN KY/NRN MS...
MID MORNING SURFACE ANALYSIS SHOWED A COLD FRONT EXTENDING FROM
CNTRL IL INTO CNTRL MO WITH WARM FRONT FROM SERN MO EWD INTO THE OH
VALLEY. DEWPOINTS WERE INCREASING INTO THE MID 50S F SOUTH OF THESE
BOUNDARIES. MEANWHILE...VISIBLE IMAGERY SHOWED EXTENSIVE MID/UPPER
LEVEL CLOUDS OVER MUCH OF THE REGION...WITH SHARP CLEARING LINE
ACROSS ERN OK INTO N CNTRL AR. MORNING SOUNDINGS INDICATE STRONG BUT
SHALLOW CAPPING INVERSION IN PLACE BELOW 850 MB. THIS
INVERSION...ALONG WITH THE CLOUDS WILL INHIBIT CONVECTIVE POTENTIAL
OVER MOST OF THE WARM SECTOR.
BEST CHANCE FOR DAYTIME DEVELOPMENT WILL BE NEAR SURFACE COLD FRONT
ACROSS FAR SRN MO INTO NRN AR/FAR SERN MO LATE THIS
AFTERNOON...WHERE STRONG HEATING WILL OCCUR AND WEAK LOW LEVEL
CONVERGENCE WILL PERSIST. SUPERCELLS WILL BE LIKELY WITH A HIGH
PROBABILITY OF LARGE HAIL GIVEN STEEP LAPSE RATES AND STRONG SHEAR.
LARGELY STRAIGHT LINE HODOGRAPHS INDICATE POTENTIAL FOR SPLITTING
STORMS. MODERATE LOW LEVEL SRH WILL EXIST MAINLY E OF MS RIVER
BENEATH VEERED BUT STRONGER LOW LEVEL JET WITH POTENTIAL FOR AN
ISOLATED TORNADO AS STORMS CONTINUE EWD OUT OF AR INTO WRN TN.
..JEWELL.. 02/20/2007
CLICK TO GET WUUS01 PTSDY1 PRODUCT
NOTE: THE NEXT DAY 1 OUTLOOK IS SCHEDULED BY 2000Z
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