SWODY2
SPC AC 241720
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1120 AM CST TUE FEB 24 2009
VALID 251200Z - 261200Z
...NO SVR TSTM AREAS FORECAST...
...SYNOPSIS...
PROGRESSIVE ZONAL PATTERN WILL CONTINUE THROUGH WEDNESDAY. PRIMARY
FEATURE OF INTEREST IS A SHORTWAVE TROUGH OVER THE NE PACIFIC NEAR
36 N AND 138 W THAT WILL ADVANCE INTO THE CNTRL PLAINS AND MID MS
VALLEY REGION WEDNESDAY NIGHT. AT THE SURFACE...HIGH PRESSURE WILL
RETREAT ALONG THE ERN SEABOARD WHILE A LEE TROUGH DEVELOPS OVER THE
CNTRL AND SRN PLAINS. A WARM FRONT WILL LIFT NWD INTO THE MID MS
VALLEY.
...CNTRL PLAINS AND MID MS VALLEY REGION...
SLY LOW LEVEL JET WILL STRENGTHEN OVER THE SRN PLAINS AND LOWER MS
VALLEY WEDNESDAY NIGHT WITHIN GRADIENT BETWEEN RETREATING SURFACE
HIGH AND DEVELOPING LEE LOW. THIS WILL RESULT IN AXIS OF PARTIALLY
MODIFIED GULF AIR RETURNING NWD THROUGH A PORTION OF THE SRN PLAINS
AND MS VALLEY REGION BENEATH EWD ADVANCING PLUME OF STEEPER MID
LEVEL LAPSE RATES. MARGINAL ELEVATED INSTABILITY WILL LIKELY DEVELOP
AS A RESULT OF THESE PROCESSES. THE ATMOSPHERE WILL LIKELY REMAIN
CAPPED OVER MUCH OF THE WARM SECTOR INCLUDING MOST OF OK AND TX
WHERE WARMER AIR IN THE 850-700 MB LAYER WILL EXIST.
HOWEVER...INCREASING ASCENT ACCOMPANYING THE SHORTWAVE TROUGH AND
ISENTROPIC LIFT ALONG THE LOW LEVEL JET AXIS SHOULD PROMOTE
THUNDERSTORM DEVELOPMENT LATE WEDNESDAY NIGHT...MAINLY ON NERN
PERIPHERY OF THE STEEPER LAPSE RATES WHERE THE CAP WILL BE WEAKER.
THE STEEP MID LEVEL LAPSE RATES...COLD AIR ALOFT...AND EFFECTIVE
SHEAR FROM 40-50 KT MAY SUPPORT A THREAT OF ISOLATED SMALL TO
MARGINALLY SEVERE HAIL WITH THE STRONGER UPDRAFTS. HOWEVER...WEAK
INSTABILITY SHOULD REMAIN A LIMITING FACTOR.
..DIAL.. 02/24/2009
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