SWODY2
SPC AC 130556
DAY 2 CONVECTIVE OUTLOOK
NWS STORM PREDICTION CENTER NORMAN OK
1256 AM CDT TUE OCT 13 2009
VALID 141200Z - 151200Z
...THERE IS A SLGT RISK OF SVR TSTMS ACROSS THE ARKLATEX...
...SYNOPSIS...
PROGRESSIVE/LOW AMPLITUDE WESTERLY FLOW WILL INITIALLY PREVAIL OVER
THE CONUS INTO WEDNESDAY...ALTHOUGH THE PATTERN WILL BEGIN TO
AMPLIFY LATE IN THE PERIOD WITH THE ONSET OF LARGE SCALE HEIGHT
FALLS ACROSS THE LOWER MO VALLEY/ARKLATEX TO THE MIDDLE/LOWER MS
VALLEY.
...SOUTHERN PLAINS/ARKLATEX TO LOWER MS VALLEY...
RELATIVELY STRONG/FLAT WESTERLY MID/UPPER FLOW...WITH ONSET OF
LATTER PERIOD HEIGHT FALLS...WILL FAVOR GRADUAL LEE CYCLOGENESIS
ACROSS THE SOUTHERN HIGH PLAINS...ALONG WITH THE NORTHWARD RETURN OF
A GULF AIRMASS /AROUND 70F SURFACE DEWPOINTS/ ACROSS PORTIONS OF TX
AND THE LOWER MS VALLEY. IT STILL APPEARS THAT MUCH OF THE WARM
SECTOR ACROSS NORTH TX/ARKLATEX COULD REMAIN CAPPED
DIURNALLY...OWING TO LIMITED FORCING ACROSS THE WARM SECTOR AND MID
LEVEL WARMING IN THE 800-500 MB LAYER...IN SPITE OF AN OTHERWISE
FAVORABLE JUXTAPOSITION OF STRENGTHENING MID LEVEL FLOW AND A RATHER
MOIST/POTENTIALLY UNSTABLE AIRMASS. WHILE A CONDITIONAL
SUPERCELL/ASSOCIATED SEVERE THREAT WILL EXIST DURING THE
AFTERNOON...PERHAPS MOST LIKELY IN VICINITY OF THE NORTH TX SURFACE
TRIPLE POINT...THE PRIMARY SEVERE RISK FOR THE PERIOD MAY NOT OCCUR
UNTIL WEDNESDAY NIGHT ACROSS THE ARKLATEX VICINITY.
THIS WOULD BE COINCIDENT WITH MORE APPRECIABLE HEIGHT FALLS/LARGE
SCALE FORCING FOR ASCENT AND STRENGTHENING DEEP LAYER/LOW LEVEL WIND
FIELDS...ALTHOUGH GIVEN THE ORIENTATION OF THE FORCING AS RELATED TO
THE WARM SECTOR/FRONTAL ZONE...IT APPEARS THAT MUCH OF THE
CONVECTION COULD REMAIN CONFINED TO IMMEDIATELY ALONG/NORTH OF THE
SURFACE BOUNDARY. IN SPITE OF THIS MODAL UNCERTAINTY AND/OR POSSIBLE
WARM SECTOR INITIATION FAILURE...STRENGTHENING DEEP LAYER FLOW/LOW
LEVEL SRH COINCIDENT WITH A RATHER MOIST AIRMASS APPEARS TO WARRANT
AT LEAST A CONDITIONAL-TYPE SLIGHT RISK. THIS WOULD INCLUDE THE
POSSIBILITY OF QUASI-DISCRETE/LINE-EMBEDDED SUPERCELLS/BOWS WITH THE
POTENTIAL FOR ISOLATED DAMAGING WINDS AND/OR A TORNADO WEDNESDAY
EVENING/NIGHT.
...SOUTHEAST AL/SOUTHERN GA/NORTH FL...
PLENTIFUL SHOWERS/TSTMS SHOULD BE ONGOING EARLY IN THE PERIOD ALONG
THE ROUGHLY WEST-EAST EFFECTIVE FRONTAL BOUNDARY ACROSS THE
SOUTHEAST STATES/NORTH FL. GIVEN THIS SCENARIO...IT IS UNCLEAR HOW
MUCH SURFACE BASED DESTABILIZATION WILL OCCUR DIURNALLY. BUT
MODERATELY STRONG/LARGELY UNIDIRECTIONAL WIND FIELDS AND A
MOISTURE-RICH AIRMASS COULD SUPPORT AN ISOLATED RISK FOR DAMAGING
WINDS AND/OR A BRIEF TORNADO THROUGH THE AFTERNOON.
..GUYER.. 10/13/2009
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