MESO: Mesoscale Discussion 1532

ACUS11 KWNS 262236
SWOMCD
SPC MCD 262235
LAZ000-MSZ000-270100-

MESOSCALE DISCUSSION 1532
NWS STORM PREDICTION CENTER NORMAN OK
0535 PM CDT FRI JUL 26 2013

AREAS AFFECTED...PORTIONS OF LA...W-CNTRL/SWRN MS

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 262235Z - 270100Z

PROBABILITY OF WATCH ISSUANCE...40 PERCENT

SUMMARY...SOME SVR POTENTIAL MAY EVOLVE EARLY THIS EVENING TO THE E
OF WW 447...AND THERE IS SOME POSSIBILITY THAT THIS MAY REQUIRE WW
ISSUANCE.

DISCUSSION...SEVEN- AND NINE-KM RADAR CAPPI DATA DEPICT SOME RECENT
UPTICK IN CONVECTION ACROSS PARTS OF LA INVOF A SHALLOW
QUASI-STATIONARY FRONT THAT RUNS APPROXIMATELY ALONG THE I-20
CORRIDOR...AND INVOF A WARM FRONT THAT INTERSECTS THE STATIONARY
FRONT JUST SW OF MONROE LA AND ARCS SEWD INTO SERN LA. THE UPTICK IN
CONVECTION MAY ALSO BE ENCOURAGED BY INCREASING FORCING FOR ASCENT
ACCOMPANYING A REGION OF DCVA PRECEDING A SHORTWAVE TROUGH
APPROACHING THE AREA. MODEST WAA IS EVIDENT IN THIS REGIME VIA THE
VERTICALLY VEERING...LOWER-TROPOSPHERIC WIND PROFILE PER SHV/POE VWP
DATA. THERE IS SOME POSSIBILITY THAT ADDITIONAL CONVECTION MAY
DEVELOP ACROSS THE AREA WITHIN THIS WAA REGIME DURING THE NEXT FEW
HOURS. AND...WITH A MOIST BOUNDARY LAYER SUPPORTING MODERATE TO
STRONG INSTABILITY NEAR AND S OF THE QUASI-STATIONARY
BOUNDARY...INTENSE UPDRAFTS MAY ENSUE.

EFFECTIVE BULK SHEAR MAGNITUDES OF 30-35 KT WOULD SUPPORT SOME
CONDITIONAL THREAT FOR ORGANIZED STORM STRUCTURES INCLUDING POSSIBLE
SUPERCELLS. IF SUCH CONVECTION OCCURS...DMGG WIND GUSTS WOULD BE
POSSIBLE. SOME CONDITIONAL TORNADO POTENTIAL CANNOT BE RULED OUT
WHERE SFC WINDS ARE RELATIVELY MORE BACKED IN AREAS OF AT LEAST
MARGINAL INSTABILITY NEAR AND JUST N OF THE STATIONARY BOUNDARY.

HOWEVER...WITH THE WAA REGIME NOT EXPECTED TO BE PARTICULARLY STRONG
IN THE ABSENCE OF STRONGER LOW-LEVEL JET SPEEDS...THERE IS
CONSIDERABLE UNCERTAINTY REGARDING THE COVERAGE OF CONVECTION/SVR
POTENTIAL DURING THE NEXT FEW HOURS. LATER THIS EVENING INTO THE
OVERNIGHT HOURS TONIGHT...THE SVR THREAT COULD FURTHER INCREASE AS
CONVECTION CURRENTLY DEVELOPING OVER NERN TX IS POTENTIALLY STEERED
INTO PARTS OF THE REGION.

..COHEN/BROYLES.. 07/26/2013

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...JAN...LIX...LCH...SHV...

LAT...LON 32379320 32679203 32589080 31599083 30789083 30119114
30059190 30659263 31399329 32379320

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