MESO: Mesoscale Discussion 2104

ACUS11 KWNS 060135
SWOMCD
SPC MCD 060135
MSZ000-LAZ000-TXZ000-060330-

MESOSCALE DISCUSSION 2104
NWS STORM PREDICTION CENTER NORMAN OK
0735 PM CST MON NOV 05 2012

AREAS AFFECTED...PARTS OF SERN TX...SRN LA...EXTREME SERN MS

CONCERNING...SEVERE THUNDERSTORM WATCH 673...674...

VALID 060135Z - 060330Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
673...674...CONTINUES.

SUMMARY...THE THREAT FOR SVR TSTMS CONTINUES ACROSS WW674 AND
REMAINING VALID PORTIONS OF WW673.

DISCUSSION...LATEST SFC MESOANALYSIS DEPICTS A DIFFUSE FRONTAL
BOUNDARY LYING FROM S OF GULFPORT MS TO A FRONTAL INFLECTION NW OF
BATON ROUGE LA. THE BOUNDARY BECOMES LESS BAROCLINIC WITH WWD EXTENT
INTO S-CNTRL TX...WHERE IT ALIGNS WITH A NOTABLE WIND-SHIFT AXIS
THAT LEADS A STRONGER COLD FRONT APPROACHING FROM THE NW. STORMS
CONTINUE ALONG/AHEAD OF THE COLD FRONT OVER THE COASTAL PLAIN
ADJACENT TO THE UPPER TX AND SWRN LA COASTS. MODIFICATIONS TO THE
LAKE CHARLES 00Z RAOB TO MITIGATE WET-BULBING EFFECTS WOULD SUGGEST
1000-1500 J/KG OF MLCAPE AMIDST AROUND 60 KT OF EFFECTIVE BULK SHEAR
TO SUPPORT ORGANIZED STORMS WITH SVR HAIL/WIND ACROSS REMAINING
VALID PORTIONS OF WW673. WW673 SHOULD BE ALLOWED TO EXPIRE ON
SCHEDULE AT 03Z AS STORMS MOVE OFF THE COAST.

FARTHER EAST ACROSS THE WARM SECTOR INTO S-CNTRL/SERN LA...A RECENT
UPTICK IN CONVECTION HAS BEEN NOTED NEAR AND WEST OF LAKE
PONTCHARTRAIN IN CONCERT WITH INCREASING FORCING FOR ASCENT LEADING
AN UPSTREAM MID-LEVEL VORT MAX. THIS ACTIVITY WILL SHIFT ESEWD
THROUGH THE EVENING...PERHAPS REACHING THE NEW ORLEANS AREA DURING
THE NEXT COUPLE OF HOURS. UNIDIRECTIONAL FLOW THROUGH THE CLOUD
LAYER WITH A 0-6-KM BULK SHEAR MAGNITUDE OF 71 KT PER SLIDELL VWP
DATA WILL CONTINUE TO FOSTER DISCRETE/SEMI-DISCRETE SUPERCELL
STRUCTURES WITH SVR HAIL AND POSSIBLY SVR WIND GUSTS. MODEST
DIRECTIONAL SHEAR IN THE LOWEST 1-KM AGL MAY YIELD A BRIEF TORNADO
THOUGH RELATIVELY MORE MARGINAL BUOYANCY WITH EWD EXTENT ACROSS THE
WARM SECTOR SHOULD MITIGATE THIS THREAT.

..COHEN.. 11/06/2012

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

ATTN...WFO...MOB...LIX...LCH...HGX...

LAT...LON 30478850 29948834 29398850 28758897 28749012 29019137
29249263 29279377 28729505 28659588 28889612 29239604
29739553 30339457 30659361 30859219 30859018 30728911
30478850

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