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Mesoscale Discussion 263
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   MESOSCALE DISCUSSION 0263
   NWS STORM PREDICTION CENTER NORMAN OK
   0753 AM CDT THU MAR 24 2016

   AREAS AFFECTED...PORTIONS CENTRAL/SRN LA...SEWN MS.

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 241253Z - 241530Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...STRONGEST PART OF TSTM BAND THAT HAS PRODUCED SUB-SVR
   GUSTS ACROSS SE TX IS FCST TO PROCEED EWD OVER MAINLY SRN LA...WITH
   SOME INCREASE IN ORGANIZATION NOTED AND NWD EXTENSION POSSIBLE INTO
   SLOWLY DESTABILIZING ENVIRONMENT PRECONVECTIVE WAA REGIME.  WW MAY
   BE REQUIRED IF ADDITIONAL ORGANIZATION TAKES PLACE.

   DISCUSSION...CLUSTER OF TSTMS THAT PRODUCED SVR GUSTS IN AUS AREA
   AROUND 07Z SINCE BECAME MORE POORLY ORGANIZED...YET STILL
   MAINTAINING SOME OF ITS ORIGINAL COLD POOL WHILE PRODUCING 30-45-KT
   GUSTS ACROSS PORTIONS HOU METRO AND SURROUNDING TERRITORY.  THIS
   ACTIVITY THEN FIRMED UP SOMEWHAT INTO SQUALL LINE THAT EXTENDED AT
   1230Z FROM NEAR BKB SWWD ACROSS SABINE PASS REGION...BUT SINCE HAS
   DISORGANIZED SLIGHTLY AGAIN.  

   12Z LCH RAOB APPEARS TO HAVE SAMPLED IMMEDIATE PRECONVECTIVE
   ENVIRONMENT REASONABLY WELL...WITH SFC DEW POINT 67 F AND 1.3-INCH
   PW SUPPORTING AROUND 600 J/KG MLCAPE.  BUOYANCY DECREASES WITH NNEWD
   EXTENT AHEAD OF SQUALL LINE...AND INCREASES SWD OVER GULF...LARGELY
   COMMENSURATE WITH SFC THETAE.  BOUNDARY-LAYER MOIST ADVECTION AND
   WAA JUST AHEAD OF THIS CONVECTION SHOULD MAINTAIN AT LEAST MRGLLY
   UNSTABLE ENVIRONMENT.  MEANWHILE...BASE OF EML LAYER HAS BEEN LIFTED
   AND WEAKENED...EVIDENT IN COMPARISON OF 00Z AND 12Z LCH RAOBS...AND
   THAT PROCESS SHOULD CONTINUE IN NARROW ZONE JUST AHEAD OF CONVECTIVE
   BAND.  THAT MAY BE RELATED PARTLY TO PASSAGE OF GRAVITY WAVE...
   APPARENT FOR LAST FEW HOURS IN REFLECTIVITY ANIMATIONS AND
   CONSISTENT SFC RESPONSES ABOUT 60-90 NM AHEAD OF CONVECTIVE BAND.

   WINDS HAVE TEMPORARILY WEAKENED AND/OR VEERED IMMEDIATELY BEHIND
   GRAVITY WAVE...AS SAMPLED BY THAT LCH RAOB AND BY EARLIER OBS. 
   HOWEVER...SOME BACKING IS NOTED IN NARROW CORRIDOR BETWEEN THAT
   PROCESS AND CONVECTIVE BAND.  ACCORDINGLY MODIFIED SOUNDING AND VWP
   DOES RESULT IN LOCALLY ENHANCED LOW-LEVEL SHEAR AND HODOGRAPH
   SIZES...DESPITE RATHER VEERED 850-MB FLOW...SUCH THAT 150-250 J/KG
   0-1 KM SRH MAY BE AVAILABLE TO SOME PARTS OF CONVECTIVE BAND. 
   50-50-KT EFFECTIVE-SHEAR MAGNITUDES ALSO ARE APPARENT OVER AREA.  AS
   SUCH...SMALL/SHORT-LIVED TORNADO OR TWO CANNOT BE RULED OUT WITH
   TRANSIENT MESO/MISO-CIRCULATIONS ALONG LEADING EDGE OF QLCS. 
   HOWEVER...MAIN THREAT WILL BE DAMAGING GUSTS.  LIMITING FACTOR MAY
   BE LACK OF MORE ROBUST INSTABILITY...WITH 
   1.  ONLY LOW-MID-60S F DEW POINTS PRESENTLY APPARENT OVER MUCH OF
   INLAND AREA NEAR/N OF I-10 FARTHER E...AND 
   2.  DENSE CLOUD COVER PER VIS IMAGERY THAT WILL IMPEDE DIABATIC
   HEATING.

   ..EDWARDS/DIAL.. 03/24/2016


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

   LAT...LON   29739367 30729299 31279251 31419206 31449093 30579081
               29809111 29259131 29419150 29379130 29519129 29519141
               29519150 29649158 29629165 29499178 29499188 29579207
               29539225 29599274 29779325 29739367 

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