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Mesoscale Discussion 414
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   MESOSCALE DISCUSSION 0414
   NWS STORM PREDICTION CENTER NORMAN OK
   0554 PM CDT MON APR 18 2016

   AREAS AFFECTED...PORTIONS S TX.

   CONCERNING...SEVERE THUNDERSTORM WATCH 97...

   VALID 182254Z - 190100Z

   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 97
   CONTINUES.

   SUMMARY...SVR TSTM POTENTIAL CONTINUES OVER WW.

   DISCUSSION...PRINCIPAL MESOSCALE FEATURE IS PROGRESSIVE OUTFLOW
   BOUNDARY...EVIDENT IN SFC ANALYSIS...VIS IMAGERY AND REFLECTIVITY
   LOOPS AT 2230Z FROM WILLACY COUNTY NWWD ACROSS ZAPATA COUNTY.  THAT
   BOUNDARY CONTINUES TO BE REINFORCED BY OUTFLOW FROM PERSISTENT
   CONVECTION TO ITS N...GENERALLY IN HBV-CRP SWATH AND OFFSHORE TX
   COASTAL BEND.  BOUNDARY IS MOVING SWWD 10-15 KT AND SHOULD CONTINUE
   TO DO SO FOR ANOTHER COUPLE HOURS BEFORE DECELERATING...POTENTIALLY
   NEAR RIO GRANDE.  EARLIER SUPERCELL THAT DEVELOPED WITH APPARENTLY
   SFC-BASED INFLOW NW LRD HAS BEEN WEAKENING OVER ERN WEBB COUNTY
   WHILE BEING UNDERCUT BY DENSITY CURRENT...AND SHOULD CONTINUE MOVING
   OVER MORE STABLE AIR.  TSTMS N OF BOUNDARY WILL MAINTAIN MRGLLY SVR
   HAIL THREAT...THOUGH DEEP-LAYER/CONVECTIVELY DRIVEN STABILIZATION
   WILL CONTINUE TO WEAKEN ORIGINALLY FAVORABLE LAPSE RATES EVIDENT IN
   18Z CRP RAOB.

   MEANWHILE...SEA-BREEZE FRONT WAS MOVING WNWWD ACROSS SERN STARR AND
   NRN HIDALGO COUNTIES.  EACH BOUNDARY WILL SUPPORT CONTINUED TSTM
   DEVELOPMENT...THOUGH ACTIVITY ALONG OUTFLOW FEATURE SHOULD BE
   UNDERCUT FOR OPTIMALLY SFC-BASED INFLOW UNTIL THAT BOUNDARY STALLS. 
   ENVIRONMENT ALONG AND S OF OUTFLOW BOUNDARY...AND ALONG AND W OF
   SEA-BREEZE FRONT...WILL REMAIN FAVORABLE WITH SFC DEW POINTS UPPER
   60S TO LOW 70S CONTRIBUTING TO 2000-2500 J/KG PRECONVECTIVE
   MLCAPE...AMIDST ROUGHLY 30-40 KT EFFECTIVE-SHEAR MAGNITUDES.  WEAK
   LOW-LEVEL FLOW WILL CONTINUE TO LIMIT HODOGRAPH SIZE AND LOW-LEVEL
   SHEAR...EXCEPT ALONG AND BEHIND BOUNDARIES...IN NARROW CORRIDOR
   WHERE LIFTED PARCELS STILL ARE ROOTED AT SFC.  BRIEF MESOCYCLONE
   INTENSIFICATION MAY OCCUR AS MATURE TSTMS ENCOUNTER THOSE
   BOUNDARIES...INCLUDING ANY ACTIVITY THAT MAY MOVE ACROSS RIO GRANDE
   FROM MEX.  OTHERWISE MULTICELLULAR/MARGINALLY SUPERCELLULAR
   CHARACTER SHOULD PREVAIL...WITH DAMAGING GUSTS AND SPORADIC LARGE
   HAIL POSSIBLE.

   ..EDWARDS/PETERS.. 04/18/2016


   ATTN...WFO...CRP...EWX...BRO...

   LAT...LON   28530043 28629947 28389848 27769706 27419721 27169729
               26379717 25709704 26069872 26329922 27019950 27489979
               27880014 28530043 

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