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Mesoscale Discussion 421
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   MESOSCALE DISCUSSION 0421
   NWS STORM PREDICTION CENTER NORMAN OK
   0548 PM CDT WED APR 22 2015

   AREAS AFFECTED...CNTRL AND NCNTRL TX

   CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

   VALID 222248Z - 230045Z

   PROBABILITY OF WATCH ISSUANCE...40 PERCENT

   SUMMARY...CLUSTER OF STORMS OVER CNTRL TX JUST WEST OF WACO MAY
   CONTINUE TO POSE A THREAT FOR LARGE HAIL...DAMAGING WIND AND PERHAPS
   A TORNADO. STORMS APPEAR ONLY LOOSELY ORGANIZED WITH SPARSE
   COVERAGE...SO ANY WW ISSUANCE WILL DEPEND ON CONVECTIVE TRENDS.

   DISCUSSION...STORMS THAT DEVELOPED ALONG WHAT APPEARS TO BE A
   CONVECTIVELY ENHANCED BOUNDARY CONTINUE OVER CNTRL TX WEST OF THE
   WACO AREA. THIS ACTIVITY HAS EXHIBITED MARGINAL HP SUPERCELL
   CHARACTERISTICS BUT OVERALL THE STORM APPEARS TO BE ONLY LOOSELY
   ORGANIZED. VWP DATA INDICATE STRONG EFFECTIVE SHEAR THROUGH A DEEP
   LAYER DUE TO LOW-LEVEL VEERING AND STRONG WINDS ALOFT...BUT WINDS IN
   THE 0-2 KM LAYER REMAIN MODEST /GENERALLY AOB 20 KT/ WHICH IS
   LIMITING THE SIZE OF LOW-LEVEL HODOGRAPHS. BACKGROUND LARGE SCALE
   PATTERN IS DOMINATED BY A LOW-AMPLITUDE RIDGE...BUT WITH EMBEDDED
   WEAK PERTURBATIONS. RAP SOUNDINGS ALSO INDICATE AN INVERSION AROUND
   700 MB WHICH /ALTHOUGH NOT SUFFICIENT TO PREVENT INITIATION ALONG
   THE BOUNDARIES/ MAY ALSO BE LIMITING UPDRAFT STRENGTH TO SOME DEGREE
   WITHIN THE LOWER HALF OF THE STORMS. GIVEN THESE LIMITING
   FACTORS...ONSET OF NOCTURNAL COOLING WITHIN THE NEXT COUPLE HOURS
   AND ONLY A MODEST INCREASE IN THE LLJ...IT REMAINS UNCERTAIN WHETHER
   OR NOT STORMS WILL BECOME ORGANIZED SUFFICIENTLY FOR WW ISSUANCE.
   NEVERTHELESS THE ENVIRONMENT REMAINS SUFFICIENT FOR AT LEAST A FEW
   INSTANCES OF LARGE HAIL...DAMAGING WIND AND PERHAPS A TORNADO.

   ..DIAL/THOMPSON.. 04/22/2015


   ATTN...WFO...FWD...

   LAT...LON   32649839 32759735 32799590 32079583 31509700 31259833
               31939881 32649839 

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Page last modified: April 23, 2015
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