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Mesoscale Discussion 420
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   MESOSCALE DISCUSSION 0420
   NWS STORM PREDICTION CENTER NORMAN OK
   0632 PM CDT TUE APR 19 2016

   AREAS AFFECTED...PORTIONS OF SRN OK AND NRN TX

   CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

   VALID 192332Z - 200200Z

   PROBABILITY OF WATCH ISSUANCE...20 PERCENT

   SUMMARY...TSTMS WILL MOVE EWD ACROSS PARTS OF THE RED RIVER VALLEY
   AND VICINITY THROUGH THE EVENING HOURS...AND WILL BE CAPABLE OF
   PRODUCING ISOLATED SVR HAIL/WIND. HOWEVER...THE ISOLATED NATURE OF
   THE SVR RISK IS PRESENTLY EXPECTED TO PRECLUDE WW ISSUANCE...THOUGH
   CONVECTIVE TRENDS WILL CONTINUE TO BE MONITORED.

   DISCUSSION...FORCING FOR ASCENT ATTENDANT TO A MID-LEVEL IMPULSE
   ORBITING THE SERN QUADRANT OF BROADLY CYCLONIC FLOW HAS ENCOURAGED
   THE DEVELOPMENT OF A FORWARD-PROPAGATING CONVECTIVE CLUSTER...
   CURRENTLY CROSSING PARTS OF WRN N TX AND SWRN OK. AN AGGREGATE
   SYNOPTIC/OUTFLOW BOUNDARY TRAILS W OF THIS ACTIVITY ACROSS SRN PARTS
   OF THE S TX PLAINS. WARM ADVECTION ATOP THE SWD-SETTLING COLD DOME
   IS FACILITATING CONVECTIVE BACKBUILDING WWD TOWARD LOCATIONS SE OF
   LUBBOCK.

   ANTECEDENT DIURNAL DESTABILIZATION OF INFLOW FOR THE AFOREMENTIONED
   CONVECTION IS SUPPORTING AROUND 500-1500 J/KG OF SBCAPE BASED ON
   MODIFIED RAP SOUNDINGS...AIDED BY EARLIER INSOLATION AMID RECYCLED
   BOUNDARY-LAYER MOISTURE /SFC DEWPOINTS AROUND 60F/.
   FURTHERMORE...PRE-CONVECTIVE FDR VWP DATA INDICATE AROUND 45-50 KT
   OF DEEP SHEAR AND AMPLE HIGH-LEVEL FLOW FOSTERING EFFICIENT
   CONVECTIVE VENTILATION. THESE FACTORS SUGGEST THAT TSTM CLUSTERS
   EVOLVING FROM THE AFOREMENTIONED ACTIVITY WILL LIKELY SPREAD EWD
   DURING THE EVENING HOURS. MEANWHILE...TSTMS COULD BLOSSOM TO THE
   S/SE OF ESTABLISHED CONVECTIVE CLUSTERS IN RESPONSE TO A SLIGHT
   INCREASE IN POLEWARD MASS FLUXES RELATED TO DECOUPLING OF THE
   BOUNDARY LAYER. IN FACT...INCIPIENT CONVECTIVE GROWTH MAY BE EVIDENT
   FROM WEAK RADAR-REFLECTIVITY RETURNS DEVELOPING NE OF ABILENE. SUCH
   ACTIVITY COULD INTERACT/MERGE WITH THE ESTABLISHED CONVECTIVE
   CLUSTERS LATER THIS EVENING. ALSO...OKLAHOMA CONVECTION MAY TEND TO
   DEVELOP NWD IN ASSOCIATION WITH EXPANDING COLD POOLS OVERTAKING
   CONDITIONALLY UNSTABLE AIR N OF THE RED RIVER.

   THE AFOREMENTIONED DEEP SHEAR WILL BE SUFFICIENT FOR MAINTENANCE OF
   ORGANIZED CONVECTIVE STRUCTURES THROUGH THE EVENING...WITH BOWING
   SEGMENTS CAPABLE OF PRODUCING ISOLATED SVR WIND. ISOLATED SVR HAIL
   MAY ALSO OCCUR WITH MORE DISCRETE/INCIPIENT CONVECTION...AND/OR
   EMBEDDED SUPERCELLS. ONE LONGER-LIVED SUPERCELL WITH STRONG
   INDICATIONS OF PRODUCING LARGE HAIL IS MOVING ACROSS BAYLOR
   COUNTY...AND WILL LIKELY REMAIN S OF WICHITA FALLS IN THE SHORT
   TERM. REGARDLESS...BOUNDARY-LAYER MOISTURE AND LOWER/MIDDLE-
   TROPOSPHERIC LAPSE RATES ARE QUITE MODEST...AND NOCTURNAL GAINS IN
   STATIC STABILITY WILL LIKELY LIMIT TSTM INTENSITY WITHIN A FEW
   HOURS. THESE FACTORS WILL TEND TO MARGINALIZE SVR COVERAGE...
   PARTICULARLY PAST THE ONGOING DIURNAL CONVECTIVE PEAK. HOWEVER...IF
   UPSCALE CONVECTIVE GROWTH WERE TO EVENTUALLY YIELD A HIGHER-COVERAGE
   SVR-WIND RISK -- MORE THAN PRESENTLY ANTICIPATED -- WW PROBABILITY
   WOULD CONDITIONALLY INCREASE.

   ..COHEN/EDWARDS.. 04/19/2016


   ATTN...WFO...FWD...OUN...SJT...LUB...MAF...

   LAT...LON   32559884 32620061 32880155 33470133 34759907 35069791
               35039705 34529622 32879681 32559884 

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