ZCZC SPCSWOMCD ALL ACUS11 KWNS 192332 SPC MCD 192332 OKZ000-TXZ000-200200- 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 ...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT... ATTN...WFO...FWD...OUN...SJT...LUB...MAF... LAT...LON 32559884 32620061 32880155 33470133 34759907 35069791 35039705 34529622 32879681 32559884 NNNN