ZCZC SPCSWOMCD ALL ACUS11 KWNS 311302 SPC MCD 311302 MSZ000-LAZ000-ARZ000-311500- Mesoscale Discussion 1746 NWS Storm Prediction Center Norman OK 0702 AM CST Mon Dec 31 2018 Areas affected...Louisiana and southern Mississippi Concerning...Severe potential...Watch possible Valid 311302Z - 311500Z Probability of Watch Issuance...60 percent SUMMARY...Showers and the occasional thunderstorm will continue this morning, gradually increasing in coverage and intensity. A damaging wind gust or brief tornado may be possible with the strongest activity. In the near term, the threat remains too marginal and spatially limited for watch consideration. However, later this morning a watch may become necessary as convection develops/intensifies along the Pacific front. DISCUSSION...Showers continue to develop this morning across Louisiana and southern Mississippi within a zone of isentropic ascent within a warm-conveyor regime. Despite 12Z soundings from across southern Louisiana suggesting mixed-layer CAPE around 1000 J/kg, poor midlevel-lapse rates and tall, skinny CAPE profiles have not produced strong enough ascent for charge separation. Even absent lightning, ongoing convection is developing within a strongly sheared environment, leading to episodic rotation within some of the stronger showers. Although low-level buoyancy is somewhat limited, near-neutral low-level-lapse rates may support the potential for a damaging wind gust or brief tornado through mid morning. Later this morning stronger mid-level ascent will begin to overtake the Pacific front moving into far western Louisiana at present. Despite low-level wind fields remaining somewhat backed behind the Pacific front as low-level mass fields respond to stronger surface pressure falls across Oklahoma, a modest increase in low-level convergence along the Pacific front will combine with the increasing synoptic ascent to strengthen convection along the front and support thunderstorm development. Expectation is that a narrow band of thunderstorms will develop across portions of central Louisiana and lift north-northeast. Again, strong wind fields in the presence of modest instability and near-neutral low-level-lapse rates will support an isolated damaging wind gust or brief tornado. ..Marsh/Grams.. 12/31/2018 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...JAN...LIX...LCH...SHV... LAT...LON 30529296 32909181 33668874 30758965 30529296 NNNN