SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1029 AM CST Sat Dec 28 2024 Valid 281630Z - 291200Z ...THERE IS A MODERATE RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND TONIGHT ACROSS PORTIONS OF EAST TEXAS...LOUISIANA...CENTRAL AND SOUTHERN MISSISSIPPI...AND SOUTHWESTERN ALABAMA.... ...SUMMARY... Tornadoes (some strong with at least EF2 damage possible), severe gusts and hail are expected today into tonight. The threat area will shift eastward from parts of north and central Texas early, across east Texas and the lower Mississippi Valley today, then over the Tennessee Valley, parts of Georgia, and the central Gulf Coast tonight. ...East TX to AL/GA... A powerful mid-level shortwave trough and associated 80-90 knot jet max will rotate quickly eastward across TX today and become negatively-tilted as it tracks into the lower MS Valley this evening. Ample low-level moisture (dewpoints in the mid 60s to lower 70s) is in place ahead of this system across east TX, much of LA, and central/southern MS. Morning convection is slowly weakening across the warm sector, and low-clouds will continue to erode. This will help to develop a corridor of moderate instability with MLCAPE values of 1500-2000 J/kg. This will set the stage for a significant severe weather event through the evening as supercells and bowing structures form over east TX and race eastward across LA into MS. The co-location of the mid-level jet, strengthening winds in the low-levels, surface cyclogenesis, and ample moisture provide a synoptically-evident setup for all severe hazards through the evening. The corridor of greatest concern will be late afternoon through the evening from central LA into central MS. Considered an upgrade to HIGH for this area, but will maintain the ongoing MDT after consultation with local WFOs. Strong and long-tracked tornadoes and widespread damaging winds are possible in this region, with the primary uncertainty regarding storm-mode and linear forcing mechanisms. Activity will spread across AL overnight, where slightly less low-level moisture will somewhat decrease the overall severe threat. Nevertheless, an active squall line with damaging wind potential and embedded rotating storms/tornado threat will likely persist. ..Hart/Lyons.. 12/28/2024