...SEVERE WEATHER OUTBREAK POSSIBLE ON D4/SUN... ...DISCUSSION... An outbreak of severe thunderstorms appears possible on Sunday across parts of Louisiana, Mississippi, Alabama, and possibly into Georgia by Sunday night. Tornadoes (potentially strong/long-tracked) and widespread damaging winds are expected to be the primary hazards. ...D4/Sunday: TX Gulf Coast eastward through the Southeast into the Carolinas... Ingredients for a potential severe thunderstorm outbreak appear likely to come together Sunday into Sunday night. An ejecting shortwave trough is forecast to take on a neutral to somewhat negative tilt by Sunday afternoon as it moves quickly east-northeastward across the Southeast states. Rich low-level moisture will be drawn inland from the Gulf of Mexico in advance of a deepening surface low that will move from the mid-MS Valley into the Ohio Valley by Monday morning. Moderate destabilization in conjunction with an 80-100 kt midlevel jet and 50-60 kt low-level jet will result in a very favorable environment for organized convection, including the potential for long-track supercells and a corresponding strong tornado risk. Very strong low/midlevel flow fields will also support widespread damaging wind potential. Some uncertainty remains regarding the northward extent of the most significant severe potential, given the presence of widespread convection in advance of the ejecting shortwave. Guidance also continues to trend slightly slower, with the GFS still a notably fast outlier. A 30% probability contour has been introduced from LA into central/southern MS/AL and southwest GA, where confidence is highest in the outbreak potential at this time.

Right now it appears the only factors that could disrupt the overall severity of this system would be the development characteristics of the convection related to mode and interactions. Conversely, mesoscale/stormscale factors could result in enhanced corridors of storms producing significant weather. Either way, there are several factors evident that support higher end wording and probabilities in the forecast. Persons are urged to stay tuned & be prepared to act should a warning be issued for their area. These will be fast-moving storms, so people really need to be alert throughout Sunday, especially late in the day.