re: Tornado! High Risk Day w/ 3 Active PDS Watches

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This is the first time since 4ish that we've had zero active tornado warnings in LA, Arkansas, Mississippi, Alabama, or Florida.

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***Significant tornado outbreak expected today across north Florida and south Georgia*** ...Synopsis... An amplifying mid-upper trough over TX/OK this morning will continue eastward to MS/AL by this afternoon. The initial synoptic cyclone near Texarkana will likely be replaced by cyclogenesis today at the triple point of the effective warm front across southern AL, and the eastward-surging cold front/trough from LA/MS. This new cyclone will deepen and move north-northeastward today across AL/GA in association with the strong height falls/ascent within the exit region of a 100-130 kt mid-upper jet. Likewise, very strong deep-layer tropospheric flow is expected within the warm sector, where boundary layer dewpoints in the 65-70 F range and a lingering steep lapse rate plume will support moderate buoyancy. The net result of these factors will be the potential for a significant tornado episode today across north FL into south GA. ...AL/FL/GA today to the Carolinas this evening/tonight... A broken band of severe storms that formed overnight persists this morning across south GA. This convective band was associated with low-level warm advection, as well as an ejecting midlevel trough that is now over north GA and east TN. It is not clear if this convection will weaken this morning, or if it will persist until new thunderstorms begin to form farther to the west across south AL and the FL Panhandle. Regardless the boundary should begin to move northward by midday as cyclogenesis proceeds across AL. Likewise, as the synoptic midlevel trough approaches from the west, strengthening vertical shear is expected within the unstable warm sector. Observational data confirm the most important aspects of the thermodynamic and kinematic profiles, thus confidence is high in the unusual combination of ingredients today. Forecast soundings suggest the potential for MLCAPE of 1000-1500 J/kg, with effective bulk shear in excess of 70 kt, and effective SRH in excess of 300-400 m2/s2. The orientation of deep-layer shear vectors across the cold front/trough will favor broken bands of tornadic supercells. Aside from the ongoing storms across south GA, the severe/tornado risk will likely ramp up again later this morning across south AL and the FL Panhandle along the residual rain-cooled boundary/warm front, and then spread east-northeastward across north FL and GA through the day. Long-tracked, strong tornadoes will be possible with fast moving supercells, in addition to damaging winds and large hail. The severe/tornado risk will spread northeastward into the Carolinas this evening as the cyclone deepens and moves northeastward to the southern Appalachians. There are some concerns regarding the degree of near-surface destabilization with northeastward extent into the Carolinas. However, very strong low-level shear would favor maintenance of any supercells that mature a bit farther southwest in the warm sector, with the risk for tornadoes persisting after dark into SC and perhaps southern NC. Farther south, the band of storms with the cold front will reach south FL overnight, with a continued risk for damaging winds and a couple of tornadoes.

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