SparkServiceWx

SATURDAY and SUNDAY, October 10-11 could feature tornado activity across Alabama, Florida and Georgia. An isolated significant tornado is possible. This is in association with a landfalling tropical system that will earn the name "Isaias." The system's will probably come ashore somewhere between New Orleans and Apalachicola. As the system makes landfall, dry air will swirl in on its back side. That will weaken the tropical storm/hurricane, BUT make a recipe favorable for tornadoes. As dry air clashes with moist, tropical air, we'll probably get one or more bands of thunderstorms on the east (right) side of the system. Those thunderstorms will tap into the remnant storm's rotating wind field and acquire rotation themselves. At least a very isolated tornado is possible as far north as eastern Tennessee or western parts of the Carolinas. The greatest risk of an isolated significant tornado or two is between Pensacola, Tallahassee and Jacksonville. This forecast is made both based on forecaster intuition and deterministic/machine learning models. StormNet, the most accurate of any severe weather-focused machine learning model, is already highlighting this region. The threat could begin Friday night and last into Sunday, shifting from the Gulf Coast northward. The European model in particular is highlighting an overlap of shear (changing winds with height) and instability (thunderstorm fuel). That juiced-up air mass will allow thunderstorms to blossom vertically into an environment that will twist them counterclockwise. For now, remain abreast of the evolving forecast.