Damaging Winds & Tornadoes - October 22 & 23, 2007
Tornado and Severe Thunderstorm events in October have been relatively rare occurrences across Central Alabama. October has been one of the driest months of the year climologically. Most of the severe weather that has occurred during the month of October has been related to Tropical Cyclone activity. The last time Central Alabama had a tornado in October was October 13, 2001, when two tornadoes occurred in Perry and Marengo Counties.
A deep longwave trough approached the area from the west and was forecast to cut-off over the Lower Mississippi Valley. Along with this upper level feature, jet level winds were forecast to strengthen over the Tennessee and Ohio Valleys. These wind speeds usually do not affect Central Alabama until the Fall Severe Weather Season in mid November. The atmospheric instability was forecast to be only marginally favorable for severe weather. But, the wind shear in the lower layers of the atmosphere was such that rotating storms were possible if thunderstorms could develop.
As a strong low level jet developed during the evening hours on October 22nd, this marginal instability was eventually realized as a very warm and moist airmass worked its way into Central Alabama from the northern Gulf of Mexico. Three tornadoes and a few damaging wind events took place during the evening and overnight hours. Lightning activity was minimal during the entire event as the instability was not conducive to strong, deep updrafts. In other words, the storms were low topped and generally lightning free.