November 15, 1989…The Precursors

On the afternoon of Monday, November 13, 1989, I downloaded all of the information from a service called Weather Brief and printed it all out on my dot matrix printer. The first hints of trouble were beginning to surface over a potential severe weather situation on Wednesday the 15th. The afternoon state forecast discussion from the NWS Birmingham talked about the possibility of a significant squall moving through Alabama on Wednesday and said that the potential for severe weather would have to be monitored. Forecasts issued that afternoon called for the likelihood of severe weather on Wednesday.

On the morning of Tuesday the 14th, I printed out all of the data. The situation was becoming more ominous. The early morning state forecast discussion from the NWS Birmingham stated that severe storms were expected for Wednesday. The mid-morning discussion reported that Wednesday was looking like a severe weather day as all of the models continued to show a very strong system moving towards Alabama. By afternoon, the same trends were continuing. The National Weather Service in Jackson said that nearly every discussion was making reference to Wednesday as a significant convective outbreak. The Day Two Convective Outlook issued around lunch time placed all of Alabama in the risk category for severe weather for the next day. They didn’t specify categories on the Day Two Outlooks back then. The discussion warned that significant severe weather was possible across Tennessee, Mississippi, Alabama and western Georgia, where strong upper level divergence was forecast to be over the highest low level moisture and instability. The models were showing a digging upper trough over the Central U.S. A surface low was forecast to move across the lower Great Lakes with a strong cold front trailing south to the Gulf coast.

Strong upper level winds of around 100 knots were expected to be blowing at 18,000 feet over Kentucky and Tennessee and a dynamic system developed. A strong low level jet was expected to be blowing at 40 knots up at about 5,000 feet from the Lower Mississippi into the Upper Ohio Valley. This conduit would draw very unstable air well northward. Lifted indices were expected to run -4 to -8 ahead of the surface system. The 12z NGM model indicated that lifted index values over Alabama would be as low as -6 Wednesday. Strong southerly surface winds at over 20 knots were also indicated. Forecasters concluded that strong thunderstorms were expected to develop from the Gulf Coast region to the Upper Ohio Valley. The stage was being set for one of the deadliest November tornado outbreaks in U.S. history. It would have terrible impact on Alabama. More in the morning.

Category: Uncategorized