The tornado that tore through a Family Dollar store on South Broad Street in Mobile on May 6 struck without any advance warning from the National Weather Service, and local meteorologist Alan Sealls says that gap is not a failure of technology so much as a reminder of how quickly and quietly some tornadoes can form.
The Mobile twister lasted about one minute and carved a path roughly 25 yards wide. No injuries were reported, but the storm caused significant damage to the retail building. It was the first tornado of the night, spinning up rapidly from a thunderstorm that gave forecasters only a brief and subtle signature on radar before it touched down.
Later that same evening, a second tornado developed as a storm crossed Mobile Bay and moved into Daphne. That storm displayed a clearer, more sustained rotation signature for several minutes before producing a tornado, giving the National Weather Service enough lead time to issue a warning ahead of impact.
The difference between the two storms illustrates a challenge that meteorologists face every severe weather season: no two tornado-producing storms behave exactly alike, and the atmospheric conditions that determine when a rotating thunderstorm actually drops a tornado can vary from one storm to the next, even within the same weather system on the same night.
Sealls, who serves as chief meteorologist for a Mobile television station and also teaches as an adjunct meteorology professor at the University of South Alabama, has fielded frustrated questions from residents who could not understand how a warning was possible for the Daphne tornado but not for the one in Mobile. He said the honest answer is that forecasters and radar technology cannot catch every tornado before it forms, particularly the first one in a developing severe weather event.
Meteorologists rely on Doppler radar to detect rotation within thunderstorms, but that rotation does not always appear clearly enough, early enough, to support a warning before a tornado actually touches down. A storm can intensify and spin up a brief, small tornado faster than the radar signature develops into something unmistakable. Once a storm has already produced one tornado or shown sustained rotation, forecasters have a better basis for anticipating additional tornadoes from that same storm or storm mode.
Issuing a warning for every disturbance with even a slight chance of becoming a tornado would come with its own costs, according to Sealls. A dramatically lower threshold for warnings would mean many more false alarms, and residents would be more likely to tune out warnings altogether if they came too often without a tornado materializing. Weather officials have to strike a balance between warning early enough to protect the public and maintaining public trust by keeping false alarms manageable.
That same balancing act carries into hurricane season, which is now getting underway along the Gulf Coast. Long-range tropical outlooks and forecast graphics circulate widely on social media, often stripped of the nuance and caveats that came with them. Sealls urges residents to pay close attention to the specific language used in forecasts, noting that words like “could,” “might” and “may” describe possibilities, not certainties, and are very different from “likely” or “will happen.”
Social media algorithms tend to boost posts that generate strong reactions or that look dramatic, regardless of their accuracy, which can distort public perception of an approaching storm’s actual threat. Sealls said no amount of online speculation changes what the atmosphere is actually going to do, and he encourages residents to maintain a realistic understanding of the limits of forecasting science and computer models.
Longer-range forecasts, including 14-day models, are also a frequent source of confusion. A model run two weeks out can look every bit as detailed and confident as one showing tomorrow’s weather, but its accuracy drops considerably the further out it projects. Sealls suggests that anyone tempted to treat a two-week forecast as fact save the graphic and revisit it once that day actually arrives to see how closely it matched reality.
Ultimately, forecasters can speak with certainty only about the past and the present, according to Sealls, while anything involving the future is a matter of probability rather than fact. That distinction, he said, is easy to lose sight of amid the volume of weather content shared online, but it remains central to understanding both the successes and the limitations of modern forecasting.