It’s been a March of severe weather. We’ve lived the cycle of southern low-pressure storm systems approaching and increasing our temperature, humidity and wind, followed by severe thunderstorms arriving from the west. The result — disruption to our lives and sometimes destruction to our communities. We saw that with a tornado in West Mobile on March 9, then straight-line wind burst damage near Atmore on March 18, followed by a tornado that moved from Silverhill to Robertsdale on March 23.
What all of these incidents had in common was they followed days of weather outlooks hinting at the possibility of severe storms. Two of the events occurred under a tornado watch. A watch means you have to watch and be prepared to take action. The tornado touchdown in Mobile was not during a watch, but there was a warning issued for it. The warning means danger is imminent, and you have to take immediate action. The Atmore wind damage happened without it being in a warning area, although it was seven miles outside of a severe thunderstorm warning polygon. The tornado in Baldwin County touched down while the location was under both a watch and a warning.
The lingo may be a bit confusing, but the nature of nature simply says stay updated on all weather threats, and follow forecast updates from a trusted source, like the NBC15 weather team on TV, online, on social media or on our weather app. The exact location of where storm damage may occur is not predictable, but the conditions that can produce it in a general area, are. Each of these incidents impacted less than one one-thousandth of the area of their respective counties.
It may surprise you to know that each of those three events had damage resulting from wind traveling 90-100 mph, even though two of them were the spinning wind of an EF-1 tornado, and one was not. Contrary to common belief, the sound of sudden damaging wind, the threat to you and the impact on a single structure are virtually the same, whether the wind is rotating or moving in a straight line. While the minimum threshold wind speed for a severe thunderstorm is 57 mph, the highest wind bursts are over 100 mph and have exceeded 130 mph. That’s like the wind of an EF-3 tornado.
Most vulnerable to any wind burst or tornado are mobile homes and recreational vehicles. Think about a cross-wind on an interstate that blows a tractor-trailer off the road. It doesn’t have to be extreme since the trailer is a large box, raised above the ground. If you are in a vulnerable structure, you must have a plan to stay with friends or family who are in a stronger structure when damaging wind is likely, but you must put that plan into action before you have no option.
Alan Sealls is chief meteorologist at NBC15, and an adjunct meteorology professor at the University of South Alabama.
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