Spring Storms (13 March 25)

Whenever air masses with different characteristics collide, you generally get stormy weather. This is especially true when cold dry air encounters warm moist air. That means spring is the main season for severe thunderstorms and tornadoes. The geometry of the US is especially conducive to tornadoes. Cold dry air moving south from Canada meets warm moist air streaming up from the large body of water south of Louisiana occasionally known as the Āyōllohco Mexihco, Yucatan Sea, Gulf of New Spain or Mexico or America, whatever. No matter what you call the sources this interaction causes the highest tornado frequencies in the world over the Midwestern and Southern states.

The simple fact is any time there is a thunderstorm there is the potential for severe weather. The question is “how severe?” In my not so humble opinion people have lost their minds over weather hazards. There are a lot of reasons why the hype seems to have gotten out of hand, mostly due to the changing media landscape where “news” is a commercial product, and social media has made anybody with pretty graphics and a melodramatic writing style an expert.

One issue I see is how NWS forecasts are now being distorted. For example, the standard language defining a “severe storm” is one with gusts to 58 mph, hail over 1″, or a tornado. So I’ll hear something like “we could experience tropical storm force wind gusts!” As I have ranted, that’s not how tropical storm winds are measured, and we get wind gusts into that range a lot more frequently than you might think. Yet saying “tropical storm winds” conjures up images of recent events where power is out for days and widespread damage – something that isn’t likely or even possible in many of these events, which tend to be more localized and, as noted, gusts aren’t the same as sustained winds. But it’s worse than that: the Storm Prediction Center also factors in the probability an even can happen, and both bloggers and local media often mangle that message.

Most of the time the risk of being killed by one of these storms, especially in Coastal Georgia and South Carolina, is pretty low. Your chances of being murdered in Savannah by a fellow citizen in most years is around 120 times greater than being murdered by a tornado. Of course, your lifestyle has a lot to do with those chances. If you’re not a drug dealer or gang member your chances are a lot less than that; likewise, if you are a criminal, your chances are a lot higher. Your chances of being killed driving on Abercorn is about 160 times higher than being killed by a thunderstorm or tornado. Imagine how you would feel if the traffic accident rate were hyped as much as storms? If the TV advised you to download their app that warned you every time someone ran a traffic light? (oh, crap, hope I didn’t give anyone any ideas!) You’d be a nervous wreck. So people tend to worry about storm more even though the risk is less. 

That said, like most hazards, you can and should reduce your risk of being harmed by severe weather. The first, smartest thing you can do is get a weather radio. They aren’t expensive (under $50), and are programmable so you only get alerts for your county (although I recommend turning on at least the ones on either side so you can follow what is going on nearby). The weather alerts on the radios come direct from the National Weather Service. Other means of notification have steps in between – that causes delays and the potential for problems. Commercial radio/TV are probably second best, but of course that means you have to keep them on all the time, which makes advertisers happy but is annoying. Sirens aren’t meant to be heard inside, and depending on the wind and the other conditions may not travel as far as you think.

Apps can be terrible and should be a last resort. In my office I get alerts directly from NWS via satellite, have a weather radio, and monitor other means. Sometimes apps and phone alerts have been as much as 10 minutes behind! That’s literally a lifetime when there is a tornado.

So you got an alert. Now what? Try to take a look at the FEMA web site – although unfortunately, like many aspects of government right now, it is in transition and turmoil. It seems the checklists are still there, which are good resources.

When should you start to plan for severe weather? It doesn’t make sense to worry about it much more than the day before. Forecasts for thunderstorm intensity and tornado outbreaks are rarely actionable before 24 hours out, and often less than that. So what does that mean with respect to closures? It’s a complex question that, surprisingly, really doesn’t involve risk directly as much as it does the perception of risk, logistics, and liability. 

Most of the time when we speak of closures, we mean schools. The biggest issue with respect to school closures is not safety from the storm at school, it’s traffic safety getting to and from school. Once at school students are probably more safe from severe weather than at home. Generally speaking, bus operations become dicey when sustained winds get over 35 mph, and gusts over 45 mph. You could look at a forecast of severe storms and go “oh, my, that’s over 45, so we close.” But that is missing several issues such as that thunderstorm winds generally are brief and you have to factor in probability as well – so most of the time, unless it looks like the storms are going to be rolling through during arrival or dismissal, closing for spring time severe weather doesn’t make a lot of sense.

There are other issues that should be considered such as the fact that public schools perform a vital social safety network in urban areas, in terms of providing meals to lower income students as well as what is effectively state sponsored child care. Those issues are (or should be) additional factors in the closure decision. Saying “we always err on the side of caution” is both foolish and often untrue, when secondary factors like that are not considered. As usual, this already long post would be even longer to fully explore those aspects, but I hope this gives you material for thinking about how complex this discussion can get, and how it’s not really only about weather and risk, but about lots of other issues like perception of risk, media hype, politics, and economics.

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If you’d like to learn more about severe weather like thunderstorms and tornadoes, try the National Severe Storms Laboratory web site. It has resources for educators, students, and the general public.

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