Tuesday’s series of tornadoes weren’t the first to strike south Louisiana, and they won’t be the last. In fact, some meteorologists say the area might face a heightened threat, even this year, as thunderstorms grow more intense and the temperature of the Gulf of Mexico continues to rise.
Thanks to the combined effect of a lingering cold event known as La Niña and a warmer Gulf, forecasters at AccuWeather are predicting an especially active severe weather season this spring that could produce the conditions needed for tornadoes deep into April.
Because the Gulf Coast is generally the first to enter the peak of severe weather season, senior meteorologist Paul Pastelok said Louisiana has “more opportunities to get hit with severe weather.”
Pastelok, who also leads long-range forecasting for AccuWeather, said similar conditions that led to Tuesday’s EF3 tornado, which had peak winds of 160 mph, caused significant damage and resulted in one death, could repeat as early as the middle of next week.
That’s because there’s a chance for another “upper-level system” — or a disturbance capable of creating an upward motion or lift in the middle or upper parts of the atmosphere — to move across the area again. On Tuesday, one of those systems traveled down from the Pacific Northwest, pulled south by a jetstream.
Right now, the Gulf is running 2 to 4 degrees hotter than usual, so next week’s system would mix with the warm, moist air again, likely causing more disruptive weather. Though the system might push just north of New Orleans, he said the storm was too far out to predict exactly where it might hit, so anyone recovering should prepare. If not a tornado, the weather could at least bring heavy rain and strong winds.
And this severe weather, while it may vary from year to year, is only expected to grow more intense as the planet warms due to human-induced climate change.
So far, the world has warmed 1.1 degrees Celsius since people ramped up the burning of fossil fuels and wood during industrialization, and research has found that with each additional degree of warming, conditions become 14-25% more favorable to create severe storms.
With more severe storms and a longer storm season, there’s potentially a greater opportunity for more tornadoes.
Though the Great Plains deals with the most tornadoes in the country, Louisiana and other states along the Gulf also bear a significant number of tornadoes that result in the most deaths due to several factors, including population density and increased likelihood to occur at night, like Tuesday’s twister.
“The reality is for the Gulf Coast, the conditions that make it such a lovely place to live are also the conditions that make it such a risk to some of these other hazards,” said John Allen, an associate professor of meteorology at Central Michigan University.
The warm, juicy air fuels the thunderstorms that could create a tornado. The hotter the air, the more energy there is in the atmosphere that might be released in the form of a severe thunderstorm or tornado.
Or at least, that could be what’s happening. Climate science still isn’t settled on what aspects of tornadoes are affected by global warming.
“Intuitively, I might've guessed this because of climate change because what is a tornado? If it's a manifestation of the available energy, that's there. And as things get warmer, there's more energy. But that's just a story, that's not really science,” said Michael Wehner, a senior staff scientist at Lawrence Berkeley National Laboratory and a lead author on the sixth international climate report. “The question is does that story make sense scientifically? And I don't think we're there yet.”
Allen and Wehner said it’s clear that more tornadoes are developing east of the traditional “Tornado Alley” region, cropping up more frequently in the Midwest and Southeast, particularly in the winter and early spring. That’s linked to climate change, they said, but scientists just aren’t sure how yet.
Because tornadoes are composed of so many ingredients — temperature, moisture, winds, upward motion — and a small weather event in terms of size, they’re more complicated to model on a longer, climatic scale. Even when the conditions are prime for a tornado, one might not appear.
Allen compared a tornado to the many moving parts and components of an orchestra. Research is looking to understand how the whole orchestra will change in time, as opposed to one section.
There are also studies that suggest while the number of days with tornadoes are decreasing, the number of outbreak days — or days with several tornadoes spawned by the same weather system — might be increasing. Those are storms that are the most likely to produce strong tornadoes at an EF2 rating or higher, which cause the most devastation, Wehner said.
But Allen, whose research centers on the relationship between tornadoes and climate change, said some of the increase might be related to improved identification of tornadoes over the past few decades.
The gray area leaves more room for study in the years to come, especially as more computing power becomes available to model tornadoes on a longer timescale and young researchers enter the field. That will take more money.
“It's a hard problem. But for a scientist, that's good. The easy problems are all solved,” Wehner said.
Whether a funnel touches the ground, it is acknowledged that the likelihood of severe thunderstorms will increase in the coming years, especially in the winter months when Louisianans usually hope for a reprieve from extreme weather.
That means residents should expand their preparation beyond hurricane season, Pastelok said, and craft a plan for when they’re alerted of severe storms and tornadoes.
“Just say ‘What would I do if a tornado was coming at my house? Where am I going to go?’ And try to figure that out right now so that when it happens, everyone is on the same page and ready to go,” he said. “Predictions are getting a little bit better as far as lead time goes (before tornadoes). So you do have some time to get to that plan if you can.”
