Tornado alley is shifting. So, why are there still so many in the High Plains?

Tornadoes have been unusually active this year, battering much of the Midwest and Southern U.S. and reaching as far north as Michigan and west as Wyoming.

Having just completed the first half of the year, the U.S. is already closing in on the annual average tornado count, said Chris Weiss, lead investigator for Texas Tech’s National Wind Institute cooperative and professor in atmospheric sciences.

“We’re definitely above average this year,” Weiss said. “We’re almost to 1,000 now, total for the year, which is really close to our yearly count.” (The annual average is about 1,200 tornadoes, according to the Scientific American.)

In springtime, USA TODAY wrote that this year began as the busiest on record for tornado reports between January and March before dropping to fifth-busiest at the end of May, following two months of below-average activity. Then, another surge occurred.

On its own, June accounted for about one-quarter of this year’s total tornado count, USA TODAY reported earlier this week citing preliminary numbers from the National Oceanic and Atmospheric Administration. According to the data, at least 202 tornadoes had been reported from June 1 to June 29, nearly doubling the three-year average of 106 in the same period.

Among the worst of those from last month were the two EF-3 tornadoes that struck the Panhandle towns of Perryton and Matador less than a week apart, killing seven and injuring more than 100 combined. According to the storm database with the NOAA's Center for Environmental Information, there has been only one other instance on record in which multiple separate storm systems produced multiple deadly tornadoes in the High Plains within a week. (Although, in April 1970, there was one storm that formed a series of deadly tornadoes in the same night.)

And with the exceptions of 1975 and 1970, when one of the deadliest tornadoes in U.S. history barreled through Downtown Lubbock —  killing 26 and injuring 500 — just weeks after the April storm, the High Plains has not otherwise experienced multiple deadly tornadoes from multiple storms even within the same year, according to historic data.

In fact, the chances of tornadoes in the High Plains becoming fatal at all are fairly narrow at 0.81% between 1950 and 2022. Prior to last month's tragedies, the most recent tornado that resulted in death took place more than 16 years ago on March 16, 2007 when an EF-3 tornado traveled through two drilling rigs in Canadian, hitting several mobiles homes and two unanchored camper trailers — one of which was occupied by a man who initially survived but later died from critical injuries.

Before that, it was five years prior, and before that, another five years.

Given this historical context and the recent tragedies that occurred, many locals now wonder the odds of this becoming the norm on the High Plains, the 42-county region that encompasses much of the Texas Panhandle and South Plains.

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From the 1950s to the 1990s, tornadoes have primarily touched down in the states centered along the 100th Meridian (or the 100-degree west longitude line) from South Dakota to Texas — otherwise dubbed "Tornado Alley."

In the past decade, however, the dryline has shifted eastward by about 200 miles, ramping up tornado activity over a large portion of the Midwest and Southeast. This includes the lesser-known tornado-prone region called "Dixie Alley," which is distinct because its outbreaks are often more destructive and deadly. (Note: The Weather Channel has abandoned the term citing racial insensitivity, but a new term does not yet exist.)

And while tornadoes and severe weather remain a threat on the High Plains, historic data does align with expert claims of decreased tornado reports in the Great Plains.

From the 1950s through the 1990s, the region saw a steadily increasing number of tornadoes each decade, peaking at an annual average of about 39.5 tornadoes between 1990 and 1999. Then, the yearly average rapidly dropped off in 2000, down to 26.7 each year between 2000 and 2009 — excluding the abnormally high outlier of 102 in 2007 — and has consistently lowered since. Between 2010 and 2019, the annual average fell to 25.7, and again, dropped between 2020 and 2022 to an average of 22.6 each year. (Although, it's important to note that meteorologists don't often use data prior to the 1990s, because reporting was not as reliable in the years prior.)

This year, however, tornado reports have already surged above the three-year annual average, according to preliminary data from the National Weather Service offices in Amarillo and Lubbock. Combined, they've issued 55 tornado warnings and received 23 tornado reports, though a representative with NWS Amarillo warned that the preliminary reports may represent a number lower than actual.

"It's one of those things that our numbers are so variable," said Mark Conder, the science and operations officer with NWS Lubbock. "But we've definitely received more than what we have the past couple years."

While it's true that the frequency of tornadoes has dropped in Tornado Alley in recent decades, Northern Illinois University meteorologist Victor Gensini, who led the study that determined Tornado Alley's eastward movement, told USA TODAY in 2018 that the region remains the top U.S. area for tornadoes regardless.

“It’s not that Texas and Oklahoma do not get tornadoes,” Gensini said then. “They’re still the No. 1 location in terms of tornado frequency, but the trend in many locations is down over the past 40 years.”

Weiss noted that this year may be particularly active for tornadoes for a number of different reasons climatologically. At the root, the weather has featured all the right ingredients: large amounts of water vapor and vertical wind shear, which is essentially "how winds change speed and direction in height."

This often happens in the eastern half of the U.S. when dry winds coming in from high over the Rockies meet moisture-rich, low-level winds coming from the Gulf of Mexico, the recent USA TODAY story reported.

"Typically, by this time of year, the jet stream has retreated well north of Texas, taking the vertical wind shear along with it," Weiss said. "This year, however, we have held on to enough flow aloft, about four miles up, to take advantage of the seasonably hot and humid conditions and produce tornadic storms later into the season."

On average, tornado season ends around June 15 for the High Plains, according to a representative from the NWS Lubbock office.

Weiss said there is also a possibility for increased tornado activity with the presence of climate change due to expectations of increased thunderstorm activity.

"As water temperatures warm, the capacity for water vapor in the air increases as well, which readily fuel these thunderstorms," Weiss aid. "However, for tornadoes specifically, we have to look at the vertical wind shear, and that evolution with climate change is much less certain."

But aside from the climatological explanations, experts agreed to one primary reason for why it appears that tornadoes have increased on the High Plains in recent years: human perception.

Because of the region's population growth — up by 25 to 30% since 2000, according to the most recent data from the U.S. Census Bureau — there are now people living in areas that used to be empty fields, where only experts might have seen tornadoes in the past. Additionally, with the rise of social media, there's an increased number of storm chasers compared to the past, while modern technology - including smart phones and social media - allows for a greater dissemination of information from weather events.

The rapid regional sprawl — or the increase in new developments — in areas that may not have previously had much human activity has also consequently increased the likelihood of tornadoes killing or injuring someone.

"There are definitely more observers and people living in broader expanses of the country now," Weiss said. "That's definitely a part of it."

Robert Barritt, a senior forecaster in the NWS Lubbock office, added that people are more likely to know about the human-impacted weather events. For instance, because there hadn't been a fatal tornado in the region since 2007, there is a greater human awareness of last month's deadly tornado outbreaks than that of the less-destructive tornadoes that occurred over the 16 years prior.

"We've actually issued fewer tornado warnings this year than the average," Barritt said. "People just believe that (there's an increased frequency), because they've been hitting residential communities."

This article originally appeared on Lubbock Avalanche-Journal: Why there are still so many tornadoes on the High Plains