While numerous tornadoes did form through the Plains, in the swath traditionally known as Tornado Alley, the vast majority of strong tornadoes avoided communities and structures. The fortuitous distribution of storms, coupled with advanced forecasts and warnings, are credited for the lack of serious casualties.
The month tallied 289 preliminary tornado reports, more than double the 126 observed tornadoes in May 2020. In May 2020, not a single significant tornado struck the Plains. The National Weather Service in Wichita didn’t log a single tornado in its coverage area in 2020.
“So far, there have been no reported tornado deaths in May of 2021,” Matthew Elliott, a meteorologist at the National Weather Service Storm Prediction Center in Norman, Okla., said in a phone interview Friday morning. “The most recent year without a tornado fatality in May was 2014. Also 2012.”
He said that, looking back at all Mays since 1950, only about 15 percent of them passed without a tornado fatality in the United States.
The data is “really highly variable, both in the number of tornadoes in May, which typically is the most active month for tornadoes, and the number of fatalities,” Elliott said. “It’s really influenced by these very large death-toll years. Often it’s one or two storms that may be causing those high fatalities. In 2011, there were 178 tornadoes fatalities [in May]. There were 163 in 1953, and 106 in [May] 1955.”
The 289 preliminary tornado reports received this May were marginally greater than the 2000-2020 average of 283 tornadoes. A whopping 556 tornadoes spun up in May 2019.
“At this point, since we’re only a few days into June, … some tornadoes toward end of month haven’t been surveyed,” Elliott said. He also noted many had been assigned EFU ratings, marking a tornado of “unknown” intensity on the Enhanced Fujita (EF) scale for twister damage. That’s what happens when damage can’t be found — the symptom of twisters skimming along over empty, rural landscapes.
That was the case with many of the tornadoes that hit southwestern Nebraska on May 26. Up to a dozen touched down within an hour during prolific tornado-producing storms.
Most of the tornadoes in May, particularly over the Great Plains, occurred west of the populous Interstate 35 corridor, spinning up over the High Plains instead. That placed them in more sparsely inhabited locales — ideal for storm chasers and communities alike.
“Maybe the dryline was farther west than usual,” said Bruce Thoren, a meteorologist with the Weather Service office in Norman. He referred to a boundary of dry air that intrudes from the west, kicking up pockets of air and generating severe storms. “We’ve been seeing higher dew points [and increased moisture] even in eastern New Mexico.”
High-altitude jet stream winds weren’t as fierce as they could have been over the central Plains, either. That meant fewer rotating storms. The long-regarded epicenter for tornadoes, Oklahoma, was anomalously quiet. The Panhandle ended up with several tornadoes, but the remainder of the state logged only one tornado touchdown.
Unfortunately, the Lower 48 did see killer storms in May — the fatalities just didn’t stem from tornadoes, underscoring the danger associated with the other hazards tied to severe thunderstorms.
On May 3, a severe thunderstorm swept through parts of the Atlanta metro area in the morning, its rotating updraft dropping a tornado west of the city. It lifted just outside the Perimeter Highway near Interstate 20, a few miles west of downtown. Additional severe storms spun up May 4.
At least six tornadoes were confirmed by the Weather Service during the two-day event in Georgia. Several fatalities were reported, but they were not attributed to twisters.
“As far as we’re aware, there were no fatalities associated with any tornado during that stretch on May 3 and 4,” said Kyle Thiem, a meteorologist at the Weather Service in Atlanta.
Elsewhere during May, tornadoes struck near several other population centers, including Tupelo, Miss.; Dallas; and west of San Antonio, but none proved fatal.
The National Weather Service Storm Prediction Center highlighted a Level 4 out of 5 “moderate” risk for severe storm areas three times during May. That’s in stark contrast to May 2020, when not a single forecast for moderate storm risk was issued.
June has started quiet when it comes to severe windstorms and tornadoes, but that may change late week with an upper-level pattern shift over the High Plains. Thereafter, severe weather could become more widespread over the central and eastern Lower 48 toward the end of the month.
“May might be the most active month for associated risk and impact, but it’s important to remember tornadoes can occur any time of year,” Elliott said. “It just takes one really bad storm in the wrong place to cause catastrophic impacts.”