A scientific explanation behind tornado that hit Davis in unlikely weather event

A scientific explanation behind tornado that hit Davis in unlikely weather event

Photo Credits: A storm cloud hovers above Yolo County as seen from West Village on September 28, 2019 in Davis, Calif. Photo by Ben Cheng / Contributer.

EF0 rated tornado struck Davis area Sept. 28 due to instability in atmosphere, twisting wind

In an improbable event, a tornado touched down just north of Davis on Saturday, Sept. 28. The tornado formed around 6:40 p.m. and ended at about 6:55 p.m., with wind speeds estimated between 68 and 74 mph, according to a tweet posted by the National Weather Service (NWS) Sacramento. The tornado occurred because the right conditions were present, instability in the atmosphere and a twisting motion in the wind, according to Matthew Igel, an assistant adjunct professor in the department of land, air, and water resources. 

Dani Caputi, a fifth-year graduate student in the department of atmospheric science, said she communicated with a colleague who observed the storm, prompting her to send the information to the NWS to verify the warning already in effect. This information included that the storm began forming about 10 miles northwest of Woodland, and the storm tracked southeast over the course of a couple of hours, strengthening as it moved. When it touched down just north of Davis, observers reported large hail falling. As it kept moving to the southeast, it continued to strengthen into a tornado. 

The tornado is classified as an “EF0” on the Enhanced Fujita scale — the weakest reading that is still considered a tornado. EF0 tornadoes can cause minor damage to structures and signs, as well as knock down weak-rooted trees and branches, according the NWS Storm Prediction Center website

Touching down closer to UC Davis were a series of “gustnadoes,” which preceded the tornado by about 10 minutes, according to a tweet by the NWS Sacramento office. Gustnadoes are different from tornadoes because they are not connected to clouds, making them smaller and weaker.

Although first-year atmospheric science major Ameya Naik did not directly see the tornado, he said he saw it forming. He could tell the storm was in an environment where it might start to rotate and form into a tornado.

“First when it was kind of far away, you could see a tall towering cloud,” Naik said. “You could see the beginnings of a RFD cutout, which is weather lingo for the beginnings of rotation.” 

The tornado occurred in Davis because the two elements needed were present, Igel said. 

“The first thing is some kind of instability, so something to make a cloud to make warm air rise,” Igel said. “It was relatively warm on the surface, since we had high temperatures the week before and there was some cold air above that. That was sort of an unusual set up for Davis, so the air could easily rise and form clouds. The second thing you need for a tornado is some kind of twisting of the wind. That exists in the central valley, and did on Saturday.”

Although this event seemed very unlikely, California does have about 10 tornadoes a year, according to Igel. Usually the tornadoes are classified as EF0s, like the one that occurred last month.

“Tornadoes in Davis are not totally uncommon, but relatively infrequent,” Igel said.

This tornado luckily did not cause any harm, Caputi said. It could have broken some windows or caused some damage to buildings if the tornado had taken a different route. The NWS Sacramento office tweeted out pictures that some trees had been bent over, however no other damage had been reported. 

“It was not a Wizard of Oz case with any houses lifted,” Caputi said. 

When the storm was first detected by radar, the NWS Sacramento office sent out a warning that there was a tornado forming to advise people to take shelter, according to third-year atmosphere science major Alexis Clouser. 

When a warning is sent out, Igel said it is important for everyone to listen and to get updates from local media. 

“General advice from the national weather service is to stay indoors, to stay in an interior room of your house on a lower level,” Igel said. “They aren’t incredibly dangerous, but you wouldn’t want to get caught in one. It’s always best to stay indoors and not to panic, keep a level head and stay out of the storms path.”

Clouser said she saw some people who did not heed the warning and went outside to take pictures. 

“Don’t go out and pretend you are a storm chaser, since unfortunately that is how people get hurt,” Clouser said. 

Tornadoes in other parts of the world, like in “Tornado Alley” in the Great Plains, can get much larger than the EF0s in California and much more damage occurs. The right conditions are present in these areas that allow for stronger, more frequent tornadoes, said fourth-year atmospheric science major Josh Zucker. Vast flat areas allow winds to flow unobstructed. Additionally, when warm moist air coming up from the Gulf of Mexico meets dry, cold air moving east off of the Rocky Mountains, storms can develop easily.

Whether or not climate change affects tornadoes is a topic of debate in the scientific community, Igel said. The lifting of warm, moist air is expected to be more common with overall world temperatures increasing, which could increase the likelihood of tornadoes forming. However, the second ingredient of tornadoes, twisting in the wind, is something that naturally occurs in the air even before a storm exists, so scientists are unsure how that will change with climate change. 

“I would imagine that if you have slightly increased temperatures, that might cause more instability in the atmosphere and more extreme weather events,” Caputi said. “But it is very hard to make a case since there is not a lot of research. In the case of the climate, you really have to put it into a model, and then test different scenarios and see what might happen.”

Davis may not see more tornadoes for a while, so Clouser said people should not take this event for granted. 

“This is kind of a once in a lifetime storm for a lot of Davis and Sacramento Valley natives,” Clouser said. “We might not ever get weather like that, with such magnificent storm structure.”

Written by: Margo Rosenbaum — science@theaggie.org