If you live in Wisconsin and think that the summer of 2024 has been especially rainy, you’re onto something.
“We have had an extraordinarily wet period since May 1,” says Jonathan Martin, a UW professor of atmospheric and oceanic sciences. “And in fact, it goes all the way back really to April 1. Five days is the longest interval since April 1 where we’ve had no rain at all, the 14th to the 18th of May. That’s really remarkable.”
Martin and his colleague Steve Ackerman, a professor emeritus of atmospheric sciences, produce a regular radio segment and a newspaper column under the byline “The Weather Guys.” For more than 25 years, they’ve lent their expertise to explain weather events and put them in context for the general public. On July 16, Martin and Ackerman appeared on The UW Now Livestream to share insight about extreme weather and to explain why it seems to be more common.
Martin explained to viewers that, for meteorologists, following weather trends isn’t just a matter of how things feel but rather based in objective data. The National Oceanic and Atmospheric Administration’s Storm Prediction Center in Norman, Oklahoma, uses clear criteria to describe extreme weather events, citing wind speed, hail size, and tornados. “Those are systemically counted for number and distribution,” Martin says.
Ackerman noted that the frequency of extreme weather events is increasing, not just around the country in general but specifically in Wisconsin. “If you look at the weak tornadoes in Wisconsin, the number has been going up,” he says, adding that the region of America known as “Tornado Alley” — where tornados are most common — has been shifting eastward.
Martin said that the change in extreme weather shows the impact of global warming. “The frequency of intense precipitation events, both in winter and summer but more predominantly in the summertime, is increasing,” he said. “That can be measured, and that’s changing. It’s consistent with the notion that, as the globe warms up, … the atmosphere is able to hold more water vapor.”
Mike Knetter, the CEO of the Wisconsin Foundation and Alumni Association, hosted the livestream and brought forward questions from viewers, who wanted to know about the effects of such phenomena as El Niño currents and dust from the Sahara desert. Martin and Ackerman noted that there are many factors that influence weather, but they both emphasized that the evidence of global warming is extensive.
“Cherry-picking [data] is easy when you’re in a science or any kind of inquiry that’s advancing incrementally with new knowledge and new experiments and new observations,” said Martin. “Anybody can cherry-pick. What’s really difficult to do is argue against the systematic cohesion of all of the different observations and the theories that explain the predictions.”
