How one ASU professor became the lead authority of weather world records

Randy Cerveny, climatologist and chief rapporteur of climate extremes, has been capturing and archiving powerful weather events for 14 years

Randy Cerveny

Randy Cerveny, climatologist, President’s Professor in the School of Geographical Sciences and Urban Planning and chief rapporteur of climate extremes.


The TV hurricane report was wrong and Randy Cerveny knew it. Sitting on his couch in 2005, Cerveny shuddered as he watched news anchors inaccurately claim that Hurricane Katrina was the worst hurricane of all time. 

“It was bad, but it was nowhere near the worst hurricane we've ever had,” recalled Cerveny, an expert in climatology and an Arizona State University President’s Professor in the School of Geographical Sciences and Urban Planning. “I like to see things right. When I see a number that's part of a news report, I want to have some trust in it.”

Cerveny spoke to colleagues and realized that an official list of what the biggest, the worst, the strongest and the deadliest categories of weather were didn’t exist and he wanted to do something about it.

Cerveny co-authored an academic article describing the need for an official list of extreme weather occurrences and a body of experts that would validate them. The World Meteorological Organization (WMO), the weather agency of the United Nations, read it and contacted him. 

Less than a year later, the first global archive of weather and climate extremes was born and Cerveny was at its helm. 

“I realized that if you are going to open your mouth, you have to back it up,” said Cerveny, who directs ASU’s meteorology department, with a chuckle. “So, I put together this big project of weather extremes which has been going on now for 14 years. We've become the official source for all weather extremes around the world.”

Today, Cerveny, chief rapporteur of climate extremes for the WMO, and his team are transforming the way we think about weather, our understanding of the potential power of natural events and how accessible this valuable information is to the general public.  

An arduous worldwide effort

From validating the hottest temperature ever recorded (134°F, Death Valley, Calif.), to the fastest wind gust (253 mph, Barrow Island, Australia), to the highest mortality from a single tornado (estimated 1,300 individuals, Bangladesh) and everything in between, Cerveny and his team have been busy behind-the-scenes confirming and archiving extreme weather events for a more accurate understanding of the power nature possesses.  

Most recently, Cerveny validated two new world records of lightning — the horizontal distance a bolt traveled (441 miles plus or minus 5 miles, Brazil) and the time duration of the longest flash (16.73 seconds, Argentina). The two records more than doubled their predecessors and prompted the WMO to officially change the scientific definition of a lighting flash. 

“The old official atmospheric science definition of a lightning flash is a lightning discharge event that is a stream of electricity lasting less than a second,” Cerveny said. “Well, we showed that we can have a lightning flash event that can last 16 seconds, so we are literally rewriting the dictionary of atmospheric science.” 

Validating that record was enabled by recent advances in space-based remote sensing, which offers the ability to measure flash extent and duration continuously over a broader geospatial area. 

But beyond the technology, it’s an international team of experts and an arduous evaluation process that ultimately leads to the verification of a weather world record. 

Following the notification of an extreme weather event, Cerveny assembles a committee of the top international experts in the specific field related to the weather extreme in question. 

The committee then evaluates every aspect of original data, from raw observations, to specifics on the equipment used, to quality control checks, calibration records, and even the observational practices: Was the equipment used in the right fashion? Was it placed in the right location? Did the measurements at that weather station match up with trends with the surrounding stations in the neighborhood? 

Cerveny recalls an instance last year while evaluating a heat record, the entire instrument had to be flown more than 2,000 miles across international borders from Kuwait to a testing facility in Italy to evaluate the accuracy of its readings. A single weather event evaluation takes an average of six to nine months, although some evaluations have gone on to span several years.

“There's a lot of information that goes into these committees and then these committees carefully debate the merits of that particular observation. They will tear it to shreds in some cases,” Cerveny said. “I've had this project going on for 14 years and we have never had any of our evaluations overturned. It's a testament to the quality of the people involved, I think.” 

Once reaching a conclusion, the committee makes a recommendation to Cerveny and he then has the final say to accept or disallow the record.

“With the quality of the teams, I've never rejected any of the recommendations, but eventually the decision has to come down to one person. Right now, that person is me,” Cerveny said. 

More than trivial pursuit 

People have been fascinated with records since the dawn of time. The first international network of meteorological observations is said to be recorded temperatures dating back to 1654. But the value of keeping accurate data on weather extremes is more than just novelty and a place in the record books, but it also informs important decision-making in engineering, medicine and climate change. 

“In order to know how the climate is changing you need to have good information about what it's doing over time,” Cerveny said. “Additionally, in engineering if you're designing a building or a plane, or you're doing any kind of design that is associated with outdoor weather conditions, you need to be able to design the structure you’re building so it can handle the type of extremes that we see.” 

Cerveny says that knowing things like what the strongest wind was, where that occurred and when it occurred become critical bits of information for an engineer. Similarly, in medicine, knowing how hot the climate has gotten can become an important part of figuring out how to keep people safe through heat waves and mitigate the challenges that come with it. 

Despite its scientific merits in other disciplines, one of the most important aspects of why an archive of weather extremes is important, Cerveny believes, is for the visibility it brings to the field of meteorology and its effective role in capturing the imagination of the general public, and promoting atmospheric science education. 

“I get lots of emails from kids around the world who get interested in weather by seeing some of the weather extremes that we list on our page,” Cerveny said. “I’ve kept in touch with some of them and some actually have gone on to become meteorologists themselves.”

“All of us (scientists), and in particular in the geosciences, want to feel like what we're doing has impact and to be in a place where that impact is seen by even the general public. This archive has become a nice way to help promote our discipline.”

Sun Devils put records on the map 

A complete list of all the validated records by Cerveny and the WMO can be found on the WMO's World Weather and Climate Extremes Archive official website, which is hosted by ASU.

Geographic Information System students in the School of Geographical Sciences and Urban Planning created the interactive map on the site that plots the extreme weather occurrences. 

“One of the cool things about the archive is that a lot of the technology that is part of the website, the maps, the designs, the symbols are all done by ASU GIS students,” Cerveny said. “It’s a collaborative effort.” 

The website attracts hundreds of visitors from around the globe daily and that number rises to several thousands of visits around new announcements of weather verifications.

Advancing the course of science

Cerveny is pleased to see the grown acceptance both by scientists and the general public of the extreme weather and climate archive that started all those years ago. For him, he says it’s rewarding to be a part of something that is simultaneously stimulating excitement around weather and to be adding to a growing body of scientific findings. 

“I love what we're doing, this particular research is fun,” Cerveny said. “It's a chance to work with some of the top people in the world and we are doing work that is groundbreaking. We're advancing the course of our science, which is something that I think we all should try to strive for.” 

Randy Cerveny talks more about his role with the WMO and what is causing rising temps in cities like Phoenix on the School of Geographical Sciences and Urban Planning podcast Earth+Humans.

See a full list of all validated weather events at World Meteorological Organization’s World Weather and Climate Extremes Archive official website.

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