When Helene made landfall in Florida earlier this year, 234 people lost their lives to the worst hurricane to strike the US mainland since Katarina in 2005. It’s natural disasters like that, and their growing intensity due to climate change, that have pushed scientists to develop more accurate weather forecasting systems. On Wednesday, Google’s DeepMind division announced what may go down as the most significant advancement in the field in nearly eight decades of work.

In a post on the Google Keyword blog, DeepMind’s Ilan Price and Matthew Wilson detailed GenCast, the company’s latest AI agent. According to DeepMind, GenCast is not only better at providing daily and extreme weather forecasts than its previous AI weather program, but it also outperforms the best forecasting system in use right now, one that’s maintained by the European Center for Medium-Range Weather Forecasts (ECMWF). In tests comparing the 15-day forecasts the two systems generated for weather in 2019, GenCast was, on average, more accurate than ECMWF’s ENS system 97.2 percent of the time. With lead times greater than 36 hours, DeepMind’s was an even better 99.8 percent more accurate.

“I’m a little bit reluctant to say it, but it’s like we’ve made decades worth of improvements in one year,” Rémi Lam, the lead scientist on DeepMind’s previous AI weather program, told The New York Times. “We’re seeing really, really rapid progress.”

GenCast is a diffusion model, which is the same tech that powers Google’s generative AI tools. DeepMind trained the software on nearly 40 years of high-quality weather data curated by the European Center for Medium-Range Weather Forecasts. The predictions the new model generates are probabilistic, meaning they account for a range of possibilities that are then expressed as percentages. Probabilistic models are considered more nuanced and useful than their deterministic counterparts, which only offer a best guess of what the weather might be like on a given day. The former also harder to create and calculate.

Indeed, what’s perhaps most striking about GenCast is that it requires significantly less computing power than traditional physics-based ensemble forecasts like ENS. According to Google, a single one of its TPU v5 tensor processing units can produce a 15-day GenCast forecast in eight minutes. By contrast, it can take a supercomputer with tens of thousands of processors hours to produce a physics-based forecast.

Of course, GenCast isn’t perfect. One area the software could provide better predictions on is hurricane intensity, though the DeepMind team told The Times it was confident it could find solutions for the agent’s current shortcomings. In the meantime, Google is making GenCast an open model, with example code for the tool available on GitHub. GenCast predictions will also soon make their way to Google Earth.

• Winter storms may disrupt Thanksgiving travel in the Northeast US this year.
• Heavy snowfall is forecast in New England and Great Lakes.
• Lake effect snow could bring up to five feet of snow in northern New York.

Winter storms could disrupt Thanksgiving weekend plans for some of the record 80 million Americans who traveled more than 50 miles from home this year.

Heavy snowfall is expected in New England through Friday morning and areas along the Great Lakes through Saturday, according to the National Weather Service.

Parts of New England could see up to one foot of fresh snow by Friday morning. And over the weekend, a lake-effect snowstorm downwind of Lake Ontario could total up to five feet of snow in northern New York. The lake effect snow is expected to cover from Cleveland to Buffalo.

The lake effect snow is expected to start over the weekend and will likely continue through the next week.

"You can often get thundersnow with it and extremely high rates of snow, so it's a spectacular thing but a relatively small-scale thing," William Churchill, a meteorologist for the National Weather Service, told Business Insider.

Thundersnow occurs when there is lightning during a snowstorm.

The vast majority of Thanksgiving travelers travel by car, according to the American Automobile Association. This year, 71.7 million people were expected on the road.

The number of Americans expected to travel more than 50 miles for Thanksgiving this year was up from pre-pandemic levels. In 2019, there were 77.8 million travelers, according to AAA.