When everyone sounds like a weather forecaster, who should people trust?

This winter, as atmospheric rivers crash into California one after another, Daniel Swain isn’t just worried about rain and flooding.

The UCLA climatologist, who has dedicated his life to studying weather, is keeping an eye out for a different kind of storm.

“A lot of noise,” he says. “A lot of confusion.”

Independent and amateur meteorologists, armed with global data available online, have disrupted the quiet, calm science of meteorology by posting their own weather predictions on blogs and social media.

Many of these self-proclaimed “weather nerds” get information from books and the internet while adding a touch of local knowledge. They can be surprisingly perceptive.

But professional meteorologists worry that some are trying to gain attention by predicting massive storms when the chances are slim. Or trying too hard to be first, issuing forecasts based on premature and unreliable information.

In this season of epic rains, snowfalls, and even “bomb cyclones,” the public looks to meteorologists for potential life-and-death advice: shelter or evacuate? — the key is to provide advance warning without exaggerating the situation.

“There are fans on Twitter who sound good but are extrapolating wildly,” says Swain, 33. “How is the average person different?”

The forecasting business has changed radically since (for as little as $10 a month) anyone can subscribe to the same raw data and analytical models as National Metereological Service and other professionals use. As Swain says: “You don’t need a PhD to be pretty good at understanding certain parts of the climate.”

Access to information has emboldened younger fans like Colin McCarthy, who launched his US_Stormwatch Twitter account as a teenager in Northern California.

Now studying atmospheric sciences at UC Davis, McCarthy says he feels pressure to be accurate, but he was confident enough in his abilities to jump ahead of the NWS by warning 90,000 followers that a massive snowfall would hit Southern California last month.

“I turned out to be right,” says the 19-year-old student. “I was glad I posted it because it went viral.”

There is an important point here about time: according to the National Oceanic and Atmospheric Administration, five-day forecasts are 90% accurate. With 10 days or more, the success rate is cut in half. Still, some fans wonder if the NWS is being overly cautious or concerned about its reputation, being too hesitant to issue weather warnings.

“I have my own way of doing things,” McCarthy says. “And I have the freedom to do what I want.”

This individualistic approach is taken to an extreme by a Riverside County meteorologist who has spent decades not only posting forecasts but also “going against the NWS at all costs.”

Raiden Storm, his professional name, promises visitors to his subscription website and SCWeatherForce account on Twitter that he will “save your life one day.” With a fedora pulled down on his head, he holds live chats to criticize government meteorologists and discuss his unique brand of meteorological math.

“I’m kind of filling in the gaps,” says the 38-year-old. “I get a lot of criticism for that.”

The NWS typically declines to comment on other forecasters. But, in 2011, officials issued a statement clarifying that they had “no association” with Storm, whose legal name is Kevin Martin, or his forecasts that they warned “could be visually confused” with government reporting. Contacted for this story, an NWS spokeswoman encouraged the public to obtain weather information “from sources they deem to be reliable.”

When it comes to taking chances with predictions, Howard Sheckter learned a lesson early on.

In the 1980s, when he began a dual career as a real estate agent and part-time meteorologist in Mammoth Lakes, Sheckter based his daily reports on limited information: marine forecasts, conversations with National Weather Service veterans, and weather segments from the news. Sacramento Television. He was fired by a local radio station for predicting a storm that never materialized.

Since then, Sheckter, 72, has grown closer to the NWS, using his popular mammothweather.com blog to repackage government forecasts with their own brand of fan talk:

“La Niña has ended and ENSO-neutral conditions are expected to continue through the Northern Hemisphere spring and early summer of 2023,” he wrote in a recent post. “Of interest, see the Kelvin warm wave and its observed effect on subsurface water temperatures.”

Says Sheckter: “I can read weather models, but not to the extent that the NWS can. With my discussions, I go into detail about how and why it is happening and how it relates to our area.”

To understand the tension that can exist between professionals and freelancers, it helps to know a little about the complexity of what they do, starting with the use of ensemble forecasting.

This process starts with the current conditions measured by weather stations, satellites, etc. In Los Angeles County, the NWS tracks more than 700 ground stations, or about five per square mile. The data is fed into a mathematical model that calculates a prediction.

There are problems from the beginning.

Due to the physical distance between stations, meteorologists must estimate conditions for all spaces. Small errors can create larger inaccuracies in a long-range forecast. The mathematical model could also be a bit off.

An employee removes his bicycle from his damaged car at the Royal Paper Box Co. in Montebello, California.

(Allen J. Schaben/Los Angeles Times)

“We can’t write a perfect equation for nature,” says Shuyi Chen, a professor of atmospheric sciences at the University of Washington. “There is a legacy uncertainty built into the system.”

The ensemble forecast compensates by running dozens of forecasts using slightly different estimates for the gaps, adjusting the numbers based on temperature, wind, and precipitation. The result is a range of possible outcomes.

Reading all the “noise” means ignoring outliers and focusing instead on the most closely clustered forecasts in the middle, which represent the most reliable estimate of the weather ahead.

Other factors include El Niño and La Niña weather patterns and something called the Madden-Julian Oscillation, but Swain cautions that scientific calculations “are not the whole story.”

As a recent storm approached southern California, the UCLA scientist spoke with emergency officials about the worst-case scenario: an outlier that showed a small chance of widespread catastrophic rainfall. But, in his weatherwest.com blog and in media interviews, he leaned towards the most likely and least severe prognosis which ultimately turned out to be correct.

“Context is everything,” he says. “You don’t want to emphasize an outcome that has a 19 out of 20 chance of No happening.”

Sharing grim but unlikely forecasts too often can lead to “warning fatigue.” If dire predictions don’t come true, Swain says, “people are less likely to take it seriously when the big one is coming.”

That’s why professionals balk when independents issue long-range forecasts, like announcing a freak hurricane that was supposed to hit the California coast last summer but never came. Or an ARkStorm, an atmospheric riverine megastorm that devastated much of the state, that didn’t happen earlier this winter.

“Sometimes these people on social media can get a huge following if they make big, bold predictions,” says Swain. “They are choosing from dozens of possibilities and choosing the most extreme.”

Heavy snowfall last month in the mountains of southern California, which trapped residents and vacationers alike, prompted many flags.

With some independents posting early forecasts, people blamed the government for not warning them soon enough. As chief meteorologist for a Big Bear radio station, Ben Brissey remembers all the information going around as “nothing short of chaos.”

Like others, Brissey believes that only government agencies should issue severe weather warnings.

“It’s a tough job accurately forecasting five days, let alone five weeks,” Brissey says in an email. “We all need to be discreet when choosing what information we use and post for the world to see, especially if it directly affects our daily lives.”

Independents like Sheckter and McCarthy agree that the NWS should be the public’s primary source of weather information. They claim to play a complementary role, using a common language to help followers understand highly technical forecasts.

This distinction is crucial for professionals who see a difference between predicting a widespread catastrophe and warning of localized flooding. Brissey calls it “a fine line between creating panic and situational awareness.”

At UCLA, Swain finds himself in an unknown position; As a climate scientist often cited by the media, he is often the one who is criticized as a doomsdayer.

He likes that the fans care so much about the weather and understands their need to share this passion with the public. Long before earning multiple degrees in the field, he wrote a weather blog as a teenager.

The difference is that only about 50 people read their forecasts for high school.

“Now if your tweet goes viral, millions of people see it,” he says. “That’s precisely why it’s so important to get it right.”