If you live in snow country, it’s likely you’ve seen snow maps show up on your social media timeline. While some of these maps are the product of careful work by meteorologists and forecasters, others are generated directly from runs of various weather models, each with its own quirks or biases.
Nowadays, thanks to the Internet, anyone can share snow maps — often leading to viral posts that can be misleading.
It’s a problem meteorologists have been grappling with for years. Now, many are speaking up, warning people to be savvy.
“[The maps] tend to be made with pretty colors, and the structure of snowfall data lends itself to having an aesthetic appearance,” said Levi Cowan, a meteorologist with the Joint Typhoon Warning Center and the operator of Tropical Tidbits. His site is one of the most popular websites to access weather model data.
“Similar to any other extreme weather event, snowstorms also tend to drum up excitement and anticipation among meteorologists and people who enjoy snow,” said Cowan, who has operated Tropical Tidbits since 2012. He believes that snowfall forecasts from models are useful but, like any model forecasts, have their limitations and shouldn’t be taken literally.
Models are simulations — not forecasts
Caitlin Roth, a television meteorologist for Washington’s Fox 5 Weather Team, sees raw model outputs as a “quick and dirty” way to start a forecast.
“I have seen some wildly high snowfall amounts five days out from a storm, and when all is said and done D.C. gets a trace of snow (i.e. the mid-December nor’easter) so you absolutely have to take the raw data with a grain of salt,” Roth said.
Roth has found that social media often recirculates old snow maps, including outdated maps that were once carefully crafted by professionals.
“If you’re watching the weather forecast on the news you only see the latest snowfall forecast. When you pull up Twitter you could see today’s map followed by yesterday’s map followed by someone else’s map … that gets confusing!” Roth said.
The consequences of falling for clickbait
James Spann, a meteorologist for WBMA, the ABC affiliate in Birmingham, Ala., has seen the consequences of people taking modeled forecasts literally.
“Some people will cancel a vacation because they saw on Facebook there’s a big snowstorm coming in 15 days. People have actually canceled elective surgery cause they saw something on Facebook,” Spann said. “And, again, they don’t know it’s a 15-year-old kid sitting in the basement [posting maps] and it gets all the likes and all the shares.”
Spann theorized that people share the maps for various reasons: to gain a following, to share a passion for the weather and also simply for the satisfaction when your content goes viral.
“I guess it’s just the thrill of getting the likes and the shares, and in a way, I think some of them just like driving professionals crazy,” Spann said. “After awhile, I think that addiction becomes a problem where they’re just going to go out anywhere and find the most outrageous snow map they can find and share it with no regard to truth and with no regard to the harm it can cause,” Spann said.
A challenge for meteorologists
Both Spann and David Tolleris, a meteorologist and operator of WxRisk, a private weather forecasting company, say the increased access to weather data has both positives and negatives.
Tolleris believes the access to these maps increases Americans’ interest in science, something he sees as a positive. But there can be a downside.
“When [a clickbait forecast] busts … it weakens the science,” Tolleris said. “Because you’re like, ‘Oh my God I told my friend there was gonna be 14 inches of snow and we got three again — can’t these guys get anything right?’ ”
But Roth also says that the increased access to model data online has boosted people’s interest in science, especially on social media, where these maps are propagated and shared.
“A great thing about this is public awareness; so many people have an interest in weather and now they, too, can learn some basic forecasting,” Roth said. “I love how it increases people’s understanding of the weather.”
But with more information comes the need to educate consumers about the data they’re looking at.
“For meteorologists, when there’s a big snow coming or a hurricane on the East Coast, the workload goes up automatically just because of the interaction with the public,” Tolleris said.
In addition to putting out good information, now meteorologists are tasked with dispelling rumors or bad information.
“I don’t have time to be putting down this wild stuff. I need to be focusing on what I’m paid to do, which is forecast the weather,” Spann said.
Spann advised those who create weather pages or share weather maps online to properly identify themselves as hobbyists and to direct people to credible sources like the National Weather Service.
Spann, Cowan, Roth and Tolleris all agree that snow maps can be useful but that they require the analysis of a professional to address their inherent problems.
What to look for
One of the most common issues with model-generated snow maps is that they typically display snowfall at a 10 to 1 snow-to-liquid ratio.
“The most common snowfall map assumes that one inch of liquid is equivalent to 10 inches of snow, which gives you a ballpark estimate of what the model is predicting, but it is a simplistic estimate that can be very wrong,” Cowan said.
Snowfall ratios can range anywhere from a much lower ratio like 5 to 1, when heavy snowfalls at temperatures near freezing, or a much more extreme ratio in cold conditions, such as 30 to 1, when the snow is light and powdery.
Other problems with snow maps include the degree to which they count mixed precipitation like sleet and freezing rain as snow — something that differs between websites. While the data that each model website gets is the same, it is easy for someone looking to find the snowiest map to pick and choose the website that shows the most extreme outcome.
“The problem that’s developed, you know, with people sharing long-range deterministic model output, they don’t understand the limitations of the physics; they have no rudimentary knowledge of how the whole thing works,” Spann said. “That’s just a byproduct of making it publicly available, but again, I’m of the firm belief that it should be made publicly available, despite the problem we have.”
The author, Zachary Rosenthal, is double-majoring in leadership and public policy and in media studies at the University of Virginia and is a senior writer for the Cavalier Daily.
