December 19, 2019

Those New 'Snow Squall Warnings' Are Designed To Prevent Deadly Pileup Accidents

Millions of smartphones across the Northeast flashed an unfamiliar warning on Wednesday afternoon. The message came across as a push alert with the iconic screeching tone and an abrupt vibration: "Emergency Alert. Snow squall warning until 4:15 PM. Sudden whiteouts. Icy roads. Slow down! -NWS" These alerts may seem a little excessive on first glance, but they're targeted at motorists who need to know that they're approaching a potential whiteout that could cause a deadly pileup accident like the one that occurred in Pennsylvania on Wednesday.

The National Weather Service created snow squall warnings as a way to warn people in the path of snow squalls that they could experience sudden whiteout conditions, giving them enough time to pull off the road and wait for things to calm down before driving again.
Source: NWS New York

A local NWS office can issue more than a hundred different types of watches, advisories, and warnings. Some of the products are more urgent than others. The most important warnings—the ones that require you to stop what you're doing and pay attention to the weather instead—are usually issued using polygons, which allow forecasters to target warnings to only the areas at risk for life-threatening hazards like tornadoes and severe thunderstorms.

There's a different target audience for each of those polygon-based warnings. Tornado warnings and severe thunderstorm warnings are "everyone" warnings, no matter who or where you are. Flash flood warnings are important to people who live in flood-prone areas and motorists who may approach a flooded roadway, but the vast majority of us can usually ignore them if we're going about our business at home or work.

Beginning in November 2018, the National Weather Service officially began issuing polygon-based snow squall warnings, giving forecasters the ability to instantly warn people that they could be in the path of a sudden burst of snow. Snow squall warnings are "driver" warnings. They're not targeted to people sitting in their living room or working at their cubicle. They're targeted at people on the road or those who are getting ready to head out.

Snow squall warnings are handled with the same urgency as tornado and severe thunderstorm warnings for good reason.
We hear about pileup accidents all the time during the winter. A chain-reaction crash is pretty much the worst-case scenario for anyone out on the roads when a sudden burst of snow turns the roads to ice and drops visibility down near zero. Pileups can involve hundreds of cars in the most serious incidents, amassing dozens of injuries and fatalities as people get stuck in the wreckage and absorb the blow of every car and truck careening toward them.

The warnings worked exactly as expected on Wednesday. Several snow squalls moved across portions of the Northeast today, bringing whiteout conditions and dropping up to two inches of snow in under an hour. It doesn't look like much on radar (shown at the top of the post), but the tweet above shows how abruptly a cloud of snow can drop visibility down near zero.

Unfortunately, a snow squall in central Pennsylvania actually did cause a deadly pileup on I-80 about 20 miles east of State College. The Daily Item reported that two people died and dozens more were injured during the chain-reaction crashes.

There's only so much meteorologists can do to warn people of what's on the horizon. Just like a tornado or severe thunderstorm warning, it's not always possible to pull off the road or avoid a wreck when you find yourself driving into a snow squall. The new warnings are designed to give you an opportunity to seek safety that wasn't available before. It's all worth it if each warning helps even a couple of people stay safe.

[Top Image: Gibson Ridge]

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I graduated from the University of South Alabama in 2014 with a degree in political science and a minor in meteorology. I contribute to The Weather Network as a digital writer, and I've written for Forbes, the Washington Post's Capital Weather Gang, Popular Science, Mental Floss, and Gawker's The Vane. My latest book, The Skies Above, is now available. My first book, The Extreme Weather Survival Manual, arrived in October 2015.