Snow Squalls: Sudden Whiteouts on Winter Roads

Direct answer: A snow squall is a short, violent burst of snow and wind that can turn a clear winter highway into a whiteout in minutes. The National Weather Service says snow squalls are usually very short-lived, on the order of 30 to 60 minutes, and extremely intense. When one is coming, the Weather Service issues a Snow Squall Warning, a short-fused warning focused on a distinct area, which can set off a Wireless Emergency Alert on your phone. If a warning reaches you, the advice is simple: avoid or delay motor travel until the squall passes through your location. There truly is no safe place on the highway during a snow squall.

How a squall differs from a snowstorm

The difference is duration. A snowstorm can last for several hours or even days, while a snow squall is usually over within the hour. That brevity is exactly what makes squalls so dangerous: drivers set out in fair conditions and drive straight into a wall of snow. The National Weather Service warns that despite lasting less than an hour and producing only minor snow accumulations, the combination of gusty winds and quick visibility drops is extremely dangerous for motorists, frequently resulting in deadly traffic accidents. The road can also ice over in minutes as the squall passes, so conditions behind the whiteout are often worse than they were ahead of it.

How a squall differs from a blizzard

A blizzard is a sustained event: blowing or falling snow with winds of at least 35 mph reducing visibility to a quarter of a mile or less for at least three hours. A snow squall needs none of that endurance. It is a fast-moving burst, often arriving on an otherwise fair winter day, and it is gone before a blizzard warning would ever be issued. That is why the two warnings exist side by side: a blizzard warning tells you a long, dangerous event is coming, while a snow squall warning tells you a short, violent one is already here or about to be. Do not wait for blizzard conditions to take a squall seriously.

Why your phone buzzes

Snow Squall Warnings are short-fused and focused on distinct areas, much like tornado and severe thunderstorm warnings. They are also one of the few warnings the National Weather Service issues that automatically alert cell phones through the Wireless Emergency Alert system, precisely so drivers heading into danger get the message in time. If your phone buzzes with a snow squall warning, treat it as an instruction about the road ahead, not background information: a squall is occurring or imminent where you are, and the safest response is to stay off that road until it passes.

If you are caught in one

If you are already driving and cannot exit the road in time, the National Weather Service advice is to reduce your speed, turn on your headlights and hazard lights, and allow plenty of distance between you and the car in front of you. It is also best not to slam on your brakes: with slick or icy roads, hard braking can contribute to a loss of vehicle control and increase the risk of a chain-reaction crash. Keep your speed low enough that you can stop within the distance you can see, and take the first safe opportunity to get off the road entirely and wait for the squall to pass.

Before you travel

Check the latest forecasts and warnings on weather.gov before you start your car, and check warnings on our weather alerts page. Prepare your vehicle for winter and carry a car emergency kit, so a delay caused by a squall is an inconvenience rather than an emergency. Squalls are most dangerous precisely because they arrive fast on days that look fine, so the habit that protects you is checking the forecast even when the sky looks clear. For the wider winter plan, read our severe cold and winter storm safety guide.

Frequently asked questions

What is a snow squall?

A short, intense burst of snow and gusty wind, usually lasting 30 to 60 minutes, that creates sudden whiteout conditions and icy roads in minutes. Unlike a snowstorm, which lasts hours or days, a squall arrives fast and is over quickly — but it is extremely dangerous for drivers while it lasts.

How is a snow squall different from a blizzard?

A blizzard is sustained: winds of at least 35 mph with visibility at a quarter of a mile or less for at least three hours. A snow squall is a brief burst, usually under an hour, that can strike on an otherwise fair winter day. Both can white out a road, but only the squall arrives with almost no warning.

What should I do if a Snow Squall Warning is issued while I am driving?

Reduce your speed, turn on your headlights and hazard lights, and leave plenty of distance to the car ahead. Do not slam on your brakes on slick or icy roads. Take the first safe opportunity to get off the road entirely and wait until the squall passes.

Why does a snow squall warning buzz my phone?

Snow Squall Warnings are one of the few warnings that automatically trigger Wireless Emergency Alerts, so drivers heading into danger get the message in time. If your phone buzzes with one, a squall is occurring or imminent in your area — delay travel until it passes.

Sources

• National Weather Service - Snow Squall
• National Weather Service Green Bay - Winter Weather Safety
• National Weather Service Baltimore/Washington - Winter Weather Awareness Week

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