Pacific Northwest – Snow squalls are brief but intense bursts of snowfall that can rapidly create dangerous travel conditions across the Pacific Northwest.
According to the National Weather Service, a snow squall is a narrow, fast-moving band of heavy snow often accompanied by gusty winds. Visibility can drop to near zero within minutes, even if roads were clear shortly beforehand. Most snow squalls last between 15 and 60 minutes, but their impacts can be severe.
In the Pacific Northwest, snow squalls commonly develop as cold fronts move inland from the Pacific Ocean, especially when colder air follows periods of rain. As temperatures drop, rain can quickly change to heavy snow, particularly at higher elevations and near mountain passes. Gusty winds can intensify snowfall rates and reduce visibility.
Mountain and foothill terrain increases the risk. Major routes such as Interstate 5, Interstate 84, Interstate 90, and key mountain passes including Snoqualmie Pass, Stevens Pass, Santiam Pass, and Siskiyou Summit are especially vulnerable. Wet pavement can quickly turn icy as temperatures fall, creating flash-freeze conditions.
The greatest danger comes from the rapid change in conditions. Drivers may encounter rain or dry roads before suddenly entering blinding snow and slick pavement, increasing the risk of spin-outs and chain-reaction crashes.
Because of the immediate threat, the National Weather Service may issue Snow Squall Warnings for parts of Washington, Oregon, and northern Idaho. These warnings urge drivers to slow down immediately, turn on headlights, increase following distance, and avoid sudden braking.
Snow squalls in the Pacific Northwest are most common from late fall through early spring and can occur even outside major winter storms.
For commuters, mountain travelers, and freight drivers, snow squalls can significantly disrupt travel with little advance warning.
