UFO Invasion? Strange 'Fallstreak' Clouds Seen Over Washington

BELLINGHAM, WA - A series of frankly scary, strange cloud patterns were seen in skies across Western Washington and British Columbia on Monday — so strange, no one would blame you for thinking aliens were invading Earth.

The National Weather Service in Seattle quickly identified the clouds as "fallstreak hole clouds" (other names include: "punch hole cloud," "skypunch," and the straight-forward "cloud hole"). These happen when ice crystals form in clouds, and then surrounding water vapor evaporates.

Or, less scientifically, it looks as if a flying saucer just plunged through the clouds:

Here's the full, non-apocalyptic explanation of fallstreak hole clouds from the Weather Underground:

They form in these high to mid-level clouds which are comprised of tiny water droplets that are below the freezing temperature but have not yet frozen (called supercooled water droplets). Airplanes passing through the cloud help the supercooled water droplets freeze. Air expands and cools as it passes over the wings and the propellor blades, decreasing the ambient temperature just enough to allow the droplets to freeze. The ice crystals grow and start to fall, while causing the water droplets around the ice crystals to evaporate. This leaves a large hole in the cloud with brush-like streaks of ice falling below it.

One fallstreak cloud was seen over Bellingham on Monday afternoon, but a satellite image of the Pacific Northwest showed several of the clouds headed southeast.

Image courtesy NWS Seattle