Free-Range Weather

Cage-Free Weather Commentary

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‘Spaceship’ Clouds Soar Over Sisters

There were some other worldly looking clouds hovering over the Three Sisters mountains this morning. I took this iPhone photo minutes after the sun illuminated them.

Lenticular clouds near Sisters Oregon

Lenticular clouds are sometimes mistaken for spaceships. You can see why.

How Lenticular Clouds Form
The Cascade Mountains create a perfect environment for lenticular clouds; we see them quite often. Here’s how they form, courtesy of the National Weather Service’s Albuquerque office.

“Known as Altocumulus Standing Lenticular (ACSL) or Altocumulus Standing Lenticularis clouds, they are associated with waves in the atmosphere that develop when relatively stable, fast moving air is forced up and over a topographic barrier that is oriented more or less perpendicular to the direction from which the upper-level wind is blowing. This deflection creates a gravity wave downwind of the topographic barrier not unlike a wave you might generate by throwing a pebble into a pond. When sufficient moisture is present above mountain-top level, ACSL clouds develop within the crest of these mountain waves where the air is rising. ACSL clouds are continually developing and dissipating in the vicinity of the wave’s crest and immediately downwind of the crest, respectively. That is why they appear to remain stationary (hence the name) even though winds are swiftly (sometimes very swiftly) moving through the entire cloud. They are most often seen in the winter or spring when winds aloft are typically the strongest.”

Lenticular Cloud Eye Candy
As beautiful as these clouds are, a Google image search shows some even more mind-blowing photos of lenticular clouds around the world.

The images will show why they’re called lenticular clouds – many look like lenses. Enjoy!

 

 

 

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Beware the Atmospheric River!

Atmospheric River Animation :: Courtesy ESRL

Mother Nature will unleash a torrent of water at the Pacific Northwest this weekend. Portland could get up to 4″ of rain by Monday morning, a huge amount for September, typically one of the city’s driest months of the year. In fact, dozens of September rainfall records could fall due to this unusually juicy storm.

As for the “atmospheric river” (literally a narrow band of fast moving, super soggy air; in the United States, ARs take aim at the West Coast) that will make for an über-drippy Northwest weekend, it’s not really that visible on today’s satellite images. Or at least it’s not as apparent as in the images from this excellent Weather Channel post from Dr. Greg Forbes, explaining an AR event from 2010.

NOAA’s Earth System Research Laboratory AR page is worth a visit.

The river of moisture in the air (if that doesn’t sound too weird) has moisture from Typhoon Pabuk (named after a Laotian fish) as well as the usual Pacific Ocean moisture. It’s going to get very windy, too.