Day 364: Mt. Rainier's incredible cloud shows make 2011's Seattle rains worth it

Fri, 30 Dec 2011 09:00:00 +0000

(Scott Sistek is a meteorologist and producer for KOMONews.com. He has been producing weather reports for broadcast and the web since 1994 and can be found on the 'Partly to Mostly Bloggin' weather blog. Keep up to date with Scott via @scottSKOMO)

Distance travelled ~ 934'891'200 km

The Pacific Northwest is known for its beauty, from the lush greenery to the tranquil waters to the majestic mountains. But no mountain is as iconic to the Northwest as Mt. Rainier, which stands just over 14,000 feet tall about 70 miles southeast of Seattle.

But while the Seattle area is world famous for its rainy, cloudy weather, at times, Mt. Rainier can act like its own paintbrush and using the sky as its canvas, bring a whole new awe-inspiring level to a "cloudy" sky. Thanks to it's status as the tallest peak around and its unique position to catch the moist jet stream, it flows in off the Pacific Ocean - Mt. Rainier can create its own weather patterns.

Perhaps the most dramatic are its frequent lenticular cloud displays. Seen maybe a dozen times a year, it still looks amazing every time it's showcased.

The cloud is formed when warm, moist air runs into the surface of Mt. Rainier. The mountain's topography forces the air upward, which cools and condenses the air -- turning it into a cloud. As the air sinks back on the other side of the mountain, it dries out and the cloud dissipates. That's why it just hangs over or near the summit area. (Although it looks like it is "hanging" over the mountain, air is continually flowing over the summit.)

Sometimes if the atmospheric set up is just right, you can get layers upon layers of stacked lenticular clouds that combine to make dramatic shapes -- many times mistaken for UFOs years ago.

Image credit: David Embrey

Locals have used this cloud as a sign that rainy weather is on the way -- many locals might think the cloud is the mountain's version of an umbrella? -- as that cloud usually occurs with west or southwesterly flow in the upper atmosphere, a usual precedent to rainy weather. However, that's not always the case -- especially in the summer. Then, it can just be an indication that we have a good westerly, marine flow and that it won't be too hot anytime soon.

Or on rare occasions, the mountain can have the opposite effect, as seen here:

Image credit: John Meadows

This time, the mountain caused some turbulence that created some sinking air in the vicinity of the mountain peak. Sinking air dries as it does so, in essence "eating" away a hole in the cloud!

Finally, when the mountain isn't creating or destroying clouds, it can just put on a show using the clouds that are already there.

In the autumn and early winter in the Seattle area, the Sun's position on the horizon during sunrise is just in the exact right spot to where Mt. Rainier will cast a shadow against a cloud layer!

Image courtesy of Nick Lippert/YouNews

So while yes, it rains a lot around here, there are plenty of advantages to living in an area with such unique terrain and meteorology!

BBC | 23 Degrees

Day 364: Mt. Rainier's incredible cloud shows make 2011's Seattle rains worth it