Lennies are gorgeous

Florida has hurricanes... Oregon has lennies.

Both are generated by very powerful winds. Thankfully, — most of the time — winds that generate lennies stay at higher altitudes and cause few problems to humanity, except for airliners.

“Lennies” are known to the world of weatherfolk as “altocumulus standing lenticularis” or just “lenticulars” and sometimes appear as an enormous pile of cloud tortillas standing on the tops of the Three Sisters, Mt. Jefferson and Mt. Hood and other Cascade peaks.

Here’s how it works: Very high velocity (150 mph) oceanic winds loaded with moisture sweep eastward into Oregon and slam into the Coast Range lifting the air mass. It then sails across the Willamette Valley (which I lovingly call “The Swamp”) and then strikes the western slopes of the Cascades.

There is only one vertical direction this colossal air mass can go when it slams into the Cascades and that is up and eastward into colder air. That usually results in forming a “standing wave,” which generates lenticulars clouds, also known as “wave clouds” or “lennies.”

While the upwind or front side of the wave cloud is smooth as glass, the backside is a terrible “rotor system:” an extremely powerful rolling air mass that can tear the wings off airplanes, and has pushed many an airplane right into the ground. (Such as the four-place Mooney that crashed on the downwind slopes of Mt. Bachelor years ago.)

Savvy airplane pilots tend to avoid flying near the down wind side of mountains because they know rotors generate such roiling air masses, known without lennies as “clear air turbulence.”

Sailplane pilots, on the other hand, actively seek out lennies. This is because the system of atmospheric standing waves also involve large vertical air movements and the precise location of the rising air mass is easy to predict from the orientation of the clouds.

“Wave lift,” also known as “orographic lift,” is often smooth and powerful, and enables sailplanes to soar to remarkable altitudes and great distances. The current sailplane world records for both distance (over 3,000 km) and altitude (14,938 m) were set using wave lift.

Paul Bickle, the man who helped develope the Lockheed U-2, set a world record on February 21, 1961, when he reached 46,267 ft. in a single place aluminum Schweitzer sailplane. (If you would like to read about the glider pilot who bested Bickle’s record in 1997, go to: http://www.nasm.si.edu/research/aero/aircraft/grob102.htm).

I once got into wave lift in a Blanik sailplane while teaching a student soaring lessons over Newberry Crater back in the ’70s. It took us upwards at 1,200 feet per minute in air that was as smooth as glass. We were trying for 25,000 (yes, we had oxygen) to set a two-man Oregon record. But at 22,000 feet the inside of the sailplane’s windshield frosted over with ice and we couldn’t see anything, so we opened the spoilers on the sailplanes wings and descended.

You can often see lennies appearing in the sky miles to the east of us, because the powerful wind is rippling behind the Cascades as water does downstream of a boulder. I always wanted to fly my sailplane from Sisters to Sun Valley, Idaho, on those “ripples,” but never got up the guts (or time) to try it.

All kinds of peculiar phenomena have been identified because of lennies. They have been mistaken for UFOs as they have a characteristic saucer-like shape. Consequently, if only one lennie is seen high in the desert sky (as is often the case over Nevada in winter where the Sierra Nevada Range generates a wave system) it causes great excitement among the UFO believers.

The photo above was taken a few weeks ago as I was on my way home from Sisters. I believe the shape of the lennie was an echo of the Three Sisters to the west and caused their mountainous appearance. In the few minutes it took me to pull over to the side of the road and get to a fence post to rest my camera firmly, the lennie changed shape from the scene above to a line of lennies with no humps.

In our part of Oregon, lennies are usually as accurate an indication of weather change as: “red in the morning, sailor take warning.” They are sometimes accompanied by strong surface winds that will drop off when the sun sets, then frost overnight — which causes great consternation to those who left their tomato plants out. You have been warned…