Cloudy with snow above 15,000 feet

On deck, this cloud stream for today, as presented by the University of Washington Huskies Weather Department.  As you will see, the whole stream rotating around that low off southern California has been thickening up overnight, a process that will continue, and so it looks like it will be a frequently gray day with Altocumulus, Altostratus, and Cirrus of various types piled on top of each at times.  Don’t look for much direct sunlight today.  Virga (snow), too, but no rain beyond the slight chance of a sprinkle.  Most of the clouds you see will be composed of ice crystals and snowflakes.  Also, with the wind picking up aloft today, lenticular clouds are likely again.  Look to the NE of Mt. Lem.

Don’t miss a nice sunrise shot this morning.

Yesterday’s clouds

Your approaching Cirrus/Cirrostratus deck, 1/8 inch above SW horizon at 7:13 AM
Its been overcasting Cirrus/Cirrostratus (though verging on Altostratus due to some slight shading) for a coupla hours by 3:29 PM.
You got yer Altocumulus lenticularis, left of the sun but not as far away. ABove that, there are some small Cirrus uncinus clouds with little trails of ice, quite delicate looking. 6:13 PM
Between dead queen palm killed by last year's historic February cold wave and the yucca stalk is Cirrus floccus trying its best to look like Altocumulus perlucidus. But its too high to be Altocumulus, and you can tell that by all the icy clouds at the same height to the right of that little cluster. 6:32 PM

Below, after you have read all the captions, yesterday afternoon’s sounding from our friends in cowboy-on-a-bucking-horse-license-plate-land which, BTW, I think is a pretty cool looking license plate since I’ve been bucked off horses myself a few times and when I see that license plate can say, quite haughtily, “been there; done that”, and tip my hat to the driver. In fact, the horse I was bucked off most recently kicked about as big as the one rendered on that WY license plate, and while I ended up in the hospital with a big bill, HELL it was worth it when you can say things like this and show that you are truly embedded in western culture, which I love after leaving the Temperate Rain Forest-Starbuck’s culture of Seattle:

What do you see in this sounding?

The pinching together of the two heavy lines (temperature to the right, dewpoint to the left) tells you the height of the moist layer in which these clouds formed.

How high was that, you ask, or not?

The “300” line (refers to millibars of pressure) is about 30,000 feet above sea level (27,000 feet above Catalina) and the top of the moist layer, about at the “200” line, is 40,000 feet above sea level, 37,000 feet above Catalina.
So, they were damn high yesterday, running between 27,000 and 37,000 feet above the ground. The bottom temperatures were about -35 C (-31 F), and the top about -63 C. What’s interesting is that lenticular cloud was almost certainly comprised of liquid water drops on its upwind edge before glaciating (turning completely to ice a short distance downstream from that upwind edge.) One of the mysteries of ice formation in clouds is that Cirrus clouds don’t generally form until the conditions for a droplet cloud have been met. This means that when ice is present, it is in a highly supersaturated environment with respect to ice and in spite of the very low temperatures, the crystals can grow and fall out producing trails or fallstreaks as you could see in the Cirrus uncinus clouds.

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.