This shot, yesterday just after 7 PM. Light snow (virga) is falling from relatively thick Altocumulus (opacus) clouds. Just above the horizon you can see some little turrets poking up from a row of cloud bases making those clouds Altocumulus castellanus.
Bases of these clouds, according to the balloon data obtained from Tucson Int AP indicated that the bases of these clouds were at about 13,000 feet above us here in Catalina, and the temperature was about 15 degrees F (about -10 C). The tops of the clouds were about 18,000 feet above us, or at a chilly -5 F (-20 C), hence the thin, red-orange curtains of light snow illuminated by the setting sun below these clouds.
The clearing on the horizon marked the last of this “mid-level” moisture that streamed over us here in Catalina yesterday as an upper level bend in the winds, called a “trough” was passing by.
Below is a weather map of the winds (blowing along the green lines) at around 30,000 feet (300 “millibars” of pressure) and the clouds as shown on the satellite imagery. If you look closely where the TUS data is, you can see a little fluff of cloud that made our sunset. A loop of the whole sequence can be found here from our friends at the University of Washington Huskies’ Department of Atmospheric Sciences.
Speaking of the Huskies, here’s what it was like today in Seattle, my former home.
The end.
