I guess that title is a little long…
Yesterday’s lack of much temperature change during daylight hours here in Catalina reminded those of us from the Wet Life in Seattle and other locales west of the Cascade Mountains of our fall and winter and early spring days. Its not unusual in those locales for the temperature to stay about the same all day due to the weak sun. Here temperature as Cat mtn profile is our Catalina temperature record for yesterday, one that resembles a west to east cross section of the Catalina Mountains.
However, and only about 10% of the size of the shower line I expected later in the day yesterday, clusters of “mild” showers, not really having good shafts, moved across that had a tiny pellets bouncing off the hard surfaces. Nice. When they’re as small as they were at my house (about 1/8 inch in diameter is all) they’re generally referred to as graupel, or soft hail. These originate as ice crystals or snowflakes that collect a lot of cloud droplets on the way down and end up being little snowballs. The process is the same as opaque rime icing on aircraft, or when clouds are below freezing on mountain tops and the trees collect ice from the impacting cloud drops. You can usually crush soft hail/graupel in your hand. On the other hand, if they originate from much larger drops, the icing is clear. Won’t go into drop size differences here. Some nice examples of rime ice can be found here from a “Romantic Asheville” (NC) website that popped up under a “rime icing” search. Hmmm, “romantic”….
Next, while viewing the time lapse movie of clouds over the Catalinas and over us from the U of A campus, I noticed a nefarious cloud making machine that I did not know about before this morning. Take a look at this movie here and see this little plume on the far left of the picture tooting little clouds up into the lowest layer of clouds yesterday, beginning about 40% into the movie. At that time ther is an eruption of much lower clouds from the southeast. What kind of weather making experiment are they doing to us now? (hahahha, just kidding)
Looks like a steam plant plume ejecting a moist and heated plume right into those lowest clouds, adding some density to them. Kind of neat to see that. Also, you can see how the wind changes during the day yesterday.
BTW, some of the tallest buildings in Seattle (We calls’em, “cloudscrapers”) also put out little cloud forming plumes, adding to the body of clouds already in place. “Great!”-sarcastically spoken.