Late bloomers; Canadians forecasting wet spell just ahead

Yesterday was interesting because Mr. Cloud Maven person¹ gave up on ANY rain around here as late as 5:30 PM yesterday, when the sky was punctuated by only Cumulus mediocris clouds. Sure, there were large, and quite pretty Cumulonimbi to the NW-NE over the distant high terrain, but it seemed Ms. Lemmon could not take part in producing the rainfull joy those distant clouds indicated as she so often does; was a real Cb wallflower. See below.

DSCN5227 — 5:21 PM. Under 104 F skies, Cumulus mediocris over the Cat Mountains having bases way up at about 14 kft above sea level (of course, less high above sea level in future decades) produces a yawn.

5:23 PM. Nearly solid mass of Cumulonimbus tops line N horizon.

Within half an hour, things began to change. What happened? Sometimes when you see changes taking place all around you its a sign of some upper level trigger, some pattern in the upper level winds that is causing the air below to come together under it, and produce large areas of clouds and thunderstorms, a little cyclonic swirl. I can’t really see anything to explain the suddeness, so I will quit this topic rather than leaving you hanging. I think I will show you two ant cones now.

Two symmetric ant cones. But why? — Thought break: 7:57 AM, before the cloud development mystery, two symmetric ant cones. But why? There are many mysteries in life that can’t be solved, so I’m not feeling bad at all.

5:45 PM. Nice, but still, at this size can only produce sprinkles and virga. Note slight bit of virga above Pusch Ridge. This WAS a sign that these modest clouds with high bases were beginning to reach upward to the glaciation level, where ice forms, a level that changes in height from day to day generally because it is partly dependent on the aerosol content in the air. This begain happening in several clouds almost simultaneously! — 5:45 PM. Nice, but still, at this size can only produce sprinkles and virga. Note slight bit of virga above Pusch Ridge.
This WAS a sign that these modest clouds with high bases were beginning to reach upward to the glaciation level, where ice forms, a level that changes in height from day to day generally because it is partly dependent on the aerosol content in the air. This began happening in several clouds almost simultaneously! I am sure you started to get worked up, as I did.

5:58 PM. Cute narrow shaft falls from a glaciated turret that has also climbed that bit farther from the prior photo. You also can see that while there is a big fluff of ice up there above the base, the rain that falls out represents only a tiny portion of where ice formed in the cloud. This would be the graupel/hail region of the cloud, melting of course on the way down because its so friggin' hot, to be colloquial there for a second. — 5:58 PM. Cute narrow shaft falls from a glaciated turret that has also climbed that bit farther from the prior photo. You also can see that while there is a big fluff of ice up there above the base, the rain that falls out represents only a tiny portion of where ice formed in the cloud. This would be the graupel/hail region of the cloud, melting of course on the way down because its so friggin’ hot, to be colloquial there for a second.

Cutting to the chase, these surrounding cloud eruptions that occurred simultaneously, suggesting some help from above:

6:01 PM. Rainshaft fibers began emitting from this pile of Cumulus crumpulus. It was amazing since it now seemed everything was starting to rain! And rain reached the ground under this in Oro Valley. Stupendous, because now you’re looking everywhere for something to go over you.

DSCN5297 — 7:02 PM. Great looking oval base about to “unload.”

DSCN5308 — 7:11 PM. The hammer is down. Likely 0.50 inches or so in this short-lived water bomb.

: 6:51 PM. “Man with hat and beer”; sun illuminated rain in background.

DSCN5316 — 7:11 PM. Part of the spectacular electrical show last evening.

The weather ahead….from the Canadians.

This output that was churned out yesterday during the day is so good for us, I thought it was worth repeating today. Note green and yellow areas in southern AZ over this period. It represents, after our “June in August” spell, what I would like to see happen over the next week to 50 days to green things up again, if its not too late already.

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¹ Best to refer to yourself in the third person if you’re wrong or surprised about something in your field of expertise.

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.

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