Too much “Altostratus cumulonimbogenitus”

Yes, that really is a cloud name;  kinda silly really.  Oh, well….

First, since there wasn’t enough rain here to make me happy–there wasn’t ANY in Catalina yesterday, I thought I would start out by making people feel better with a “Clouds R Fun” photo from yesterday.  Here are two “puppy” clouds, side by side, ones I thought might grow up to be Great Danes, but didn’t.  Still, they’re awfully cute anyway.  You just want to cuddle them.

Now that we’re all feeling that bit better thinking about puppies, we can move ahead to solving what happened and why Mr. Cloud Person’s expectations of signicant rain in the immediate area were not realized.   If you are a really good sky watcher, off in the distance, large Cumulus and Cumulonimbus erupted explosively well before noon.  I was so happy!  This could be a “totally awesome” day, I thought!   Look at these photos taken  at distance “Cbs” to the south of Catalina before Noon.

In the first shot taken at 11:45 AM, to the right, a full blown “Cb”, to the left partially hidden by Pusch Ridge, Cumulus congestus clouds.  Now look at the next photo in that same direction.   That group of Cumulus congestus beyond Pusch Ridge have exploded into a massive Cb with a giant anvil (“incus”)!  Areas near Green Valley, toward which these photos are taken,  got 1-1.5 inches.

But there was something pernicious going on right in front of my eyes; those huge anvils (“inci?”) that were being ejected by these explosive thunderheads.  Those can actually be a BAD thing because if they spread over the whole sky, they tend to kill off the Cumulus clouds underneath them by shading the ground, often teamed up with a subsiding air pattern.  While the air rushes upward in hot spots in these complexes, there must be compensating downward and cloud killing motions somewhere around it. It seemed to be the case as that huge complex S of us yesterday afternoon fizzled out and left a giant mass of—you’ll want to exercise you tongue before trying to pronounce this—“Altostratus cumulonimbogenitus” spread over the sky in the afternoon (last photo of a Seattle-like sky over Catalina). This smooth layer cloud is really just the remains of thick anvil clouds from all those “Cumulonimbus capillatus incus” clouds earlier in the day to the south of us.

Were there huge storms relatively nearby yesterday?

You bet!  Take a look at this loop from IPS Meteorstar, one that combines radar echoes and shows the spread of the thunderstorm anvils, the “whitest” and coldest topped clouds in this loop.   Notice what happens near the southern Arizona border about the time the second two photos above were taken.  Just an explosion of grouped thunderstorms with their flash floods that we call “meso-scale” complexes.  With luck, a bit different weather pattern, we could have been under that. Darn.  We’re still having conditions to produce large severe storms.  Maybe today will be our day.

Here’s are the cloud signs for today for why it is especially ripe for high rainfalls:  Its moist through about 40,000 feet above the ground and the cloud bases are LOWER today than yesterday.

How could you tell that just gawking at the sky and our Catalina mountains?  Well, you got yer Cirrus (high level moisture), you got yer Altocumulus (mid-level moisture) and you got yer Stratocumulus, some of which are topping Mt. Sara Lemmon (low level moisture)!

Now this last factor is really good in indicating the chances of 1-2 inch rains under the main shafts of our thunderstorms today–nothing too unusual, however, for AZ .  Lower cloud bases means warmer cloud bases, and warmer cloud bases in the summertime is like adding a furnace inside those towering Cumulus clouds due to heat released when condensation occurs.  And the warmer the cloud bases, the more water that is being condensed inside them.  Is anybody still reading this? Better quit here; I’m even getting saturated.

 

The End.

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.