The Lemmon cloud factory; smokin’ yesterday

The first t yesterday, from growing clouds topping Mt; Lemmon was at 9:30 AM, the earliest such event of the summer.  Cumulus that grew immediately into Cumulonimbus clouds, then one cell after another in a continuous stream came off Mt Lemmon with no breaks in the dark bases above the spawning area.  Had never seen that before.  Usually there are breaks between cells, a brief clearing on even the most active days.  And those cells really must have sprouted upward around 11:10 AM when, finally, a second blast of thunder occurred.  After that  grew much more frequent, and by early afternoon, it was almost continuous.  Very exciting, as steady rain fell here.

Here in Catalina Sutherland Heights, we were the beneficiaries of the more stratiform (flat, dissipating) part of those Cumulonimbus that stayed rooted on the mountains.  Those flat portions provided a more or less gentle rain amounting to 0.18 inches here.  However, more than an inch fell in the Mt. Lemmon and Samaniego ALERT gauges.  You can see more rain data here from the U of AZ rainlog. org home page.  It is a certainty that some mountain sites got considerably more yesterday if you saw the repeated dense shafts of rain S of Samaniego Peak, where 1.10 inches fell.  Guessing the peak (but non-measured total) was more like an 1.5 inches.  This should recharge many of the normally dry creeks and streams on the Catalinas, and keep the green coming.

Another aspect, making yesterday one of the best visually pleasing days was the absence of haze and smoke.  The sunlit Cumulus clouds that were forming away from the mountains and over Oro Valley were especially, pristinely white and gorgeous; took your breath away to see them piling up so high, and so purely, brilliantly white, so clean looking.

Here are some shots from yesterday, beginning with some “morning castellanus”, which were nice to see, too:

7:50 AM. Always a hopeful sign, Altocumulus castellanus float lazily to the north of Catalina.
7:50 AM. Always a hopeful sign, Altocumulus castellanus float lazily to the north of Catalina.
8:27 AM. Altocumulus castellanus growing into sizes that they would now be called, Cumulus clouds. Those very flat bases tell you that they are not from plumes of warm air from the ground, but are associated with a moist layer that's being gently lifted. Its clouds like these that produce our dawn thunderstorms and showers from time to time, and indicate there's a disturbance in the area lifting the air. It was another hopeful sign of a significant rain. These clouds, unlike the ones that off our mountains, tend to dissipate like Dracula when the sun comes up and burns them off.
8:27 AM. Altocumulus castellanus growing into sizes that they would now be called, Cumulus clouds. Those very flat bases tell you that they are not from plumes of warm air from the ground, but are associated with a moist layer that’s being gently lifted. Its clouds like these that produce our dawn thunderstorms and showers from time to time, and indicate there’s a disturbance in the area lifting the air. It was another hopeful sign of a significant rain. These clouds, unlike the ones that were starting to grow over  our mountains, tend to dissipate lin the morning hours after the sun comes up and burns them off.
8:12 AM. In the meantime, actual, ground launched Cumulus, from the slight amount of morning heating, were already starting to puff up from Ms. Mt. Lemmon. This was really unusual. You can tell that these are "real" Cumulus because such ground plumes of warmer air produce more irregular bases and scattered shred clouds, show more turbulence (movement) when you watch them than Ac cas clouds, the latter seeming to be almost motionless. Looks like today will be a big day for captions!
8:12 AM. In the meantime, actual, ground launched Cumulus, from the slight amount of morning heating, were already starting to puff up from Ms. Mt. Lemmon. This was really unusual. You can tell that these are “real” Cumulus because such ground plumes of warmer air produce more irregular bases and scattered shred clouds, show more turbulence (movement) when you watch them than Ac cas clouds, the latter seeming to be almost motionless. Bases of these starting Cumulus not too much different in height than the castellanus clouds in the prior shot.  Looks like today will be a big day for captions, if nothing else!

 

9:25 AM. The first Cumulonimbus is about to announce its presence with a thunderblast. No precip evident here, but aloft, next shot, is the "ice" in the overhanging anvil.
9:25 AM. The first Cumulonimbus is about to announce its presence with a thunderblast. No precip evident here, but aloft, next shot, is the “ice” in the overhanging anvil.
9:25 AM, overhead view showing that this buildup had already deepened upward enough to form ice, and was about to let go of some precip. See arrows.
9:25 AM, overhead view showing that this buildup had already deepened upward enough to form ice, and was about to let go of some precip. See arrows.
9:31 AM. Seconds after first, and completely unexpected thunderblast. Didn't look big enough. Top of Mt. Lemmon is obscured in heavy rain.
9:31 AM. Seconds after first, and completely unexpected thunderblast. Didn’t look big enough. Top of Mt. Lemmon is obscured in heavy rain.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

11:13 AM. Finally a second blast of thunder occurred in this cell, though one rain shaft after another drifted across the Catalinas, fading away as they continued across Catalina and Oro Valley.
11:13 AM. Finally a second blast of thunder occurred in this cell, though one rain shaft after another drifted across the Catalinas, fading away as they continued across Catalina and Oro Valley.
11:14 AM. A look at the downwind part of these storms where only the deep, flat portion remains. Yesterday we were lucky since it is often too dry underneath these portions for the rain aloft to reach the ground. Steady light rain was occurring at the time of this photo, while deluges were taking place on Samaniego Ridge.
11:14 AM. A look at the downwind part of these storms where only the deep, flat portion remains. Yesterday we were lucky since it is often too dry underneath these portions for the rain aloft to reach the ground. Steady light rain was occurring at the time of this photo, while deluges were taking place on Samaniego Ridge.  Rain from these Cumulonimbus portions  shown here is mainly due to melting snowflakes while the strong shafts are produced by melting hail and or graupel,that began as as frozen drops or ice particles that subsequently get heavily rimed (coated with ice) as they collide with supercooled drops in the vigorous rising portions of Cumulonimbus clouds, finding their way down as the updraft weakens or collapses entirely. I can;t believe how big these captions are getting, but it can’t be helped.
11:27 AM. While things were "humming" along from the Catalinas, Cumulus arose elsewhere in a hurry, producing these gorgeous scenes. This cloud is a Cumulonimbus calvus, that short-lived stage when a congestus begins to form ice in its top, but has not gotten to an obvious fibrous stage. That ice is present is seen in the rainshaft already pouring out of this cloud. Can you see that the very top is ice?
11:27 AM. While things were “humming” along from the Catalinas, Cumulus arose elsewhere in a hurry, producing this gorgeous scene. This cloud is a Cumulonimbus calvus, that short-lived stage when a congestus begins to form ice in its top, but has not gotten to an obvious fibrous stage. That ice is present is seen in the rainshaft already pouring out of this cloud. Can you see that the very top is ice?

 

 

 

 

 

 

 

 

 

 

 

 

 

6:52 PM. As with many active days, yesterday ended with "debris" clouds from the many Cumulonimbus clouds that formed early in the day, providing a comfortable evening. The clouds are Altocumulus, looks like at two different levels, with an Altostratus overcast above.
6:52 PM. As with many active days, yesterday ended with “debris” clouds from the many Cumulonimbus clouds that formed early in the day, providing a comfortable, overcast evening. The clouds are Altocumulus, at two different levels, with an Altostratus overcast above.  Who says Arizona is unbearable in July?  Some of the most pleasant days of the year are now.

 

 

 

 

 

 

Today is supposed to be another early starter as well with rain on The Lemmon before noon, the model runs at the U of AZ from last night say. However, the longer term model runs indicate a break in the summer rain season for a few days after today. I guess that’s when our weather can be that bit unbearable here in July.  Phooey.

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.