About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno
Eruption! CDO ran big last night (updated with golf balls shown in the wash))
This just in
Just back from a horsey ride with Zeus the horse. Rode into the CDO to see the surprising view that it had run bank-to-bank last night after that mighty cell passed by along the foothills. In the wash, were golf ball-sized golf balls scattered throughout the wash, indicating that it hit the planned community of Saddlebrooke with it many golf courses very hard. No golfers were found.
The Pima County ALERT gauges really did not call out that such a flow would occur from precip data around here, the greatest amount being barely over an inch, and its likely that such a flow in the CDO, bank to bank would need 2-3 inch dump in its watershed.
This morning around 10 AM in the CDO south of the E Golder Ranch Drive bridge,
———-end of updated material unless I get more updated——
After an afternoon of “steady-state” Cumulus congestus and small Cumulonimbus clouds trailed northward from the Catalina Mountains, the “Mighty Kong” erupted about 5 PM providing one of the most intimidating, yet majestic and beautiful scenes of the summer rain season; this or any.
Cloud Maven Person was indoors drowning his sorrows concerning what appeared to be a a grotesquely failed forecast of a good rain day (“about half an inch”) here in Catalina in flavorful Indian cuisine when the unexpected began to take place outside. So, the photo record is incomplete for this event. “CMP” had given up on the day.
Just measured in NWS-Style 8-inch gauge and CoCoRahs gauge:
0.12 inches was our total here in the Heights.
And, the photos aren’t quite as good as they should be, slightly out of focus since CMP didn’t adjust his camera for the dark scenes his was seeing. Oh, me. Missed the great sunrise, too, due to not having memory stick in the camera! Oh, me.
6:48 AM. The day started propitiously enough with a ton of clouds, and a line of weak Cumulonimbus heading for us from the SW -W. horizon. A small Cb ahead of this line can be seen on the left.7:14 AM. Looking at this scene, and pondering a day and evening of these, “CMP” is wondering just how many inches of rain we might have,
However this line faded, bringing only sprinkles, a trace of rain to Catalina, and was followed by a huge clearing and sunny skies, thought to be a good thing at the time. Soon, gigantic Cumulonimbus clouds would erupt to over the mountains all quadrants… Nope. By mid-afternoon, only Cumulus congestus had formed with an occasional bit of ice and rain visible, all to the north.
2:08 PM. Cumulus congestus repeatedly formed in the lee of the Catalinas. Occasionally one produced a shower. The clouds are moving from right to left in southerly flow, probably pinching together in the lee of the Catalina Mountain “sky island” as happens in the lee of real islands.4:21 PM. Another nice Cumulus congestus, but where’s are the Cumulonimbus clouds, that big line of them coming in from the S and SW? Pretty much threw in the towel, gave up except to document for purposes of training a little conversion from water to ice visual lesson in one of these turrets that climbed just high enough to convert.4:25 PM. Thus in a series is just 5 min long. Shows how fast the liquid looking cloud can convert to one that is all ice and droplets evaporate due to incursions of dry air, and their molecules race over to that ice crystal next to them. When water and ice are together, its supersaturated with respect to ice, and water molecules head toward any ice around, accumulating as a solid on the ice (a process called deposition), racing over there as a vapor.4:27 PM. A very slight change has taken place. The tight cauliflower look due to liquid water “cells” (such as those on the left side where a new turret is rising up) are disappearing, Its not very obvious at all, but you should be thinking even with this little bit of change, “There she goes! It made it to the “glaciation level” today.”
4:28 PM. Underneath this converting turret are ice particles that are just starting to fall out. Can you see the little fibers of ice? Since they don’t have a long water path to fall through, these would be pretty pristine ice, maybe only lightly “rimed” covered in frozen cloud droplets. Notice to here and in the next shot, that they are sloping a bit, indicating they’re not heavy ice particles at all. If you’re really good, you can see that the whole turret has changed, no longer looks “watery”; that tight, hard, cauliflower look has “mellowed”, the crenelations have mostly disappeared. What is a “crenelation” anyway? Better look it up….4:30 PM. Its a gonner here, no liquid water is left in that turret. The question we still struggle with is how this conversion happens so fast?
This was the last photo I took until walking out of a local Indian restaurant and exclaiming, “What? When did this happen?” It was so clear to the S-W with the exception of a single dissipating Cb that it didn’t even seem worth a photo.
6:04 PM. Hope for that great, meaningful rain in Catalina, though I am in Rancho Vistoso when shooting this.6:04 PM. Looking over the Catalina Mountains as much as I could. Look at that nice, solid base!6:08 PM. Luxurious shafts of rain begin to pour out of solid cloud bases. And look at the one protruding outward toward Rancho V. THis is looking incredible for something humongous to happen. Not sure why this happened? Was there a trigger aloft that was going over this late in the day?6:11 PM. Now, a rainbow to boot! This shot from Honeybee Canyon Park.6:13 PM. This is becoming something memorable. Losing control, photos every minute or so, but ISO level too low!6:14 PM. In the meantime a shelf of clouds, Stratocumulus I’d say, spreads westward from the storm. Would they, could they erupt, too? No, as it turned out.6:16 PM. As darkness fell at Honeybee, and the rainbow faded, it was now becoming evident that this odd late eruption was becoming something special. The rest of the time was spent racing home to be there when it hit Catalina/Sutherland Heights.6:26 PM. Got this kind of crummy shot waiting at the light at Rancho Vistoso Blvd and Oracle Rd. By this shot, I am thinking, unbelievable what has happened! This has become the “Mighty Kong” of summer storms, and its spreading away from the mountains toward Sutherland Heights!6:33 PM. Car was blasted going down Golder Ranch Drive by not blowing dust but blowing gravel as outflow winds slammed down Golder Ranch Drive. Estimated gusts 60 mph. Afraid to look at front of car this morning. Also look at how firm, solid that leading base is, telling you that there is a strong updraft feeding into it. More cells will develop downwind. That’s Jenny and Matt’s house shining in the sun on the hillside.6:33 PM. Looking from Golder Ranch Drive toward Samaniego Ridge, obscured in rain.
Well, as it turned out it was a near hit, only 0.06 inches fell in a violent few minutes of huge drops at my place in Sutherland Heights. From what I saw going by, and needing 0.44 inches on yesterday morning’s forecast of 0.50 inches in Sutherland Heights. about 500 yards farther west for this remarkable, dramatic storm would have given us that amount easily. 1.06 inches was recorded at Cargodera Canyon, NE corner of Cat State Park, and several sites in the foot hills of Catalina toward the mountains area had more than half an inch.
A quickie take on a U of AZ model run from last evening’s global data, has Cumulonimbus clouds developing to our southwest and rolling across Catalina in the afternoon. This would be, appropriately, considering the definition of the end of our summer rain season as September 30th, very appropriate.
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.
