Happened around noon yesterday. I could see it from here that the shaft consisted of graupel mixed with some rain. Nice video of this exceptionalism-of-the-day event here from the U of AZ.
Its interesting to me, and to you, too, most likely, was that yesterday it was asserted here that there would be no ice in the “small” Cumulus clouds that were expected to form during the day. And yet we had a momentary Cumulonimbus cloud with a ton of ice and a graupel/rain/snow shaft! Huh.
In related1 distractive headlines:
Fields of gold erupt in Catalina!
Hours: 10 AM to 3 PM, M-S, otherwise closed. Why do they do that? You won’t find the answer here, so move along now…
4:00 PM yesterday, on hills west of Spirit Dog Ranch. Numerous poppy flourishes in this area. On horseback,, Nora Bowers, co-author of the popular guide, Wildflowers of Arizona. Those poppy blossoms were pretty much closed here. You really should get out and see them if you can. Well, worth it.
Rasslin’ Dogs!
“Emma” border collie, bottom, “Banjo”, border terrier mix of some kind, top. 2-day old distractive photo. More distraction. Few readers will likely go farther than this….
Yesterday’s clouds and explanations
8:22 AM. Altocumulus, bases about 14, 000 feet above sea level, or about 11,000 feet above the ground here in Catalina. The temperature at cloud top, via the TUS balloon sounding, was about -15 C (5 F), pretty cold for not having some virga or ice showing. It happens. There could be several reasons: Lack of ice nuclei in that layer? Tiny droplets, ones that resist freezing more than larger cloud drops? Lack of mixing with very dry air above cloud top (it was moist all the way up to Cirrus levels))? Mixing in very dry air at cloud top can lower the temperature of a drop a few degrees before it disappears completely, thus increasing the chance that it will freeze. That last effect is mostly operating in Cumulus clouds whose tops can penetrate relatively far into very dry layers. So, once again, we have no real answers, or maybe, all of them. It is worth noting that going to -15 C here and no ice in a Cumulus cloud is a virtually unknown occurrence, one that speaks to ice nuclei, those specks of mineral dirt that are known to cause ice to form in clouds, like kaolinite, etc. originating in the boundary layer/dirt interface being a primary culprit.
10:49 AM. In fact (!), “small” Cumulus clouds DID form yesterday, hold the ice. Quite a forecasting triumph.10:51 AM. While small Cumulus clouds pervaded the sky, there was an exception; the usual cloud street that forms off the Tortolita Mountains was trailing over Catalina and those clouds in it were at least of mediocris size (likely a km deep or so), and due to the low freezing level yesterday, getting close to the ice-forming level for Cumulus clouds here of around -10 C (14 F). Was actually outside, as you probably were, too, as it passed over, shifting gradually to the south, hoping for a drop so’s I could report a trace of rain today. “Great weather folk don’t miss traces!” (Dry-fit tee shirt in preparation….)11:00 AM. I want to keep reminding you of the prevalence of small, “docile” Cumulus clouds (ignore large dark cloud shadow at left). Just trying to balance out the cloud day picture the way media balances things out, regardless of whether they are Democrats or Republicans.
11:52 AM. Graupel begins to fall from a Cumulus congestus just beyond Pusch Ridge. It would be hard to describe the magnitude of the embarrassment I began to feel having stated that there would be no ice. I realized I had been careless as a forecaster, not really looked hard enough at the conditions, the lapse rates. It was truly humiliating to see this happen. Oh, in case you can’t see anything, the next photo is a blow of this humiliation as it began to take place.11:58 AM. Picture of graupel particles emitting from a cloud from 10 miles away. Note fine strands, a sure sign of graupel especially on day with a low freezing level and cloud bases at below freezing temperatures. Note too, ice is not visible at cloud top, something that indicated an abundance of droplets over ice crystals in the cloud, the conditions that lead to the rapid formation of graupel (soft hail).
12:10 PM. More humiliation and graupel; a forecasting disaster is in progress for all to see!
12:17 PM. Turret at left side, under fragment, appeared to be softening to the look of an icy composition that all would recognize immediately, but external ice composition not apparent yet. Note the “harder”, more cauliflower look of the turret on the right half of the photo, indicating an all liquid external composition. Graupel was forming inside that right half, though.
12:29 PM. Total icy humiliation. The “cotton candy” transition of the prior turret to “Mr. Frosty” (left of center) was complete for all to see. Looking toward Catalina, I could almost hear the laughter, “Calls himself a ‘cloud-maven’, said there wouldn’t be any ice today, and look at all that ice! What joke!” Now that the turret has become a modest Cumulonimbus, likely completely glaciated, the precipitation falling would be snowflakes (not graupel since the liquid water droplets are gone inside it) melting into rain farther down.
4:21 PM. The clouds returned to their former “small”, ice-less, sizes for the rest of the day after the humiliating exception.
6:18 PM. Revealed in yesterday’s near cloudless sunset, undulations in the ever present high altitude haze layers that circumscribe our planet. Layers like this, that are featureless except for the revealing waves causing the undulations, are extremely old, days, and are often reffered to as long range transport events because they likely traveled thousands of miles before arriving over Arizona. They are likely to be composed of old, old contrail emissions, emissions that have worked their way up in the atmosphere from over heated land surfaces, distant forest fires, and so on.
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1Its not really related but sounds like something that should be said.
While living the big western life yesterday by riding a horse, me and my ridin’ pal, Nora B., came across some water flowing in the Sutherland Wash by the rusty gate on the east side of the wash that leads to Coronado National Forest land.
So, with with a 3-5 inch rain on the Catalinas, there WAS some water in the Sutherland here in the Catalina area. It was remarkable that there was no sign whatsoever of water having flowed at the Cottonwoods at the Baby Jesus Trail head on the north side of this flow (shown below), but water was flowing in it a few hundred yards farther downstream.
Nor was there any sign that water had flowed from our big rain in the Sutherland Wash at the back gate to Catalina State Park. In fact, we saw where this Sutherland Wash water disappeared just down from the rusty gate.
So, a lesson has been learned here about wash water flows: it can be flowing modestly between two dry points. Huh. Might not see this again for some time, and it will all be going away soon. Too bad so many of us have to pass hiking or horseback riding to these rare scenes today due to a necessary Pac 12 football TEEVEE vigil beginning just after 12 noon today and lasting through midnight I think. Kind of sad when you have to make choices between two equally worthy activities like these.
Cloudwise, I hope you logged the occurrence of distant Cumulonimbus clouds in the high country on the NW-NE horizon late yesterday afternoon.
The End.
9:18 AM. The Sutherland Wash near the rusty gate.9:54 AM. The apparent source of the water, the tributary Big Rock creek a few hundred yards south of the Baby Jesus trail head at the Cottonwoods.
Sure, there was a little mischievous wind in the early afternoon, BUT, as a day in late May in Catalina/Sutherland Heights zone of Arizona, wherein the temperature is less than 100 F, well, it was pretty darn great. Another one is on tap today just like yesterday today, too. Feeling sad about the early, northerly ejections of “snowbirds” who thought because of the warm winter, May would be an inferno here and are missing some splendid weather. Doesn’t work that way. You just don’t know.
Lot of interesting clouds yesterday, too, real cold ones. Those Cumulus that formed in the late morning and afternoon started producing ice almost immediately. Wonder if you caught the first ones over there beyond the Charouleau Gap around 11 AM? They did not look as high-based as they were, thus, as cold overall, dad-gum, those cloud bottoms were running around -10 C (14 F)!
How high off the Catalina ground were they? Oh, about 13,000 feet, or about 16,000 feet above sea level (about 550 millibars). I woulda guessed, as you would have, about 8,000 feet off the ground when I first saw them forming (and not looking at the temperature and dewpoints, from which you can make a pretty good calculation of the cloud base height). From the Cowboys at the U of Wyoming, this sounding for TUS yesterday afternoon:
The Tucson balloon sounding for yesterday afternoon, launched around 3:30 PM, ascends at about 1,000 feet a minute.
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Weather Hints for Every Day Use by “Art”: You can calculate the height of a Cumulus cloud base by taking the difference between the temperature and the dewpoint, dividing it by 5, square that number, add the number you started with, and subtract the square root of 2.
DId I get the number you started with?
(Actually, stop at “dividing by 5”, multiply that number by 1000, and you’ll come out just about right. Yesterday, 85 F temp, 20 F dewpoint, leads to 65 F difference, divide by 5, you get 13, and times a thousand is an estimated CUMULUS cloud base of about 13,000 feet above you, not too bad).
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Continuing….. Since bases were so cold, tops were exceptionally cold, too, for shallow Cumulus and started producing ice when they were only about 1,000 to 3,000 feet thick, with cloud top temperatures of -15 C to -20 C (about 4 F to -4 F). Some of the highest tops, all east of us, and mostly on the east side of the Catalina Mountains, were likely as cold as -30 C (-22 F).
You can see yesterday’s small Cu spewing ice in the great U of AZ time lapse movie here. Only plays for one day, though.
You may also have noted in your cloud diary the bifurcation in the Cumulus array of yesterday. Almost no Cumulus west of Catalina, and plenty in the east half of the sky, appearing to be largest in the distance in the east. We were literally on the edge of the moist plume from the south that was hoped to end up been west, with us deeply embedded in it, and where measurable rain might have fallen here as it did east of us yesterday. Oh, well.
Today, with a low center passing over us tonight and a blob of Pacific Ocean air in it, and while that air is cold and pretty dry aloft, it will be a little more moist and so cloud bases today should be a little lower, and warmer, than yesterday’s. That means a little more water condensing in them than in yesterday’s clouds, and a greater chance of sprinkle here. Hoping for measurable, but its probably less than a 50-50 shot at that. Likely will be some thunder in the area of SE AZ, too. And, as always with high cloud bases, gusty winds that arise due to virga and rain falling through the dry air below cloud base. (Yesterday afternoon’s gales in the Sutherland Heights, momentary blasts of 40-50 mph, were NOT due to virga, but a rather to something I didn’t see coming, maybe a smallish low center–nothing really showed up on the maps.)
You will also see in the above loop that our low takes its time moving along, and will keep the skies interesting with Cumulus and weak Cumulonimbus clouds today and tomorrow, along with temperatures below seasonal norms for late May (aka, less than 100 F) ((Snowbirds left too soon; ice still melting off some areas of the Great Lakes!))
From the cloud vault; yesterday’s clouds
10:28 AM. Small Cu with lenticular type tops began forming in the lee of the Catalinas during a horseback ride with a friend, in case you didn’t think someone as cloud-centric as me could have a friend. Calm winds, then, too.11:08 AM. First ice! Can you spot it in the distance? Horse can’t believe that ice is forming already, and is rolling around in ecstasy, thinking about what it might mean for the afternoon.1:43 PM. Approaching low with air moving upward ahead of it, triggers a batch of Cirrus and Cirrocmulus lenticularis (really high lenticularis) upwind of Catalina and above some Cumulus fractus.3:18 PM. One of the more remarkable sights yesterday, were the small Cumulus clouds (humiilis or mediocris) that iced out. Look at ll the ice that formed in this small cloud, exiting on the left side, but dominates the whole cloud from this viewpoint. When you see this, it tells you how COLD those clouds are. First guess should be around -20 C at top when you see this much ice in a cloud this SMALL. Clouds having warmer bottoms, can have warmer tops that look this icy because ice forms in clouds at higher temperatures when the drops in them are larger (see Rangno and Hobbs 1994, Quart. J. Roy, Met, Soc.) Oh, yeah, baby, have some pubs!
6:58 PM. Iced out Cu/weak Cumulonimbus beyond the Gap, the Charouleau one, end the day. Shoot, a slight change in trajectory from the south, and they woulda been here.7:00 PM. Meanwhile, all quiet to the NW, no Cu whatsoever demonstrating the moisture edge we were on.
The weather ahead and WAY ahead
Now what I think is really interesting, which is almost everything to do with weather, is that the models are suggesting a tropical injection again at the end of MAY into early June, with a chance of a decent rain again. As you can see in the plot below from the NOAA spaghetti factory, a trough to the west of us and over California is a virtual certainty now at the end of May. That means the air above us will be, while quite warm, originating from the deep Tropics with the likelihood of clouds and precip coming up from there. Nice. Will keep me posted on these developments, in case no one else is reading this far.
Still a chance, a small one for a shower today, before it dries out for a few days. Mods pretty sure about rain on the Cats this afternoon, which is good. Should be a very photogenic day, with nice shots of more isolated thunderblasters.
With that out of the way…let us reprise yesterday, the good and the bad.
Only 0.17 inches here in Sutherland Heights yesterday while Saddlebrooke was getting shafted, rain shafted, that is. Moore Road at La Cholla, over there, also got more than TWO inches yesterday afternoon. You can check the interesting amounts here and here.
Another near miss here at the house. May have to sell if this keeps up. July rain here in Sutherland Heights, now at only 2.87 inches (normal is 3.5 inches) while everywhere within radius of two miles has more, for example, about 3.5 inches already over there to the south on Trotter (just S of Golder Ranch Drive), and 4 or so inches in places in and around Saddlebrooke, almost within ear shot.
Here are the effects of more July rain than here; these shots from yesterday morning down in the Regional State Park next to Lago del Oro Road:
8:05 AM. For depth perspective, riding pal, Nora B., co-author with hubby of “Wildflowers of Arizona”, admires the vegetation as she usually does being a big vegetation “author” and all that. This is how the summer vegetation is erupting in Cat Regional Park now where they have had more rain than I have. :(…. Might be worth a look down there. Think about it. Also note; she forgot to put the saddle on my horse, Jake. How funny is that? Also shows I have a friend that doesn’t mind an excessive amount of cloud chatter, unlike our former engineer, Jack R., , who had to rip his headset off when I spoke about clouds to crew members on our research flights at the University of Washington. I liked Jack, though, shown below for reasons of nostalgia.
The late Jack Russell, 1942-1998, engineer with the Cloud and Aerosol Research Group, University of Washington. He kept EVERYTHING running, though he was not fond of cloud talk! I ahd to tell him about cloud instruments that were busted, but we kidded around a lot, too, leading a grad student who observed our relationship to say, “I don’t know whether Jack loves you or hates you.”
Continuing with vegetation shots after nostalgia break:
Also had a surge down the CDO wash. I know you like to see this, you love water, so here are two shots from yesterday afternoon after the Saddlebrooke mash down:
3:17 PM. The CDO wash at Wilds Road.3:12 PM. Just as the surge passed at Wilds Road down by the mail boxes.
While the rain was a disappointment, all the other scenes yesterday caused more than 200 photos to be taken from it. Since I have termed myself, rightly or wrongly, as a “cloud maven”, I should show you ones I thought were exceptional, pretty and or dramatic. The first one, while I was looking forlornly at the Saddlebrooke cloudburst, “Why there, and not on me?”:
1:17 PM. The Saddlebrooke mash down as it was happening. Thought it might propagate this way, that is, the push of wind out of this send up a giant Cumulus to Cumulonimbus over ME, and while the sky darkened for awhile, no real cloudburst occurred.
Here’s what rips your heart out, the big, smooth-looking base indicating a good updraft right overhead but nothing comes out. The giant drops, those ones that are the biggest ones in the cloud could be coming down, defeating the updraft that’s been holding them up there because they’ve gotten too big and heavy for it, and likeyly they were even were big hail stones or giant graupel particles (soft hail), and they’re up there. but the strands of those biggest drops begin to streaming downward just a mile away you see. First, you have some sky rage seeing those strands reach the ground just a mile away, your face reddening, but then, being by nature more contemplative, resign yourself to yet another miss as now the sky fills with dead looking debris cloud upstream of you, only producing light, steady “little baby” rain at best, rain that wouldn’t amount to that much, only might be important to a flying ant colony, but that’s about it. Heartbreak Hotel, right here, overhead yesterday, started thinking about moving on again:
12:51 PM. Harris hawk takes advantage of updraft feeding Cumulus congestus base over the house. My heart was aching for those giant drop to start falling out. Did the hawk know he was safe from that event somehow wherein he might have had trouble flying? Maybe he was sensing that the updraft was too chaotic, broken up into small bits, some genetic implant passed down over the eons? Will be watching for hawks under dark cloud bases and what happens now.1:38 PM. Another Cu congestus base almost directly overhead. Was overhead a coupla minutes earlier. Not as smooth now as it was then, suggesting the updraft is getting chaotic. Darn.
Thought back, too, to all the promise, the propitious start to the day with those thunderheads, mimicking hydrogen bomb blasts, over the Mogollon Rim on the north horizon at 9:30 AM. As a cloud maven junior, you would been thinking, “THIS is going to be a special day today.” Here’s that distant scene, so fabulous to see, from Equestrian Trail Road:
9:34 AM. Giant Cumulonimbus calvus clouds line the Mogollon Rim already! This is a great sign for a “big day” with a good chance the same kind of air that let this happen there is over us, too! Watch out, Catalinas!11:45 AM. Sure enough, there they go, thunder on the Cats! Superb. Note anvil peaking out on the right side, middle. Oh,well, you know the rest of the story. Still, there were so many great cloud scenes all day. I loved it overall.
12:29 PM. Total icy humiliation. The “cotton candy” transition of the prior turret to “Mr. Frosty” (left of center) was complete for all to see. Looking toward Catalina, I could almost hear the laughter, “Calls himself a ‘cloud-maven’, said there wouldn’t be any ice today, and look at all that ice! What joke!” Now that the turret has become a modest Cumulonimbus, likely completely glaciated, the precipitation falling would be snowflakes (not graupel since the liquid water droplets are gone inside it) melting into rain farther down.
