Been dreaming about a white Lemmon for quite awhile, ever since the New Year’s Eve snowstorm here. Finally got one yesterday, as we saw. Here are a few extra Lemmons for you:
3:11 PM.3:42 PM.Finsihing off here with an orange Lemmon, if that’s possible, at 6:50 PM.
Yesterday’s clouds
(includes photo of a small, cute dog)
7:58 AM. Not one, but two layers of Stratocumulus.7:58 AM.7:59 AM. Interesting how the scattering of diffuse light through the clouds lights up our cherished cholla cacti.8:57 AM. Paper flowers still going…. They’re not used for making paper, btw.9:30 AM. Occasional sprinkles fell from these clouds. Likely was due to ice, but texture if the precip also suggests drizzle formation (or warm rain processes, wherein larger cloud droplets collide to form drops big enough to fall out.) I hope your cloud diary also reflected this ambiguity.3:42 PM. Later in the afternoon, small Cumulus provide the light and shadow show on the Catalinas, one of the best things about living here. No ice evident.
Looking closer, I hope you recorded the slight fall streaks (fallstreifen, ger.) in the scene above. It would have been quite an important observation for you to have acquired since these small clouds had not shown ice prior to this time. See below for the VERY delicate trails emanating from this Cumulus mediocris cloud; look between and above the orangish rock faces on the top of Sam Peak and a bit to the left:
6:48 PM. Fine snow trails fall between and above the two orange colored rock faces on the left side.The baloooooon sounding launched from the U of AZ at 3:30 PM yesterday. Where the lines pinch together was likely around cloud top, or about -10 C, close to the natural ice forming temperature we usually see here in AZ. More ice fell from layer clouds to the north at sunset, that were colder still.
The weather ahead, way out there
Next rain chance in about a week. Looks like May will start out hot, but “too hot not to cool down”, to quote Louis Prima and Keely Smith doing the Porter songbook, and pretty much that cool down before the month is hardly underway. I am sure lingering snowbirds, not wanting to have their feathers singed, will be glad to receive this news.
How can we say that with any acuity?
Check the spaghetti! Looky below at how troughy the flow is by about the 8th of May (red lines dipping toward the Equator along the West Coast). No extreme heat then, just normal warmth or below average “warmth.” This is a circulation pattern that persists, too. And with “troughy”, there’s always the chance of a rogue rain.
Valid on May 8th, 5 PM AST. No heat here. Some snowbirds have clearly left too early IMO.
Gasp these late April totals from the Pima County ALERT gauges, as of whenever you look, along side our Sutherland Heights total, as of 7 AM now, of 0.58 inches. This total is about the normal for the month of April here. Fantastic. Several nearby mountain and Catalina foothill totals are well over an inch with Oracle Ridge having 1.50 inches! However, the top of Ms. Mt. Lemmon is reporting nothing, which means the precip there is falling as snow. Nice couple of thunderblasts last night between 1:30 and 2 AM, too.
Yesterday, the latest wrf-goofus model (executed by the U of AZ at 11 PM AST night before last), had no rain in Catalina, and only a pittance in the mountains east of us.
Still a chance for measurable rain during the day today, too, but it’ll be gone by tomorrow, and it’ll likely bt a long time before rain returns.
Yesterday’s clouds
2:53 PM.2:54 PM. Cloud street again.5:39 PM. Disappeared for awhile, then came back.5:52 PM. The look of a storm, Altostratus above Cumulus and Stratocumulus.
The End, for now, anyway.
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1Total is from a CoCoRahs gauge, not the Davis Vantage Pro online tipping bucket, which registers slightly low.
Well, those showers were a surprise to “me and my model” yesterday morning, at least the one I looked at just before going on the air. There were no upstream echoes in the clouds upwind of us, either, something normally seen before cool season showers get here. Fortunately, I was able to get in a prediction that rain would fall just as the drops began coming down.
However, there are a few times when that bit more lifting as the air moves from the lower ground to the southwest of us to here can trigger precip; the tops get that bit colder, form ice, voila, out drops the rain (and snow). That’s probably what happened yesterday to cause a sudden development of light showers, “all quads” it seemed.
Cloud tops may not have gotten colder than about -10 C yesterday, too, and so our rain likely fell from ice crystals rarely seen in Arizona, hollow sheaths and needles (columnar crystals), which have to be in big aggregates before they can form a drop big enough to reach the ground. So, not only are they rare here, but there also have to be a LOT of them )10s to 100s per liter in the clouds) for them to form big enough snowflakes so that a drop reaches the ground. In fact, when columnar ice crystals form in clouds, they often do so prolifically so that, at least at the University of Washington where the present Arthur worked for about 30 years in airborne studies of clouds, needles and sheath crystals were always associated with the highest concentrations of ice crystals that we observed. Some of those rare ice crystals were STILL forming in the clouds above us near the time of the second sounding, shown below, launched at 3:30 PM! That was really shocking!
This ice crystal happenstance, and the surprise light showers, made yesterday particularly worth commenting on from this cloud pulpit, if that’s what it is. Some nice examples of needle and hollow column ice are shown here at CalTech. These kinds of crystals are rare in Arizona because they require larger (greater than 23 microns in diameter2 in clouds at temperatures between -3 and -8 C. Like the needle crystals themselves. Since the clouds were shallow, one has to speculate WHY the cloud droplets might have been extra large. It may have been that there were few of them (seems kinda unlikely this far from clean oceanic air. More likely, those clouds had large (micron-sized) dust particles in them, known to help form larger cloud droplets. So, I’m guess those clouds were helped by dust so’s they could have larger droplets in them, ones big enough to help produce ice splinters consisting of needle and hollow sheath crystals at such high temperatures (higher than -10 C).
Our U of AZ model predicted soundings were pretty much what we saw, too, cloud capped by a stable layer that got stronger as the day went on, and the air drier above it. Below, from IPS MeteoStar, these TUS soundings from yesterday morning and afternoon.
Baloon1 sounding launched from the U of AZ yesterday morning around 3:30 AM AST. Shows tops were marginal for ice in AZ at this time.The baloon sounding from the 3:30 PM AST launch from the U of AZ. Where the lines pinch together is the top of the boundary layer where cloud tops were, -10 C. A few shocking rain drops fell in Catalina (stop light at Oracle and Golder Ranch Drive construction zone) soon after this launch (4:22 PM) from a shallow complex of Cumulus/Stratocumulus clouds. Unbelievable. Carried out a little photo documentation when I saw them on my windshield to record the remarkable event. It was pretty darn exciting, and I hope for you, too, if you felt a coupla drops about that time.
But let’s drag this out and look at yesterday’s clouds now…
6:13 AM. Clouds much fatter than expected this morning, but nothing to worry about. Not gonna rain. Mod says so.6:14 AM. Looking to the north, not much, just some harmless Stratocumulus. Maybe will go inside, not think for awhile….6:33 AM. Its raining over there, cloud has a tremendous amount of ice in tops (that smooth area to the right and above Pusch Ridge. Unbelievable, since the tops aren’t that high!6:34 AM. Another soft turret filled with ice trailing light rain! That softness suggests to this observer that they are not the usual ice crystals, but rather jillions of needle and hollow column (sheath) crystals, too.7:38 AM. By this time, the light showers were everywhere, especially in Oro Valley and drifted over Catalina for the next few hours. Here. light rain, not haze, produces crepuscular rays.3:29 PM. By mid-afternoon, the clouds had gotten shallower, not warmer though, as bases rose more than the tops did. Tops were still around -10 C at this time, but the bases were higher, above the mountains, as you can see here. And, we had our usual “mountains shadows” (would be a nice motel name) light show.
During the afternoon, a nice cloud “street” formed, came all the way from Mexico way, one that spawned a little more anomalous ice, and those few raindrops; see below for evidence if you don’t believe me.
3:39 PM. Long cloud street trails over Catalina. Isolated veils of ice formed, with a few drops reaching the ground. See car front windshield below for the shocking evidence.4:20 PM. Raindrops fell on windshield as part of the long cloud street still in progress overhead. Grabbed camera immediately, of course, as this astounding event occurred! Was at the Golder Ranch Drive and Oracle intersection “war zone” as we would call it these days. (Hope they’re done before 2020. :}
BTW, here’s our cloud street as seen in the “visible” satellite imagery at 4 PM AST, just before the drops fell on my windshield. You can see that it originated near the border with Mexico, as many things do.
The End, except I think there will be some more rain tomorrow morning, trace to quarter of an inch are the bounds, meaning about a tenth is the most likely amount from this cloud pulpit.
The End, again.
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1I prefer this spelling today; more “o’s” than “l’s” in that word make you think more of a thing full of air; maybe a few more “o’s” would help even more, too, like “baloooon”…
2That size is considered “large” for a cloud droplet, and lab studies have shown that they splinter when they hit something, like soft hail, also called “graupel.” Splintering is thought to lead to all those extra ice crystals at temperatures between -3 and -8 C.
Clouds got more enthusiastic than expected here yesterday, reaching sizes big enough to produce light rainshowers to the NE of Catalina, and THUNDER just after 6 PM up toward Oracle town! Nice. Looks like a small Cumulus, postcard day today in Catalina. Cloud tops marginal for ice, holding around -10 C, capped by subsiding, dry air. (Except for the light showers this morning between 7 and 9 AM; this note added at 7:32 AM when I saw a shower developing to the west over Oro Valley!) This, from the U of AZ model. Since the air is colder aloft to the N today, ice will likely be seen in some clouds up thataway.
7:26 AM, looking toward Samaniego Ridge. Water still flows down from the upper reaches of Samaniego Ridge from the winter rains. You’ll have to click on the image to really see this water.1:22 PM. Small Cumulus get underway.
2:25 PM. While Cumulus occasionally filled in, they weren’t getting any deeper. No ice visible at this time.4:11 PM. There was plenty of ice around at this time, but most of it, as shown here above and to the left of the right most light standard, ejected out the downstream end of the clouds. This meant that the ice crystals had no chance to grow inside a cloud, but were thrown out into dry air and evaporated. Wider and taller clouds were needed for even decent virga to happen.5:38 PM. Those deeper and wider clouds began to develop. Here a sprinkle or light rain shower reaches the ground toward the town of Oracle. Fifteen minutes later, thunder was even heard coming from this complex.6:45 PM. The thunderstorm that occurred near or over the town of Oracle weakens and recedes. For a time it appeared building Cu overhead of Catalina might produce a sprinkle, but no.6:50 PM. The day ends quietly.
While depressed about a waterless trough approaching us today, well, maybe a few hundredths is all that can fall from its passage, I thought I would depress you that bit more by showing how our smoggy world is connected.
Perhaps you thought, wrongly, of course, that the smoke layer above us yesterday was from from southern California or Mexico. After all, smoke and haze does leak into the SW deserts from the LA area all the time.
But no.
That layer was too high up (estimating above 20,000 feet above sea level); it was in a very noticeable thin, dark layer to the southwest in the morning, then spread over the sky during the day.
Maybe yesterday morning after sunrise you even thought it was “cirrostratus nebulosus”, that vellum ice cloud with little internal structure.
Let us look at the smoky evidence (before any clouds formed):
9:51 AM. Its not Cirrostratus nebulosus. There was no indication of cold clouds over us, as would be the case with Cirrostratus nebulosus.9:51 AM. a thin smoke vellum covers sky. Best seen toward the sun. Looks dark on edge when the sun is shinning on it, like to the southwest yesterday morning.4:21 PM. Still there, ABOVE the Cumulus fractus, though the Cu fra is also impacted by smoke. The faint undulations are above the Cu fra, and show gentle waves, the kind that exist above the “boundary layer” and are not mangled by surface convection and Cu formation.6:46 PM. “Ugh” sunset. Smoky haze layer now really evident. More waviness, betraying its high altitude.6:49 PM, looking SW. Ditto.
Below, a satellite looks at our smog invasion, as indicated by the values of the “Aerosol Optical Depth” (AOD), how muddy-looking it is from up there. Blue is clear, anything else is muddy. Red is incredible. You can see it streaming in from the southwest yesterday morning, 5 AM AST. An annotated version below, in case you’re lost.
Same image, annotated.
Now, let’s see where it came from using the NOAA HYSPLIT model for obtaining backward trajectories for FIVE days, ending at yesterday morning. We saw it streaming in from Mexico, but did it really originate there? Nope.
Backtrajectories for three parcels of air at three levels above us, ending at 5 AM AST yesterday morning. The model thinks that two of the layers above us started way up above 30,000 feet some five days ago, but were lower when they arrived over us. The stuff about 20,000 feet above us (the red line), started lower than those, but was rising as it got to Tucson, that due to passing through the trough that’s approaching us this morning, One would expect to see more layering of smoke today.
And there you have it, “smog across the waters”, the Pacific ones.
Hard to say how it got up there, often its due to forest or other fires in Asia, rather than comes from low level urban smog. It gets here mostly in the springtime because the low pressure systems with their rain belts are weaker, less able to process smog via rain out as smoke layers cross the Pacific, while the jet stream is still quite strong and can carry layers a long ways in a hurry.
Dust plumes from Asian deserts like the Gobi also make it across the Pacific to the US from time to time, again, mostly in the springtime.
—–end of smoke diary module——
Expect shallow to moderately deep, high-based Cu today, ones that will form ice and virga, and of course, it will be windy as well. Seems too dry for much anything to reach the ground here in Catalina below those high bases, a pitiful situation with such a strong trough passing over us today. Check out the U of AZ model for further details. Maybe we’ll see some great lenticulars above the Cu tops…
After a sumptuous day of Cumulus and Cumulonimbus clouds yesterday, a long period mostly devoid of any Cumulus clouds is expected to begin after today.
Cumulus congestus and Cumulonimbus clouds rose early and often to the north of Catalina, but did not launch off of the Catalinas as expected with a minor exception that only the best of the CMJs would have noticed. If you want to see the whole day, devoid of blabber, take a gander at the U of AZ Weather Department time lapse film here. Very summer-looking video yesterday with the Cu moving from the SE as we see on most summer rain season days.
9:30 AM. Heavy Cumulus clouds erupt on the high terrain NNW-NE of Catalina.9:53 AM. Cumulus over the Catalinas are beginning to shoot small turrets up.
10:45 AM. Lookin’ good for a Cb launch at this point, especially with all the Cbs on the N horizon by this time, indicating unusually fertile grounds for a big cloud growth on the Catalinas.
1:58 PM. As Bob Dylan wrote, “You Ain’t Goin’ Nowhere”, you Cumulus clouds. But why? Too dry aloft right here over Catalina, and less so to the north? Probably.
The wait for an explosive development over or near the Catalinas went on and on with nothing happening. In the meantime, Cumulonimbus clouds were getting closer and closer to the north of us.
2:22 PM. As close as they got. Cumulonimbus calvus (“bald”) top about 20 miles N of Catalina protrudes above the lane divider line on Oracle Road.3:25 PM. One pitiful Cumulus congestus cloud rose up to ice-forming levels, glaciated and died. Its head passing almost directly over the house, as you will see. Here, no ice is evident externally, but its in there if you could judge how much higher this cloud was than those that preceded it.3:30 PM. Dissicated by the surrounding dry air, that poor turret dies, leaving visual evidence of the ice inside. Can you see it? Anyone under this would have felt a few drops of rain at this point.3:33 PM. Only three minutes later, death is almost complete, leaving more visual evidence of the ice that had been inside it. The cloud in the foreground obscures the highest part of the turret that shot up so much higher than its nearby brethren. Feeling pretty sad here.3:33 PM. Life-size close up so that you can see what I am trying to describe. The faint veil between the cloud shreds is composed of ice. The shreds are droplet clouds, but also with some ice in them.3:42 PM. The icy top of that lonely turret finally shows.3:42 PM. Close up, just about looking straight up.
3:43 PM. Frame from the U of AZ time lapse camera showing icy top over Catalina. Was it the “Little White Cloud That Cried?”, produced a few raindrops? I think so, since you really have to have ice nearly all the time around these parts to get rain. I’ve spent a LOT of time on this cloud. Maybe its because we won’t see anything like this for so long now.
While the rain at the beginning of April has disappeared altogether in recent model runs (ones after 11 AM AST yesterday), it will likely return in the future. Also, mods now think some rain might occur a week from now.
Litterfolk continue to prefer Bud Light cans and bottles over craft beers. While its interesting to make these surveys, CMP reminds readers, “Litter responsibly; in a receptacle.”
The trash you see here was collected during a single trip to the Sutherland Wash and back.
The Sutherland Wash Flow Report
A little water has resumed flowing in the Sutherland Wash hereabouts due to our recent rain:
The Sutherland Wash yesterday near the Baby Jesus Trail Head. Dog head also included.
The Cottonwoods Blowdown Report
The wind damage below was confined to an area only about 100 yards wide, and at the bottom of a small canyon leading down from Samaniego Ridge. Once suspects that a narrow microburst, some supergust, hit just in here as a rivulet of air collapsed down from the east-northeast after having gone over the mountains. It was likely further funneled by that little canyon and blasted these poor trees.
Note shoe size in lower left of photo.
Yesterday’s clouds report
Cumulus got off to an early start, a line of Cumulonimbus to the north providing a hint of what was to come when the sun came out.
7:06 AM. Cumulonimbus line the northern horizon.7:07 AM. An interesting set of very narrow shadows appeared briefly. The darker one might have been due to a young contrail. They seem too narrow to have been caused by cloud turrets.10:34 AM. Cumulus congestus clouds arose early and often on the Catalinas, becoming Cumulonimbus clouds later in the afternoon.12:07 PM. Some Cumulus congestus clouds sported the rarely seen “pileus” cap, suggesting stronger than usual updrafts pushing moist air above the top upward slightly, just enough to form a sliver of cloud.12:07 PM.12:54 PM. Before long, 47 minutes actually, big complexes of Cumulonimbus capillatus had formed to the north, and distant SW of Catalina.1:47 PM. While pretty, but this expansive Cumulonimbus capillatus incus (has an anvil), pointed to a potential rain-inhibiting problem: perhaps the exuberant convection would lead to an over-anvilated sky? Yes, it became a concern, I’m sure to all of us. Cumulus cloud killing anvilation.3:54 PM. While lightning forked in distant rainshafts, over-anvilation pretty much terminated any chance of rain in Catalina due to Cumulus buildups. The anvil debris clouds are termed, “Altostratus opacus cumulonimbogenitus.” Only clashing winds due to outflows from showers could possibly force rain now.4:43 PM. Clashing shower winds (SW in Catalina, NE towards Oracle) did produce a large final shower in the area. That lower cloud on the left side marks the area above and a little behind outflowing NE winds. Sadly, that wind push from the NE, one that could have launched a big shower here, fizzled out.
The weather ahead and WAY ahead report
More pretty Cumulus clouds today, likely some will reach Cumulonimbus stage (develop ice) and shower here and there. Flow will be off the Cat Mountains and so we here in Catalinaland are a little more elgible for a shower building on those mountains and drifting this way.
WAY ahead?
The models continue to occasionally produce a very heavy rainstorm in southern AZ on or about April Fool’s Day, once again appearing yesterday on the 18 Z (11 AM AST) run. See below, a really pretty astounding prediction again. This system comes from deep in the Tropics, so deep you wonder if it might have some hair from a giant Galapagos tortoise with it. It comes and goes in the models, but there is continuing modest support for a low latitude trough to affect Arizona in the “ensemble” outputs, or “spaghetti” plots.
The End
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1“The Cottonwoods” is a local name given to a portion of the Sutherland Wash next to the Baby Jesus Trail Head. It appears on most trail maps, and is a popular spot for underage drinking parties on weekends.
Drops, that is. There were about 140 or so the night before last, noticeable only if you left your dusty car outside, and TWO drops yesterday between 4:08:22 and 4:08:51 PM, as the last remnant of a shower cloud moved overhead from The Gap (the Charouleau one).
You HAD to be outside running around to encounter them, I do mean “running”, to increase the sample volume and your chances of detecting a drop in marginal rain situations. You have to “want it”, to be the best you can be about traces, that is. And I wanted to report another trace real bad. I love to report traces of rain, the most underrepresented rain event of all, the poor relative of measurable rain.
And, of course, more shower chances ahead, March 17th through the 20th, as remnant of the upper level trough that produced our last two days of clouds and sprinkles returns to us like a boomerang after producing generous rains in Mexico. It also meshes with a weak trough from the Pac at this time, so its pretty troughy for a few of days. Nice.
Today’s cloud pic archive will begin with the sunset the evening before last, since domestic responsibilities1 prohibited posting the usual tedious cloud array yesterday.
6:32 PM, March 12th. Rosy glow, a nice name for a female western singer, as well as a sunset, that bloomed late in the day (was less spectacular than expected that day, but still something). Lots of virga spewing out of iced up, high and cold-based, Stratocumulus clouds. Since you wanna know more, the TUS sounding indicated bases at -10 C, and tops at -20 C (4 F), that latter temperature explaining all the ice that formed that day.
Yesterday’s clouds
The temperature structure aloft was pretty much the same as the previous day, except that cloud bases were slightly lower and warmer, “only” -7 C or so, with tops again around -20 C (4 F), plenty cold enough for plenty of ice and virga from the modest Cumulus and Stratocumulus clouds that developed later in the morning.
Rainshafts were that tiny bit heavier it appeared, seeming to reach the ground with more gusto than the similar day before.
11:44 AM. Groups of small Cumulus began forming over the mountains.1:23 PM. Cumulus and Stratocumulus fill in the sky. Slight virga is apparent if you look really hard.2:29 PM. A light rainshower douses Marana and vicinity. Note the rumpled top of this cloud suggesting dominance of the water phase with just ice underneath. The dark bottom of the cloud is often called a “cloud base” by pilots, but is really the transition zone where the snow is melting into the more transparent rain and is not really a Cumulus cloud base, one composed of droplets forming in an updraft, as in the prior photo.
3:58 PM. Rain shaft on The Gap. Can you detect it? Its coming right at us! Here’s where the responsible observer realizes that he must be outside, or provide another means of detecting isolated drops as the cloud head begins to pass.
And, below, why we love our mountains and desert, especially on these kinds of days. About this time, the “light show” begins, ending with a dramatic sunset.
6:14 PM. Even the horrible becomes beautiful in the evening light.
The End
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1I had to take my mom, whose she’s really old and fragile, to the doctor , and then to the supermarket. This personal information posted for the purpose of inducing empathy in case I have a really bad forecast. People will remember that I take my mom places.
First, you should always begin your day, not with the breakfast of champions, but by reviewing the prior day’s clouds in the University of Arizona time lapse movie. Here’s what you will see:
Lots of Cirrus, varies species, Altocumulus, Cirrocumulus, a high temperature contrail go through some Cirrocumulus just after 4 PM, and flocks of medium-sized Cumulus clouds emitting ice.
First, one interesting, but inexplicable Cirrus scene. I know you were likely going to ask Mr. Cloud Maven Person, “Hey, what gives here?” I get a lot of calls like that1.
1:15 PM. That tuft of Cirrus on the right seems to have trails of ice falling out then coming together, almost like they missed each other and want to be together as snow trails until evaporating away. There is no explanation for this2 so I will next post a distraction. (Remember, when you can’t explain something, and this is a life hint, you can either talk around the question without answering it, beginning with, “I’m glad you asked me that question…..” when you’re lying and really NOT glad, or launch a distraction. Here, we launch a distraction.
“I don’t know how that happened; let look at a flower instead”:
Seen yesterday morning on a dog walk, evening primrose. Pretty restful image; problems gone…
In the meantime, after being flustered over a cloud in the early afternoon, those Cumulus clouds aroiund, only two or three thousand feet thick were beginning to snow away, first way off to the south of us, then downstream of the Cat2 Mountains.
Here is the rest of your interesting and learningful cloud day yesterday:
7:17 AM. Riff of Altocumulus castellanus/floccus to the north. Remember in Cloud Maven’s Person’s poster-sized cloud chart it says when you see this cloud it could rain in 6 to 196 hours, as it does for all the cloud formations in it.7:18 AM. Iridescence in a patch of Cirrocumulus, indicating that the droplets comprising it were very tiny, less than 10 or so microns in diameter (one tenth the diameter of a human hair). It could rain in 6 to 196 hours when you see this cloud….9:43 AM. Cirrus, various species/varieties overspread the sky. Blockage of some Cirrus here by a bird of some kind, lower center.
Moving ahead…..
1:14 PM. The cloud-maven cloud indicator blimp was positioned to draw your attention to some building Cumulus clouds southwest of us. No ice evident, but was soon after this shot.
2:47 PM. Cumulus complex shows no ice, but its up there inside, as you would have known from looking at other similar-sized clouds.3:02 PM. “Droop, there it is!” Virga, there it is, drooping out just below the farthest cloud bottom downwind end of this cloud stream.3:17 PM. Virga’s pretty obvious now (above that protruding tree in the distance. Cloud that produced this virga likely no thicker than the white backed one at the start of the cloud stream, etimated depth, 2000-3000 feet. Bases, however, were about -8 to -10 C (18-14 F)! Tops, of clouds even that shallow, were really COLD, maybe to -15 to -20 C (down to 4 F)! But you would have guessed this anyway based on the amount of ice coming out of such shallow clouds. Sorry to insult your Cloud Maven Junior intelligence..3:23 PM. Getting excited here so zoomed in for you. A sprinkle of rain was likely reaching the ground. Here you can see how cold the cloud bases were since that whiteness in the shaft is snow. Where it has completely melted into rain drops is where the bottom of that whiteness ends, The freezing level is typically about a thousand feet higher than where than whiteness ends below cloud base in steady, not too heavy precip, which is what we have here. Small clouds can’t precip too much. That snow is hanging down about 3,000 feet.4:34 PM. A streamer of shallow clouds forming ice heads out from the south toward Oro Valley from Tucson. Estimated depth, 2000-3000 feet is all.4:34 PM. Zoomed view of some of the ice in this cloud with an education module inserted into the photo, wrecking it some. Concentrations here likely around 1 per liter of ice crystals. If depth correct, the crystal habit will be stellars (“Christmas card” crystals) and dendrites, ones that form between -13 C and -18 C.The TUS balloon sounding (AKA, rawinsonde for technophiles) launched around 3:30 PM AST yesterday afternoon (from IPS MeteoStar). Sounding calculates a cloud base of about -9 C, at about 10,000 feet above the ground (over Catalina). That is cold! Cloud base is just about where the two lines come together at the bottom.5:46 PM. Mock sun or parhelia; couldn’t tell if is was due to the lower ice cloud, or a Cirrus way above. Caused by hexagonal (six-sided) plate-like crystals falling face down. What a great optical phenomena day it was for you, starting out with a nice iridescence!6:25 PM. Sunset photos continue to get later and later. These shallow clouds continued to produce virga into the evening hours.
There’s still water in the Sutherland Wash. Its been running now since the end of January! Amazing.
The End
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1FYI, this is a lie.
2I suppose someone could posit that “Dark Magic”, oops, “Dark Energy” may have caused those trails to “come together over me” , by Lennon and McCartney. “Dark Magic”, OOPs. “Dark Energy”, dammitall, is invoked to explain a lot of impossible things, like how the Universe blew up from something smaller than the head of a pin (!) and was 200 million light YEARS across in the tiniest fraction of a ONE second. Clearly impossible without magic, oops, Dark Energy. This impossibility was deduced on cosmic microwave radiation measurements at the farthest edges of the Universe as we know it.
However, instead of checking their measurements, cosmos (not Cosmos Topper of early movie fame with Carey Grant, but cosmos scientists that study the cosmos invented Dark Magic, oops, Dark Energy, dammitall again, to explain how something that’s impossible happened.
Recently, cosmos scientists retracted that finding and said their measurements in retrospect were likely compromised by cosmos dust. How funny izzat? Sure, I am a weather man and make a LOT of errors myself, but that cosmos one is pretty big.
Just kidding, cosmos guys, the cosmos is tough. Science mag reported that only 4 % of the visible Univserse is made up of known stuff, 96% (gasp) is made up of Dark Matter (23%), and 73%, of “Dark Magic”, oops again, “Dark Energy”, that stuff that is still thought to be behind the increasingly rapid expansion of the Universe3. That is, 96% of the Universe is composed of stuff we’re clueless about.
3It was originally posited that the expansion of the Universe should be slowing down until around the 1990s, when measurements indicated it was speeding up. Hmmmmm. Will there be a retraction of that claim, too, in our future? Stand by for more measurements. Just kidding, cosmos guys. Try being a weatherman….
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.
Looking closer, I hope you recorded the slight fall streaks (fallstreifen, ger.) in the scene above. It would have been quite an important observation for you to have acquired since these small clouds had not shown ice prior to this time. See below for the VERY delicate trails emanating from this Cumulus mediocris cloud; look between and above the orangish rock faces on the top of Sam Peak and a bit to the left:
