That’s about all we can muster in Catalina these days it seems, just a trace of rain. Several drops came down out of stratiform debris clouds overhead around 7 PM. If you weren’t outside, or driving, you would never have noticed. I guess you could call those dull icy clouds with virga streaks hanging down from them “Nimbostratus cumulonimbogenitus” (derived from Cumulonimbus clouds) if you really want to know.
At the bottom of those were dark looking Stratocumulus droplet clouds that gave a sense of drama and portent, but they were only so dark because it was near sunset, there was a higher layer above them, and likely the high droplet concentrations in our clouds deflected what little light was reaching them back from where it came from (scattered and absorbed that bit of light). They were not dark looking, in this case anyway, because a deep Cumulus turret was piled up on top of those bases. The patchy areas of light and dark help tell you that those dark bases are going to lead to zip.
6:15 PM yesterday.
Below is a reprise of the whole dramatic day, one that had a little fakery in it where for a time it appeared it was going to be a dry day, but ended up with some tremendous storms in the vicinity.
If you don’t want to look at stills, go here to the U of A time lapse movie. The dust storm goes by at about 15:20 if you can make out the tiny time hacks. This is a great movie and really shows how much “action” there is up there, even in those Ac cas clouds shown in the second shot.
8:36 AM.
The day started with promising heavy clouds at sunrise, then those thinned and disappeared, but there were also some great Altocumulus castellanus clouds that moved up from the S after that.
Those clouds, too, thinned away as well under the blazing sun, and then our little Cumulus began to arise over the Catalinas, early again, just after 9 AM, a timing that is always filled with portent for a good storm day.
By mid-morning, some sharp turrets were “pluming upward” off the Catalinas, though those clouds were “behind” in size from where I thought they would be by late morning, shown next (11:45 AM shot).
11:45 AM.
Then awful things began to happen. These clouds started to stagnate in size or even wither over the next two hours! Clearly, drier air was moving in, a very discouraging thought.
While I was up on the rise at the Marana landfill to get a better look at the overall situation over the Catalinas, the stagnating Cumulus clouds began to erupt upward into Cumulonimbus clouds! At the same time, a huge complex was moving toward Tucson from the S, one that was to shove a lot of dust up Oro Valley and into Catalina. I started to feel better, get excited.
Here are a couple of photos of that dramatic reversal of cloud fortunes:
2:15 PM, from the Marana landfill showing a cross section of the Cumulus clouds that were about to explode into thunderstorms.2:44 PM. A large Cumulonimbus (capillatus) cloud had blown up over the Catalinas.4:04 PM. Amid all the thunder and cloud to ground strikes, for a moment it appeared that those Cumulonimbus clouds would build westward from the Catalinas into Catalina. But no.5:03 PM. The clouds did build out over Oro Valley and to the NW of Catalina. Here a huge, solid base tells you that a large updraft has coalesced with a ton of precip up there about to drop out. The back of the dump truck is rising now.5:06 PM. Just THREE minutes later!5:17 PM. A little after the main load had been dumped; some lightning for you in case you missed it.
Today?
Still enough water in the air for Cumulonimbus clouds here and there, but likely not so many as the past three days as we head for a HOT dry spell, as I am sure you all know about by now.
Not only did Tucson set a daily record for rain on June 16th with 0.29 inches, breaking the old record of 0.20 inches that fell in 1918 (!), but here in Catalina, the 0.11 inches was the first measurable rain on June 16th in the 35-year combined record maintained at Our Garden, and then here for the past few years.
It was only the second day with measurable rain in Catalina since mid-April, and that prior rain was only a paltry 0.01 inches that fell in mid-May.
Regional rainfall totals for yesterday’s magnificent day can be found here, courtesy of the Pima County Flood Control District. Two sites in the Catalina Mountains got hit hard, with 0.94 inches at Pig Spring, and a whopping 1.54 inches at CDO at Coronado Camp. Those two gages are close to one another near the top of the CDO watershed. Here is a map having those locations. You can also get 24 h rain totals, ending at 7 AM today, from the U of A network here.
The best part, though, may have been those desert aromas that spring out of the desert when it rains, and that cool air that rushed around Catalina yesterday afternoon and evening. Makes you happy to be alive. However, those two close lightning strikes were somewhat unsettling when you’re running around outside with a camera..
The drop in temperature as the rain hit was stupefying, about 35 degrees, from 100 F to 65 F!
Here are some photos, since I am still alive, the first ones of the Altocumulus perlucidus clouds that were mutating into Cirrus uncinus, a bit of an oddity. The TUS sounding indicates that these droplet Altocumulus clouds were extremely cold, -30 C (-22 F). And their presence was another live demonstration about how odd ice formation is in the atmosphere, still not completely understood.
By late morning the Cumulus were sprouting over the Catalinas, and the Altocumulus/Cirrus were gone. Those Cumulus clouds were a great sight since the models had very little rain indicated, and these were fattening up nicely suggesting those models might not have gotten “the scene” for yesterday right; there was more hope for rain after all.
Ice clouds on the left, droplet clouds on the right side.Parhelia (sun dog) in the fallstreak of a former Altocumulus flake.1:16 PM: Cumulus mediocris, center right, portends a good shower day.2:11 PM. We are underway!2:32 PM: Heavy rain falls on the upper CDO wash watershed.3:01 PM: A strong shower complex appeared to the S toward TUS, giving hope of some rain here.3:02 PM: Two very strong dust devils developed ahead of the outflow winds coming into Marana. They seemed odd since they were under the cloud cover and you start looking up to the base to see it there is a tube up there, and whether it is one of the dry tornado funnel cases.3:09 PM. The thunderstorms over the Catalinas propagated to the west and here Saddlebrooke gets a dump.7:33 PM: After our nice little rain, and as happens so often here in the summer rain season, we polish the day off with a spectacular sunset.
The weather ahead
The next chance for rain, the best one I could find, of course, is next Friday and Saturday afternoons. For Friday afternoon, this, from the U of WA’s model. The lightly colored, filled in areas represent rain.
Looking for just Cumulus today, maybe a very isolated Cumulonimbus cloud.
Another nice day of high heat and high, patterned clouds. at times. Here are a few shots of the latter, beginning with another flaming sunrise shot. The U of AZ time lapse movie for yesterday is really informative. The clouds shown in the second shot go by just after 6 AM, soon after the movie begins and you can really see the ice/snow falling out of those guys.
Those central clouds could be called Altocumulus floccus virgae. But then they are at 29,000 feet above Catalina at -35 C, too high for Ac! In spite of the temperature, those tops look an awful like droplet clouds with ice crystals falling out underneath. So, "CIrrus floccus" would be a better designation, if you care.Some more of them CIrrus floccus looking like Ac floccus virgae
"Webby" Cirrus, probably best designated as "perlucidus" (honey-combed).
At first, it appeared that the Cirrus "perlucidus" might be the result of a droplet cloud. But here, that delicate pattern was developing in the distance without a droplet cloud (as at left).
They’re not zero, but the chances of rain twixt now and the end of the month are pretty small. However, a tremendous surge of humid air is indicated as the month closes from the remnant of a tropical storm-hurricane along the Mexican Gulf of Mexico coast. Of course, that’s so far out it can’t be TOO reliable, but its something that would bring substantial rains. Here’s what it looks like in green (moist air) and brown (dry air) from IPS Meteostar. All that “green” air to the east of us is heading our way.
Probably most people didn’t notice much yesterday, but at times, especially in the mid-afternoon it was spectacular up there due to delicate little patterns within Cirrus and Cirrocumulus clouds. Some examples below.
1. Cirrostratus undulatus (Cs having waves in it).2. Cirrocumulus.3. Cirrocumulus (upper), Altocumulus floccus in distance.4. Cirrocumulus.
5. The after life of those Cc and Ac clouds was Cirrus!6. Oddity: extremely thin Cirrocumulus with holes.
The Tucson rawinsonde sounding indicated that these initially liquid droplet clouds (Cirrocumulus and Altocumulus) were at 26,000 feet (at the 330 millibar level) above Catalina at -30 C (-22 F) . So, being that high, its no wonder those delicate Cirrocumulus clouds (Cc) became fuzzy masses of ice. Long ago it was noticed that nature liked to produce a droplet cloud before it froze to become ice, even at these low temperatures. Only around -35 to -40 C does ice form directly without going through the water phase, though liquid drops have been reported at -44 C!
To watch some of this transition happen before your very eyes, go to the University of AZ time-lapse and, about 1:02 from the finish (about 15:35 PM if you can read the time on this movie!) before the end of the movie, a really nice patch of Cc appears on the left, but by the time its about to exit the field of view, it has magically transformed into a thin patch of ice cloud. This little patch of Cc in the movie is likely the same one I shot at 15:32 PM in photo number 4.
Just ahead, our upper air anticyclonic summer regime
And with that big mound of hot air over the Southwest US, the first onset of summer rains are now indicated in the models twelve days from now, around June 25th. Too far in advance to bother showing, but am very hopeful of an earlier onset of the summer rain season, and we hope, a LONG, juicy one!
In the meantime, we will be in a trough for a few days, but, as tantalizing as that is, the models still see insufficient moisture for rain in AZ when the trough peaks over us this weekend. However, rain is shown in Sonora near the AZ border this weekend so its not impossible that a few Cumulus might get overly enthusiastic and bust those model predictions of complete dryness this weekend in the mountains. If rain did unexpectedly develop over the weekend from our little trough, it would probably fall from very high-based Cumulonimbus clouds producing mostly virga.
More flaming cirrus this morning, perhaps reminding us of the ascension of the temperature later this morning. In some photographic razzle dazzle, two photos have BOTH clouds and THE MOON! The IR sat image loop makes it appear that we may have these kinds of clouds for at least a couple of days. Below, I also am having a climate issues tantrum due to an unfolding story at Oregon State University.
Later, with more light, Cirrus fibratus.Cirrus fibratus with hints of floccus elements (more compact, dense areas where Cirrus is forming).
Below some of the interesting patterns seen in yesterday’s Altocumulus/Cirrocumulus clouds. Most of the Cirrus had long departed by this time.
Cirrocumulus (liquid cloud elements) with moon.Iridescence caused by the refraction of the sun's light around tiny cloud droplets.Cirrocumulus at the top of the photo. Elements broaden and thicken some downstream and would be termed Altocumulus where the shading starts. Cirrocumulus clouds can have no shading by definition.Cirrocumulus with a lenticular-like upstream edge (bottom of photo).
Dark Ages of science?
Here are two links below to a disturbing science story that is just unfolding in Oregon:
A senior chemistry instructor was fired without notice APPARENTLY because he did not follow the global warming line. He was a skeptic, posted stuff about his views, and spoke on talk shows in the Oregon area. The exact details of this firing are not yet known.
Unfortunately the average temperature in the Pacific Northwest has been falling over the past 10-30 years, particularly very lately (see dip at the end of the record), and this has given rise to some skepticism about the effects of global warming since the temperatures are supposed to be INCREASING, not DECREASING. And ESPECIALLY “lately” with all that extra CO2 that’s been pumped into the air in the past 10 years.
Now, the ORDINARY person might understand why some skeptics might pop up in view of these data. What is going on? But instead of reacting in the ideal way, “Wow, this is interesting data! I will have some of my grad students look into this for their Masters or Ph. D. dissertations”, it is ignored, it is pretended as though it doesn’t exist, but riles people when it is brought up by those outside their organization/discipline, as has happened here.
Those social scientists who study science and how it works will yawn at such “non-idealistic” science behavior. They have been telling us for decades that we are a bastion of White Male Culture, and that no science worker can really be objective in his or her work, be disinterested, only care about “truth” and not where the chips fall, but will always be intrinsically influenced, biased by that culture, even those female workers.
Of course, we folk who actually practice science get mad about those kinds of allegations, conclusions; I do anyway. Those of you who follow this page know that I parody that inability to be “disinterested” by only showing those model runs with the most rain in southern Arizona, because that’s what I want to have happen.
But here again, in the case of Oregon State University, those sociologists who study sceince have been proved correct. Dissenting opinion is not really allowed, particularly by an “outsider” to the climate science social-science cult, even when it is based on contrary evidence that clearly needs explaining.
OK, the Oregon State guy that was fired was not a meteorologist/climatologist. Maybe we should muzzle anyone who speaks outside of his/her trained domain, like Linus Pauling the Nobel Laureate in chemistry who then thought he could cure cancer with vitamin C.
Or Alfred Wegner, the METEOROLOGIST who first proposed the theory of continental drift around the turn of the 20th century but was laughed at by the geologists/geographers of his day. He would have had the last laugh, had he still been alive when they finally accepted his tenet.
The OSU “firee” wasn’t a tenured faculty member, either, and so he wasn’t protected by the golden shield of academia, that shield that once attained allows lifetime employment far beyond productive years. Perhaps when these lesser persons (research staff, instructors) at a university speak out on something that causes us some discomfort, provide a dissenting opinion on something, they SHOULD be fired immediately!
Yes, that’s it! No dissent!
Think how great things would be if there was no dissent on anything in the scientific realm! Whatever the majority thought, that would be the end of the story. No reporters asking difficult questions, kind of like things are now, , no reporting of any digression in opinions; there would only be the official line.
Think how happy we’d be not having to THINK or be disturbed by contrary thoughts!
Of course, not thinking is appealing, but, its not right.
Dissenting opinions/findings, if they are WRONG, have a way of disappearing quietly. Remember the NPR story back in the 1980s about the Newman Motor, the motor that produced more energy than it consumed? NPR gave it a lot of credibility back then, but, of course (!), it was bogus.
That’s OK. Mr. Newman tried real hard to get something for nothing, and failed.
Remember, too, “Cold Fusion”, the promise of endless power generation at room temperature, as reported by Stanley Pons and Martin Fleishmann of the University of Utah? Hey, they gave it a good shot, but that, like the Newman Motor, its gone, too.
Crackpot ideas have a way of disappearing. Let the dissenters have their say. IF the earth’s temperature rockets upward in the immediate future, they, like Henry Newman, Pons and Fleishmann, will quickly disappear. But don’t fire them!
So, to take action as the Oregon State University did, in my mind is shameful, and is the worst kind of anti-science I have seen lately. Shame on you, Oregon State!
Here is the temperature change from yesterday morning at this time to today at this time, courtesy of The Weather Channel and due to that dry cool front that went through yesterday. Its about 8 degrees cooler this morning here in Catalina compared to yesterday at this same time. Nice.
But, its back to above normal temperatures for a few days after this respite. Normal is around 90-92 F here in Catalina for this time of year, but a 100 F is just ahead I’m afraid. No rain seen in mods for the next 15 days, too. Feeling glum.
Yesterday’s clouds
Had some nice supercooled Altocumulus translucidus clouds yesterday after the Cirrus departed. Here’s a shot that was taken as an aircraft flew through a patch of it. Note fine contrail. These clouds, from the Tucson sounding at 5 AM AST, appear to have been at temperatures between -15 and -20 C, ripe for aircraft to produce icy canals or holes, and that’s what happened. Below is the rest of the sequence, taken from different locations. In the last shot, the tip of that icy contrail began to light up and I thought I might see some color due to refracting ice crystals, but it didn’t happen. These aircraft effects on supercooled clouds are receiving more attention in the scientific community, BTW.
For a time, too, we had our lenticular cloud friend downstream of the Catalina Mountains in its normal position.
Powerful, but dry system progged for later next week
Check this “four panel” out, bottom of blog, from the Canadians from their model run last night. Its valid for the afternoon of Thursday, May 24th at 5 PM AST.
My first thoughts: Egad! Holy Smokes!
Looks like low temperature records will be broken in the West and Pac Northwest as this comes through those areas. However, the thought of the ovenly air over the Southwest at this same time, being drawn into the western High Plains States was alarming. This is because it could get superhot over there as our hot air comes down out of the Rockies. Fortunately, the models don’t show the 120 F temperatures in the Plains my alarmist mind was generating.
What WE will get here in Catalina as this giant trough settles in the West for several days is a LOT of wind and dust in a lot of hot air before the cooler air arrives sometime after May 25th.
This period of wind and hot air will be awful for the fire situation. No rain is indicated with this giant low, too.
I dread these days because you’re thinking about how much is on the line as far as our forests go.
This is pretty interesting; don’t see this happen too often where a lobe of low breaks off and spins from Montana, back toward the south-southwest to pretty much over Rocky Point, MX, as you will see in this past 48 h water vapor loop. In a water vapor loop, you pretty much see all that the movement that is taking place in the atmosphere and here you can begin to understand why it takes biggest computers on earth to model it. Here’s a close up from IPS Meteostar.
Note, too, those white puffs exploding in west Texas as our little low spins thisaway. Those are massive thunderstorms that our low has and will be triggering in west Texas and eastern New Mexico over the next few days. This is great to see that happening due to the drought those poor folks have been experiencing over the past couple of years. This little low, as tiny as it is, will make a huge dent in those conditions in some areas. It really would be great to be there in some little town, like the well-named town of “Plains”, TX, and see how happy the folks are getting as the rains hit. It would be like the end of a Hallmark movie where everyone is quite happy about how things have turned out.
Here are two shots showing what its like now in Plains-Floydada, TX, area, First, you can see that the earth is quite flat there.
Note green along highway. It has been raining off and on in these areas for the past month, so things are perking up. There were occasional bursts of wildflowers, too.These aren't horses. What are they?
But while Texans are getting happier and happier (and I hope they don’t complain about flooding because that would be just plain WRONG), what’s in it for us?
Well, the quality of moisture is less here toward the center of the low, maybe about 1/3 as much in the air over us as in Texas. So, what does that mean we will see? Maybe a few Altocumulus in streaks, maybe finely patterned Cirrocumulus, and then as afternoon comes on, some Cumulus with high bases because its so dang dry. I better predict some Cirrus cuz I see some now! Also, I think I will forecast that the low temperature this morning will be about 62 F here in Catalina because that’s what it is now. Maybe some ice optics, too, now in progress! Continuing, these clouds, too, mean some great opportunities for sunrise/sunset color and ice optics now that I see one (parhelia).
But with those high bases goes low temperatures, likely well below freezing, and you know what that means. The tops are likely to be colder than -10 C to -15 C, 14 F- to 5 F), an ice-forming threshold hereabouts for small, high based Cumulus. With the formation of ice, VIRGA, snowflakes and ice crystals come out the bottom. You can see this by the hazy look around the clouds where it is evaporating–ice takes longer to evaporate.
In the higher terrain, the virga will melt into rain and reach the ground, and the clouds will likely get tall enough to produce lightning, but not here today, but to the north of us at least early in the afternoon and evening. Our best chance of rain with thunderstorms in southeast AZ will be tomorrow as the moisture gradually increases over us from the backflow around the north of the low. The low is forecast to pass to the south of us tomorrow and Thursday. You can see all this happening in our local U of AZ weather model here. (Note the local time is in the upper left hand corner. You will see the precip is only forecast to occur in the afternoon and evenings with this system.
So, finally, some weather excitement in the offing!
Kind of got distracted with chores after the big trip to NC and didn’t get to this until today… If you can remember as far back as April 26th, we had a “FROPA” (“frontal passage” in weatherspeak) that day. The U of A weather model indicated beforehand that the bases of the clouds last Thursday would lower to the tops of Samaniego Ridge.
Well they did, though it seemed in doubt for a time, and occurred a bit later than the model had predicted.
Also, a few drops came down here late in the morning; more precip was visible to the north of us and that was reflected in the NCAR precip estimate for Arizona the following morning, an estimate that suggested the heaviest rains were up to half an inch just 150 miles away.
Here are a few of last Thursday’s clouds with some commentary.
Row of Altocumulus castellanus top lower center.
These clouds came in two separate segments, the first batch were at Altocumulus levels, some 12,000 feet above the ground according to the TUS balloon sounding that morning at 5 AM AST. Those were the clouds that produced the sprinkles around 5:30 AM. Poor snowflakes melting into drops had to fall such a long way!
After a brief clearing, a surge of lower Altocumulus and Stratocumulus came in. For a time, they looked awful threatening, and appreciable rain could be seen falling from them to the north. They produced a few sprinkles here in the late morning and early afternoon about the time the clouds had lowered (as predicted by the UA model, to the tops of Samaniego Ridge to the east).
In the distance is Altocumulus opacus virgae, that is considerable precip is dropping out of them.Here the faint whitish cloud ghosts near splotches of the Altocumulus clouds are due to ice crystals, indicating that these clouds are colder than -10 C at cloud top.Our regular neighborhood cloud, an Altocumulus lenticularis formed downwind of the Catalinas in the usual spot after most of the Altocumulus had departed.After the brief clearing, a surge of threatening looking Stratocumulus invaded the sky. Rain can be seen falling above the horizon to the north.
Why didn’t they rain more?
The answer, as always here, is that the tops were much shallower, and therefore warmer, than those early Altocumulus clouds sporting considerable ice at times. You can be sure that those Stratocumulus clouds over us had tops warmer than -10 C (14 F), a general threshold for ice formation around these here parts. (Over the oceans, where the drops inside the clouds are larger, the threshold temperature for ice formation is higher.)
Just to the north of us, where rain was occurring, you can be sure that the tops sloped upward in that direction, becoming colder than -10 C.
That second batch of lower clouds looked dark and threatening, but lots of times with lower clouds its because they have higher concentrations of drops in them, not because they’re especially thick as you might guess at first. The droplet concentrations in those dark Stratocumulus might have been twice as high as in those early higher, Altocumulus clouds.
Drops in clouds with higher droplet concentrations, say due to smog, reflect more of the sun’s light off the top. That makes them darker on the bottom, and because they are then also harder to get precip out of, they last longer.
This is a real problem, BTW, for climate models, since longer lasting clouds reflect more light back into space and in that sense, and help counter the global warming expected from trace gases like CO2. But, would you rather have ugly clouds and smog infested skies and a cooler planet, or clean skies and clouds and a warmer planet?
The weather ahead
No rain in sight. But a big heat wave, probably temps around 100 F now looming toward mid-may. May is our driest month, BTW, averaging only a quarter of an inch.
Who can forget those profound words of Aerosmith and Steve Tyler, “I’m BACK in the saddle again”? Just the way he says, “I’m BACK…” is really something. Well, if you can’t remember anything anymore, here’s a reminder. Wasn’t that great “rockumentary” movie by Rob Reiner, “Spinal Tap” about these guys? BTW, pilots on VFR flew through cloud saddles between turrets all the time… So, there really are “cloud saddles.”
First of all to start today, you budding cloud-mavens out there should, as always, be reviewing yesterday’s skies here to make sure you got all the clouds down in your cloud log, a service provided for you by your University of Arizona Weather Department. Since this link is overwritten each day, you probably should go there now.
In the meantime, while you’re scrutinizing that time lapse film, a cool front will go by this morning. Nice, except no rain outside of isolated sprinkles from mid-level clouds like….Altocumulus opacus virgae, you know, those dense loooking clouds with little snowstorms under them meaning their tops were colder than -10 C (14 F).
Later, after a brief gap in those mid-level clouds, some honest to goodness LOW clouds are supposed develop just after the front goes by later this morning. How do I know that? I cheated by going to the Wildcat Weather Department model results produced by the MASSIVE Beowulf Cluster and saw that clouds are supposed to get low enought to top Samaniego Ridge by mid-morning. Check the sounding predictions here if you don’t believe me. You’ll see the temperature and dewpoint lines pinch together at sharply lower altitudes beginning around 9-10 AM AST, with cloud bases predicted to be down to about 7,000 feet!
Haven’t seen cloud bases (bottoms of Cumulus and Stratocumulus) as low as that since the last rain which I missed because I was driving mom all the friggin’ way to Asheville, NC, and back to see my brother in his “new life” there. There’s a lurid story behind that new life, one that you would naturally be quite interested in, but it shall remain hidden from view.
But why don’t those lower clouds that move in and top our Catalina Mountains rain/snow? Tops too warm, predicted to be warmer than -10 C, so, no ice can form, a necessary ingredient for stuff to fall out the bottom. You probably knew that already, and I am beginning to feel a little useless. Oh, well.
Here’s a nice plot of today’s weather around the SW and the satellite cloud scene at 5 AM AST from the U of A (again): Wow! Rain drops hitting roof now, 5:37 AM! Overhead cloud tops still colder than -10 C!
Remember, if you are an intelligent person you will NOT CALL THESE FEW SCATTERED DROPS “DRIZZLE”!!!!!!! Its a rain shower, a very very light one, that you might “code” as RW— (three minuses). Drizzle drops float in the air, and are close together; these are not. There are IMPORTANT cloud reasons for denoting this difference. Some day I will tell you the “science story” about a well-known scientist, really considered the best in his field, who told me to leave his office and never come back after I informed him it had been drizzling outside. So, I Mr. Cloud-maven person has some “drizzle baggage”…..he is carrying around.
Note the gap in clouds over us now and that little scruff to the west. Those are the lower clouds that will move in later. Below this, our Tucson sounding for 5 AM AST, where you can see that the tops of these Altocumulus clouds are around -20 C (-4 F). Bases are indicated to be around 15,000 feet above sea level, or 12,000 feet above Catalina. Poor drops have to fall such a long way in such dry air. No wonder only the biggest ones, likely HUGE snowflake aggregates, or maybe even “graupel” up there, made it down.
Lots of nice Cirrus clouds yesterday, but no Altocumulus castellanus later in the day yesterday as it was asserted there would be. Only a flake or two of Altocumulus “uncastellanus”, (flat-as-you-can-get lenticular) clouds off in the distance (see bottom of page). BTW, I obsess over being right. I thought you’d want to know that about me since you come here every day and I am part of your life now. So, I made up the word “uncastellanus” because it sounds like in some way I might have been right about yesterday if you are reading quickly.
BTW#2, as per usual tendencies, the bottom of the moist layer where the Cirrus clouds were yesterday did slide down toward us during the day, from about 24 kft above the ground at 5 AM and -34 C to 21.5 kft and -27 C at 5 PM, the latter still pretty cold for clouds comprised of droplets, but they were there.
Below are a few “character of the sky” photos from yesterday. If you want the whole day, go here to the U of A time lapse. In this movie for yesterday are a few spectacular Cirrus castellanus clouds just after 11 AM AST. You’d swear they were real Cumulus clouds at first, but then you see them moving along at the same speed as the Cirrus clouds, glaciated with fall streaks beginning to come out as they go by.
You’ll also see in this movie, a lot a wind shear, changes in wind direction and or speed, with height, quite at lot visible early on. It will be easy to see how those trails of ice crystals get skewed away from the parent cloud producing these sometimes incoherent patterns when viewed from below.
Expecting castellanus TODAY, dammitall!
I think you can kind of sense my ferocity here about getting things right… A LOT of weatherpersons are like this, so its not just me.
As a potent trough blasts into Cal today, AZ will be in the rising motion part of that trough. So what happens? The air temperatures aloft begin to fall as the subsiding air pattern over us lessens and moves off to the east. With that tendency for subsiding air gone, some layers of the atmosphere will develop larger drops in temperature (lapse rate) as you go higher, a situation ripe for castellanus clouds, ones that look like miniature clouds that have been on a growth hormone. Those clouds (Ac cas) are probably my most favorite clouds, itty-bitty towering Cumulus clouds and so I do have a tendency over predict them based on a desire to see them. You can see what the TUS sounding is supposed to do here from the U of A model run. You’ll see the temperature falling just that bit over us late in the day. Well, it will be interesting to see what really happens!
Lots of other kinds of clouds are likely, too, such as a patch of Cirrocumulus, more Cirrus, and a lenticular here and there as the winds continue to increase over us. Gee, with the air coming from so far to the south, maybe even a scruff or two of small Cumulus clouds may show up, too, though Mr. Model doesn’t think so! Quite a cloud day possible.
Due to the high altitude the Altocumulus are likely to be at today, above 15, 000 feet above the ground, they’ll likely be cold enough (tops colder than -10 C, 14 F) to produce ice crystals and snowflakes, which we will see as virga coming out. Again, a fabulous sunset is possible because of the presence of more than one cloud layer.
Still only a dusty cold snap in the offing as the main upper trough bashes Cal Thursday and Friday before settling in over AZ on Saturday and Sunday.
Cirrus spissatus center (mostly).Altocumulus "uncastellanus" clouds begin to appear. I am somewhat happy since clouds composed of droplet are beginning to be present.Another Altocumulus "uncastellanus" lenticularis in the distance with Cirrus clouds.Another nice sunset, ones with mostly Cirrus spissatus (bloby Cirrus)
