0.22 inches was, indeed. how much rain fell in the form of drops from Nimbostratus clouds yesterday as a modest little rain band generated by a rapidly moving trough swept through during the afternoon. Regional precip values can be found here. Our local area got the most, up to about a quarter of an inch, as often happens in marginal storms.
Yesterday’s storm marked the beginning of the new, more normal weather regime for southern Arizona, as has been blabbed about here in recent weeks. No more week after week of droughty weather with temperature far above normal, the kind of weather that has marked this whole fall and winter so far! I. e., “Thank you very much, a snowbird might say, but get the hell out!”, the rest of us might conjure up, thinking about the needs of our desert’s wildlife and vegetation.
Indications are now that below normal temperatures and above normal precip are ahead for us and all of Arizona in late Jan and early February.
The evidence for these claims?
Below, the stunning, jaw-dropping evidence for this seemingly outlandish assertion in the form of an ensemble (spaghetti) plot generated by NOAA last night. I have followed these charts for almost ten years now, and I cannot remember when such a strong signal (clustering of flow lines) 15 days out has occurred before in our region.
So, excessively excited this morning when I saw it! Its been annotated with excitement text.
This troughy pattern begins to take place on January 30th. Until then, a strong but dry cold front with a lot of wind comes by in a few days, on the 25-26th.
Valid at 5 PM AST, February 4th. You can pretty much count on a trough hereabouts in two weeks. Since the blue lines, the colder portion of the jet stream, do not dip down this way so much, our troughiness likely would be in the form of something we call a “cutoff low.” A full latitude trough extending from the “blue jet” up there in Canada, instead of a “cut off”, would be excessively cold. We probably don’t want that anyway.
Yesterday’s clouds
The whole interesting, if excessively gray story is shown below:
7:24 AM. It was breezy already, and with Cirrus underlain by Altocumulus lenticularis clouds in the lee of the Catalina Mountains, you knew that a storm day was ahead without turning on your favorite TEEVEE weatherman.8:53 AM. With Cirrus and Altocumulus spreading rapidly from the SSW, lenticulars downstream from the mountains, the wind gusting to 25-35 mph, you knew a great gray cloud day was in store!11:32 AM. Before long, an entire sheet of Stratocumulus spread over the sky, making you sure that rain would fall.12:50 PM. First drops begin to fall on Sutherland Heights. That layer of Stratocumulus appeared to be deepening as it approached from the SSW to where the tops were getting just cold enough upwind of us to produce ice and snow that melted into those sparse drops. Not enough ice /snow formed to hide the bases, though, in virga.1:26 PM. Snow begins to fall on the Lemmon.2:04 PM. Lower Stratocumulus clouds begin to show up below the original deck that overran us.
3:16 PM. Pretty and dramatic. Stratocumulus piling up over and upwind of our Catalina Mountains/Pusch Ridge.3:19 PM. Oh, so pretty.3:27 PM. Crazy, I know, but I thought these scenes were so pretty!3:28 PM. As that rain band approached there were some nice lighting highlights.3:40 PM. Here comes that rain band across Oro Valley/Marana.4:19 PM. A truly great scene for a desert; mountains partially obscured in precipitation.4:19 PM. Nimbostratus. Its hard to get a better photo of rainy Nimbostratus than this. Drops coming off the roof, NOT raindrops, can also be seen. This was at the peak of the rain, too! Very exciting.5:54 PM. Sunset Stratocumulus, hold the ice. Yet, that Stratocumulus was cold, way below freezing.
The weather way ahead
The title sums up where we are now. Will we go have more rain? Oh, yeah. But not right away, as you already know.
I use that expression not only to draw attention to myself since my name is Art, or, “Artie boy” to mom, but also because I had a role in bringing this phenomenon to the attention of the scientific community; that is, that an aircraft could glaciate portions of clouds at temperatures as high as -8°C. This in a peer-reviewed article so controversial it was rejected twice by journal reviewers before “getting in “(pdf here)! Some background on why this happened is found in a footer way down below….
Its common knowledge today that an aircraft can produce in essence a contrail in clouds at temperatures down to about -10°C and must be avoided when researchers are sampling the same cloud over and over at below freezing temperatures.
Back to the beginning:
The day began well enough with a nice sunrise over the Catalinas:
7:28 AM. Really cold Altocumulus perlucidus lurks over the Catalinas. The sounding suggests that this layer was at -26̂°C, and yet no ice or virga is present. This is not unusual. Ice tends to form more readily when the droplets in clouds are larger–these were likely tiny, 10-15 microns in diameter, and, being a layer high in the atmosphere, not connected to the ground, meant there would be a dearth of ice-forming substances like dirt, well, kaolin mineral particles.8:01 AM. Well, OK, for the really sharp-eyed cloud maven juniors, yes there was a trace of ice here and there in those clouds.
Here’s the early morning National Weather Service balloon sounding from the U of AZ:
This sounding was launched about 3:30 AM AST yesterday morning. During the day, the bottom of the Altocumulus clouds lowered and got a little warmer, but still plenty cold for aircraft ice production.
Then, as the Altocumulus layer filled in from the west, the aircraft effects roared to life. An example from yesterday, one that passed right overhead of little Catalina!
10:01 AM. A parch of aircraft-induced ice in this Altocumulus perlucidus translucidus composed of supercooled droplets otherwise, is about to pass overhead of Catalina.
10:08 AM. High temperature contrails rip through a Altocumulus perlucidud translucidus layer up around -25°C.10:10 AM. Looking for some optical fireworks here, such as a tangential arc (halo curving the wrong way), but only a hint of one showed up. Can you see it?11:23 AM. Another clearing with ice below it is seen just SW of Catalina from the parking lot of Basha’s where I went to get some cottage cheese.11:33 AM. Sun dog (parhelia) lights up in the ice patch above after I came out of Basha’s with some cottage cheese. Note to writers; little, seemingly irrelevant details like what you bought in a supermarket makes your writing come alive for the reader.1:21 PM. There’s another couple! They were just everywhere yesterday!3:52 PM. Later as the moist layer deepened and lowered further, there was ice aplenty, but it was impossible IMO to tell whether it was au natural or aircraft-induced. Surely, some was due to aircraft penetrations of supercooled clouds. However, when the air is rising enough, a hole or ice canal may not appear since droplets can reform rapidly.3:52 PM. Looking more to the west where the long trails of ice are more visible.4:14 PM. I feel asserting here. I assert that this one is from an aircraft, but with droplet backfill that prevented a hole from forming. Looks like “phony” virga to me, and, of course, to you, too, as a certified member of the cloud maven society.5:21 PM. Interestingly nearly all virga disappeared about this time, certainly nothing extraordinary that led to the suspicion of aircraft induced ice. The sounding suggests that the higher temperatures that the Altocumulus layer was at may have been the reason. See below…The U of AZ balloon sounding launched at 3:30 PM suggests the bases of the Altocu have dropped down to about 18,000 feet above sea level, 15,000 feet or so above Catalina, and are much warmer, and thicker than when the day started as we could see.
The weather ahead
More interesting middle and high clouds, probably a great sunset/sunrise or three, but no rain, just virga. The present mass of middle clouds passing over has some virga and sprinkles, but that’s about it from this episode. No real support yet for a change in our dry, warmer than normal weather regime in spaghetti plots though one trough a week or so out is forecast to bring a little rain.
The End
Some background on “APIPs”
This phenomenon had been shot by photographers for decades, yep, DECADES, BUT, it was believed (apparently) by those doing cloud research, that it only happened at very low temperatures such as those when the normal contrails we see occur (at temperatures lower than -35°C), viz., it was ignored.
Another factor was that all of the rare photos of this phenomenon, dubbed “Aircraft Produced Ice Particles” (APIPs, by yours truly, though not the greatest name) appeared in lay or quasi-lay publications and were likely missed by those with big Ph. Ds. who only read technical journals. An example of this was on the cover of the Bulletin of the American Meteorological Society in 1968, a cover shot which drew the greatest amount of reader comments that the journal had ever seen! They went on for a couple of months, some suggesting that the ice and hole in cloud was due to a meteorite!
Also, it was a rare case indeed when the photographer could report the temperature at which it occurred.
I was thinking how great yesterday was for you. Started out with a spectacular sunrise (lasted just a couple of minutes), and then you could watch for pretty much the WHOLE day, orographically-formed Altocumulus opacus and castellanus transition to ice crystal clouds (in this case, Altostratus with virga and some mammatus) right before your eyes!
Sunrise:
7:16 AM. Flecks of Altocumulus clouds below Altostratus.
After sunrise….this odd scene below of an extended Altocu lenticular cloud:
7:33 AM.12:24 PM. Altocumulus opacius shedding ice as they moved westward across Oro Valley.3:01 PM. Altocumulus castellanus forming just upwind of the Catalinas, moving toward the west (to the left in this photo). No ice is falling out yet, though tiny ice crystals are likely starting to form.3:01 PM. Looking farther downstream from the prior photo. Some ice is beginning to show up and fall out (center and left side of photo).3:02 PM. Looking still farther downwind, those Altocumulus clouds are mostly glaciated, that is, mostly consist of ice. This transition has taken about 10 minutes of travel downwind. The sounding near this time, indicated that tops a little downwind of the U of AZ campus release site, were about -27°C (-17°F). However, tops were likely rising some small amount in this region downwind of the Catalinas, and so were almost surely, even a little colder than that.4:33 PM. Nice example of what some of the Altocumulus castellanus looked like yesterday. That tallest turret will fall back. Its partner is just to the right, one that was previously as high, but fell back, its load of ice crystals drifing down. Some of the ice in the taller one is still being held up there until it, too, collapses. A error in aircraft sampling can occur if you don’t realize that tops have collapsed from lower temperatures, such as when collecting ice concentrations in the collapses one. You could easily assign a cloud top temperature that was too high; would not reflect the temperature at which they really formed.
Hope you saw them and recorded them in your cloud and weather diary. I’m thinking that at the next Cloud Maven Junior meeting we should devote a lot of time to this issue. It was a rare day yesterday that the WHOLE day had that phenomenon occurring as aircraft penetrated those clouds, usually on ascent or descent. Sharp descents/ascents produce holes. See the sequence below if you don’t believe me (ppt from a recent talk):
Yesterday’s clouds: lots and lots of aircraft-produced ice
(btw, see note below about pop-up ads in this blog, ones that started to appear after downloading latest WP software)
6:44 AM. Altocumulus at sunrise. As we say so many times here in old AZzy, “So pretty.”Also at 6:44 AM. From a smartphone, color not so great, though not bad either.U of AZ Wildcats balloon sounding, launched at about 3:30 AM yesterday. Those Altcumulus clouds were way up there for Altocu, 22,000 feet above Catalina, 25,000 feet above sea level.because they were so high, were so cold, AND were composed of supercooled liquid water, they ripe for aircraft to create ice going through them, likely on climb out and descent from TUS and perhaps PHX as well, Davis-Monthan. What was unusual, was that it was happening most all day as the clouds filled in some. They remained liquid, high, and cold.7:23 AM. Wasn’t long before aircraft made their presence known in this cold, cold layer.6:54 AM. I should point out that a colder topped Altostratus layer was present to the N. Its not represented well in the TUS sounding. That layer was all or mostly all ice (the rosy colored segment of this photo).7:37 AM. An unperturbed view of Altocumulus perlucidus (“Mackerel sky”). Are there any mackerel left? Also, from a cloud viewing standpoint, these are much higher than one would guess. The fact that aircraft were making ice in them is a clue that they were higher than we would normally think of a “middle-level” cloud. I like patterns like this. I thought you would like to know that about me.9:03 AM. Slicing and dicing. An aircraft has left a contrail through a Altocumulus line . What’s really unusual here is the ice contrail so far outside the liquid water cloud. It is thought that hole-punch and ice canals are limited to regions where there are liquid droplets, and so this is quite an anomaly, one that suggests the humidity was almost 100% with respect to water outside the cloud boundaries. Also, can you just make out the partial 22° halo, indicating very simple ice crystals like columns and plates? Streamers of tiny ice crystals are also evident, trailing to the right, below the contrail? This shows that the wind decreased rapidly with height just below the flight level, but was still from the southwest to west.9:24 AM. Coming at you, another ice-canal has formed SW-W of Catalina, a favored locale for the formation of these canals on days like this.9:40 AM. What’s left of it is almost to Catalina. Note streamers of ice. Below, a close up of a couple.9:40 AM. The intensity and narrowness of these streamers point to an artificial origin. So, even if you didn’t see the canal, and here, some of the clouds are reforming at the top of the streamer, you would make a good guess that this was not natural ice. Sometimes the canals can fill back in if the air is in overall ascent at cloud level.9:57 AM. Here’s what those contrails in Altocumulus look like as they first appear. Can you spot’em? There are two.1:45 PM. Another aircraft-produced ice event as the Altocumulus increased and became thicker, making detection of these events less obvious. Sometimes a canal clearing is very muted.4:12 PM. Aircraft-induced hole punch cloud with ice below the hole. Can you spot it? See close up below.4:12 PM. Close-up of that hole punch, ice mostly below the Altocumulus layer.4:35 PM. That hole punch cloud 35 min later. The long trail indicates high humidity well below the Altocumulus layer in which it appeared.The 3:30 PM balloon sounding from the U of AZ. A study in ambiguity.The day ended with an unusually bright sun dawg, mock sun, or parhelia. So bright it did, again, suggest a plume of ice from a prior aircraft passage through extra cold Altocu or Cirrocu clouds. But, just wild speculation here. Hope you don’t mind.5:41 PM. Nice sunset, but one strongly impacted by clearing from aircraft-produced holes and lines of ice, the ice now mostly gone.
The End
——————About those nuisance ads—————
Note to me and the two other people that drop by my cloud or “clod” blogulations: The embedded pop-up ads are due to a WP third party plug-in that needs to be repaired. It will likely happen today.
After consultations about ads…
Oddly, those pop-ups and blue highlighting and double underlining do not seem to be present outside of my personal view of my own blog, this according to hoster, “godaddy.” Even using a different browser other than FIrefox does not show them as I have just verified.
As here, just to reinforce that assertion a bit. Its a link to a recent blog by my cloud-obsessed friend and author, Maria Mudd Ruth. I strongly recommend buying a few of her books. Really, I do!
But in viewing our deep blue skies, pocked with little fluffy Cumulus clouds over the past two or three days, you would not need convincing that even tiny clouds are beguiling, a wonderful attribute for a planet to have. Having mountains on a planet is great, too, and watching the interplay of clouds and their shadows on them is a never ending pleasure. We’re pretty lucky when you think about it to be on a planet like this one. Hope you think so, too.
No rain ahead, glumly, though some sprinkles are out there this morning as frontal cloud band passes over. Just a little too high off the ground for real rain. And the cloud tops aren’t quite cold enough to form much ice, too. Those cloud tops get colder going to the NE, and so higher terrain up thataway (e.g., Show Low) are getting some light rain this morning. Right now, there’s a little sprinkle just beyond Romero Canyon, so we got a little ice this morning in them clouds.
What was interesting is that I never saw no ice yesterday, to continue the slang of rock and roll, in another cheap attempt to reach out to another demographic. The clouds were just a bit too warm for ice-formation, tops running in the -4°C to -5°C range according to yesterday afternoon’s Banner University of Arizona’s balloon sounding. Some may have bulged up to nearly -10°C, but still not quite there. I looked constantly for signs of ice and never saw none, and neither did you, of course.
The U of AZ balloon sounding for yesterday afternoon, released about 3:30 PM AST, courtesy of MeteoStar., I hope.
Bases were cool, at about 4°C, at 11, 000 feet above sea level, or 8,000 feet above Catalina. Tops, about 15,000 feet above sea level. So, they were running around 3,000-4,000 feet thick with no ice. This was a situation where dropping dry ice into those clouds would have created snowfall, then sprinkles, that would not have fallen naturally. Doubtful anything would have reached the ground anywhere near our elevation, however, but up at Ms. Mt. Lemmon, something would have likely even measured from doing that far enough upwind.
In summary, yes, there are some fairly rare times you can get some precip out of clouds by seeding them and yesterday was one of them1.
Today the clouds are thicker, drop sizes therefore larger in those tops of a cloud band similar to the one we had yesterday evening. As drop sizes increase, the temperature at which they freeze also increases. Well, at least that’s what we found over and over again at the U of Washington.
The balloon sounding launched about 3:30 AM this morning from the U of AZ. Our cloud band is almost twice as thick as it was yesterday afternoon as bases lowered and tops went up some. The sounding, too, went right up into the middle of that band, now exiting the area.
The result, some ice has formed even though they’re hardly colder than just -9°C or -10°C (14°F). Check the radar:
From Wundermaps, 6:219 AM.
Here are some cloud shots from the past couple of days. Should be some more great scenes today:
The last summer Cumulonimbus harrah. Goodbye sweet summer thunderstorms. 🙁 See you next year.10:37 AM September 19th. A field of Cumulus fractus, those shred clouds from which even might oaks can form. Not this day, though.10:58 AM, September 19th still, way back there still. Hope you remember this scene. We now have a Cumulus mediocris. Work hard in life, try not to be “medocris” if you can.12:44 PM. Got pretty cloudy that day for a few minutes, then cleared off.3:10 PM. After it cleared off and the clouds went small again, we had some nice shadow effects on our mountains.
Due to time constraints, we now move ahead in the action. Well, its not really “action” is it?
Well, not that much, just a day ahead….
4:02 PM, September 20th. Oh, so pretty Cumulus humilis against that deep blue sky. Thanks you, “Cosmic Muffen” or “Hairy Thunderer1.”4:48 PM, September 20th. A cloud street is launched off the Tucson mountains and sails over the Oro Valley and Catalina.4:49 PM. More dramatic shadows, ones produced by that cloud street.6:24 PM, September 20th. The fading sun colorizes those last of the Cumulus.3:15 PM, September 21st, another breezy day with small Cumulus. I hope you like to see small Cumulus over and over again…
Moving ahead to yesterday and the day long cloud band….
6:19 AM, yesterday. That band of Stratocumulus had sprung up overnight, providing a really pretty sunrise color. Hope you saw it. Only lasted a couple of minutes.7:17 AM. Not much upwind at this point but wind.12:05 PM. Some Altocumulus began to appear upwind of us, eventually merging in a band.1:48 PM. Our band is really beginning to consolidate at this time (looking S on Equestrian Trail Road, aka, Lost Hubcap Trail Road).5:10 PM. Bases had lowered to about 8,000 feet above us from the afternoon shot. Because the air way above us was cooling, the cloud began to sprout Cumulus towers. Looked for ice but none seen, so no virga around either, though it sure looked ready for that. Without ice, you’d be thinking tops must be warmer than -10°C (14°F).5:52 PM. Our band remains in full display and will overnight. I would deem these clouds Stratocumulus, hold the ice.6:09 PM. You can’t have a better scene than our Catalina mountains highlighted by the setting sun. We are so lucky to be here!6:27 PM. Still going after all those hours, but not doing anything, just sitting around up there looking pretty.
Haven’t had much to say, brain pretty empty again after the big review of the NAS 2003 review which really needed reviewing and commenting on real bad….
(More “late homework” in the offing.)
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Nice sunset last night; we have had a series of pretty nice ones over the past few days.
April 26th. Sunrise over the Charouleau Gap.Orangy mountains highlighted by a gap in the Altostratus layer that allowed the setting sun to shine through.7:04 PM. There was some turreting in this line of Altostratus that passed over, and because of those deeper tops, indicating stronger, if still slight updrafts, larger snow particles developed and produced this line of heavier virga underneath it.7:10 PM.A contrail that’s more than about ten minutes old, now, after the new Int. Cloud Atlas has been released, termed, Cirrus anthrogenitus, maybe castellanus in this case, too.
From IPS MeteoStar, this interesting map for tomorrow morning.
The orangy colors denote the strongest winds in “Jetty Jetstream”, and as you know, the colder, low clouds, ones capable of reaching the temperatures where ice forms, are contained within that ring of strongest winds at this level (500 mb). So, while the models I have looked at so far have no rain here, I think there’s a pretty good chance of a rogue shower tomorrow morning anyway. At least there should be some nice Stratocumulus/Cumulus tomorrow and some will have ice in them. As you know, it’ll be awful windy today, too, maybe 40 mph or so in brief gusts here in The Heights of Sutherland.
Also will be looking for some nice lenticulars since “Jetty” will be right over us, but a little toward the warm side where lenticulars mostly occur.
Map valid for tomorrow morning at 5 AM AST.
In the meantime, spaghetti suggests a big trough in our area again about nine days from now. The later ACTUAL model outputs don’t show much of anything. What’s up with that? I’m hanging with spaghetti that later model runs will indicate a strong trough, and at LEAST another pulse of cooler air, and another minor chance of rain as we are going to see today and especially tomorrow as when become within the “ring of winds” aloft. Didn’t Johnny Cash sing something about that? Maybe it was Wall of Voodoo…
Below, some spaghetti for you showing a big trough over Arizona and the Great Basin which is not much reflected in the actual models, as noted. But, just watch my friend, how those model outputs will change to reflect a bigger trough about this time!
As of the end of February 2017. You can see were right about at the average for the Water Year,, but it took some “heavy lifting” in December and January to get there.
Doesn’t look promising for much rain here in Catalina in March, however. No rain in sight through the next 10 days at least.
Let’s check our 7 inches with what’s happening upwind, say, in CALIFORNIA, and see if there’s been any drought relief there, through February, via the CNRFC:
California water year totals through the end of February 2017. Note one station in the central Califorina coastal range is already over 100 inches! There are 20 stations already over 100 inches as can be seen from the table at right. March looks to have substantial rains north of SFO, which will add appreciably to those highest totals. Amazing! You can go to the CNRFC and expand these interactive maps, btw.
As you are likely to know from many media stories last year, Cal was in a drought siege of five straight years, with but got a little relief last year in the northern part thanks to help from the giant Niño, one of the strongest ever.
Alas, it was one that failed to deliver as the big rain producer for the south half of Cal and the SW in general as was expected.
In case you’ve forgotten how bad things were in Cal, let us look back at what was being said, those horrific appearing drought maps, and also how hopeful were were at the time that the Big Niño would take a bit bite out of drought. This is a really good article:
Then, when the Big Niño faded away like maple syrup on a stack of buckwheat pancakes last spring and summer, we were surely doomed for more dry years. And, for a time, the dreaded cold tongue of water in the eastern equatorial region, the so-called, La Niña, started to develop, which would be no help at all for a good rain season like a Big Niño is, usually.
The Niña faded away, too, to nothing as the winter went on, so we really didn’t have much going on in the tropical Pacific to help us figure out what kind of winter rainfall regime we were going to have om 2016-17. Not having anything going on meant winter rainfall could go either way, a difficult to figure out situation for season forecasters.
In retrospect it is pretty astounding how big a signal must have been out there SOMEWHERE that this winter was going to be one for the history books on the West Coast in general, and in particular, for Californians. Californians saw their drought chewed up and spit out in a single winter, including snow packs so high the height of some mountain peaks have been revised. (I’m kidding.)
No one saw such an astounding winter coming.
This winter sure makes one think of the QBO (Quasi-biennenial Oscillation, one up there in the Stratosphere where there’s almost no air (haha, well, practically none)… Did the QBO have a role in this astounding winter; was there a delay in the effects of the Big Niño even without a bunch of convection in the eastern Pac tropics? Doesn’t seem that could be right…
But, William “Bill” Lau, U of Maryland scientist, reported some statistical evidence of such a lag way back in ’88 due to a QBO connection of some kind and ENSO, no physical cause could be discerned, however, not yet, anyway. Lau, 1988, is reprised below for readers who want to go deep:
Sure has looked like the Big Niño WY we expected last year!
Some recent clouds; after all, this is CLOUD maven, not RAIN maven:
I’ve been kind of holding out on you. I dropped my camera and busted it. Its no fun taking pictures when you don’t have a real camera. Still doesn’t work right, but take these anyway:
March 4th, afternoon. Hope you logged this; the rarely seen CIrrus castellanus (almost “congestus” in size) or, informally, “Cumulo-cirrus.”Poppies are out, btw, in case you haven’t noticed. Nice display on “Poppy Hils” just across and southwest of the Pima County Pistol Club, off Bowman.March 4th, late afternoon. Nothing terrifically special in this tangle of Cirrus spissatus (“Cis spis” to cloud folk) but I thought it was just a really nice scene
Moving to the next day, Sunday, that REALLY windy day:
March 5, Sunday morning 6:13 AM. Altocumulus lenticularis alerts cloudwise folk to the possibility of windy conditions although it was already windy.3:55 PM, March 5th. After a day of solid Altostratus overcast with underlying Cumulus and Stratocumulus, a layer of Altocumulus began to move in to add a little more interest to the sky.3:57 PM. Looking to the north revealed that some of the lower Cumulus/Stratocumulus complexes reached heights where ice could form. That smooth region on the bottom and right side of the cloud is a fall of ice from this cloud with a RW- (text for “light rainshower”) if you like to text stuff) right below that. This is not a lot of ice and so you’d be thinking the cloud barely made that ice-forming temperature. CMP doesn’t think it was caused by an ice fallout from that higher layer, which sometimes can happen. Let’s look at the most timely sounding, just to check. From the real Cowboys at the University of Wyoming, this:The TUS sounding which I only now just saw, showing a vast separation between the lower Stratocumulus and the higher layers of Altocumlus and Altostratus on top. Note, too, that over TUS the tops of the lower cloud is not quite at -10°C the temperature we start to look for ice formation in AZ. However, our clouds were NW of that balloon sounding, and it would have been that tiny bit colder, and tops were also lifted some when they passed over the Tortolitas earlier, meaning that the tops of this complex were colder than -10° C (14° F) at some point.
Wow, too much information….after a hiatus in blogging I feel like that Oroville Dam in California, metaphorically overflowing with too much hand-waving information.
6:03 PM, March 5. Its still real windy. Line of virga brought a few drops when it passed overhead at 6:30 PM.6:04 PM. Nice dramatic shot toward Marana as the backside of the middle cloud layer approached allowing the sun to shine through.6:09 PM. Virga getting closer. May have to park car outside to make sure I don’t miss any drops!6:22 PM. SW-NE oriented virga strip about to pass overhead. Drops fell between 6:30 and 6:40 PM, but you had to be outside to notice, which you would have been as a proper CMJ eccentric. You would have WANTED that trace of rain report, maybe slackers would not have observed.6:30 PM. Climax; the great sunset allowed by that backside clearing.
The full moon of December 11, 2008. Thought maybe you’d like to see it in case you missed it, or see it again if you did see it. Maybe you had a special memory with this moon.7:09 AM. Altocumulus perlucidus with a little lenticular underneath.7:10 AM. Zooming and zooming.7:10 AM. Zooming some more.7:14 AM. Iridescence is evident in the cloud ripples just above the mountain silhouette.7:16 AM, Contrails were soon visible in our Altocumulus layer, the aircraft making it at the right edge of the photo. Appeared to be in a climb out going right to left. And, when you see these “high temperature contrails” in Altocumulus, you can be sure ice will form and rifts will develop as a little bit of light snow develops and falls out. The jillions of ice crystals in the contrail cause the droplets in the Altocumulus to evaporate, in a way, gutting it. An ice crystal is like a low pressure center when amid droplets; the droplets evaporate and those water molecules deposit themselves on the ice crystal, a process named after the discoverers, Wegner-Bergeron-Findeisen. Eventually the crystal is large enough to settle out and a clear streak results unless the air is rising rapidly and can replace the droplets (as generally happens in storms). Sometimes the lift in the Altocumulus layer is enough that a clear canal caused by an aircraft can fill back in after many minutes.7:18 AM. Two aircraft contrails, about a minute old. After two or three more minutes, they will not be visible within the cloud, though ice is forming, decimating the droplets around the intense streamers of ice in the contrail.7:28 AM. The small ice canal (the ice is hanging just below the Altocumulus clouds–kind of hard to make out, but its there.7:42 AM. Those little clear streaks are hardly noticeable now, partly because they were quite narrow, and because of perspective and things bunching up in the distance.
Suggested locations of cloud layers. The Altocumulus layer in which the contrails were embedded seems to be at -25°C, a “normal” temperature for this kind of “high temperature contrail”. In general contrails are not supposed to occur until the temperature is below about -35° C and the air is moist, thus they are usually seen amid or near Cirrus clouds. not down in Altocumulus. See usual contrail height at Cirrus levels in moon photo.
As the morning wore on, the Altocumulus deck faded away, moving east, and we were left with some Cirrus clouds, but what kind?
10:58 AM. Cirrus of some type, but notice there is absolutely no fibrous details (strands and such) as we normally see in Cirrus. Could be transverse waves in a Cirrostratus deck since Cirrostratus can be fog like, have no detail, in a version we call, Cirrostratus nebulosus. The up and down motions would cause clearings perpendicular to the wind up there. The lack of strands and uniformity in these bands suggests very tiny ice crystals, ones having very little fallspeeds.2:34 PM. Some nice “hovercraft” clouds, Altocumulus lenticularis off in the distance SSW. Hung around out there for a couple of hours.3:17 PM. This one appeared to be concave upward, which was a little odd. Zoomed view next.3:17 PM. Looks like the inside is higher than the outside. Huh.
Well, that was it for photography yesterday.
Doesn’t seem to be any reliable indication of rain in sight. Oh, sure, rain here pops up in the models almost every day, but its about 12-15 days out. As the model gets closer to the day it predicted rain, it seems to go away like the “water mirage” on a hot paved road; always ahead of you, but you never get to it. We’ve had some major rains indicated in the models as of a few days ago, but spaghetti was never very high on those events (clustering those crazy lines in a trough over us), so it wasn’t even worth mentioning.
Not much else to talk about, no rain of course; what is that?
But with so many colorful scenes yesterday, we can be partially sated by the lives we lead here sans rain here. October ended with a puny 0.01 inches in Sutherland Heights.
Now, because I grew up in California and remain a little Cal-centric, this brief diversion from AZ:
But droughty Cal got nailed though, from about San Luis Obispo, so we can be happy about that I guess. One station, Gasquet RS, near the Duck border, got just under 28 inches in October; stations in the Santa Cruz Mountains, way down by Monterrey, got between 14-17 inches! From the California-Nevada River Forecast Center, this nice map of October rainfall anomalies in that domain. Red is real dry, and that’s the color we would be in if it was the California-Nevada-Arizona River Forecast Center:
Many departures are far over the map color-coding limit of 350%, but are over 1000% of average! Note red below normal swath. This tells you that the mean area of low pressure at the surface and aloft was just off the West Coast. Pac NW set maximum October rainfall records, too.
But let us not dwell any more of generous rains that others got, but celebrate the color and clouds of Arizona. Here are yesterday’s glorious scenes, beginning with a spectacular Altocumulus lenticularis under some Cirrus at dawn:
6:37 AM.6:47 AM. Ac len stack.10:51 AM. Tiny patch of Cirrocumulus tried to hide in front of some Cirrus. Hope you weren’t fooled and logged this sighting in your cloud diary. Cloud maven person almost missed it himself.12:50 PM. There were lenticulars aplenty yesterday. Here’s another one in a location a little different from normal, beyond the Catalinas. Upwind edge is the smoothest one at right. No ice streamers coming out the downwind end, so must have been pretty “warm”. Lenticulars, due to their tiny droplets and those droplets having short life times, have been known to resist ice formation to temperatures well below -30°C -22° F). Pretty amazing.2:42 PM. Kind of clouded up in the afternoon, and with breezes, made it seem like something was up. It was, but far to the NW of us. We have been under a streamer of high to middle clouds originating deep in the Tropics for a couple of days. Here some lower level moisture has crept in on cat’s feet, to be poetic for a second, and has resulted in small Cumulus and Stratocumulus clouds underneath the Cirrus and lenticulars standing around. All in all, though the temperature here reached 87° F, a very pleasant day.
Now, just some nice lighting and color:
5:32 PM. The almost flourescent plant in the foreground is what is known as a “cholla.” The end elements fall off quite easily and attach to things like your pant leg if you brush by them on a horse, or if back into them while walking and correcting your horse for something when he’s acting a little “wild.” I can report that when seven or eight of them are stuck to the back of your shirt, its really hard to get that shirt off. In fact, it just about won’t come off without a major scream.5:35 PM. The higher Cirrus are shaded by clouds to the west, but the lower remnants of Stratocumulus/Cumulus and a few Altocumulus are highlighted as though they were meant to be for this photo. So pretty. Notice, too, how there seems to be more than one layer of Cirrus.5:44 PM. Cirrus and Altocumulus, the latter with some turreting making those the species, “castellanus”, if you care.5:47 PM. A nice flame-out of Cirrus occurred as those pesky clouds blocking the fading sunlight from striking them opened up below the horizon. A few Altocumulus castellanus can be seen, too, but relegated to shadow status.
In a further celebration of dryness here, let us examine the rainfall cumulative rainfall predictions calculated by the University of Arizona’s Dept Hydro and Atmos Sci computer the period ending at Midnight on November 5th. Says the coming rain in the State misses us here in SE AZ while falling just about everywhere else, of course. Dang. Let’s hope it one of the worst model predictions ever!
This really poor forecast is based on the global data from last evening at 5 PM AST.
Truly LATE breaking news, untimely really, but Augustober 18th was too special a day to ignore:
Giant clouds, dense rain shafts, frequent lightning in the area throughout the afternoon, dewpoints in the high 50s to 60 F; can it really be after the middle of October? Or, is this some kind of preview of climate change we can look forward to in the decades ahead, that is, if you’re thunderphilic?
5:05 PM. An amazing scene, and thunderstorm with such powerful updrafts that when those updrafts are blocked by the inversion at the base of the Stratosphere, they force the winds at that level to slow or backup and the anvil protrudes upwind (center left), something that is common with severe thunderstorms. This was significant here because the winds at 40,000 feet were around 50 kts, far stronger than anything we have here during a typical summer rain season. Summer Cumulonimbus cloud anvils can splash outward easily against weak winds up there in summer when they hit that barrier at the top of the tropopause. This just in from Mark A: severe thunderstorms, I have just learned here on the 20th , were observed in the PHX, and the NWS has a great link going describing all the mayhem it produced. I did not know this until just now in the middle of writing this first caption when I read Mark’s e-mail.1:40 PM.
1:56 PM. Anvil of the Cumulonimbus over west Tucson, drifts overhead of Catalina, and in three minutes, rain drops started to hit the ground. This is amazing because those drops had to fall from at around 20, 000 feet above the ground (estimated as bottom height of this thick anvil) and could only have happened if those isolated drops had been hailstones ejected out the anvil, something that also only occurs with severe storms with very strong updrafts in them. So, if you saw those few drops fall between 2 and 2:05 PM you saw something pretty special.
6:26 AM. Early portent: Cu congestus, aka, “heavy Cumulus) piling up this early.6:29 AM. Mammatus of the morning., an extraordinary scene for mid-October, pointing to the possibility of an unusual day ahead with strong storms. as was the scientific basis for giant clouds on the 18th in the amount of CAPE predicted, over 1,000 units of Convective Available Potential Energy, later that day from computer models. That is a lot for mid-October, take my word for it.3:45 PM. Strong storms did not form over or near the Catalinas yesterday, but they did get something. As you can see the top of this guy (Cumulonimbus calvus) is very subdued compared to the giants that formed elsewhere.5:53 PM. Peakaboo Cumulonimbus calvus top east of Mt. Lemmon provided a nice highlight after sunset. And to have convection like this going on this late was remarkable. Some heavy showers and a thunderstorm formed downwind of the Catalinas about this time,, too.5:51 PM. Pretty nice, summer-looking sunset that day, too.
The weather just ahead, and this might be it for precip for the rest of October
A nice-looking upper level trough is ejecting over us from the SW this morning but the computer model says its going to be a dry event. A second low center forms just about over us in the next day. AZ model doesn’t see much rain for us throughout these events, and rain doesn’t begin here until after dark today.
I think that is WRONG; bad model. Watch for some light showers this morning, then a break and rain overnight (which the models do predict). Due this quite bad model forecast, as seen from this keyboard, I feel must interject for the blog reader I have, an improved rain prediction for Catalina over that rendered by a computer model.
Feel like guesstimating a minimum of 0.25 inches between now and Thursday evening, max possible, 0.60 inches, so the median of those two, and maybe the best guestimate being the average of those two, or 0.425 inches here in Catalina. When you see a prediction of a rainfall total down to thousandths of an inch, you really know that the person predicting it knows what he is doing…..
Below, your U of AZ disappointing, but objective, take on the amount of rain based on last evening’s data and one that is the result of billions of calculations. One must remember that cloud maven person’s calculation of the rainfall amount for Catalina is only based on three.
From the 5 PM AST run executed by the U of AZ Beowulf Cluster.
