Yesterday was one of those ideal days for us here in Catalina, the kind that draws visitors from all over the country to be together with us. It was also kind of like that space-age, relaxo-elevator music; goes nowhere in particular with a hook or melody, or if there is one, its been eviscerated by sleepy, sedated violin players.
But, going back to yesterday’s weather, you could have taken a nice snooze in the sun yesterday afternoon, with only zephyrs to brush up against you, and with temperatures in the upper 70s, it was perfect for being unconscious for a bit, not having to worry about missing an ice crystal, a patch of virga, or an interesting pattern in middle-level or high clouds that you should write about in your weather diary, or document with a photo.
BTW, tops of the small Cumulus (humilis) were warmer than -10 C (14 F) yesterday, and so not one ice crystal or snowflake fell out of them.
6:52 AM. Residual Altocumulus castellanus from the little rainband that went through the night before last.
2:00 PM, from along Equestrian Trail, these picaresque small to medium Cumulus clouds, hold the ice, with dramatic shadows on the Cat Mountains.
Imagination going dry. I’ve talked about these kinds of days a lot. Will insert cow with cholla ornamentation here as a distraction. Might be best part of blog today.3:44 PM. Cumulus clouds wither to Cu fractus as temperature falls. These days are so clear that it seems the earth ends just over the horizon.
Today’s clouds (should be interesting)
Should see a band of Cirrus and thicker ice cloud, Altostratus, off to the NW horizon by about mid-day. Some Altocumulus likely around, too. That band (you can see it here, courtesy of the U of AZ Department of Weather). should arrive here here during the mid to late afternoon, producing a fair amount of gray. But also there should be thinner portions before the main icy mass gets here. In those thinner portions and leading CIrrus, there could be some some great patterns, like Cirrus uncinus, hooked Cirrus (“Angel’s hair”). Lower Cumulus clouds are likely to form over the mountains during the mid-late afternoon. Could be really pretty overall if you can get out of your windowless office for a moment to take a peak this afternoon.
Freezing level and the critical -10 Centigrade (14 F) level for ice formation in clouds here in AZ will be lowering especially during the evening and overnight hours, and should lead to ice formation/virga as the clouds fill in later in the day and overnight. This means a chance for measurable rain here. Noticed just now that yesterday morning’s U of AZ mod (available after about 10 AM) did have a few hundredths in Catalina overnight tonight. You can also see this progression of clouds, more or less, in the U of AZ model output from that yesterday morning’s run here1.
Will write more about later happenings in November when the prior forecasted rain in the models returns; its gone for now!
The End.
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1The 11 PM AST model run from the U of AZ is not yet completed, so to HELL with it! Hahaha, just kidding, but must move on to other chores, like digitizing old research flight videos from the University of Washington’s Cloud and Aerosol Research Group I was once a part of but now its over, plane gone, group gone. Life changes, not always for the better, I can see that now. I liked flying in clouds, hearing the graupel hit against the bubble where I had my head, standing on a little stool in the back. BTW, here is what the bubble looks like. I like to look at it even now and remember all the great cloud friends I got to know and write about.
The aircraft dome that was atop the fuselage of the University of Washington’s research aircraft. RIP. For awhile after retirement, I felt lost as many do. So, I would put this on my head, maybe while doing yard work in Seattle before coming here. It seemed to help the withdrawal I was feeling in those days. Great as a rain hat, too! It really didn’t look that bad.
Some rare drizzle precip1 fell yesterday. Suggests clouds were pretty “clean”, that is, didn’t have much aerosol loading and the concentrations of droplets in them was low (likely less than 100 cm-3) Also likely, in view of the recent strong winds, some of the aerosols in those clouds might have been large dust particles2 rather than those due to just “smog” and other tiny natural aerosols. Large dust particles can not only influence the development of ice at higher temperatures than normal (above -10 C), but is also known to aid the formation of rain due to cloud drops bumping into each other and sticking together; collisions and coalescence because large dust particles can accelerate this process by forming large initial drops at the bottom of the cloud where drops first condense. Here, drops are nearly always too small to bump together and join up unless clouds are deep, like our summer ones, and ice is going to form anyway.
So, yesterday, was a bit of a novelty. Some photos and story telling:
1:34 PM. Drizzling from Stratocumulus!
1:35 PM. Drizzling here. Hope you noticed and wrote it down. I remember how excited I was in 1986 when I was in Jerusalem and it drizzled! I did not expect to see drizzle there, and I remember how I screamed out, “DRIZZLE?” after putting my hand out the window of the modest hotel I was in. In those days, the cloud drops were reported to be too small by researchers there to form drizzle in them. Yes, Mr. Cloud Maven person was the first person in the world to report in a journal article3 that it DRIZZLED in Israel! One of the great things about blogging is that you can write ALL of the things that you like to read about yourself, and this one is no exception. I am really enjoying today, reliving past efforts and accomplishments since there don’t seem to be too many ahead….The late Jack Russell, flight engineer, listening to Art tell another cloud investigation story.
2:43 PM. Cumulus humilis field over Saddlebrooke.3:06 PM. Drizzle precip just a memory. These clouds too shallow to rain via collisions, and too warm to form ice.
Looking ahead….
Mods paint dry weather for the next 15 days, and so yesterday’s disappointing “trace” (don’t recall here that Mr. Cloud Maven person had predicted at least 0.02 inches!) may be it for October. Phooey.
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1Drizzle: Fine (size range, 200-500 microns in diameter drops) close together, that nearly float in the air. Very difficult to bicycle in drizzle even with a cap or big hat. Fallspeeds, just a few mph. Smaller sizes can’t make it out of the cloud, or evaporate within a few feet almost if they do. Even true drizzle occurrences, you can’t be too far below the base of the clouds or those tiny drops won’t make it down to you.
2What is a “large” dust particle in a cloud? Oh, 1-10 microns in diameter, real rocks compared with the other stuff normally in them. So’s you get a drop that’s already pretty large as soon as condensation takes places. And, if the updrafts are weak at the bottom, then only them big ones might be activated, keeping the whole cloud’s droplet concentrations low! Happens even in places in the middle of huge land masses where in Riyadh, Saudi Arabia, we saw this happen on a dusty, moist day in shallow Stratocumulus clouds. They developed some drizzle drops. I was with the National Center for Atmos. Research on a field project then.
31988: Rain from Clouds with Tops Warmer than -10 C in Israel (Quart. J. Roy. Meteor. Soc.)
I wonder if you caught it? Fell between 8:10 and 8:12 AM. Very isolated, and pretty small drops. If you weren’t driving in it, or outside, you would never have known this happened. But observing and reporting events like this is what makes us who we are, you reader of CM. We take pride in seeing and observing what others don’t.
8:12 AM. Photographic documentation of the total rain event on a car window, zoomed view. The largest raindrops are about 1 mm in size.
Before the rain hit, some two or three RW– (weather text version of “very light rainshowers”) began to fall to the SW of us from that deck of Stratocumulus clouds. Must have been where the tops were higher than anywhere else. Here’s the first sign, and upwind of Catalina, that you, as a CMJ (cloud maven junior) know to pull your car out of the garage. (BTW, thinking about having a CMJ cookie drive next month…so look around for your best recipes.)
7:42 AM. A full 30 minutes before the trace event in Catalina, a weak shaft of rain is observed on Twin Peaks, part of a broken line of sprinkles-its-not-drizzle rain.
It may seem strange, a non-sequitor, for those blog passersby to be talking about taking your car out of the garage or carport if a slight amount of rain might occur, as was the case yesterday. Here’s the “skinny”, as we used to say in the last century when we were young and could do things: a “clean” car, one that been wiped of all evidence of prior rain drops, but one having a thin coating of dust (you don’t have to apply a thing dust layer, its goes with the territory here) is great as a “trace detector.” And for us, CMs and CMJs, observing a trace such as yesterdays, when ordinary observers miss it (fumble the ball), is like hitting a low outside slider from former Husky pitcher Tim Lincecum, for a game winning touchdown. Or Boise State beating Oklahoma in a bowl game.
Why not just use the radar instead of parking your car outside and if the 24 h depiction of precip shows an echo over you, just mark yourself down as having a “trace”?
That would be cheating! Besides, some echoes seen on radar are only aloft.
And what if you’re in a “data silent” zone, where the radar beam is blocked by terrain, or is too far away? You’re adding unique information with your trace. Sure, nobody around you really cares if you had a trace or not, but, what the HECK.
8:01 AM. Heavy looking cloud produces sprinkle on the Tortolitas. Looks so dark partly because of the time of day, and partly because there was a fair amount of aerosol in the air. When higher aerosol concentrations get into clouds, it causes the drops in them to be small, and when small, they reflect more light off their tops and the bottoms appear darker. But it also indicates that the clouds are thicker than surrounding clouds, there’s a mound on the top. Still, among those higher droplet concentrations must have been drops large enough to collide and stick together and become small raindrops.
Did the tops reach -10 C or so to form ice and cause this shower? Nope. Capped out at 0 to -5 C, so almost impossible to have had ice form to cause our sprinkles. Check this sounding from the WY Cowboys, who are off to a good season BTW.
The Tucson sounding for 5 AM AST yesterday morning during our cloudy conditions.
In examining this TUS sounding closely, its good to remember that we are NOT Tucson, but in Catalina. We are 14 miles from the city limits; have a road sign that sez so. “Hey”, we aren’t even on the same side of the mountains as is “Tucson.” In fact, you have to go through the city limits of Oro Valley to get to Catalina! Only the Post Office thinks that Catalina is in “Tucson.” OK, got that in…
And, during the cooler season when troughs go by, as yesterday, the temperature profile from Tucson balloon is not accurate for us here in Catalina; its always that bit colder to the north and west of the balloon launch site for days like yesterday. So, like a chef, adding that bit more of butter or garlic, OUR sounding should be tweaked from the TUS one to show slightly higher and colder cloud tops, probably near – 5 C, not at ZERO or slightly cooler in overshooting Cumulus/Stratocumulus tops as would be expected from the Tucson sounding. Also, since it sprinkled at 8 AM, and not 5 AM, its also likely that clouds tops were going up some as the trough from the west approached yesterday. So there are lots of possibilities.
Sure wish we’d had a PIREP! (Texting form of, “Pilot report”). Any CMJ’s out there have an aircraft that we could take up and kind of poke around up there, see for sure what really happened instead of “hand waving”?
Absent aircraft reports, I am going to say that almost certainly yesterday’s sprinkle was a case of rain formed by “collisions with coalescence, or via the “warm rain” process (called that because it doesn’t have ice), sometimes called here, “coalision” rain. Very unusual in Arizona and, you can see that if you have to park your car outside to see how much came out of a cloud producing rain through “coalision”, it doesn’t amount to much.
You know, this is a great story for you. First, you observe rain that no one else did, or even cares about, until maybe you tell them it was almost certainly caused by collisions among cloud droplets, and then watch their eyes bug out!
Had some spectacular highlights again on the Catalinas, and also evidence of the aerosol loading as we say, in the crepuscular rays (colloq., crepsucular) shown below.
8:03 AM. Evidence of smog, maybe some dust, too, aka, aerosols that were getting into our clouds yesterday.8:04 AM. Gorgeous highlights continuously moved across the Catalinas. Hard to stop watching, snapping photos like mad, HD filling up, not much room left, gasping for more empty sectors now.
1:39 PM. Its all over. Only a field of small Cumulus (“humilis”) are left. Photo taken from inside a horse corral to give it a western flavor, make it more accessible to reader, maybe make you feel more comfortable after a heavy dose of “science-hand waving” today. Note rust on panel piping; adds artistic content. “Rusty corral and Cumulus humilis”; yours today only for $2,000.
Since there is STILL no rain indicated for the next 15 days in the models, just dry (for now) trough passages, I may have to discuss yesterday’s sprinkle again tomorrow. Thinking of a title even now: “That sprinkle; more insights on what happened.” Yeah, that should do it.
Breezy, deep blue skies were pocked with Cumulus humilis (“humble”) but as the afternoon wore on, they became more numerous, and spread out to nearly fill the morning’s clear sky, while remaining “humble”; about the same depth, 1,000 to 1,500 feet, max. Cloud tops were above freezing, so no chance to form ice and snowflakes, which would have fallen out as virga. Nor was there a single Ac lenticular, as opined here that there might be one yesterday.
These kinds of days with scattered clouds producing shadows on our spectacular Catalina Mountains is one of the most mesmerizing. If you can, you want to be somewhere where outside where you can see those shadows trek across our mountains, their rocky faces highlighted and then dimmed, while another portion lights up highlighting some other characteristic of those mountains, particularly in the late afternoon when the sun light is that bit richer (due to traveling through a greater path of the atmosphere as it sinks toward the horizon and more of the harsher, shorter wavelengths of white light are scattered out). Ask any photographer or artist.
And its no wonder we draw so many visitors in the cooler half of the year when there are so many days like yesterday; no rain, pleasant temperatures, but astounding, simple beauty just in the passing of a cloud shadow on a mountain.
3:11 PM.3:11 PM, looking farther toward the north. So pretty. You can just sit there and watch these ever changing scenes for hours. “Less doing, more watching.”5:15 PM.5:33 PM. Even our dreaded cholla cactus can have so much beauty in the right light.4:19 PM. Wonder how many of you noticed this line of small Cumulus clouds, called a “cloud street”? At first I thought it was caused by a bounce of the air going over and around Pusch Ridge, but later it was clear it had origins far to the south.5:29 PM. “Cloud street” still going, but you can see the origin is not much related to Pusch Ridge as it shifted westward and extended overhead and downstream into Pinal County. The clouds were filling in pretty fast at this time, but barely deepening.6:07 PM. While the sunset itself wasn’t spectacular, the lighting on the mountains was. Aren’t you glad you live in Catalina?
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In spite of overcast Stratocumulus clouds right now in the pre-dawn hours, there are no echoes on the radar anywhere near us. Boohoo.
And, if you’ve read this blog, and studied its contents, taken all the quizes, you know its because the tops aren’t cold enough to form ice (generally requires -10 C, 14 F here), pretty much required for rain here in old Arizony. Of course, some of our citizens are older than “old Arizony” as a State, which is pretty darn amazing, so maybe it should be, “not-that-old-Arizony”, to depart from whatever it was I was going to say before thinking about “Arizony.”
Now, back to weather…. Looking at the satellite and radar from IPS MeteoStar, it would appear that there are enough clouds around that a sprinkle is possible before noon as an upper trough goes by today. The air will be getting colder aloft, and there appears to be a line of colder clouds in a band right now in western Arizona, maybe ones cold enough to do that. Measurable rain is a very remote possibility, however.
Another trough, very similar looking to this one today, with a blast of cooler air comes through on Friday, October 4th, but like this one, looks dry. So, we have two pretty nice weekends in a row ahead of us as far as moderate temperatures go, and more great cloud shadows.
No rain for SE AZ in models for the next 15 days. Dang.
Our WY total has crested over 11 inches now. Its at 11.08 inches for the water year ending on September 30th, still about 5.5 inches below normal with only dry days ahead. Still it was nice to see a great thundersquall come through on the last day of the summer regime, though I was about 12 miles away from Catalina when it hit. So, I missed the last summer-type rain of the season with its momentary blinding rain and 40 mph winds; I had to be told about it. That season will be just a memory now.
If you’re a reader of this blog, and I know who both of you are, you MAY recall that yesterday, off-handedly really, it was written here that, “I don’t think it will rain today.” But it did rain, which is pretty remarkable in itself. It has previously seemed that if I think or say something, that’s what happens, almost like a supernatural connection of some kind with the future. Some of the astrologers out there know what I am talking about, maybe palm readers, too.
I will go through what happened just that bit, well, quite a bit, while I display some photos and our thinking was about what we were seeing. I know that our thinking would be exactly the same since you read this so much.
Now, when I started yesterday morning on this blog, the dewpoints were very high around here, 60s, and there was a little line of clouds in the satellite imagery on our doorstep to the west. Part of that north-south oriented cloud line is what you saw when you got up yesterday morning.
However, the dry air was already into central Arizona, with dewpoints in the 40s at PHX and Yuma; it was coming fast as the trough above scooted over us dragging a cool front. Behind the cool front would be the dry air.
So what are you and me looking for when we think an LL Cool Front is approaching, along with its wind shift?
A line of clouds, solid, broken or even scattered. So, when you saw that line of heavy Cumulus piling up in a line, SW to NW from Catalina, you and me were both thinking, “Droop, there it is!1“, to recall a song first heard on the TEEVEE show, “In Living Color.”
8:26 AM. Front on the doorstep or not. Looking west toward the Tortolitas. Even though the clouds are piled high, notice that there are NO rain shafts. No ice, and even with the warm bases at about 10 C (50 F), rain from drop collisions with each other also did not form. See smog shots later; smog is an impediment to that process.
8:24 AM. Heavy Cu line extends off to the N as well, strongly suggesting a wind shift is causing it. Again, no rain shafts are seen from these large clouds.8:20 AM. While the sights to the west were promising, the amount of smog (not dust here) was deafening. Sure there were pretty highlights as the crepuscular rays focused on our still green mountains, but still, its not a good sign for precip; works against it by causing the drops in clouds to be smaller than they would be in “clean” conditions.8:38 AM. Eventually those tops did reach ice-forming levels, those likely colder than -5 to -10 C yesterday, and rain shafts began to emerge, as here. But, that was off to the north beyond S-Brooke, and the clouds to the SW of us were turning ragged, drying out.9:06 AM. By 9 AM, any hope for rain here had seemingly vanished as the clear signs of dry air moving in, along with subsidence aloft, were now clear to you and me. It hadn’t rained, and though I always hope it will, I was amazed at how my risky forecast of “no rain” had magically occurred, leading to a slight case of megalomania, grandiosity, if you will. It was though I had spoken to those smoggy clouds directly. It was finished. I thought I might as well leave and go on some errands; no chance of rain now! I also think of myself as kind of a Garrison Keillor of clouds, tellling stories about them, and continuing a megalomaniacal theme here. “I try to tell the truth”, Garrison once said, then continuing, “but the truth doesn’t always take you as far as you need to go.”9:03 AM. Looking NW. Those huge clouds of just a few minutes earlier are gone, and now only suppressed versions of Cu are seen.
Then, the transformation back to what we had just seen earlier that morning! It was amazing, with HUGE Cumulonimbus clouds arising from the same appearing line of heavy Cu. Here we go into “error”, and I would add, humility:
9:49 AM. Was in route to Marana at this time from SH, but stopped to take a photo. Though these Cu had fattened up from nothing, thought they would be dessicated by the dry air moving in, that is, would look ragged and shredded and not amount to anything.10:14 AM. What? This was a shocking view, this Cb and rain shaft, upwind of Catalina. I still had to keep going to finish an errand though; not race back and enjoy what could be the last storm of the summer rain season.11:15 AM. Your storm, about to strike. Those clouds on this side of the giant, mounding Cb were the ones that done it, ones that exploded upward a few minutes later. Fortunately, I got some first hand reports from neighbors and used some imagination to experience how bad it was for a few minutes.11:57 AM. Just back in SH country, and the showers are still around, here to the NW.11:58 AM. But this view to the SW and upwind, is really The End, its over, it is finished, etc. The summer rain season has ended for us. The dry is moving in now, the clouds will wither and die even as the afternoon warms up some.
The only weather ahead now for the next couple of weeks is temperature changes. That’s about it, so will take a little break here, maybe only post once in awhile, and more on climo or science stuff.
The End.
————————— 1Modified for baseball to, “Bloop, der it is!”. A “bloop” is a weakly hit ball that falls for a base hit.
Yesterday, in a ploy to get some rain, I “dared” it to rain on the water year data I presented for Catalina. I didn’t think it would, to be honest, and also wanted a data “scoop” over other presenters of data who might be too shy to present data prematurely. Remember, the rubric here is, “Right or wrong, you heard it here first!”
Yesterday, the water year total I presented has ended up being slightly wrong.
It did rain. Furthermore, the 0.08 inches, is the heaviest amount around if you check our Pima County ALERT gauge data.
Our new Catalina water year total is 10.91 inches after a hard, few minute rain just after 8:30 PM. Mountains to the east were obscured, too, in a whitish haze so quite a little Cumulonimbus cloud emerged from that evening cloud deck, so rain-free for so many hours.
All in all, it was a dramatic day yesterday since the U of AZ rendering of the GTS-WRF had showers developing quickly in the middle of the afternoon and it was SO CLEAR, the sky SO BLUE for so long (a deep blue sky suggests dry conditions aloft), and I wondered if I hadn’t seen an obsolete model run (while out tramping around on a horse yesterday morning)1.
Finally, just before 11 AM some Cumulus started to form on the Catalinas, but more on the north sides. But then clouds slowly started to form everywhere and they gradually filled as the day went on, but were precip-free. Cloud tops remained too warm to form ice, which as you know is the -10 C level (with some exceptions; very warm cloud bases, or, very cold ones).
So, while the sky was very pretty, thank you, there was no virga, or showers visible, at least until very late in the afternoon after I had pretty much given up on seeing precip or ice, though came out to look every 8 minutes to make sure I didn’t miss any surprises. Diligence was to be rewarded; yours, too, I hope. I might also note that the U of AZ Beowulf Cluster run from 5 AM AST, available by mid-morning, also saw that the inversion capping cloud tops was going to be eliminated by 5 PM yesterday; this as a major trough in the westerlies cruises into Arizona from California today. It was just about as perfect a forecast as you can get, since it was just after that time, that cloud tops were able to sprout that bit higher and form ice, and an icy top appeared east of the Catalinas, and showers and virga appeared off toward the N.
Today?
Bye-bye, tropical air and summer-like clouds by later today (dry westerlies blasting in behind cool front). I will miss you terribly, summer clouds, but will have to wait until next June or July to see you again. Boo-hoo. Will be a very pretty day, but, rain not likely with front.
Below, your cloud pictoral for September 21st:
11:13 AM.11:12 AM.1:33 PM. If you’re like me, and I REALLY hope you are or you’re not going to get much out this blog, yesterday you were straining your eyes for an icy sprout upwind. But, it never happened. I don’t know how many good plays I missed during football day because I kept coming out to look upwind; all over really, for some ice. The Washington Huskies won, my former company team, BTW, taking care of “cupcake”, Idaho State. Its great when you play non-competitive teams and don’t have to worry about anything, like so many teams do these days. Oh, BTW, the clouds are coming right at you here.4:47 PM. By this time, several Cumulus in the area began to bulk up to congestus size, reflecting the loss of that capping stable layer up top. View is looking N across SaddleB.5:07 PM. While the Catalinas were still pretty “quiet” as far as producing clouds goes, the passing shadows on them were fabulous.5:20 PM. By this time, several light rain showers were visible to the N-NNE due to ice developing in the fatter Cu.6:05 PM. Wonder if you logged this first visible icy top, beyond the Catalinas? It was only visible for a minute or two before being obscured by the clouds in the foreground. You were probably watching football, maybe even “Johnny Football”, and letting your cloud obs slide I bet. I’ll get over it after awhile.6:15 PM. By this time, clouds were beginning to mass in over the Catalinas in the upwind direction and, with ice around, you began to wonder, well, maybe not YOU, because you’re probably still watching football, but I began to wonder, “Could it rain here? Could these reach up to the ice-forming level? And they did as little radar echoes began to form over and downwind of the Catalinas as night fell, preceded by a nice sunset.6:25 PM. Another in a long series of nice sunsets that occur in Arizona. Here, Stratocumulus clouds are under lit by a setting sun.
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9:03 AM. In case you didn;t believe that I could be a weatherman and also be able to ride a horse. Been bucked off a few times, too, though I don’t recommend it. Here, weeds of Catalina Regional Park. which most of us hope will be completed before the year 2150.
Add to text box, lower left, the words: “….unless you’re quite young.”
Looked like there was a leveling off during the past 15 years, along with the “puzzling 15-year hiatus1” in global warming, coincidentally, so I used a “poly” fit instead of a linear one that would reflect the “stabilization” of water year rainfall in these latter years. Those early wet years in our record are now associated with a big change in the positions where the lows and highs like to be in the Pacific, one that comes around every few decades called the “Pacific Decadal Oscillation” (PDO). The change to a new regime occurred in 1977-78, just when the Catalina rainfall records started at Our Garden down on Stallion where you should buy some stuff. There was also a gigantic El Nino in 1982-83 that contributed to that early wetness. Remember all the flooding in September and October of 1983?
You may notice that I have posted this some ten days before the end of the water year. I dare it to rain on this year’s data! (And I hope it does, given our meager total.)
Yesterday’s clouds
Many more and thunderstorms much closer than expected from this keyboard (heard thunder just after 12 Noon!) Here’s our day in pictures:
8:15 AM. Altocumulus perlucidus provides some nice lighting effects on the Catalinas.10:03 AM. Early risers, like that middle one, suggest tremendous instability up there.10:31 AM. See excitement note.
12:06 PM. Cumulonimbus/thunderstorm forms NE of Catalina. Due to high and cold cloud bases (at and a little below freezing later) this cloud has a high preponderance of ice compared to our more tropical Cbs.12:38 PM. Eventually becomes the “Dump of the Day” over there by the town of Oracle as it recedes (boohoo).3:44 PM. As noted in the title, yesterday’s clouds with their cold bases had a LOT of ice in them, and in most cases, not a lot of rain fell out. Here, an example of a dissipating Cb that didn’t produce much more even in its peak than what you see here, a VERY slight shaft.6:24 PM. Still, some nice color at sunset. That’s what this blog is mostly about, pretty pictures, in case you missed those scenes of the previous day..
Today…. Dewpoints are up from yesterday over much of southern Arizona, and mods suggest a similar day to yesterday, scattered to broken Cumulus clouds with an isolated Cumulonimbus, with more coverage in rain than yesterday. Whoopee! Rain is actually predicted here! How fantastic would that be? And I would have to update my opening just graph just that bit, an enjoyable task, really.
Mods are also indicating that some rain may leak into tomorrow as our first tentative cool season-style trough and front pass by. We’ll see. In any event, should be a pretty day today and tomorrow. Try not to be inside the WHOLE day watching football!
If you were on Ms. Mt. Lemmon, or just in Tucson yesterday taking your wife to the airport for some reason, you would have seen a line of large Cumulonimbus tops lining the east through southeast horizon in a broken line. It was pretty impressive, and demonstrated how close our summer rain regime still is, astronomically speaking anyway.
2:37 PM. Distant Cbs dot dot dot the horizon beyond the Rincon Mountains to the east. Photo taken while not driving; it just looks like someone held a camera pointed out a side window while driving and also not looking to see how the camera was pointed. Its a photographic niche I’ve developed. Lightning was being reported at Douglas at this time, too, though they did not add to their once-in-a-hundred-years summer rain season total yesterday.
There is still enough heat and moist air around for some small Cu around here, but that’s about it for today and tomorrow, though the Canadian model still thinks there will be some big enough clouds for them rain in the general area of SE AZ today and tomorrow.
But, just small Cu can produce dramatic scenes on the Catalina Mountains, much better ones than just a clear sky, so that’s SOMETHING to enjoy before the long clear days following the complete end of our summer rain season and the desiccating air that follows by Sunday and Monday.
About the most we can expect after the Cu are gone is the occasional appearance of CIrrus clouds once in awhile as storms in the westerlies track across the West, but to our north.
Next, I thought I would post a map of global ocean temperature anomalies for September 19th, in case you were thinking about going to the beach somewhere. Seems like most of the ocean is slightly warmer than normal for some reason, except around Antarctica.
The presence of an El Nino, as you likely know, can help jack up precip totals in the Southwest in the late winter and spring. So, its likely that official predictions will be for another drier than normal cooler half of the year (October through May).
Global ocean temperatures on September 19th.
Will have some additional Catalina climo charts in the next day or so, maybe an erroneous personal prediction of the October through May precip like last year’s…hahaha, sort of.
As water year winds down, just a couple of weeks left, its worthwhile to see where we are. Pretty dismal. You can see why the spring wildflower bloom was minimal around here. Great December, though!
Can there be any rain before the official end of the month, measurable rain that might improve our dismal 10.83 inches, droughty total?
Not if you believe our own WRF-GFS model run from last night, but, “yes” if you like Canada and the Canadian GEM model. It has some rain in the area for us on Sunday the 22nd. Here it is:
Valid at 5 PM, Sunday September 22nd. Note green in SE AZ (lower right panel), and blue for moist air around 10,000 feet ASL in the left lower panel. Excellent model run.
In the meantime, our own model run has the moist plume WAY to the east at that same time, and so no rain here. Here is that map from the WRF-GFS , as rendered by IPS Meteostar, for moisture around 10,000 feet ASL. The blue moist plume in the Canadian model above (get microscope out) is the same as the green one below, except that the green moist plume is shoved off to the east and south. Dang.
Also valid for 5 PM AST, Sunday September 22nd. The green plume here across NM and into the Plains should be compared with the blue plume at this level (700 mb) in the Canadian run above.
Saw some clouds in the moonlight just now. Seems that drier air can’t quite get rid of our summer regime moist plume, one that even yesterday was close enough to us to have produced a thunderhead off toward Mt. Graham and vicinity to the NE. The chances are small we’ll get any more measurable rain, but as in sports, that moist plume seems to be hanging around, and you know that old sports saying that when heavily favored teams let underdogs “hang around”; don’t blow them out as expected, upsets can happen. Well, of course, that’s what I am hoping for, just that bit more rain to at least push us over the 11 inch mark. Its not a BIG hope, just 0.17 inches more before October 1st.
Here are a couple of cloud shots from yesterday:
7:34 AM. When it seemed the mid-level moisture should be gone, there it is, hanging around. These Altocumulus clouds meant that Cumulus were also likely to form in the above normal heating we have going on now. 9:38 AM. Some Cirrocumulus (fine granulation with waves in it). Since some areas have shading, not allowed for Cc, it would have to be considered a mix of Altocumulus and Cc (often observed) or just termed Altocumulus since the height is much lower for this complex of clouds than cirriform clouds. Gads, I doubt that’s clear. Oh, well. 2:09 PM. Thunderheads arose repeated in this area, then dissipated soon after this shot. 3:12 PM. A little patch of Cumulus humilis, kind of looks like someone leaping at something. No ice visible.
Later I noticed that the afternoon sounding from TUS had ZERO CAPE, a measure of how unstable the atmosphere is. With zero CAPE (no instability indicated), you don’t expect a Cb. Hence the title, a sciency humor.
With yesterday’s capped clouds, capped by a horrific inversion at 16,000 feet above sea level, you may have spotted this remarkable sight late yesterday; first the wide angle view, then the zoomed view:
6:08 PM. Can you find the little rogue Cb? Has a transparent rain shaft below. I was stunned to see it!
6:08 PM. Zoomed view. Now you can just barely make out the little rain shaft, and the ice-ed out tops sticking up above the Stratocumulus clouds. Just amazing! How did this happen? Don’t know, unless it was REALLY hot over there. The 5 PM AST Tucson sounding for yesterday from the University of Wyoming Cowboys, located in Laramie, Wyoming, the happiest state in the whole US. Really, there is hardly a jollier people than those in Wyoming!1 According to our analysis software, there is no instabiity indicated that would support a Cumulonimbus cloud protruding to 25 or 30 Kft as the one in the photos above is doing. But, oops, there it is!
Still, even with mashed clouds, yesterday was often a very pretty one, in the 99 F heat here in SH, and ended with a great sunset. See below:
12:24 PM. Mounding Cumulus cloud adds a bit of interest here. Thought it was possible for some virga, but didn’t happen. Not cold enough for ice to form in mounding top, but you knew that already. Also, the high mountain horizon NW-NE was “silent” yesterday. No Cb tops seen.
3:31 PM. One of the greatest examples of Cumulus humilis (“humble”) you’ll ever see. They’re screaming at you; “my head hurts; there’s an inversion on it!” 6:32 PM. “All’s well that ends well”–Bill Gates. Yesterday’s heating and strong inversion kept the Cu hum forming and filling in so that they accumulated at the base of the inversion, eventually leading to almost overcast skies in the late afternoon and evening. And with clear skies farther west, resulted in this beauty as the sun sank below the horizon.
The weather ahead…
Seems like were destined to be on the edge of the summer rains for another week or so, meaning we might have to get telescopes out to see a big fat Cumulonimbus clouds. Canadian model from last night had some rain moving into southern AZ on the 23rd ahead of a big trough. We’ll see.
I also saw, in the “Moonlight Feels Right moonlight this morning (the singer of that song keeps laughing; must be from Wyoming….)”, some Altocu around. So, at least another scenic day, it a dry one today.
—————————- 1OBJECTIVE HAPPINESS BY STATE. I’ve posted this before, but I felt it was good to remind my reader where the jolliest people are in case he/she’s thinking of a vacation and want to go to a happy place, not a grumpy ones like those in New York State.
