A swatch of Altocumulus perlucidus translucidus (sorry, that’s the way we talk around here) passed over Catalina early yesterday afternoon, each “unit” nearly perfectly evenly spaced with its fellow cloud element creating a brief period of cloud awe for those Catalinans (or is it, “Catalina-ites”? “Catalinians”? Who knows, who cares?). Here it is, in case you work indoors and missed it. It was truly a fabulous sighting!
The afternoon was marked by a melange1 of middle clouds:
The weather just ahead
The local TEEVEE met men are, of course, pounding out the good news rain is just ahead for Catalina. Looks like, oh, 100% chance to CMP (Cloud Maven Person) starting after midnight Tuesday to Wednesday. How much?
This is a potent, but fast moving trough. Maybe will have only 2-4 h of rain with the passage of the cold front and its rainband. But, coming from the sub-tropics, should have a appreciable rain band with it.
I would expect rainrates to reach “moderate” as the heart of the band goes by for a coupla hours, anyway. Moderate rain is defined by the NWS as 0.1 to 0.3 inches per hour. So, only two hours of moderate rain should be at LEAST 0.2 inches, and most likely more.
We’re thinking here that there’s a 90% chance of more than 0.15 inches, and a 90% chance of less than 0.70 inches. So, averaging those two leads to a best estimate in CMP’s opinion of 0.425 inches! Wow. Nice.
Now, I will look at the U of AZ nested model and see what it thinks. Kind of game we play here, seeing how a seat of the pants forecast, made over a coupla minutes, measures up to a computer model with billions if not trillions of calculations:
The weather way ahead
After the nice rain just ahead, we have to get through the week-long dry spell before we move into a new stormy regime. First, a spaghetti depiction of the ridge after our nice storm:
Here’s what’s been exciting for a few days now, and below, from last evening’s global model output:
Let’s see what the actual and very latest model run from IPS Meteostar has for us:
How much these coming rains can benefit our spring wildflower bloom and spring grasses I don’t know, but I sure hope they can resuscitate what otherwise will be a dismal spring.
Expecting a snow event during the “new regime” that takes over after mid-month, too. Be ready!
First, I will shamelessly plug a book on clouds, “A Sideways Look at Clouds”, by a well-published and acclaimed author friend, Maria Mudd Ruth. Its about her odyssey into them, mentally and physically, after she realized they were something she really had not paid much attention to before mid-life, then she had to know EVERYTHING about them! Its a great read, infused here and there with humorous anecdotes.
Not that there have been that many rainstorms since the end of July.
But it would seem that today marks the meteorological end of the summer rain season as dry westerly winds sweep our remaining tropical air to the east today. The mods think there is a chance for a couple of high-based thunderstorms in the area around Catalina late in the day. But bases will be so high that not a lot of rain will reach the ground even if one passes right over us. And, they’ll be moving in from the SW or W today due to encroaching westerlies.
In a little over a week, too, you’ll be hearing about early snow in the Rockies and West! We’ll have a day or two of those gusty, dry southwest winds that accompany our winter storms as well. You’ll get a real feel for the season change then.
Check out this plot from the NOAA spaghetti factory showing (blue lines) that an unusually strong upper trough will absolutely dominate the West in just over a week
Here’s a nice one from the day before as the clouds rolled in, starting with Cirrus and Altocumulus, lowering to Stratocumulus later in the afternoon.
Yesterday’s clouds; an extraordinary day with a little drizzle amid light showers
Hope you noticed the true drizzle that occurred yesterday, namely, fine (larger than 200 microns, smaller than 500 microns in diameter), close TOGETHER (critical to the definition of “drizzle”) drops that nearly float in the air. They may make the least impression, or none, when landing in a puddle.
When you see drizzle, you have the opportunity of chatting up your neighbor by educating them informally to what drizzle really is (many, maybe most, TEEVEE weatherfolk do NOT know what “drizzle” is, btw), and 2) by telling your neighbor, if he/she is still listening to you, that the droplets in the clouds overhead must be larger than 30 microns in diameter, or better yet, “larger than the Hocking-Jonas diameter of 38 microns, at which point collisions with coalescence begins to occur” and “drizzle is not produced by ice crystals in the clouds overhead; they’re not enough of them to produce ‘fine, close together drops.'” Your neighbor has likely left the building at this point, but, oh, well, you tried.
Here, in Arizona, shallow clouds, such as we had yesterday, hardly ever can produce the broad droplet spectrum in which clouds have droplets larger than 30 microns in diameter. Its because this far inland from the ocean, where the air is very clean, the air has picked up natural and anthro aerosol particles that can function as “cloud condensation nuclei” (CCN). As a result of ingesting dirt and stuff, clouds have too many droplets here as a rule for the droplets in them to grow to larger sizes. They’re all mostly less than 20-25 microns, sizes in which even if they collide, they can’t coalesce.
In “pristine” areas, if you go to one, such as on a cruise out in the oceans, droplet concentrations in clouds are much lower, and even a little water that might be condensed in a shallow cloud can produce a broad spectrum, one that extends to droplet larger than 30 microns.
So even little or shallow layer clouds can precip over the oceans, produce drizzle or light rain showers (in which the larger drops are bigger than 500 microns in diameter). Of course, here we recall that the (whom some consider “villainous”) geoengineers want to stop drizzle out over the oceans so that clouds have longer lifetimes, are darker on the bottom, and reflect more sunlight back into space.
Those guys can be lumped into the same ilk as those who want to change the color of the sky from blue to whitish or yellowish by adding gigantic amounts of tiny particles in the stratosphere, again for the purpose of cooling the planet! Unbelievable. Please ask before doing this!!!
A Pinatubo sampler for what “geoengineering” would do to our skies, say, sunsets in particular. I took this photo from the University of Washington’s research aircraft in 1992 off the Washington coast in onshore flow. But we saw these same sunsets, sunrises, yellowed by the Pinatubo eruption of June 1991 everywhere we went, including in the Azores in June 1992.
OK, pretty boring, whiney, really, so inserting picture of a nice horse here to make people feel better if you’ve been depressed about what our scientists have been pondering to do about global warming other than controlling emissions:
Later….drizzling Stratocumulus, same view:
The second extraordinary thing about yesterday was that the top temperatures of these clouds was around -10° C (14° F), temperatures that ice does not form act as a rule in Arizona. To get ice at temperatures that high, you also need larger cloud droplets, and they have to occur in the -2.5° C to -8° C range. In this range, it was discovered that falling ice crystals, mostly faster falling ones like “graupel” (aka, soft hail) when colliding with larger drops, ice splinters are produced. The cloud droplets must be larger than 23 microns in diameter in THAT particular temperature zone, something that would occur more often in our warm, summer clouds, but would rarely be expected in our winter ones.
Again, it goes back to clouds in inland regions ingesting lots of natural and anthro aerosols that cut down on droplet sizes in clouds (by raising droplet concentrations in them). Our recent rains have helped cut down on that process on ingesting dirt, for sure, and was a likely player yesterday. Furthermore, our winter clouds are moisture challenged relative to the summer ones with their tropical origins and high cloud base temperatures, a second reason not to expect larger droplets in our winter clouds.
Here is the TUS sounding with some writing on it for yesterday afternoon from IPS MeteoStar. (Satellite imagery was also indicating warmer than usual tops for precipitating clouds yesterday.):
Here’s the punchline: If clouds are drizzling, then they are ripe, if the tops get to lower temperatures than about -4° C for what we’ve termed “ice multiplication” or “ice enhancement”. A very few natural ice nuclei at temperatures between -4° and -10° C, say, starts the process, those forming “soft hail” which then leads to ice splinters. This is the leading theory of this anomaly of ice in clouds at temperatures only a little below freezing, if you think 23° to 14° F fits that definition.
There are exceptions where this process did not explain the ice that formed at such high temperatures, so standby for further elucidation about how in the HECK ice forms in clouds at some point in the future.
As usual, no time to proof, so good luck in comprehending what’s been written.
The weather just ahead:
The second main rainband is just about here at 9:25 AM. Cloud tops will be deeper and colder than in the prior rains, raising the possibility of some thunder today, and maybe another third of an inch of rain. Watch for an windshift line cloud (“arcus” cloud) might well be seen today. That’s always dramatic and exciting here in Catalina cloud heaven.
Oh, well. Was expecting at least 0.25 inches a few days ago, and thought maybe a heavy shower last night might pull that expectation out of the trash bucket. Monthly total now up to 0.70 inches (updated after reading NWS-style and CoCo gauges here), still significantly below average (0.96 inches). Not much else elsewhere, either. Double dang.
Mostly Cumulus humilis and flat Stratocumulus yesterday. Was looking for ice as the temperatures aloft cooled during the afternoon and evening, and only as the sun went down was a slight bit of virga visible to the west. That Stratocu deck over us was deepening upward, and began reaching the magic point where ice begins to form, probably around or a little below -10° C (14 °F) in clouds such as yesterday’s. Let’s look at a sounding from the U of AZ (as displayed by IPS MeteoStar) and see what it says about those evening clouds and see if the above is just a bunch of hooey (I haven’t seen it yet, either):
Still looks like a chance for some light showers before the month closes out, but will be hard to get enough to bring the total to an above average value. Dang.
Will update my reader on December’s early cold outlook as new information that agrees with my assessment comes in. Right now, that information is not available.
Many of you probably were gasping for air after having seen the WRF-GFS model outputs from last evening’s 5 PM AST global data.
A large hurricane, really more the size of its typhoonic big brothers in the western north Pacific, and one that also dwarfs the late tropical remnant, “Newton” , that came through here a week or so ago, is shown to move along the SAME path as Newton into Arizona in about 13 days from now.
For those few of you who did NOT peruse the 00 GMT, CUT, Z output, here are the fantastic fantasy hurricane depictions that this model, with all of its calculating power, shows entering AZ on the 26th. Kind of fun to see even if it is bogus because it indicates that such a strong tropical cyclone could come through here one day.
Below, from IPS MeteoStar, these, maybe the best fake AZ hurricane depictions I have ever seen. Note all the isobars, i.e., lines of equal pressure with this tropical cyclone in AZ, and then remember for all its rain, little Newton had virtually no signature on pressure maps! Hell, the pressure didn’t even fall at Nogales as Newt approached. Pitiful.
But it wouldn’t be like that in this fantasy hurricane. Tremendous pressure falls would occur as it entered AZ giving your microbarograph quite a workout as the pressure plummeted and then went up as the center passed by.
You do have a microbarograph don’t you? If you don’t, think about it.
Next, you’re curious, though, about what steering pattern caused this hurricane, previously shown to stay far offshore and dissipate over some jellyfish and plastic particles way out in the Pacific in the models.
Let’s look, again from IPS MeteoStar at the steering situation at 500 millybars, or in around 20,000 feet or so:
What you need to have any confidence is a big trough along or just offshore as we had with Newt, not a slight little itty bitty eddy aloft that has to be in exactly the right location at EXACTLY the right time. I mean, its like a ball that goes for a home run after it bounces of the center fielder’s head1 …
Hold your cash on the sand bags.
Finally, there’s really nothing from the spaghetti factory that supports this. Boohoo. What you need in spaghetti is strong support for a trough along the coast, not the below:
Spectacular Altocumulus castellanus and floccus (no virga) passed overhead during the morning. I hope you documented them with a few photos.
Have to depart from clouds and weather to tell this tale. Yesterday I stopped here to let the mighty Zeus rest a little. I let him graze “off leash” on some of the still-green nettle grass in a gravel parking area next to our cottage. I then went to get a pail of water for him, the pail being on the north side of our house. When he saw I was leaving, he immediately followed me like a dog. It was kind of cute.
But as we got to the gravel outside the north porch of our house, our two dogs, Banjo and Emma were going nuts at the sight of a horse outside the north windows.
Zeus got distracted by all of the commotion in the house and went onto the porch to look in one of the windows to see what was up, or maybe he saw his own reflection and thought it was another horse? Here is the hilarious scene:
1This actually happened in South Dakota, at Mitchell’s Cadwell Park, during a baseball game I played in ’72. I was catching in those days for Mitchell Commercial Bank. Our center fielder, a track star, ran to get a scorching line drive to medium depth center, and racing to his left, reaching up to grab it, the ball instead bounced off his noggin and went some 40 or 50 feet over the fence! He was OK. We had no “concussion protocol” in those days. Had a chance to bat against the legendary Canova, SD, pitcher, Lee Goldammer in that game. Whiffed on three pitches; was maybe at bat for 30 seconds.
Surfaris. Except it wasn’t funny. This song begins with a mocking laugh. Well, maybe “mocking” is correct.
Used 90 min of video on an “incoming” yesterday, thinking we’d get shafted pretty good as a thin line of heavy Cumulus congestus transitioning to Cumulonimbus passed over, maybe a quarter or more of an inch from both warm rain and ice processes1 in a line of clouds produced by the winds resulting from a strong fall of rain from a cell just north of Biosphere2. I am sure you were thinking the same thing and are profoundly disappointed today, not only by that one, but also by that Big Bopper that formed in the late afternoon around the same spot to the north-northeast of us.
Wished I’d copied that Wundermap of precip amounts at personal weather stations, but here they are, to reinforce the concept of a “wipeout“:
Wind blast here out of this event? Oh, maybe 12 mph.
What started out as a happy day turned sad in a hurry.
And this wasn’t the only “wipeout“! A worse one happened in the late afternoon that was far more excruciating; pain unbearable. A real explosion into gigantic Cumulonimbus occurred in a broken line, again in the area north of Saddlebrooke. It appeared one had produced a huge outflow for a time–probably was up toward the Biosphere2.
Some background. Here’s how it all started with a gargantuan line of Cumulonimbus and Cumulus congestus clouds in familiar broken line from just north of the Tortolitas to our northwest to north of Oracle to the northeast shown in the photos below, all taken at 3:43 PM. CMP wasn’t looking when this eruption of activity suddenly occurred, and seemed to happen elsewhere as well. May have been that afternoon temperatures just reached that higher point to send these big boys up there.
After feeding a horse on another property, I am racing back home to experience “The Blast”, and the rain in its full glory. I stopped to grab this photo, heart pounding.
The arcus cloud and the once proud Cumulonimbus cloud and its incredible rain shaft wiped out, the bottom of it vaporized if that’s possible by rainout, the wind push out of it unable to reach Catalina, in spite of an auspicious start. I now insert a picture of a horse, Zeus, to keep your interest up, maybe raise your spirits after such a debilitating cloud stories as are found here today. Animals, such as dogs, miniature horses and donkeys, are often used in psycho rehab units, especially for depressed persons, such as you are right now after reading this. So, I am really doing this horse insertion for my reader, whom I have depressed royally today:
The End (for August 3rd–falling behind more and more!)
1As a cloud maven junior person, of course, you know what I am talkin’ about when I mention “warm rain” and “ice processes.”
Yesterday was another great humilis day for you, with quite a phase twist at the end. I am sure most of you out there saw the surprising final touch to a warm day with high-based shallow Cumulus.
Let’s see how close that using that old estimator technique was yesterday by examining the Tucson sounding for 5 PM AST (launched around 3:30 PM, goes up about 1,000 feet a minute). From the Wyoming Cowboys, this:
Wow! LCLP was 515 millibars, just about exactly at 17,000 feet. Also, look how darn cold bases were, almost -10 °C or 14 ° F, tops around -14 °C or just 7 °F, and yet we see no ice…yet.
While waiting for some rain in the days ahead, not backing off that in any way, though models generally have not had any (bad models!), will pass along a horse prank that happened.
Two days in the morning, as I went to fill “Zeus” water tank in the dawn hours, there was something dark at the bottom of it. I thought maybe some poor little animal or bird had drowned in his tank that night. I reached down, and found it was my State Park baseball cap! I had left it on the top of a panel, maybe above the water tank, wasn’t sure, so it likely blew off the panel into the water tank. But then again, I wasn’t sure that Zeus hadn’t put it in there on purpose.
But that was a crazy thought.
As a test, yesterday morning I decided to put the cap back on top of the end of a horse corral panel, but much farther away where it could not possible fall into the tank, just in case Zeus was telling me what he thought of me by dunking my cap.
Here’s what I found when I came back in the afternoon to feed Zeus:The same scene as the prior morning!
This was amazing. I approach one of the puddles on Equestrian Trail. I see that its raining HARD in the puddle. I am only 20 feet from it, but its not raining on my car! Here’s what that scene looked like:
How could this be? Of course, we’ve all seen heavy rain on the road and drove into it. But the illusion here that was so striking is that it only SEEMED to be raining in the puddle, not around it since the drop splashes were not obvious as I drove up to it.
The rest of yesterday was pretty great, too, lots of rainbows, brilliant clouds and skies, too photogenic for a neurotic-compulsive photographer. However, one of 221 photos was of a human, a neighbor, not of clouds and rain shafts.
Here are a few too many cloud photos; excess is kind of a specialty of mine:
Lightly looking ahead
Still a lot of “troughy” weather ahead, and chance for decent November rains in the first half of the month after cold one goes by, followed by a short dry spell.
Beginning to wonder, with all the middle cloud thickness out there over and SW of Baja that’s headed this way if we won’t get sprinkles that produce a little measurable rain later today or overnight….
Models beginning to wetten things up here as well, like that Enviro Can model that sees our tropical surge high and middle clouds passing over us now, as deep enough for measurable rain later today and overnight. Huh. U of AZ mod, the best one for us, is still dry around here except on mountain tops. Our larger scale model, however, also has some very light rain in this area now, later today into tomorrow morning.
What’s intriguing is that a little jet core at 500 mb (up there at about the height of middle clouds) passes south of us as this happens, key for precip here1 in the cool season. The major jet stream is far to the north.
As you know, we have a bit of an El Niño going, both a “Classic Niño” as well as the “New Niño” going, and El Niños strengthen the southern portions of jet streams in the very way that we’re seeing in this situation.
They do that because its warmer than usual in the central and far eastern Pacific tropics due to heat in extra big Cumulus and Cumulonimbus clouds that pump away down there over that extra warm water, and that rising warmth produces a greater than usual difference in temperatures throughout the troposphere between the tropics and the mid-latitudes. Since jet streams are the products of temperature differences between warm and cold air around the globe, so unusually deep warmth in the tropical eastern Pacific gives a little strength tweak to jet streams coming into the coast2.
SInce there are two of these lower latitude “waves” traveling along in the southern branch of the jet stream, there are TWO chances for slight rains including that for later today. The next one barges in on the 6th of December. Will again be dense middle and high clouds with virga at its worst, like this one, though again a hundredth or two could happen.
Next real rain chance, and major front passage with air that’s too cold for us, will be on the 12th. Spaghetti folk, or “Spaghetti Busters”, those who can make sense of these balls of yarn, can EASILY see that trough on the 12th and a cold front with are “in the bag” even though that’s ten days away. Rain occurrence is more dubious, since the trough may land a bit too far east to produce rain, only a lowering of temperatures. Here is that plot from last evening. Enjoy.
Your yesterday’s clouds
BTW, for horsey people, the Cement Trough had water in it yesterday after being completely dry ten days ago:
1See Rangno, 1973, unpublished manuscript and figures for the whole US using only the horizontal shear in jet stream at 500 mb as a definer of precip occurrences. Its really quite something, though, I guess you can’t see it.
2This was figured out by the Great Jacob Bjerknes of the Norwegian School of Meteorology while he was cruising into retirement (“Emeritus” status) at UCLA in the 1960s, though Chuck Pyke3,4, his grad student, did most of the work. Did a lotta work on the big “Classic” El Niño of 1957-58, which, per chance turned out to be an International Geophysical Year with a lot of extra observations! How lucky wazzat?
3Chuck, as you may recall was in the National Guard whilst at UCLA and was sent to Biloxi, MS, for two weeks of training and while there, was “gifted” with the passage of the eye of Hurricane Camille, one of the strongest of the century. Later the remnants of Camille, to go on and on, produced 31 inches of rain in 6 h in Virginia.
4Chuck P, who now lives in Arizona, also was very thorough in his evaluations of rainfall in his other studies concerning the seasonal timing of rainfall throughout the West. He once told me when I visited UCLA once to get Bjerknes autograph5 that he had gone to every rainfall measuring site in his study! Now some people go to every baseball park in America, but going every rain gauge site would be more interesting to cloud mavens. He further told me he found one that had not moved for 30 years, but the rainfall had been decreasing. When he went to that gauge, he found that it was being overgrown by a tree! This is why you have to check things.
5I failed. He was “Emeritus”; too good to be in his office that day. You see, your Catalina cloud maven was a strange person even then, wanting an autobgraph by Bjerknes rather than one by Mickey Mantle, though one by Mickey M would be worth a lot more today.
While living the big western life yesterday by riding a horse, me and my ridin’ pal, Nora B., came across some water flowing in the Sutherland Wash by the rusty gate on the east side of the wash that leads to Coronado National Forest land.
So, with with a 3-5 inch rain on the Catalinas, there WAS some water in the Sutherland here in the Catalina area. It was remarkable that there was no sign whatsoever of water having flowed at the Cottonwoods at the Baby Jesus Trail head on the north side of this flow (shown below), but water was flowing in it a few hundred yards farther downstream.
Nor was there any sign that water had flowed from our big rain in the Sutherland Wash at the back gate to Catalina State Park. In fact, we saw where this Sutherland Wash water disappeared just down from the rusty gate.
So, a lesson has been learned here about wash water flows: it can be flowing modestly between two dry points. Huh. Might not see this again for some time, and it will all be going away soon. Too bad so many of us have to pass hiking or horseback riding to these rare scenes today due to a necessary Pac 12 football TEEVEE vigil beginning just after 12 noon today and lasting through midnight I think. Kind of sad when you have to make choices between two equally worthy activities like these.
Cloudwise, I hope you logged the occurrence of distant Cumulonimbus clouds in the high country on the NW-NE horizon late yesterday afternoon.
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