Probably an Altocumulus or Cirrus.
The End.
In memoriam: Pepper

About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno
Last evening’s model1 run based on global data from 5 PM AST yesterday, gave us this, the remnant of a tropical storm barging into Arizona on November 3rd, just after our rainless October closes out:

As an expert “spaghetti” decipherer, you can easily see from the map below that there’s not much chance of this happening though its not completely impossible. Too much “noise” in the pattern around here (lines aren’t bunched like they are off Japan and in the western Pacific). I just posted the map above because its the first one in SO LONG that had any Arizona rain on it, that green and blue stuff on the map above.

Who knows, maybe there’ll be a cloud over us one day again, too.
Of note… unusually cold air for October is poised to rush into the eastern and central US in several waves during the next two weeks; those events have a much higher probability of occurring according our venerable NOAA plots of spaghetti like the one above. Likely will see cold air refugees beginning to bail to Arizona in their droves from eastern units of the country as October low temperature records fall.
Its great to be where other people want to be.
The End.
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1Namely, the Global Forecast System-Weather Research and Forecasting (GFS-WRF) model, pretty much our best.
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:





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.)
In case you missed it:

Some rain to fall on Thursday, most likely between 5 AM and 11 AM. Both the US models and the Canadian one have rain for us now, not much, but likely measurable. Best personal guess from the “pattern”: between 0.02 and .20 inches. This “pattern” is one where the Catalina Mountains are at the southernmost extension of much heavier rain/snow to the north, the clouds bank up on the west side of our mountains, and little Catalina-its-not-Tucson gets measurable rain whereas Tucson and places south do not. Jet core at 500 millibars (18,000 feet or so above sea level) will be passing just about overhead Thursday morning, and the wind at cloud levels during precip southwest to west-southwest. In the cooler half of the year, that jet core usually demarcates a sharp line between no precip (to the south) and precip on the north side of it when the core is oriented west to east. From IPS MeteoStar, this rendering for mid-day Thursday for illustrative purposes:

Adding to the rain excitement in the meantime will be scattered interesting clouds, windy conditions in the afternoons, and much colder air arriving during the daytime on Thursday.
To keep you occupied while waiting for rain, I now present an enigma. I shot this during a return flight from our B-23 aircraft as it ferryied back to Paine Field in Seattle after a study of emissions from the Mohave Power Plant near Kingman, AZ, September, 1983. Not sure of the location, might be eastern California or southern Nevada. On these kinds of ferry flights after a big field project, often with two bumpy, low-level flights a day, you don’t care where you are on the way home, you just wanna be home!
Might be a satellite calibration field of some kind. Even today this grid in rough terrain still amazes:

The End.
Hot off the Canadian presses from last evening’s global data from 5 PM yesterday, this exciting depiction (from Enviro Can) for Friday afternoon, the 10th. Note green and yellow regions in all of the SW, lower right panel! Note big upper trough over Vegas, upper left panel. Its all good, and, this being the 5th, its only a few days away!

But let’s look deeper….deep into the heart of the US WRF-GFS model for the exact same moment in time, shown below:

What caused this model bifurcation?
For one thing, the US mod sees no tropical depression off Baja, and our hurricane center is very skeptical that any tropical development will take place south of Baja, one that would move NW or N and send a moist plume up into a trough positioning itself over southern Cal on the 9th. US mod has NO tropical moist stream coming out of the eastern Pac ahead of a trough over southern Cal at all, whether there is a low down there or not. Boohoo.
So, any rain here in Catalina would be with the usual passage of the jet core and in the cold Pacific air behind the cold blast headed our way on the 10th-11th. And that rain would be very light, likely less than a tenth of an inch.
The Canadian model, sadly, has to be considered a little goofy right now with its copious SE AZ rains, and widespread rain/snow over the rest of AZ, too. It would be good to inform your neighbors that you are thinking the same thing about the Canadian model, i.e. that its a bit looney as well in case they saw it and are touting a lot of rain on the way without really looking into things. Embedded editorial note: A lot of people vote like that, too, I think; also read health claims in magazines without looking at the peer-reviewed literature, taling with their doctor, examine the results of double blind, randomized trials, that kind of thing on which we base the whole edifice of medicine on. No, they’d rather read on the side of a health pill food, “these claims have not been evaluated by the FDA” and then take the stuff anyway and enjoy the effects of a placebo, which, if you believe in it, can be pretty good.
No doubt the reports of low temperatures in Arizona with this coming big upper trough on the 10th-11th, and snow in the high mountains, will spur a flock of snowbirds to migrate south. It’ll be windy and dusty, too, as it usually gets ahead of the passage of the cold front with these big troughs. That will be interesting, as well as all the cloud forms that start to show up with it.
Note: I’d show you some NOAA spaghetti so that we could get a little more on this model discrepancy, but its been sequestered from me, as you will see here. In the meantime, will hope for Canadian vindication in the days ahead.
The End.
Here are the updated plots from the Our Garden location on Stallion where a continuous record has been maintained since way back in 1977 when the Sex Pistols, led by Johnny Rotten, were beginning to alter the face of pop music and pop culture and trigger an alternative music and fashion scene called “Punk.” Let’s see what John Lyden (aka, Johnny Rotten) had to say some years later after the SP years…
Below are the water year data for 2012-2013 ONLY from the Our Garden site, not a mixture of obs from MY gauge and theirs (which could cause “heterogeneities”, as I have posted before. Not much difference, really, between our sites, but it makes for a cleaner dataset, a “homogeneous” one. Thanks to the folks at Our Garden, Jesse, Wayne and Jenny, for letting me update their precious data into a spreadsheet lately. State climo wants it, too.
One difference that stood out this year was that Our Garden was clobbered by a few summer storms that we didn’t get and their water year total is 2 inches more than here (11.08 inches) in Sutherland Heights/Catalina, just a couple miles away.
So, here are the “homogeneous” data back to 1977 FYI:
I don’t place too much credence in a continuation of a downward trend, lately obdfuscated some by juicy summer rains. These kinds of things, even assuming some slight GW influence, usually reverse themselves rather suddenly with a burst of wetter years such as we see at the beginning of the Our Garden record in the late 1970s and early 1980s. Some of that was fueled to some degree by El Ninos, sometimes called “Eel Nino” due to its monstrous effects on Cal coast and the SW in general. Here’s what “Eel Nino” looks like when it occurs:
No “Eel Ninos” this winter… Darn.
The End.
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.

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.)

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.

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.

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.



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.
The End.
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.







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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.
The End.
You probably don’t believe that I went all the way to Douglas yesterday to see weeds from excessive, once-in-a -hundred years, record-breaking summer rains (16 plus inches). I think you’ll find my activities in this matter quite interesting. First, the documentation:

I thought I would do a comprehensive survey, radiating outward from the VC in all directions as far as I could go, even if it took several hours. But after that thought, I decided to just go across the street into a vacant lot right there in front of me, and shoot some weeds there; maybe that would be enough. It was getting pretty warm.




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On the way to Douglas from little Catalina, I passed through the tourist mecca of Old Bisbee. A sign called out as I approached it, “Scenic View”, and I am kind of a sucker for those. Thought I’d check it out.

I walked over to see what it was:

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Being a CM, I should report on the clouds of the day, Altocumulus ones:


Not much weather ahead except breezes and temperature changes, hardly anything for a CM. Maybe a lenticular with the winds aloft getting so trough with our incoming trough. Will be watching.
The End.
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.”






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:





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.
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1Modified for baseball to, “Bloop, der it is!”. A “bloop” is a weakly hit ball that falls for a base hit.