Through deliberate deception, the title is likely to bring in quite a few football-centric people, since “jumbo package” is a term used when an offensive team bring in all the “Sumo wrestlers” they have, usually in attempts to score a touchdown from 6 inches outside the goal line.
The “jumbo package”, however, is about some weather, essentially at “mid-field” rather than on the goal line (i.e., just ahead):
A large and very strong upper low center is forecast to arrive on Sunday, October 25th, football day, the last reference to football in this blog. As it passes over Arizona, the first snow of the year would likely fall on the ‘Frisco Peaks by Flagstaff.
Tremendous rains, too, would occur here in AZ with this low, espepcially2 here the SE corner, should it happen. See WRF-GFS model outputs below, as rendered by IPS MeteoStar:
Valid on Sunday, October 25th at 5 PM AST.Valid on Sunday, football day, October 25th at 5 PM AST. The bluish regions denote especially heavu rains having fallen in the prior 12 h.
But does it happen?
Let’s check the spaghetti from NOAA for a hint about whether this weather happenstance has much chance of occurring:
Valid on Sunday, October 25th, at 5 PM AST.Same map as above, except annotated for those who found the first map geographically challenging.
You, too, as an expert on spaghetti now, are as crestfallen as I was to see this spag output from last night, showing that the espepcially strong low is, in fact, an outlier; a not impossible situation, but an unlikely one since we don’t have the bunched blue contours where the jet stream is strong, down thisaway. Rather, those blue lines are grouped over the Pac NW, and only one or two bluish contours are down here, ones that would be associated with that upper low on the 500 mb map above for Oct. 25th
Still, even when you know its an outlier, it brings hope for a bountiful rain, which is good. Will monitor this as the days go by, in case the outlier spaghetti output is an outlier.
The weather just ahead
Of course, as all weatherman know, we still have our boomerang friend Joe Low returning with rain; that’s in the bag, and has a little “friend” following behind him. These, combined, should bring substantial rains overall in AZ and in the Catalina area, in the form of scattered showers and TSTMs that persist over several days beginning later Thursday through Monday. Joe et al. are slowpokes, which is good.
Haze and smoke are up, if you’ve noticed that our skies have been not so blue, but whitish. Stuff is coming up from Mexico it appears; (Smoky) Joe will bring more of that before it gets here. So, look for a hazy patches of Altocu and/or Cirrus in the next couple of days. Maybe a small Cu off in the distance.
2:06 PM, October 11th. Shows the kind of hazy, smoky conditions we’ve been having lately. There is also some delicate Cirrus up there contributing to the whiteness.
The End
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2“Espepcially” is a word I made up via some inadvertent key strokes, but I kind of like it: “In particular, but with some energy.” BTW, Coke tastes better than Pepsi, if that new, unexpected word made you think of a soft drink.
First some comparisons of clean and hazy skies so’s you’ll have some idea of what I am talkin’ about in today’s title:
Clean day, from a few days ago.5:19 PM. Yesterday’s Cumulus fractus and humilis form in haze and smoke. Not exactly the same view, but it was the best I could do to give you an idea of how crummy, well, to a clean fanatic, it was yesterdayPretty clean day from a few days ago, looking toward Twin Peaks area during the afternoon.Yesterday afternoon looking toward the same area. Note how much whiter the sky is toward the sun side of the photo. This whiteness is due to “forward scattering” of sunlight by tiny aerosol particles. Not much forward scattering in the prior photo.4:50 PM. Yesterday’s muffin Cumulus (mediocris) over Ms. Mt. Lemmon. No aerosols can be detected in this direction where backscattering of the sun’s light occurs because the aerosols are often dark, Think about when you fly commercially and look out the window away from the sun, say, to the north, and see that ever present black haze line out there, likely the result of black carbon particles. No ice formed in our Cumulus clouds yesterday, either. Top temperatures too warm.
Let us see where this Arizona smog might have come from….. Below a TEN day back trajectory plot which ends over Tucson at 5 PM AST yesterday afternoon at two levels, each below the cloud bases. Notice in the plot below that the model data thinks the air parcels that arrived here at 1945 and 2945 meters above the ground over Tucson (bottom portion of figure) started out at the surface and went a LONG way before rising up as that air crossed Baja, the Sea of Cortez and NW Mexico.
You can see, too, that it wrapped into our upper level trough, coming down the back side, then curling around from the SW–the air in troughs and ridges moves faster than do those features themselves , and that’s also what this plot is showing you.
Using a lower level end point over Tucson, ending around 3000 feet above ground level made no difference:
9:15 AM AST sat observations of aerosol optical depth. Blue is clean, red is awful. You can see a pretty contaminated air (red tones) SW of us over Mexico yesterday morning, and that’s likely what moved up this way to give us our hazy skies.
So, it looks like the air may have picked up some aerosols while it stalled around over northwest Mexico before arriving here since its unlikely that the air was hazy and contained so much aerosol loading coming out of the Pacific offshore of Washington and Oregon. No doubt it would have been out in the Pacific many days before arriving offshore of Washington and Oregon, plenty of time for deposition onto the ocean and washout one would think, leaving that bit of doubt. And of course, this is all dependent on how accurate our back trajectory calculations are. So, with those caveats, we can conclude that the aerosols likely came from Mexico and not the LA Basin as was mused about here yesterday.
Today’s clouds
Get cameras ready. Should be a nice day for patterned clouds, such as Cirrocumulus, maybe some lenticulars as well since the wind remains pretty strong aloft. Also with a minor trough coming through later today, the clouds are likely to fill in during the afternoon, and being that bit colder aloft, some of the Cu that form oughta develop a little ice and snow virga. That means a chance of a sprinkle somewhere in the area today. Right now, as the sun comes up seeing some nice CIrrus castellanus, some mammatus underneath, and a few Altocumulus clouds here and there.
Still thinking about an early cold rain on Saturday morning….
After last evening’s surprisingly heavy rain, we have now met our average for May for Catalina, having received 0.47 inches of rain over the past 24 h, some 0.36 inches during some house-shaking thunderclaps last evening.
Below are the 24 h local totals, ending at 4 AM today from the Pima County ALERT gauges rolling archive , these totals pretty much capturing all of our beautiful storm:
Gauge Location ID# —- —- —- —- —- —- —————– ——————— Catalina Area 1010 0.63 Golder Ranch Horseshoe Bend Rd in Saddlebrooke 1020 0.83 Oracle Ranger Station approximately 0.5 mi SW of Oracle 1040 0.55 Dodge Tank Edwin Rd 1.3 mi E of Lago Del Oro Parkway 1050 0.75 Cherry Spring approximately 1.5 mi W of Charouleau Gap 1060 0.79 Pig Spring approximately 1.1 mi NE of Charouleau Gap 1070 0.39 Cargodera Canyon NE corner of Catalina State Park 1080 0.63 CDO @ Rancho Solano CDO Wash NE of Saddlebrooke 1100 0.35 CDO @ Golder Rd CSO Wash at Golder Ranch Dr
Santa Catalina Mountains 1030 1.18 Oracle Ridge Oracle Ridge, 1.5 mi N of Rice Peak 1090 0.35 Mt. Lemmon Mount Lemmon 1110 1.34 CDO @ Coronado Camp CDO Wash 0.3 mi S of Coronado, 1130 0.83 Samaniego Peak Samaniego Peak on Samaniego Ridge 1140 0.79 Dan Saddle Dan Saddle on Oracle Ridge 2150 0.24 White Tail Catalina Hwy 0.8 mi W of Palisade RS 2280 0.24 Green Mountain Green Mountain 2290 0.12 Marshall Gulch Sabino Creek 0.6 mi SSE of Marshall Gulch
For more rainfall info, go here and here. And here to the USGS, too, not to mention the NWS rainfall tables. Too bad they can’t all be in one gigantic table!
The clouds and weather just ahead
A little cold morning rain, and even snow on The Lemmon, is looking likely for Saturday morning. Presently, the core of the jet stream at 500 millibars or around 18,000 feet associated with a mighty upper cold low that sits on Arizona on Saturday is forecast to be south of us (as was yesterday’s jet), a pretty black and white discriminator for cool season (Oct-May) rain here.
However, if that jet core around the low does not circumscribe TUS, you can forget rain. From IPS MeteoStar, this rendering of the upper level configuration for Saturday morning, showing that it WILL circumscribe TUS:
The 500 mb heights and winds predicted for 5 AM AST, Saturday morning, May 10th. Its gonna a cool Mom’s Day, too. One would expect rain here in Catalina with this configuration. Note how max winds are in a band well south of us. That banding circumscribes the deeper parts of the Pacific moisture that came in with this trough. This rendering is from the global crunch of data taken at about 5 PM AST, yesterday evening. These runs are updated every six hours.
In the meantime, “troughiness” today, tomorrow and Thursday, with secondary jet stream to south of us, will give us some more photogenic high-based Cumulus, maybe with some with virga in the afternoons. Today, as our upper low says goodbye, subsiding air is supposed to keep clouds from attaining tops high and cold enough to form ice. So, no rain today.
Yesterday’s clouds (going deep, as in pedantically)
There were some great scenes yesterday, summer-like ones, odd for May here, with massive rainshafts as the cloud bases lowered, reflected a huge jump in surface dewpoints to summer-like values in the mid-50s. Cloud bases yesterday morning, riding the tops of Samaniego Ridge, were near 7 C, compared with -5 C the afternoon before.
This warming of cloud bases greases the precipitation “wheel” since clouds with warm bases are be able to rain easier than ones with cold bases (say, near or at below freezing temperatures). Droplet sizes have to be larger at any given level above cloud base compared to the clouds of the day before since more moisture is forming in those updrafts at the higher base temperature. And, oddly, the larger the droplets, the higher the temperature at which ice can begin forming in clouds. And when ice forms, snow, then rain, come out the bottom.
To go on too long on this in covering all rain possibilities for yesterday, a base temperature of 7 C here is on the edge of being able to produce droplets big enough so that some begin colliding with one another and sticking together so that drizzle, then raindrops can form, a couple to a few thousand feet above cloud base, and those sizes of drops can really accelerate the formation of ice and then rain out the bottom. Are there any readers left? I doubt it.
Let us go even deeper…. It was hazy, smoky looking yesterday most of the morning, even when some good thunderstorms formed. So what? Well, smoke is bad for storms. Remember when it was reported by Warner and and the U of Arizona’s own Sean Twomey (1967) that sugarcane burning made it stop raining downwind from those fires in Australia? That effect has been verified in satellite measurements by cloud seeding nemesis, Danny Rosenfeld2 of the HUJ in Science a few years ago.
Well, too much smoke can choke droplet sizes down and inhibit the formation of rain by collisions, and delay the formation of ice. And so we had that counter effect of smoke from somewhere, maybe LA this time since it was in the boundary layer, not aloft like that smoke layer from Asia was a couple of weeks ago.
So, cloud microstructurally-spekaing, it was an especially interesting day, one, if he were cloud maven person, wishes he would have had an aircraft to sample them.
But let us look now and see what all the fuss is about:
5:40 AM. Dewpoints in the 50s; Stratocumulus clouds top Samaniego Ridge!6:41 AM. Soft-serve Cumulonimbus forms over west Tucson, Oro Valley. Icy top looks like its comprised of needles and hollow sheaths to me, ice that forms at relatively high temperatures for ice formation, higher than -10 C.6:42 AM. In the meantime, drama over Oro Valley to the west and north of Catalina as a deeper cloud unloads. Thunder, too.7:19 AM. Haze and rain. This was a pretty astounding sight, so much haze/smoke in the rain as evidenced by these intense crepuscular rays.8:19 AM. A real summer-looking sky on a big rain day. Frequent lightning was emitted by this behemoth that went on to pound Saddlebrooke.8:37 AM. Unusually strong May thunderstorm pounds Saddlebrooke.
3:42 PM. In spite of lots of convection and scattered Cumulonimbus clouds, the sky remained almost an eastern whitish due to smoke, which I will blame on southern California, absent any facts or investigation. No time.
6:59 PM. Our major evening rain and thunderstorms were developing upstream.
2Rosenfeld a “nemesis?” See the references and discussion below for kind of an interesting science story aside….
Rangno, A. L., and P. V. Hobbs, 1997a: Reply to Rosenfeld. J. Appl. Meteor., 36, 272-276, and…..
Rangno, A. L., and P. V. Hobbs, 1997b: Comprehensive Reply to Rosenfeld, Cloud and Aerosol Research Group, Department of Atmospheric Sciences, University of Washington, 25pp.
With the publication of voluminous (en toto) commentaries/critiques in 1997 by a few of our peers, but mainly by Danny Rosenfeld of the Hebrew University of Jerusalem, that concerned our 1995 paper reanalyzing the Israeli randomized experiments, yours truly and Peter V. Hobbs, had attained, according the the Technical Editor of the Journal, the status of having become the most criticized meteorologists in the history of weather–well, in the history of the Amer. Meteor. Soc. journals, anyway! How fun is that? Its fun.
Our findings, that the two benchmark Israeli randomized cloud seeding experiments conducted in the 1960s and 1970s were largely misperceptions of cloud seeding effects due to storm biases on seeded days, were independently verified in peer-reviewed publications by researchers at Tel Aviv University some many years later.
Operational cloud seeding has ended in Israel in favor of more fruitful avenues for obtaining the water they so badly need.
While depressed about a waterless trough approaching us today, well, maybe a few hundredths is all that can fall from its passage, I thought I would depress you that bit more by showing how our smoggy world is connected.
Perhaps you thought, wrongly, of course, that the smoke layer above us yesterday was from from southern California or Mexico. After all, smoke and haze does leak into the SW deserts from the LA area all the time.
But no.
That layer was too high up (estimating above 20,000 feet above sea level); it was in a very noticeable thin, dark layer to the southwest in the morning, then spread over the sky during the day.
Maybe yesterday morning after sunrise you even thought it was “cirrostratus nebulosus”, that vellum ice cloud with little internal structure.
Let us look at the smoky evidence (before any clouds formed):
9:51 AM. Its not Cirrostratus nebulosus. There was no indication of cold clouds over us, as would be the case with Cirrostratus nebulosus.9:51 AM. a thin smoke vellum covers sky. Best seen toward the sun. Looks dark on edge when the sun is shinning on it, like to the southwest yesterday morning.4:21 PM. Still there, ABOVE the Cumulus fractus, though the Cu fra is also impacted by smoke. The faint undulations are above the Cu fra, and show gentle waves, the kind that exist above the “boundary layer” and are not mangled by surface convection and Cu formation.6:46 PM. “Ugh” sunset. Smoky haze layer now really evident. More waviness, betraying its high altitude.6:49 PM, looking SW. Ditto.
Below, a satellite looks at our smog invasion, as indicated by the values of the “Aerosol Optical Depth” (AOD), how muddy-looking it is from up there. Blue is clear, anything else is muddy. Red is incredible. You can see it streaming in from the southwest yesterday morning, 5 AM AST. An annotated version below, in case you’re lost.
Same image, annotated.
Now, let’s see where it came from using the NOAA HYSPLIT model for obtaining backward trajectories for FIVE days, ending at yesterday morning. We saw it streaming in from Mexico, but did it really originate there? Nope.
Backtrajectories for three parcels of air at three levels above us, ending at 5 AM AST yesterday morning. The model thinks that two of the layers above us started way up above 30,000 feet some five days ago, but were lower when they arrived over us. The stuff about 20,000 feet above us (the red line), started lower than those, but was rising as it got to Tucson, that due to passing through the trough that’s approaching us this morning, One would expect to see more layering of smoke today.
And there you have it, “smog across the waters”, the Pacific ones.
Hard to say how it got up there, often its due to forest or other fires in Asia, rather than comes from low level urban smog. It gets here mostly in the springtime because the low pressure systems with their rain belts are weaker, less able to process smog via rain out as smoke layers cross the Pacific, while the jet stream is still quite strong and can carry layers a long ways in a hurry.
Dust plumes from Asian deserts like the Gobi also make it across the Pacific to the US from time to time, again, mostly in the springtime.
—–end of smoke diary module——
Expect shallow to moderately deep, high-based Cu today, ones that will form ice and virga, and of course, it will be windy as well. Seems too dry for much anything to reach the ground here in Catalina below those high bases, a pitiful situation with such a strong trough passing over us today. Check out the U of AZ model for further details. Maybe we’ll see some great lenticulars above the Cu tops…
Happened around noon yesterday. I could see it from here that the shaft consisted of graupel mixed with some rain. Nice video of this exceptionalism-of-the-day event here from the U of AZ.
Its interesting to me, and to you, too, most likely, was that yesterday it was asserted here that there would be no ice in the “small” Cumulus clouds that were expected to form during the day. And yet we had a momentary Cumulonimbus cloud with a ton of ice and a graupel/rain/snow shaft! Huh.
In related1 distractive headlines:
Fields of gold erupt in Catalina!
Hours: 10 AM to 3 PM, M-S, otherwise closed. Why do they do that? You won’t find the answer here, so move along now…
4:00 PM yesterday, on hills west of Spirit Dog Ranch. Numerous poppy flourishes in this area. On horseback,, Nora Bowers, co-author of the popular guide, Wildflowers of Arizona. Those poppy blossoms were pretty much closed here. You really should get out and see them if you can. Well, worth it.
Rasslin’ Dogs!
“Emma” border collie, bottom, “Banjo”, border terrier mix of some kind, top. 2-day old distractive photo. More distraction. Few readers will likely go farther than this….
Yesterday’s clouds and explanations
8:22 AM. Altocumulus, bases about 14, 000 feet above sea level, or about 11,000 feet above the ground here in Catalina. The temperature at cloud top, via the TUS balloon sounding, was about -15 C (5 F), pretty cold for not having some virga or ice showing. It happens. There could be several reasons: Lack of ice nuclei in that layer? Tiny droplets, ones that resist freezing more than larger cloud drops? Lack of mixing with very dry air above cloud top (it was moist all the way up to Cirrus levels))? Mixing in very dry air at cloud top can lower the temperature of a drop a few degrees before it disappears completely, thus increasing the chance that it will freeze. That last effect is mostly operating in Cumulus clouds whose tops can penetrate relatively far into very dry layers. So, once again, we have no real answers, or maybe, all of them. It is worth noting that going to -15 C here and no ice in a Cumulus cloud is a virtually unknown occurrence, one that speaks to ice nuclei, those specks of mineral dirt that are known to cause ice to form in clouds, like kaolinite, etc. originating in the boundary layer/dirt interface being a primary culprit.
10:49 AM. In fact (!), “small” Cumulus clouds DID form yesterday, hold the ice. Quite a forecasting triumph.10:51 AM. While small Cumulus clouds pervaded the sky, there was an exception; the usual cloud street that forms off the Tortolita Mountains was trailing over Catalina and those clouds in it were at least of mediocris size (likely a km deep or so), and due to the low freezing level yesterday, getting close to the ice-forming level for Cumulus clouds here of around -10 C (14 F). Was actually outside, as you probably were, too, as it passed over, shifting gradually to the south, hoping for a drop so’s I could report a trace of rain today. “Great weather folk don’t miss traces!” (Dry-fit tee shirt in preparation….)11:00 AM. I want to keep reminding you of the prevalence of small, “docile” Cumulus clouds (ignore large dark cloud shadow at left). Just trying to balance out the cloud day picture the way media balances things out, regardless of whether they are Democrats or Republicans.
11:52 AM. Graupel begins to fall from a Cumulus congestus just beyond Pusch Ridge. It would be hard to describe the magnitude of the embarrassment I began to feel having stated that there would be no ice. I realized I had been careless as a forecaster, not really looked hard enough at the conditions, the lapse rates. It was truly humiliating to see this happen. Oh, in case you can’t see anything, the next photo is a blow of this humiliation as it began to take place.11:58 AM. Picture of graupel particles emitting from a cloud from 10 miles away. Note fine strands, a sure sign of graupel especially on day with a low freezing level and cloud bases at below freezing temperatures. Note too, ice is not visible at cloud top, something that indicated an abundance of droplets over ice crystals in the cloud, the conditions that lead to the rapid formation of graupel (soft hail).
12:10 PM. More humiliation and graupel; a forecasting disaster is in progress for all to see!
12:17 PM. Turret at left side, under fragment, appeared to be softening to the look of an icy composition that all would recognize immediately, but external ice composition not apparent yet. Note the “harder”, more cauliflower look of the turret on the right half of the photo, indicating an all liquid external composition. Graupel was forming inside that right half, though.
12:29 PM. Total icy humiliation. The “cotton candy” transition of the prior turret to “Mr. Frosty” (left of center) was complete for all to see. Looking toward Catalina, I could almost hear the laughter, “Calls himself a ‘cloud-maven’, said there wouldn’t be any ice today, and look at all that ice! What joke!” Now that the turret has become a modest Cumulonimbus, likely completely glaciated, the precipitation falling would be snowflakes (not graupel since the liquid water droplets are gone inside it) melting into rain farther down.
4:21 PM. The clouds returned to their former “small”, ice-less, sizes for the rest of the day after the humiliating exception.
6:18 PM. Revealed in yesterday’s near cloudless sunset, undulations in the ever present high altitude haze layers that circumscribe our planet. Layers like this, that are featureless except for the revealing waves causing the undulations, are extremely old, days, and are often reffered to as long range transport events because they likely traveled thousands of miles before arriving over Arizona. They are likely to be composed of old, old contrail emissions, emissions that have worked their way up in the atmosphere from over heated land surfaces, distant forest fires, and so on.
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1Its not really related but sounds like something that should be said.
While yesterday did not have the drama of the prior few days, there was aerosol drama anyway, a real battle took place against the forces of evil, represented by air loaded with urban smog, and good, clean air to its north, in which we were initially immersed.
A rare fog bank streamed out of Tucson toward Marana, Continental Ranch, and south Oro Valley and beyond. The moist air near the ground associated with our recent deluge, and capped by an inversion, combined with very light winds allowed fog to form in the first place. Its westward trajectory into the southern reaches of Oro Valley is associated with the normal sloshing of winds in Tucson, from southeast in the morning, to northwest in the afternoon on “undisturbed” days. On most mornings, all we see is a haze layer close to the ground that streaming out of Tucson down that way. In this case, the smog layer was in the form of fog, droplets wreaking with all kinds of untoward particles and chemicals like sulfates, nitrous oxides, hydrocarbons, etc., these from cars, wood burning stoves, factories, etc, all the things associated with modern life in an urban center except for wood burning stoves. As a smog-containing fog, it was pretty, however.
However, most of the time, maybe nine out of ten, that thin smog layer stays south of Catalina, can’t quite get here. But yesterday, the forces of evil resulted in an advance of the smog-fog to Catalina. A southwest wind came up in mid-morning, and like a tidal wave, that low thin layer slurped its way up the Catalina Mountain sides and Oro Valley, rolling over everything, growing deeper as the long absent sun warmed the ground, dissipating the fog, leaving the aerosol contained in it, “naked”, as it were.
It seemed for a time that a slight north wind might rule the day, and the smog would stay south of us as it usually does. Instead an ugly southwest wind developed, as often happens here in the afternoon, as air starts rising off the Catalinas to form Cumulus clouds.
And that’s part of what happened yesterday to bring us smog, besides us being in the protected lee of the Catalinas due to northeast winds aloft. When you’re in the lee, sometimes moisture and aerosols remain trapped there, like those cattails I used to pop open at the north entrance of the University of Washington’s Atmospheric Science Department on days with a strong southwest wind and those seeds would circulate in the lee for maybe an hour in really interesting swirls that could be seen due to all the seeds floating around and around, incoming people waving their arms to get them away because they would stick on your clothes. I was younger then (40s maybe), and I guess it was pretty childish. I’m not like that today, as demonstrated by this blog. I wish I had some cattails today, though.
7:04 AM. Fog streams westward from TUS.7:06 AM. Close up of “sfog” bank. Looks pretty outside, but its not inside. There are people like that, too.7:27 AM. Another close up, almost surreal looking with Kitt Peak Obsy in the background.7:35 AM. If you ever need to get warm, popping up out of the fog and Stratus is a turret due to a heat source over there maybe off Tangerine Road, I-10 area.7:57 AM. It seemed to be a little closer….. Hmmmm.9:44 AM. NO doubt about it, its creeping on cat’s feet toward Catalina! I have never taken so many photos of fog before, too. You could see trees and other prominences disappearing as this smog-laden fog came closer.10:54 AM. The warming air had dissipated the leading edge of the fog, leaving only shreds of Stratus fractus clouds that were coming toward Catalina. But now the the invading smog with it was revealed for all to see, that hazy layer below those clouds along the mountains.11:35 AM. The smog was reaching Catalina, the smog front advancing here along the side of Samaniego Ridge, with almost a little arcus-like Cumulus cloud marking its advance (left of center). It was a profoundly disturbing moment that what seemed like it was going to be a visually pristine day, was now going to be mucked up by some Tucson smog.12:35 PM. Got pretty bad down there by Pusch Ridge, before more heating mixed it up into Cumulus and Stratocumulus clouds topping the Catalinas.Also at 12:35 PM, but looking north into the pristine air that was to the north of the smog bank. This was not clearer looking just due to not seeing aerosols in the back scattering view in which itgs much tougher to see aerosols–they’ll look dark or brown. not whitish. The prior pictures call out areas of smog due to “forward scattering” of the sun’s light toward you by the aerosol particles.
5:24 PM. The sun set amidst the smog and so the light on the mountains had a slightly more orange look. It was still pretty the way the scene was framed by Stratocumulus clouds.5:55 PM. The sun sets amidst a well-loaded aerosol layer, looking orangy-red, and producing the reddish orange cloud base in a polluted Stratocumulus layer. The yellowish orange sky below cloud base, with faint undulations in it, shows that a smog layer is present, and, if you look closely toward the Tucson Mountains at left, you will see the top of the smog layer is becoming visible as an inversion forms, trapping it once again.
Wednesdays here in Catalinaland are, of course, trash and recycling days. And, along with T and R day, we found ourselves amidst some pretty pretty scenes, and in some cases, extraordinary ones,….and a little rain (a trace here in The Heights). I reprise those scenes in case you missed them; you probably did because you’re not some kind of photonut like the writer.
However, be advised that some of the mid-day photos will show smog, smog that was ingested into our poor clouds.
That smog bank, emitted from the Tucson area, almost reached Catalina yesterday during the day. It came up around Pusch Ridge and up along the west side of Samaniego Ridge and almost reached Catalina before its advance was halted by a north wind push and it retreated to the the south. My heart was beating so fast that it might overrun us! Marana and Oro Valley were heavily contaminated for awhile. And smog is like a cloud cancer1.
7:46 AM. A rare display of Stratus along the Tortolita Mountains. If you were hiking and were in this, it would be fog to you, still Stratus to me viewing it.7:46 AM. Rare shot of what appears to be ground fog or just fog rolling eastward out of Tucson. Some flakes of Altocumulus above, and a higher layer of Stratus on the Tucson Mountains.
8:49 AM. This was an amazing sight, to see a thin Stratus cloud fronting an early morning Cumulonimbus capillatus. The Stratus is hard to see, but its the thin dark line on the horizon above Priscilla’s house below the turrets and ice of the Cb. The only other time I have seen such a sight was in Seattle after a snow with Stratus clouds and fog all around the city, but with warm Puget Sound sending up plumes of big Cumulus clouds.
10:37 AM. The day was not without some cloud levity, as these “twin tower” Cumulus clouds show, drawing attention to themselves.
11:26 AM. First ice in clouds becomes visible. It was obvious a few minutes later, but if you saw at this time, or can find it here, you are a pretty CMJ, worthy of an accolade. Of course, if you looked at a radar map of the area, you would have known where to look in advance since there was a small echo in this complex by this time. The precip just was not enough to form a shaft. Note, as well, that Twin Peaks, Continental Ranch area is NOT visible due to the smog bank that was going to move up this way, as it turned out. And look how gorgeous it is toward the Tortolita Mountains!
11:38 AM. OK, here the ice from that turret in the prior photo is now obvious (center frizzy area). However, it was also obvious that the smog toward Marana/Continental Ranch was now closer, even while we had a north wind here in Catalina. Was that southwest wind going to win and mess up our fantastic skies?11:42 AM. Here you can see the smog as it was advancing around Push Ridge and had gotten farther north along the side of Samaniego Ridge. Those lower cloud fragments along Pusch Ridge at the top of the smog tell you that the air was more moist than the air our Cumulus clouds were forming in, and therefore, that this advancing smog bank likely associated with deliquesced aerosols from cars and other urban effluents (aka, “air sewage”) accumulated during the Tucson fog earlier that morning that was now being mixed into a deeper layer and heading this way! To think of breathing air like that. in a short while..it was a ghastly thought.
12:12 PM. To make a short story long, the advance of the smog, with its lower based clouds got as far as Golder Ranch Drive over there by Samaniego Ridge (whitish area below the lowest cloud base on the left), before receding under a freshet of north wind. However, some southern parts of Catalina were affected for a short time.
1:14 PM. By this time, larger complexes of Cumulonimbus clouds, pretty weak ones, were developing over and north of the Tortolita Mountains and upstream of us offering the hope of some measurable rain in Catalina, the smog pretty much pushed back to the southern parts or Oro Valley and Marana.
2:00 PM. Widespread light rain showers were in progress from these weak Cumulonimbus clouds, but sadly, bypassing Catalina. But huge visual payoffs were ahead as the clouds broke at times, and some stunning sights emerged.
2:35 PM. Stunning….to me, anyway. View this in full screen mode for best impact. Later, more accessible stunning.
3:01 PM. Breathtaking; in total awe of this scene! Note gliaciated tower at right.
4:28 PM. And those scenes just kept coming! It was hard to be indoors for even a minute.
5:28 PM. The fading sunlight and the fading Cu only got more breathtaking. And we realize how lucky we are to be here and see scenes like this so often.
5:38 PM. The smog belt, held at bay during the day, still lurked to the SW of us, compromising our sunset by providing a reddish-yellowish sickening hue to it, a sign of a smoky presence, that may compromise today if we’re unlucky.
The weather ahead and way ahead
Well, RIP El Niño, an EN expert has written me just yesterday. Not much left of it he says, having a attached a map of ocean temperature anomalies to kind of rub it in. So we can’t count on hot water in the eastern Pacific to help fuel Southwest storms as was expected by the CPC and others last spring. But, that doesn’t mean that there can’t be a juicy late winter and spring, but the odds are down.
And, we won’t see clouds like yesterday until the long-foretold-by- spaghetti trough arrives around the 22nd of January, and with it some chance of rain. Doesn’t look like it could possibly be very much. BTW, Only 0.02 inches total in three days of light showers in the current situation. :{
BUT…..in the longer term, spaghetti is once again HINTING at a break-on-through-to-the-other side situation, your writer’s favorite as a kid, 10-14 days from now. A high builds up along the West Coast and in the eastern Pacific, gets too big for its britches, can’t maintain its giant north-south range, drifts farther and farther north and begins to break up, kind of looking like a horseshoe with the open end down (toward the south) as the jet stream “breaks on through to the other side” and “underneath”, that being a jet stream comes through from the warm subtropical central Pacific to the southern areas of the West Coast.
The north part of the West Coast and Gulf of Alaska are dominated by higher pressure with lower pressure to the south, so its kind of an upside-down-from-normal looking weather map, pretty rare, and that’s why its cherished by yours truly.
The End, at last!
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1As you know, when clouds are heavily contaminated with air pollution, they can’t rain as easily because the droplets are smaller inhibiting rain in two ways: by preventing the formation of drizzle and rain drops, and making it more difficult for ice to form since the formation of ice happens at higher temperatures when cloud droplets are larger. So, clouds have to be taller when they are polluted to produce rain, either way.
The “perfect storm”? Well, maybe the perfect rain, and it kept giving fro several hours yesterday after our best model said it should end yesterday before 11 AM. And what a nice rain! 1.18 inches total here in Sutherland Heights, as measured by a CoCoRahs plastic 4 inch gauge. (You might consider getting one, btw, or one from the U of A’s rainlog.org)
Went down to the CDO and Sutherland Washes to see what was up after seeing the gargantuan 4.96 inch total on Ms. Lemmon, and the 3.62 inches at the Samaniego Peak gauge. Below is the resul for the Sutherland, both were the same, nary a drop in them:
8:15 AM. Looking upstream in the Sutherland Wash at the back gate of Catalina State Park. I could hardly believe that there was no flow with so much rain having fallen in Catalinas! But it was good in a sense; all that rain mostly soaked in.
6:37 AM. A photo of drizzle falling from Stratocumulus clouds. Hope you got out and jumped around in our rare drizzle occurrence. Big hat, no bicycle, works in drizzle, too, the tiny drops won’t get on your glasses. Note how uniform the fuzziness is toward Catalina/Oro Valley, only gradually thickens to the left. Took about 2 h to get a hundredth when this was going on.
7:23 AM. Drizzle drops as seen by your car’s windshield after about 1 sec at 1 mph. Note how close together they are. The tiny drops and how close together they are is what differentiates true drizzle from the phony labeling of spares large drops as “drizzle” we sometimes get from our TEEVEEs by semi-pro meteorologists. Sorry to bang on them again, but REALLY, folks, they should know better. Sure, I’m a drizzle-head, but it really does matter since its a whole different process that produces drizzle compared to sparse large drops. Sorry, too, for another mini-harangue on this, but REALLY folks, we should know the difference! Feeling better now, got that out.
8:02 AM. Heading down to the Sutherland Wash on Golder Ranch Drive with temperatures and dewpoints in the mid-60s, there really was a feel for being on the wet side of the Hawaiian Islands, maybe above Hilo, HI, at 3,000 feet elevation, except for the dead grasses.10:20 AM. One of the many dramatic scenes yestserday, this one looking toward the Charouleau Gap NE of Catalina.10:19 AM. While it was nice to see all the water glinting off the rocks on the side of Samaniego Ridge, a deeply troubling aspect was the amount of aerosol that had moved in suddenly it seemed, evident in the crespuscular rays. How could it be this dirty so soon? Seems like a weather oxymoron after such a long period of rain. Also, one wondered if this aerosol loading would stop the warm rain process by providing too many, and smaller droplets in our clouds. Fortunately, that did not happen, and what appeared to be warm rain events, or ice formation at relatively high temperatures in our clouds, also requiring extra large cloud droplets, for the most part, continued intermittently into mid-afternoon.
10:32 AM. Close up of aerosols and sun glints on wet rocks.
12:23 PM. Glimpse of ice-forming top (smooth region above crinkly top). Types of crystals visible here? Needles and hollow sheaths because the top temperature was likely equal to or warmer than -10 C (14 F) and cooler than -4 C, and that is the temperature range that those crystals form under when there is water saturation, as there is in a Cumulus turret before it glaciates. OK, a lot of hand waving, but that’s what I think and I am here mainly to tell you what to think, too.
5:36 PM. The day ended quietly with a little, but pretty scruff of orographic Stratocumulus castellanus on Sam Ridge, the clouds mashed down by the subsiding air at the rear of our little trough that went by yesterday afternoon.
The weather WAY ahead, too far ahead to even speculate about:
NOAA spaghetti plots still suggesting a pretty good chance of rain here around the 23-25th of this month. Nothing before then.
Today will be a special one in the desert. Cumulus bases are going to be really LOW for summer, maybe only 3-4 kft above the ground, and likely warmer than 15 C (50 F). Maybe 50 F doesn’t sound special, but it is. A base temperature of summer clouds that warm is rarely observed here. And with that, and all the posts here about the temperatures that ice forms (around -10 C, 14 F) are out the window. Ice will form at much higher temperatures than usual.
This is because on a day when the Cumulus bases are that warm, rain forms by collisions between droplets before clouds even reach the -5 C (23 F) level, the highest temperature at which Ma Nature can produce ice. Rain mgiht even form in our clouds today even before the freezing level itself!
This is so exciting for an Arizonan who has studied ice-in-clouds development over the years because today ice will form in clouds around the -5 to -10 C level, and the mechanism of Mssrs Hallett and Mossop will be heavily involved as well as other lesser understood mechanisms to form ice in clouds today. And, along with that high ice-forming temperature will be categories of ice crystals that are rarely seen here, needles and hollow sheaths, ones that form at temperatures in clouds warmer than -10 C! You can see how excited Mr. Cloud Maven Person is. For comparison, it would be like a bird watcher seeing a _________, something pretty rare go by.
Dewpoint temperatures are running in the upper 60s and was 70 F (!) at TUS earlier this morning! Indicative of a really, really moist day from a cloud standpoint even now is that line of Stratus fractus cloud halfway down on Samaniego (Sam) Ridge. And this is BEFORE rain has fallen. Not too unusual to see something like that AFTER a good rain, but before, its pretty rare.
All in all, a very tropical day ahead, very “Floridian” I would call it, and that means more water in the clouds above us ready to fall out, and more “fuel” to send those warm plumes of Cumulus turrets spaceward. That’s because heat is released to the air around cloud droplets as then form, and the more “condensate” the more heat. The warmer the cloud bases, the more condensate that occurs. Its quite a feedback loop.
The last time we had bases this warm and low, some “lucky” areas got “Floridian” dumps of rain, that is, 3 inches in an hour. (Three inches in an hour is pretty common in Florida in the summer.)
However, need some heating and/or a good symoptic situation to gather up the clouds today if we are to get more than just high humidity from Norbert’s remains. Last night’s model run from the U of AZ was not real supportive of a great day because while the humidity is here, and upper level situation is going in the wrong direction, is not going to help much. A lot of what we needed was expended over night in huge storms that are raking central and northern AZ now, with some sites in PHX reporting up to 2 inches since midnight! And as that upper air configuration responsible for their great rains moves away, what’s right behind it up there, will try to squash clouds.
So, while we have the ingredients down low for an exceptional rain day, its not in the bag. What’s worse is that drier air is now foretold to roll in from the west by tomorrow, further diminishing (not eliminating, though) the chances for a decent rain here in Catalina. “Egad”, considering all the promise that “Norbert” once held for us!
So, in sum, a bit clueless here as to what exactly kind of day we’re going to have. “Truth-in-packaging” portion of blog. I see rain has formed just now (6:41 AM) on Samaniego Ridge, AND to the S-SW, very good sign!
—a note on air quality—as inferred from visibility in a humid situation——–
Another thing you will notice is how clean the air is. We have tremendous humidity, and unlike smog-filled air back east, the sky will be blue, and the visibility good. If you’ve ever been back East, you’ll know that in most areas the sky between the clouds on humid days is pretty white, and horizontal visibility is reduced in the moist air, say ahead of a cold-cool front in summer. This is due to large haze particles that have become droplets before water saturation has been reached, a phenomenon called deliquescence. Its horrible. Really ruins the sky back there on humid days.
Enough semi-technical blather. We’re mostly about pretty cloud pictures here.
Yesterday’s clouds
There were some spectacular scenes yesterday, even though it was disappointing as a rain day, only a late afternoon trace here in Sutherland Heights. Here are some of the best.
6:34 AM. Altocumulus lenticularis hovers over and a little downwind of the Catalinas.10:03 AM. First Cumulus begin to form on the Catalinas, later than expected. I will using the words, “expected” and “unexpected” a lot today.1:21 PM. First ice seen, lower left top of blue sky and cloud border. Can you see it?1:24 PM. Soon after the first ice is seen, out pops the rain, that very faint haze in the center of the photo.2:12 PM. Mt Lemmon receiving 0.79 inches of rain in about an hour from this little guy. Note that the peak is TOTALLY obscured by this rain shaft.12:24 PM. Cumulus clouds kind of muddled around up there when yours truly was expecting a sudden eruption at any time. Really did not happen yesterday.12:26 PM. Mostly just a pretty scene, the blue sky, the Altocumulus perlucidus, and the Cumulus congestus erectus.4:17 PM. It was especially gratifying, after kind of a non event day, to have this unexpected late eruption of a Cumulonimbus NW of Catalina. Meant chances weren’t quite over for nearby developments.5:03 PM. Cumulus cloud street trails off the Catalinas. Will it do anything?5:21 PM. The ragged edge of the higher layer leads to a series of crepescular rays in the falling rain, while the Cu congestus turret sends a long shadow Catalinaward, A gap in the clouds allows the sun to shine on the rain falling in Oro Valley then. Can you imagine how great the rainbow was on the other side, say from the Tortolita Mountains? The rainbow isn’t seen in the forward scattering direction because its due to reflected light back toward the sun from within the raindrops.5:22 PM. Nice lighting on Samaniego Ridge, rainbow imminent,5:24 PM. Magnificent, the lighting, the rainbow. How lucky we are to be here!6:56 PM. Just when you thought the day was finished, this surprise. Well, it was to me, that’s for sure!
6:58 PM. Ghostly-like late blooming Cumulonimbus calvus and Cumulus congestus clouds rise up against the falling temperatures. Pretty neat sight.[/caption]
6:58 PM. More unexpected strong developments to the west after sunset.
The End!
Heck, if I worked on this much longer, the answer to what’s going to happen today would be in!
..will be playing your favorite western tunes in the inimitable style of Johnny Cash at the Whistling Cactus Bar and Hitching Post this Friday and Saturday… :} (Hahahaha; “inimitable style of Johnny Cash”; that means Cash’s style can’t be imitated!)1
6:37 AM: I see now that there’s a lot more dust than last evening! Wow. Dusty Sunrise!
4:13 PM. Cumulus fractus. Dust is visible if you look hard on the horizon. The back scattering of sun light from dust aerosols makes them hard to detect looking away from the sun. But looking toward the sun, the sky has a whitish, gritty look as we had yesterday. When smoke aerosols are present, the sun can appear very orange or reddish, not white in the mid-day-afternoon hours. See the photo below, taken in the forward scattering direction, that whitish look near the sun. For those who want to go deeper, this. Images here.4:12 PM. Whitish, gritty dust exits Tucson and envelopes Mark Albright’s house in Marana/Continental Ranch, carried on a SE blast of wind from Texas and NM.
6:11 PM. Same view as above but most of the sun’s white light has been scattered out leaving the longer yellow and orange wavelengths to carry on.6:20 PM. Classic appearance of a dusty sunset.
Satellite image of aerosol content as seen from above (:}. Green area is the dust plume that appeared to originate in SW Texas and southern NM, then blew into Tucson town yesterday afternoon. Looks like its still here this morning. Go here to see more jpegs of aerosols.
Today’s mix of clouds and dust
Cloud action today, likely some small Cu and Ac later today as a weak upper level trough approaches and passes over us. Should be enough clouds around to pose a sprinkle threat. Imagine.
Should be an especially interesting day for cloud watchers since the dust aerosol should get into the small Cu. Sometimes that can lead to much larger cloud droplets in them because the dust particles are so much larger than the usual aerosol stuff that gets into our clouds.
What does that mean?
Will help those lower Cumulus clouds to form raindrops, since the larger the cloud droplet, the higher the temperatures at which ice forms. Sometimes, even drizzle drops, formed from just droplet collisions can result in Cu mediocris clouds with large dust particles in them (no ice involved). Would sure like to have an instrumented aircraft in the clouds of today!
Normally, ice would be expected to form at temperatures below about -10 to -12 C here in AZ. Today, it might be higher with virga falling from shallower clouds than usual.
The weather ahead
Found some rain for ya… March 21st. See those green areas in SE AZ? Been quiet on rain lately. Don’t like to talk about rain when there’s none indicated for two weeks at a time. The rain shown for us on the map above has been coming and going around this date in the model runs, mostly going, actually, but scored one here based on yesterday’s 5 PM AST global data and that has allowed me to take the rain muzzle off.
So….in sum, we can look forward to another chance of rain in March, one just ahead, and, of course, more of “Dusty Sunset” in the meantime leading up to this chance.
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1Saw a vinyl record album with those EXACT words on it in the Durango Market on Main Street, Durango, back in the ’70s when I lived there. Pretty funny, because you KNEW that imitating Johnny Cash was exactly what that singer was going to do!
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