Huh, Sounds familiar. Well, 50 shades of gray is a theme here at cloud-maven.com. Those various shades brought 0.02 inches of rain this morning to The Heights. Here are yesterday’s 50 shades:
7:58 AM. Massive ice cloud advances on Catalina from the Tropics.
This Altostratus invasion covered the sky within about 15 minutes, and that was it for sun, except some “filtered sun” at times (when this layer is called Altostratus translucidus (the sun’s position can be seen). Its an all ice or mostly ice cloud.
10:58 AM. Altostratus creates a pleasant gray sky.1:26 PM. Lower droplet clouds began to appear, high-based Stratocumulus. The globules are too large to be Altocumulus, though these were based at about 7,000 feet above Catalina, or a little above the height of Ms. Lemmon.1:26 PM. A UFO appears to be soaring toward Catalina with some kind with a trailing spider web. Other lenticular can be seen, this one was truly out of this world. But, from where? What world?1:41 PM. More lenticulars; more shades of gray.3:36 PM. Altostratus is now transitioning to Nimbostratus with lower bases as steady, but very light rain, moves in toward Twin Peaks. What you’re looking at here is mostly virga, and, as the relative humidity increases below virga bases, the virga is able to drop to lower elevations. The humidity is increasing due to gradually rising air that is accompanying an upper level trough. Got pretty wind about this time, too, before calming down. Not sure what that was from except maybe virga falling into very dry air ahead of the rain.3:42 PM. Classic look of Altostratus translucidus. “Opacus” (too thick to see the sun), just ahead. Those darkest areas near the sun are droplet clouds. Most of the scene is ice cloud.4:16 PM. Finally, as very light rain began to fall, we now see the most perfect view of Nimbostratus you’ll ever see. I hope you took plenty of shots of this scene cloud maven juniors! (Nimbostratus, the deep, deep cloud producing steady rain and snow is almost ALWAYS partly or totally obscured by lower Stratocumulus clouds so you can’t really see it. But, not here!
The weather ahead
Pretty much a sure-thing rain (we, unprofessionally forecast at least a 90-100% chance of measurable rain then) will move in late on the 16th or on the 17th. Should be a significant, vegetation-boosting rain, too–by that I mean at least a quarter of an inch–unlike this rain this morning. It looks,. too, like a second rain might move in a day or two after that one. Quite strong support in the ensembles (“spaghetti plots”) for that to happen, too. How great would that be? Very great, of course.
After that, the models are showing even more troughs affecting AZ, but the ensembles aren’t sure about it. Neither am I (CMP).
One branch of a seemingly bifurcated plume, spread north along the side of Samaniego Ridge. The other branch appeared to moved out of Tucson to Continental Ranch, “thence” northward toward the east side of the Tortolita Mountains. It’s happened before, but is pretty rare, maybe once a year occurrence.
(Took an hour for these first three jpegs to be uploaded to WP, btw.)
7:23 AM.7:25 AM.7:25 AM.8:16 AM. Smog plume at its maximum northward extend along Samaniego Ridge, Sutherland Heights area, before dissipating.7:49 AM.8:58 AM. Stratocumulus perlucidus races toward Catalina.7:59 AM. Altocumulus translucidus perlucidus undulatus, quite a cloud-filled mouthful.5:30 PM. This rain shaft is strong enough that one could suspect a weak Cumulonimbus cloud has erupted from the Stratocumulus.
Quitting here due to slower than dial-up service, hosting service, “godaddy” has confirmed its not them….
0.22 inches was, indeed. how much rain fell in the form of drops from Nimbostratus clouds yesterday as a modest little rain band generated by a rapidly moving trough swept through during the afternoon. Regional precip values can be found here. Our local area got the most, up to about a quarter of an inch, as often happens in marginal storms.
Yesterday’s storm marked the beginning of the new, more normal weather regime for southern Arizona, as has been blabbed about here in recent weeks. No more week after week of droughty weather with temperature far above normal, the kind of weather that has marked this whole fall and winter so far! I. e., “Thank you very much, a snowbird might say, but get the hell out!”, the rest of us might conjure up, thinking about the needs of our desert’s wildlife and vegetation.
Indications are now that below normal temperatures and above normal precip are ahead for us and all of Arizona in late Jan and early February.
The evidence for these claims?
Below, the stunning, jaw-dropping evidence for this seemingly outlandish assertion in the form of an ensemble (spaghetti) plot generated by NOAA last night. I have followed these charts for almost ten years now, and I cannot remember when such a strong signal (clustering of flow lines) 15 days out has occurred before in our region.
So, excessively excited this morning when I saw it! Its been annotated with excitement text.
This troughy pattern begins to take place on January 30th. Until then, a strong but dry cold front with a lot of wind comes by in a few days, on the 25-26th.
Valid at 5 PM AST, February 4th. You can pretty much count on a trough hereabouts in two weeks. Since the blue lines, the colder portion of the jet stream, do not dip down this way so much, our troughiness likely would be in the form of something we call a “cutoff low.” A full latitude trough extending from the “blue jet” up there in Canada, instead of a “cut off”, would be excessively cold. We probably don’t want that anyway.
Yesterday’s clouds
The whole interesting, if excessively gray story is shown below:
7:24 AM. It was breezy already, and with Cirrus underlain by Altocumulus lenticularis clouds in the lee of the Catalina Mountains, you knew that a storm day was ahead without turning on your favorite TEEVEE weatherman.8:53 AM. With Cirrus and Altocumulus spreading rapidly from the SSW, lenticulars downstream from the mountains, the wind gusting to 25-35 mph, you knew a great gray cloud day was in store!11:32 AM. Before long, an entire sheet of Stratocumulus spread over the sky, making you sure that rain would fall.12:50 PM. First drops begin to fall on Sutherland Heights. That layer of Stratocumulus appeared to be deepening as it approached from the SSW to where the tops were getting just cold enough upwind of us to produce ice and snow that melted into those sparse drops. Not enough ice /snow formed to hide the bases, though, in virga.1:26 PM. Snow begins to fall on the Lemmon.2:04 PM. Lower Stratocumulus clouds begin to show up below the original deck that overran us.
3:16 PM. Pretty and dramatic. Stratocumulus piling up over and upwind of our Catalina Mountains/Pusch Ridge.3:19 PM. Oh, so pretty.3:27 PM. Crazy, I know, but I thought these scenes were so pretty!3:28 PM. As that rain band approached there were some nice lighting highlights.3:40 PM. Here comes that rain band across Oro Valley/Marana.4:19 PM. A truly great scene for a desert; mountains partially obscured in precipitation.4:19 PM. Nimbostratus. Its hard to get a better photo of rainy Nimbostratus than this. Drops coming off the roof, NOT raindrops, can also be seen. This was at the peak of the rain, too! Very exciting.5:54 PM. Sunset Stratocumulus, hold the ice. Yet, that Stratocumulus was cold, way below freezing.
The weather way ahead
The title sums up where we are now. Will we go have more rain? Oh, yeah. But not right away, as you already know.
What an amazing and “productive” little rainband that was just after midnight! And more rain is likely with weaker bands just upwind here at 4 AM. Could we really approach an inch? Amazing. Didn’t seem possible in this small mind that we could amass that much. For a full regional rain table, go here to the ALERT gauge records.
Now, after this ends, a long dry spell has to be endured, at least until around the 20th of Jan, at which time we hope the troughs and rain threats at least, will begin to barge in every few days, namely, and pattern more typical of winter sets in.
Yesterday’s clouds
8:31 AM. Typically lenticular clouds form in the lee of the Catalinas as storms approach. Lenticular clouds are good signs of deteriorating weather ahead since they are usually accompanied by strong, moistening winds aloft.8:31 AM. Zoomed view of one lurking just beyond the crest of Ms. Mt. Sara Lemmon. The higher clouds were Cirrus (which can have grayness when the sun is low).10:24 AM. Wasn’t long before this deck of Stratocumulus raced over the sky, adding that feeling that rain is a comin’.11:32 AM. Some tendency to form the new supplementary cloud feature, termed, “asperatus undulatus” is shown here at the base of the Stratocumulus deck.1:13 PM. Got excited when ice began to show up, with virga and light rain showers here and there. Can you see that icy top receding from the Catalinas? It wasn’t that high and cold, either.1:14 PM. Nice highlighted view of Biosphere 2, with light rain showers in the background. Whodda guessed Bio2 would get 1.93 inches overnight? Not me!1:59 PM. Light rain showers began to fall from that Stratocumulus layer, now pocked with buildups (Stratocu castellanus?) as temperatures aloft above cloud top cooled. The haze is due to rain falling from overhead. It did not measure.1:59 PM. Looking upstream and the Stratocumulus deck whose tops were just ascending to the ice-producing level as they approached Catalina from the SSW. That clearing on the horizon maintained throughout this cloud and shower period suggesting it was caused soley by the lifting of the air as it approached the higher terrain of Catalina and the mountains. It was soon to disappear.3:02 PM. Falling apart.3:49 PM. Gone. Yes, once again, the clearing before the storm. A storm is approaching, 100% chance of rain within 10 h, and yet, the clouds are disappearing! This is a common here; a dry slot in the moisture field OFTEN precedes storms here. To some folks it may mislead them into thinking the storm’s a bust. But not to us CMP’s, who seen this happen over and over again.5:09 PM. Temperature’s in the low 70s; its getting to be a nicer day by the minute. Where’s that storm?5:43 PM. Our storm and cold front marches toward us from somewhere over the horizon, though visually you’d never know it. Wonder if the native Americans knew this odd sequence–probably.
The weather ahead
After the last drops fall today, we’ll suffer through another dry spell and warm up though about the 20th when a major trough passes by.
The End
Oops…. Have cameras ready for a great day of cloud shots once the sun breaks through.
I was thinking how great yesterday was for you. Started out with a spectacular sunrise (lasted just a couple of minutes), and then you could watch for pretty much the WHOLE day, orographically-formed Altocumulus opacus and castellanus transition to ice crystal clouds (in this case, Altostratus with virga and some mammatus) right before your eyes!
Sunrise:
7:16 AM. Flecks of Altocumulus clouds below Altostratus.
After sunrise….this odd scene below of an extended Altocu lenticular cloud:
7:33 AM.12:24 PM. Altocumulus opacius shedding ice as they moved westward across Oro Valley.3:01 PM. Altocumulus castellanus forming just upwind of the Catalinas, moving toward the west (to the left in this photo). No ice is falling out yet, though tiny ice crystals are likely starting to form.3:01 PM. Looking farther downstream from the prior photo. Some ice is beginning to show up and fall out (center and left side of photo).3:02 PM. Looking still farther downwind, those Altocumulus clouds are mostly glaciated, that is, mostly consist of ice. This transition has taken about 10 minutes of travel downwind. The sounding near this time, indicated that tops a little downwind of the U of AZ campus release site, were about -27°C (-17°F). However, tops were likely rising some small amount in this region downwind of the Catalinas, and so were almost surely, even a little colder than that.4:33 PM. Nice example of what some of the Altocumulus castellanus looked like yesterday. That tallest turret will fall back. Its partner is just to the right, one that was previously as high, but fell back, its load of ice crystals drifing down. Some of the ice in the taller one is still being held up there until it, too, collapses. A error in aircraft sampling can occur if you don’t realize that tops have collapsed from lower temperatures, such as when collecting ice concentrations in the collapses one. You could easily assign a cloud top temperature that was too high; would not reflect the temperature at which they really formed.
I first noticed the craft as I was driving up Golder Ranch Drive. At first I thought it was just an Altocumulus lenticularis… Really didn’t think that much about it. We seem them over there all the time.
But it was unusually smooth, I thought, and had a slightly humped up portion on the top I could see after I zoomed in on it. Could it be a cloaked alien space vehicle? Time would tell.
A lenticular expands and contracts while hovering over the same spot. This can go on for hours! But, as you will see, over the next 20 minutes, this cloud, or “craft” did not change in any way, clearly evidence of a cloaked space vehicle! Way too smooth to be a real cloud!
Since it didn’t seem to be doing anything, maybe just spying on me and us as do virtually all institutional entities these days, I lost interest in it and continued doing yard work….
12:47 PM.12:48 PM. Zoomed in….1:00 PM. Seems to be taking an interest in Charlotte’s house next door, kind of floating over it. Hmmmm.1:01 PM. After I looked away, it seemed to have leapt back over Charouleau Gap!1:01 PM. As I zoomed out my camera, the object seemed to be getting smaller, perhaps moving away finally! I felt relieved and went back to raking the fall leaves. But, we don’t have leaves here, so what was that about? Had I been infected? Taken over?
Later, completely different looking clouds came over, Altocumulus tending toward castellanus variety…making the early afternoon smooth-looking cloud more anomalous.
2:42 PM. Bands of Altocumulus clouds worked their way over Catalina and environs, the craft or lenticular cloud long gone. Or, wait a minute! Is that it there on the horizon???2:42 PM, looking farther to the SW. You can see how different these clouds look compared to the “lenticular.”
PS: It been said that the UFO craze began with an Altocumulus lenticular cloud in the lee of Mt Rainier in the late 1940s. Why not see if we can start a new craze right here in Catalina? Been abducted lately?
We’re often confused with the California island, Catalina, and even places in Spain. Google “Catalina” and see if I am lying again. Oh, maybe that was Catalonia, SP…
Nevertheless, isn’t it time to think about a new name for our “Census Designated Place”, Catalina? In fact, at one time, each Catalina island and our Catalina, each had a marina to further confuse things by adding superficial similarities….
Think about it.
Some sunrise scenes among too many available to the writer from his camera card:
Let’s look at the Tortolita Mountains.Cirrocumulus on the fade.Highlighted Cirrocumulus.About as complex as a patch of Cirrocumulus could be. It did seem there were TWO levels of Cirrocu here, which might help explain criss-crossing patterns.Nice Altocumulus lenticularis in the usual spot downwind of Lemmon when the flow is from the W-SW up there.Wide angle view of our spectacular sunrise. How you experienced it live.
Now, for sunset color:
5:47 PM. Will think of something later.
As you may know, there is some violent weather hitting the West Coast, California in particular. Let’s see what the Reno office of the NWS has to say about the incoming storm:
“…BLIZZARD WARNING IN EFFECT UNTIL 10 AM PST WEDNESDAY…
...WINTER STORM WARNING IN EFFECT FROM 10 AM WEDNESDAY TO 4 AM
PST THURSDAY...
THE NATIONAL WEATHER SERVICE IN RENO HAS ISSUED A BLIZZARD
WARNING, WHICH IS IN EFFECT UNTIL 10 AM PST WEDNESDAY. THE WINTER
STORM WARNING IS NOW IN EFFECT FROM 10 AM WEDNESDAY TO 4 AM PST
THURSDAY.
* TIMING: DANGEROUS BLIZZARD CONDITIONS DUE TO HEAVY SNOW AND
STRONG WINDS WILL CONTINUE TODAY THROUGH WEDNESDAY MORNING.
PERIODS OF MODERATE TO HEAVY SNOW WILL CONTINUE THROUGH
WEDNESDAY NIGHT.
SNOW ACCUMULATIONS THROUGH THURSDAY MORNING: 5 TO 10 FEET ABOVE 7000 FEET WITH 3 TO 7 FEET AT LAKE TAHOE LEVEL.(Note: The large font size, the capitalization, suggest, as we know, that the writer is screaming, which I am.)
* WINDS: SOUTHWEST 20 TO 30 MPH WITH GUSTS TO 60 MPH THROUGH
WEDNESDAY MORNING. SIERRA RIDGE GUSTS OVER 100 MPH.
* SNOW LEVELS: BELOW LAKE LEVEL...MAY BRIEFLY RISE TO 6500 FEET
THIS AFTERNOON BEFORE FALLING AGAIN.
* IMPACTS: DANGEROUS LIFE THREATENING BLIZZARD CONDITIONS WITH
NEAR ZERO VISIBILITY WILL EXIST FOR TRAVEL AND OUTDOOR
ACTIVITIES WITH HEAVY SNOW ACCUMULATION ON ALL SIERRA ROADS.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
THIS IS A LIFE THREATENING SITUATION. DO NOT ATTEMPT TO TRAVEL!
ROAD CREWS AND FIRST RESPONDERS MAY NOT BE ABLE TO RESCUE YOU.
STAY INDOORS UNTIL THE SNOW AND WIND SUBSIDE. EVEN A SHORT WALK
COULD BE DEADLY IF YOU BECOME DISORIENTED1."
As we know, extremely heavy snows in the Sierras can trigger cannabalism, It is our sincere wish that those affected by this severe storm curb his or her appetite for humans, i.e, that cannibalism does not break out in the Reno-Tahoe area, or ANYWHERE (capitalization for emphasis) in the Sierras during this terrible storm or its aftermath.
The End
————————– 1Thanks to Prof. (emeritus) Roger Pielke, Sr., Colo State, for passing this warning along. His son, a great scientist as well, btw, has the exact same name, and that’s why THIS Roger goes by “senior.” Thought you’d like to know that.
The full moon of December 11, 2008. Thought maybe you’d like to see it in case you missed it, or see it again if you did see it. Maybe you had a special memory with this moon.7:09 AM. Altocumulus perlucidus with a little lenticular underneath.7:10 AM. Zooming and zooming.7:10 AM. Zooming some more.7:14 AM. Iridescence is evident in the cloud ripples just above the mountain silhouette.7:16 AM, Contrails were soon visible in our Altocumulus layer, the aircraft making it at the right edge of the photo. Appeared to be in a climb out going right to left. And, when you see these “high temperature contrails” in Altocumulus, you can be sure ice will form and rifts will develop as a little bit of light snow develops and falls out. The jillions of ice crystals in the contrail cause the droplets in the Altocumulus to evaporate, in a way, gutting it. An ice crystal is like a low pressure center when amid droplets; the droplets evaporate and those water molecules deposit themselves on the ice crystal, a process named after the discoverers, Wegner-Bergeron-Findeisen. Eventually the crystal is large enough to settle out and a clear streak results unless the air is rising rapidly and can replace the droplets (as generally happens in storms). Sometimes the lift in the Altocumulus layer is enough that a clear canal caused by an aircraft can fill back in after many minutes.7:18 AM. Two aircraft contrails, about a minute old. After two or three more minutes, they will not be visible within the cloud, though ice is forming, decimating the droplets around the intense streamers of ice in the contrail.7:28 AM. The small ice canal (the ice is hanging just below the Altocumulus clouds–kind of hard to make out, but its there.7:42 AM. Those little clear streaks are hardly noticeable now, partly because they were quite narrow, and because of perspective and things bunching up in the distance.
Suggested locations of cloud layers. The Altocumulus layer in which the contrails were embedded seems to be at -25°C, a “normal” temperature for this kind of “high temperature contrail”. In general contrails are not supposed to occur until the temperature is below about -35° C and the air is moist, thus they are usually seen amid or near Cirrus clouds. not down in Altocumulus. See usual contrail height at Cirrus levels in moon photo.
As the morning wore on, the Altocumulus deck faded away, moving east, and we were left with some Cirrus clouds, but what kind?
10:58 AM. Cirrus of some type, but notice there is absolutely no fibrous details (strands and such) as we normally see in Cirrus. Could be transverse waves in a Cirrostratus deck since Cirrostratus can be fog like, have no detail, in a version we call, Cirrostratus nebulosus. The up and down motions would cause clearings perpendicular to the wind up there. The lack of strands and uniformity in these bands suggests very tiny ice crystals, ones having very little fallspeeds.2:34 PM. Some nice “hovercraft” clouds, Altocumulus lenticularis off in the distance SSW. Hung around out there for a couple of hours.3:17 PM. This one appeared to be concave upward, which was a little odd. Zoomed view next.3:17 PM. Looks like the inside is higher than the outside. Huh.
Well, that was it for photography yesterday.
Doesn’t seem to be any reliable indication of rain in sight. Oh, sure, rain here pops up in the models almost every day, but its about 12-15 days out. As the model gets closer to the day it predicted rain, it seems to go away like the “water mirage” on a hot paved road; always ahead of you, but you never get to it. We’ve had some major rains indicated in the models as of a few days ago, but spaghetti was never very high on those events (clustering those crazy lines in a trough over us), so it wasn’t even worth mentioning.
Not much else to talk about, no rain of course; what is that?
But with so many colorful scenes yesterday, we can be partially sated by the lives we lead here sans rain here. October ended with a puny 0.01 inches in Sutherland Heights.
Now, because I grew up in California and remain a little Cal-centric, this brief diversion from AZ:
But droughty Cal got nailed though, from about San Luis Obispo, so we can be happy about that I guess. One station, Gasquet RS, near the Duck border, got just under 28 inches in October; stations in the Santa Cruz Mountains, way down by Monterrey, got between 14-17 inches! From the California-Nevada River Forecast Center, this nice map of October rainfall anomalies in that domain. Red is real dry, and that’s the color we would be in if it was the California-Nevada-Arizona River Forecast Center:
Many departures are far over the map color-coding limit of 350%, but are over 1000% of average! Note red below normal swath. This tells you that the mean area of low pressure at the surface and aloft was just off the West Coast. Pac NW set maximum October rainfall records, too.
But let us not dwell any more of generous rains that others got, but celebrate the color and clouds of Arizona. Here are yesterday’s glorious scenes, beginning with a spectacular Altocumulus lenticularis under some Cirrus at dawn:
6:37 AM.6:47 AM. Ac len stack.10:51 AM. Tiny patch of Cirrocumulus tried to hide in front of some Cirrus. Hope you weren’t fooled and logged this sighting in your cloud diary. Cloud maven person almost missed it himself.12:50 PM. There were lenticulars aplenty yesterday. Here’s another one in a location a little different from normal, beyond the Catalinas. Upwind edge is the smoothest one at right. No ice streamers coming out the downwind end, so must have been pretty “warm”. Lenticulars, due to their tiny droplets and those droplets having short life times, have been known to resist ice formation to temperatures well below -30°C -22° F). Pretty amazing.2:42 PM. Kind of clouded up in the afternoon, and with breezes, made it seem like something was up. It was, but far to the NW of us. We have been under a streamer of high to middle clouds originating deep in the Tropics for a couple of days. Here some lower level moisture has crept in on cat’s feet, to be poetic for a second, and has resulted in small Cumulus and Stratocumulus clouds underneath the Cirrus and lenticulars standing around. All in all, though the temperature here reached 87° F, a very pleasant day.
Now, just some nice lighting and color:
5:32 PM. The almost flourescent plant in the foreground is what is known as a “cholla.” The end elements fall off quite easily and attach to things like your pant leg if you brush by them on a horse, or if back into them while walking and correcting your horse for something when he’s acting a little “wild.” I can report that when seven or eight of them are stuck to the back of your shirt, its really hard to get that shirt off. In fact, it just about won’t come off without a major scream.5:35 PM. The higher Cirrus are shaded by clouds to the west, but the lower remnants of Stratocumulus/Cumulus and a few Altocumulus are highlighted as though they were meant to be for this photo. So pretty. Notice, too, how there seems to be more than one layer of Cirrus.5:44 PM. Cirrus and Altocumulus, the latter with some turreting making those the species, “castellanus”, if you care.5:47 PM. A nice flame-out of Cirrus occurred as those pesky clouds blocking the fading sunlight from striking them opened up below the horizon. A few Altocumulus castellanus can be seen, too, but relegated to shadow status.
In a further celebration of dryness here, let us examine the rainfall cumulative rainfall predictions calculated by the University of Arizona’s Dept Hydro and Atmos Sci computer the period ending at Midnight on November 5th. Says the coming rain in the State misses us here in SE AZ while falling just about everywhere else, of course. Dang. Let’s hope it one of the worst model predictions ever!
This really poor forecast is based on the global data from last evening at 5 PM AST.
The day started with some nice Altocumulus “pancakus”, some lenticulars and breezy conditions, reminding one of fall day with a cold front approaching. Small Cumulus appeared quickly, but with the wind, you wondered if they would get enough heating to power upward into Cumulonimbus clouds.
By noon you had your answer as a large Cumulonimbus complex settled in just beyond the Tortolita Mountains west of Catalina. And it pretty much recurred there and over the Tortolitas all afternoon. In the meantime, passing light showers dotted this side of the Catalinas, but that was about it. No “Code 4” shafts on those mountains yesterday. Rain totals were less than a half inch, and most less than a third. On the other hand, would guess that parts of the Torts got well over an inch. The cores missed us again, with Sutherland Heights logging only 0.03 inches.
Developing showers passed over Catalina dropping occasional very large, sparse drops, but shafts generally fell out of those clouds after they had passed off to the northeast.
Late in the afternoon, the line of recurring showers finally approached Catalina, but as dry air encroached in the middle levels, at the same time, catching up to that standing line, all those great mushrooming clouds were no more. The cloud story board is below:
(by Chad and Jeremy but with photos of Peter and Gordon with whom the former were often confused with, the site notes! How funny is that?)
Oh, well, yesterday might well have been the end of the summer rain season here in Catalina as far as rain goes, so an ending point song seemed appropriate.
6:16 AM. Altocumulus with a underlying Altocumulus castellanus.6:16 AM. Another view of Altocumulus with an underlying line of Altocumulus castellanus.8:06 AM. Altocumulus perlucidus translucidus (real thin).10:55 AM. Altocumulus lenticularis clouds provide the real look of a fall day with a significant jet stream overhead. Cumulus begin to form on the Tucson Mountains in the distance.12:56 PM. The idea of a fall day is quickly dispelled by the rapid growth of a narrow Cumulonimbus calvus cloud.12:57 PM. Wow. At the same time, there’s been an explosion of Cumulonimbus clouds to the west through northwest of Catalina. This looked REALLY promising for a dump here, since it would surely expand southward (to the left) from the rain shafts in progress.1:30 PM. Line of thunderstorms reaches the Tortolita Mountains. This is looking extremely good for Catalina though the thunderstorm is moving left to right rapidly, not toward us. Why does it look good for Catalina? Because you expect winds pushed away by all that falling rain to blow back against the sotuhwest winds and generate new Cu congestus and Cumulonimbus clouds upwind of the shafts, and more in line with Catalina. Summary: it didn’t happen though there were numerous times it looked like it was verging on doing this. So, all those thoughts you had out there that this was going to happen were in considerable error. This was probably because the southwest wind against which the outflow was clashing, was too strong yesterday, limiting how far upwind new clouds could develop.1:34 PM. This was looking so great! Bases massing there on the right side, pretty much upwind of Catalina.1:43 PM. Tortalitas now obscured by water.1:49 PM. Showers are developing farther upwind of the main blast over the Tortolitas as expected and near to upstream of Catalina! Gloating here. Was SURE now we’d get a tankful of rain within the hour.1:53 PM. In only a few minutes its looking so much better for us, and those showers and thunderstorms are racing this way! Looks like the whole line is drifting east, too. In the meantime, the thunderstorms moving away from the Tortolitas and toward Saddlebrooke Ranch and points north have sent out a blast of northerly winds into Sutherland Heights, pretty much like yesterday. The clouds overhead begin to respond to that uplift caused by this blast of north winds.2:06 PM.2:16 PM. That first nice cloud base waited until passing by to drop its load, but another promising one appeared upwind!2:17 PM. In the meantime, another ferocious thunderstorm is dumping on the same area of the Tortolitas as the prior ones!2:21 PM. A closer look at the Tortolita blast. Expect wind from this to reach Catalina.2:22 PM. WIth the north wind blowing you’re looking for something to erupt upwind of us as the nose of that north wind pushes into Oro Valley. But here you see that the organization of the cloud bases is poor, too many little light and dark areas, no broad base indicating a strong updraft. This was a depressing shot but I took it anyway.2:27 PM, The severe thunderstorm over the Tortalitas has moved NE. Here you see the kind of cloud base you want to see just upwind of you, not that mess in the previous photo.2:29 PM. Only a few minutes later, but look at the change that has occurred upwind of us! That north wind scooting down into Oro Valley has finally triggered a massive base just upwind of us We are going to get pounded!2:33 PM. But that great cloud base moves to the west of us, adajacent to yet another blast on the Torts. Ugh. Just can’t get this right.2:36 PM. Some lightning for you in case you don’t believe me that these were thunderstorms.2:49 PM. Yet another promising base, more in the upwind direction passed over, only to leave some enormous drops. Compare splash marks to that mesquite pod on the sidewalk. Sounded like hail at first. But the main load fell downwind. I thought we were going to really get shafted right then, too. Not.3:03 PM. An example of poor cloud base structure upwind of us.3:04 PM. Curtains of heavy showers continue to bombard the Tortolitas, Amazing how many cells passed through that area as this zone of converging winds remained stationary instead of advancing toward us as I believed it would.3:18 PM. As skies cleared overhead, some of the prettiest scenes of the day were of these brilliantly white Cumulus congestus clouds over the Catalinas.3:20 PM. Ice detection drill… Can you tell that those two turrets in the last photos are now mostly ice?3:28 PM. Can a scene be more beautiful? The turret on the far left has converted to ice.3:29 PM. A single strand of hail or the largest drops have plummeted out of this base. This suggests that they were either very large particles, or that the updraft had a minute weakness that allowed some of the load aloft to escape in something of a narrow chute. And, of course, its part of the line still pounding the Tortolitas!3:47 PM. FINALLY the line appears to be shifting east toward Catalina, but the tops aren’t as high, there are no giant cells any more, an indicating that both drier air is moving in and that the instability aloft is changing to less favorable for large storms. Oh, me. This was a discouraging scene.3:55 PM. While not as heavy as prior showers, there is still hope that the line will produce measurable rain in Catalina as it drifts east.4:05 PM. By this time, its looking like the slowly advancing line will die before it gets here.5:24 PM. That line: Done and done.6:39 PM.
The End, whew.
About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno
