About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno
Author: Art Rangno
Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.
But first, continuing from yesterday: “…and a few small to moderate sized Cumulus (humilis and mediocris) clouds as well to go with the high and middle clouds.”
Sorry I took so long to finish that up, but it was worth the effort because it was pretty darn accurate.
The storm on the doorstep
Here is your very excellent Catalina forecast as of now (4:50 AM) from the computers at the NWS. There is a statement on the exciting New Mexico weather, posted by the Tucson NWS here. You can feel the excitement in NM in this message they consider quite special, labeling it a “Special Statement.” Hope our Arizona guys and gals get on board with the NWS in ABQ and issue something special soon! Being weathercentric, of course, I am at one with the ABQ office even now.
Here’s a depiction of the incoming storm from our best model, that at the U of AZ, one that downsizes the “WRF-GFS” model to smaller scales so we can see what happens in our local mountains and valleys as it barges across California and then into Arizona on Saturday. Precip is shown to begin on the Catalinas before dawn on Saturday, but probably won’t reach here for a few hours after that. The model onset time here in Catalina is 8 AM AST on Saturday. However, this model tends to run a bit fast in these situations, so it may be mid-morning before those cold, cold raindrops start falling. But, 8 AM vs maybe 11 AM AST? Amazingly close no matter how you put it. It just shows how good our modeling systems have gotten over the years.
The amounts? Seems measurable rain is certain here in Catalina–the flow pattern jetting against this side of the Catalina Mountains favors us here. The finest scale model at the U of AZ, the first place to look, is showing a range of values between 0.25 and 0.50 inches, oddly corresponding with a ludicrous guess made too far in advance here a few days ago. Hmmm. The Catalinas are shown to get more than an inch and that calls for a celebration.
Here is the scoop from the 11 PM AST U of AZ model run for total precip (snow on the Catalinas again, the best kind of precip because it just sits there and soaks in when melting):
Valid at 2 AM AST Sunday the 10th, the storm is long gone from Catalina at this time but still adding some in the mountains up to about here.
Out of character a bit, but also since we’re on the edge of the predicted range of amounts, I think the bottom is closer to 0.08 and the top likely amount is 0.38 inches, with a “median”, most likely amount of about 0.23 inches, to be a little silly here.
Clouds today?
Probably (and this time I will examine the TUS sounding more carefully than yesterday), just a few isolated Cumulus clouds again, likely dissipating during the afternoon, and a couple of Cirrus clouds.
The clouds tomorrow (more interesting)
One of the interesting cloud formation zones for Arizona is over and downwind of the mountains in northern Baja (Sierra de Baja California). Gigantic plumes of Cirrus/Altostratus ice clouds often form in these situations as moisture at high levels from the Pacific Ocean (located west of Baja, California) travels over those mountains. Those clouds would be something akin to standing wave clouds, lenticulars, but because the air is pretty moist (“ice saturated”) wrapping around this powerful low, they don’t evaporate downstream once having formed but end up as a huge, icy plume across central and southern Arizona. I think we’ll can see that start to happen today, first in the lee of the Sierras of California, as the jet stream works it way down the West Coast toward us.
Eventually, the higher level moisture dries out over those Baja mountains, as it will later tomorrow, and the icy plumage source ends, and many times we see the end of that plume from those Baja mountains (Cirrus/Altostratus clouds) as a huge clearing that, oddly, preceeds the real storm; the surge of lower level clouds that carry the precip. And with that clearing as well, the passage of the core of the jet stream (in the middle levels) above us.
I know many of you have seen this sequence over and over again, the clearing of a high dense layer of clouds from the actual storm that’s on its heels.
Such a separation in those two clouds systems, the high and the low, can lead to spectacular Catalina sunsets. Tomorrow, out on a limb here, is the kind of day where that could happen–the sun sets in the distant clearing to the west as the shield of icy plumage overhead passes.
Yesterday’s clouds
Yesterday was another one of those especially gorgeous days here in the wintertime. Delicate patterns in Cirrus, as well as the dense patches. Then, a few lower Altocumulus clouds above scattered small to medium Cumulus clouds against a vivid blue sky and limitless horizontal visibility. Here are some examples:
7:47 AM. Old Cirrus (foggy stuff above palm tree) below in altitude newly formed Cirrus (flocculent specks to left and right).
10:31 AM. Only the exceptional cloud maven junior would have noticed this rogue Altocumulus castellanus masquerading as a Cumulus. Its betrayed by those specks of Ac floccus around it. Also, if there was a true Cu fractus nearby, you would have noticed a tremendous difference in the relative movement of the much higher Ac cloud and the real Cu.
12:02 PM. Last of the high clouds (Cirrus spissatus) approach Catalina with Cumulus fractus and humilis starting to form.
2:36 PM. One of the best shots of the day; small Cumulus with a trace of Altocumulus perlucidus above.
5:51 PM. Though it was clear to the west, we still had our sunset color on the Catalinas, and an orange reflection on the bases of the last clouds hanging on above them.
Kind of rushing around today, hope this is intelligible….
You will soon notice a nice sunrise with a sky full of clouds, Cirrus-ee ones, Altostratus, some Altocumulus tending toward lenticulars (red denotes cloud forms added after the sun came up and I saw them.)
I am late today, not because I overslept some, but also because I wanted to post a great sunrise photo for you.
You know, its all about YOU again, isn’t it? Maybe you should step back and think about that for a second…ask yourself just where your life is going? Thanks in advance for doing that!
Here is this morning’s nice sunrise, Altostratus clouds with virga:
7:07 AM today.
When you see this morning’s clouds, and the great sunrise, no doubt you will be thinking along the lines of a great sunset today as well.
But you’d be so WRONG!
Using a technique developed here, you can foretell where the back side of today’s band of high and, later, middle clouds will be quite accurately. You won’t need the Titan supercomputer to do it, though it would be nice if you had one. Will reprise that methodology for you:
1. First go to, say, a web site having infrared image loops, such as here in purple and gold Huskyland up there in the wet Pac NW
2. Select a loop that you like that shows the clouds to the west of us, such as the one I have selected for you.
3. Stop the loop at a time period not less than 4 h from the current time (probably best not to exceed 12 h).
4. Get out a Hollerith card (computer punch card), and carefully mark the position of the backside of the cloud band of interest that is upwind of your location, pressing the card hard against your computer montior.
5. Proceed in stepwise fashion to the current time in that satellite loop and mark on the same punch card, the location of the backside of the cloud band. You will now have two “tick” marks denoting the movement of the backside of the clouds over the time period you chose.
6. Now, move the first “tick” mark to the current backside, carefully moving the card along the direction of movement of the band, and pressing it against the computer monitor.
7. The second tick mark you made will now be ahead of the band at a future position and time, based on the time increment you have used.
8. Determine from that future position whether local sunset will occur to the west of the backside while it is still OVERHEAD. If the answer is “yes”, then a tremendous, memorable sunset is likely.
Illustrative example, using an 11 h time increment to enhance difficulty:
Satellite image 1
6 PM yesterday. Cloud band backside is over central California.
Satellite image 2
6 AM this morning. Backside approaching Colo River Valley. But is it moving slow enough to be overhead at 5-6 PM with the big clearing to the west?
Preparation of the Hollerith card; no “hanging chads” here–some people disperse incense now:
Results
The back edge of our cloud band is too far east for a good sunset tonight. New clouds would have to form on the backside for a good sunset. Yes, that COULD happen, and it sometimes does in certain situations, but it probably won’t today. Be thankful for a nice sunrise.
The weather ahead? The cold slam?
Well, every weather presenter is on top of that big time, and so why blather about it here? Of course, tomorrow….”tomorrow is another day” to quote a quote. And after I see how this mostly clear sky sunset prediction turns out.
Let’s look at February’s climo for Catalina, now that the month is practically half over (hahahah, sort of):
Oh, my, such a sad chart so far….What the experts at NOAA’s Climate Prediction Center are thinking–a smudge of higher precipitation for Arizona, thought the chances, they feel, aren’t great, 30-40 % is all. Still, its something. This would be a pattern of precip that goes with our upcoming storm, one that will be much more of a dumpster in the northern half of the State than here. With the spaghetti plots having already indicated a high probability of a big trough in the SW US a week ago, this forecast may be based only on that one pretty sure thing which would give a monthly prediction of above normal in the Four Corners area and northern Arizona a leg up, so to speak. I mean, you wouldn’t want to forecast below normal precip in a region for a whole month if you knew there was going to be a flood in the first two days of that month! Hope this forecast is due to more than our Cold Slam, coming up!
BTW, yesterday I discovered at first sunlight that a trace of rain HAD fallen the previous night by finding raindrop images in the dust on my “trace detector” instrument (a car parked outside under the open sky). Hope you found drop images somewhere, too, and properly reported or at least, logged, your trace of rain.
Here’s a radar depiction of those areas of sprinkles from WSI Intellicast, amounts ending at 5 AM AST yesterday. If you are in one of the faintly blue areas shown below, and DID NOT report a trace, we will have to consider confiscating your Cloud Maven Junior tee….and you should consider whether being a CMJ is really for you. Its OK if its too much…
Here the rain forecast from the WRF-GFS model, our best, as rendered by IPS MeteoStar:
Valid for 11 AM February 10th. This is the first WRF-GFS run with rain here in it. Only the Canadian model had rain here before this one.
CS3 preview: its got rain in it, likely also our first real good windy day in awhile. In sum, a real action packed, thriller of a day coming. Don’t miss it!
1. We didn’t get the odd cloud bases yesterday. That lower undercutting layer of…..Altocumulus clouds (of course, you knew what they were) below the icy Altostratus clouds was too thin, not embedded in much wind shear, so the hoped for weird cloud bottoms didn’t materialize though there were hints of those concave bases off to the north late in the afternoon.
2. Since I was disappointed that really weird cloud bases didn’t show up yesterday afternoon, instead of showing the clouds that did show up right away, I thought I would annoy you first with a public service message:
“Arizona reminds drivers that when you see a sign informing you that you are on a DIRT road, that the speed limit is often no more than 15 mph.”
Sign near Red Rock.
Yesterday’s clouds
Here are the clouds that did show up yesterday, pretty much as the U of AZ model predicted:
12:50 PM. Your heavy mid-day Altostratus opacus virgae with virga.3:13 PM. An undercutting layer of Altocumulus clouds overspread sky rapidly from the west. Starting looking for strange cloud bases here.4:24 PM. Altocumulus undulatus. Actually there are two layers of Ac, and a full sky description would add the word “duplicatus”, used when more than one layer is present. I am not kidding.Ocean swells coming ashore near Monterrey, CA, in case you have never seen the ocean, breaking waves and swells. These are unusually large and were due to a giant low center off the Ca coast. Cirrostratus and Altostratus clouds, with flakes of Altocumulus droplet clouds, are present.6:09 PM. With the Altostratus now gone, a hole in the clouds allowed this brief rosy “bloom” in the remaining Altocumulus clouds. The higher layer sported some virga, and some remnant virga can be seen in the center of the photo.
Since there were sprinkles around Catalina last night, you’ll want to check your “trace detector”–a car parked outside overnight with a coating of dust on it–for drop images in that dust. I hope you didn’t forget to keep your car outside last night, as good CMJs do in possible sprinkle situations that you might otherwise miss. Happy to report a sprinkle here last night.
Today’s clouds?
Residual Cumulus and Altostratus, some Altocumulus (now that I can see them) patchy Cirrus, clearing out later in the day.
Cold slam3, the sequel
Valid for February 9th, 5 am AST. Precip is shown in the lower right panel by green coloration, and its over us, which you can see if you take out your microscope.
Saturday, February 9th. Precip looks substantial, likely MORE than half an inch here in Catalina should Canadian GEM model, shown below, verify.
Rather unsettling is that the USA! WRF-GFS, our best model, has virtually NO precip with this cold blast. When two numerical model outputs are so different the term thrown around is, “model divergence”. However, since “wetter is better”, a kind of non-viable theme here, I am now going on record as foretelling at LEAST 0.15 inches, top amount 0.60 inches, beginning on February 9th. This is the sports-like part of weather forecasting, riding the models, seeing how they change in the days ahead, and whether you get the amount you foresee, around a third of an inch median amount.
What is ASSURED for us here in Catalina is the cold blast, with or without liquid refreshments. Check this NOAA plot below out:
Valid for Saturday, February 9th. A cold spell is ASSURED! Check out that HUGE cold bowl over the Southwest US. No confusion here!
The End, unless I think of a correction or addendum, which seems to happen every day!
Here’s a nice little example of how the weather computing models start to go awry fast when a little flummoxed when little DELIBERATE errors are input into them as they start their northern hemisphere data crunch (below, from the global data ingested at 5 PM AST yesterday). Us folks here in Arizona and those in the Southwest US comprise one of two “centers” of the greatest uncertainty in all of the Northern Hemisphere, as shown below in the red and blue lines (selected height contours at 500 mb).
Model outputs and what they are predicting will go to HELL faster due to our “zone of uncertainty”. Chaos in action. Wiggle something here, and it falls apart over there and all over. This example is the contour forecasts for 5 PM tomorrow.
Valid for 5 PM AST Monday, February 4th.
Does this epicenter of uncertainty hereabouts mean we have a chance to get some real rain in the next 36 h?
No, but its great that you know about this uncertaity and how it plays out in the NOAA “ensembles of spaghetti”; useless-in-some-ways-knowledge, absorbed just for the sake of knowledge.
The uncertainty illustrated above is associated with a upper level wiggle in the winds and exactly how that will play out as that wiggle moves toward us from the NW today. Its a little baby trough in the upper air flow that the model is uncertain about but it is too weak to have much affect on the big cloud mass that will be drifting over us today, that cloud mass originally from a location about halfway between the Galapagos and Hawaiian Islands. These are real tropical clouds over us today, and they’ll be piled in layers (Altostratus, Altocumulus, Cirrus, Cirrostratus) over us to more than 350,000 feet!
Range of amounts here in Catalina: ZERO on the bottom to 0.10 inches, tops.
Below is an example (full set here) of what the Beowulf Cluster from the U of AZ sees in the moisture overhead at 3 PM local time (in other words, during the 84th hour of the Superbowl pre-game show). I realize that many of you will not be able to go outside and look at the sky at any time today due to this historical sports emergency, and so I will tell you something now about what you likely would have seen had you gone outside, perhaps even missing an equally historic commercial break of some kind:
Forecast sounding for 3 PM AST today, an hour before Superbowl kick-off.
What does this mean?
Weird clouds, most likely. Scoop clouds, concave (downward) looking cloud bottoms. Some areas of the sky might look like ocean waves upside down, “undulatus” clouds (we had a short-lived Ac undulatus yesterday to the NW of Catalina). Clouds with waves on the bottom. The bases of our tropical clouds are likely going to be in a “stable layer”, one where the temperature remains the same as you go up. It would be located just above the top of Ms. Mt. Lemon. Along with that stable layer, and is always a part of them, is wind shear; the wind turning in direction and speed as you go upward from just below this stable layer to above it.
Stable layers and wind shear produce waves, not ones always seen since the air is often too dry for clouds, but in this case, they should be visible. Could make for some interesting cloud shots this afternoon and evening. Here’s a risky example of what I think is likely, though with too much virga falling from above, they won’t happen, hence, the risk in a cloud detailed forecast:
An educated guess about how this afternoon’s cloud bases will look. There’s likely to be much more cloud cover, however, than is shown here.
Yesterday’s clouds
Lots of contrails overhead yesterday, an unusual number. Really, we are SO LUCKY not to have many days like this, kind of a sky pollution, though at present, an unavoidable one. Just be glad we don’t live right under a main, well-traveled airway (though, with predictions of a doubling of air traffic by 2020, we are likely doomed to more days like yesterday when Cirriform clouds are present).
Chance of early Feb rain still ahead, and I can prove it. This panel below is from last night’s 5 PM AST global data ingest into the WRF-GFS model, our best, as rendered here by IPS MeteoStar. As you can see, there are quite a few acres of rain showing up in southern Arizona on the 5th at 11 AM AST. I’ve added an arrow to help you find it.
What’s gone wrong with the possibilities of a good rain?
A low center is positioning itself off Baja as we speak, in almost exactly the same spot as the one that gave us our drenching rains of a couple of weeks ago. But, like a raggedy-looking hitchhiker that no one picks up, there’s no interaction with this developing low center down there by a trough zipping by in the westerlies to the north of it, one that dips down to the south just that bit and scoots our promising low and all its water to Arizona. Before that happens, that low wanders around and dies a quiet death down there.
When low centers are as far south as this one that is developing off Baja and over the warm waters out there, it’s cool center gradually warms up due to all the Cumulonimbus clouds it spawns, that warm air shooting up into its center and around it, and the circulation around it dies; it gradually just goes away. This is because there is no longer any temperature contrast between the center and regions outside of it, that which drives the circulation: no temperature contrast, no circulation.
Valid at 11 AM AST, February 3rd. This is looking very good, indeed, at this point.
You can see what happens to that low center in the panel above when no trough ejects it right away toward Arizona and it has to survive on its own in the next forecast map below.
Valid for 11 AST, Tuesday, February 5th. I thought I was going to cry when I saw what happened to our promising low and storm. That remnant passing south of Arizona means dense middle and high clouds with a lot of virga, sprinkles, and that’s what the models are seeing in that small area of rain in the first panel. Could be some great sunsets, like yesterday.
Yesterday’s cloud sequence, a classic one we see over and over again
First the thin Cirrus or Cirrostratus. Then, as though a real storm was coming, the sky lowers and thickens up in Altotratus. It non-desert locations, this sequence to Altostratus leads to rain about 70% of the time, that number from ancient cloud observation studies conducted before satellites and models. Finally, the back of the “storm”, well, at 25,000 feet you would’ve have thought is was a “storm” with all the snow that fell on you. Here is the start, middle and end, the latter of our fabulous sunset:
8:03 AM. Cirrostratus fibratus overspreads sky.1:39 PM. Too thick, too much shading to be defined as Cirrus; its now Altostratus. CIrrus typically, from vertically-pointed cloud radar studies, thickens downward to become Altostratus, with cloud tops staying at the same height.
6:01 PM. The backside, the last of the Altostratus clouds, allows the sun to illuminate their undersides, and the light snow that falls from these clouds, only to evaporate here in Arizona.
A look back at our end of January rainstorm
Radar-derived total precipitation from WSI Intellicast for the week ending January 31st, 2013. The Tucson radar was down several times and so our local heavy rains are not shown. But look at what the mountains got SE of Flagstaff, 4-8 inches! So great in this droughtful winter.
A friend sent a link to this image of the day with a discussion from NASA. I thought it was a stunning statement. NK will likely not be a big player in anthropogenic climate perturbations1.
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Computing stuff
In the most recent issue of Science mag (Jan 18th) that I received, I was alerted to a new fact:
the Japanese Fujitsu super computer “something or other” that I mentioned yesterday as the fastest, has been superseded in performance by the Oak RIdge National Laboratory’s Titan super computer at Oak Ridge, TN, USA! Oh, yeah, baby! Does 17.6 “petaflops” a second.
You can read about these developments here (or here: Exascale Science-2013-Service-264-6) as “exascale” computing is considered as the next major step in super computing, a step required for progress in several fields, including materials science.
Exascale supercomputers will run 57 times faster than the current best. Also, if such a computer that can do “exaflops”, was to be constructed using today’s technology, it would require FOUR HUNDRED FORTY-SIX MEGAWATTS of electricity to run it! That’s enough electricity to power half a million homes, this article pointed out!
But such a incredible super computer is needed for better weather and climate forecasting so I think we should go ahead and get one.
Cost?
Oh, maybe 100-200 million…IF they can make one.
But, “has the world has gone mad?”, you might ask.
Just think of how many hundreds and hundreds of these “ExecuTower” computers you could buy with that same 100-200 million, and all the computing they could do. They come with a 1-year warranty, too:
From Byte magazine, 1990.
Our clouds for awhile?
Cirrus, patchy enough for nice sunrises and sunsets.
Not mentioning model outputs….why dwell on dryness and negativity? Life is too short.
Well, you can’t really see an etage unless there is a cloud in it. And, no, “etages” are not French flying saucers, they’re the levels that clouds come in, those levels we use in metland (aka, weatherland), that help us classify clouds as “low”, “middle”, and “high” ones (the THREE etages. (Why am I suddenly thinking of stooges here in this serious moment? Well, I guess if thinking of the Three Stooges will help you remember that there are THREE cloud etages, I guess its OK; a pedagogical trick of sorts I’ve played on you).
To get back to flying saucers, I guess two or three flying saucers could have been in one of those etages yesterday, but, just for the record, I did not see any, and I am probably am looking at the sky more than most. Only a telescope looks at the sky more than I do.
But those clouds were all there, ones in different “etages”, at one time or another yesterday: Cumulus fractus and humilis (shreds, and little pancakes), Altocumulus undulatus (wavy ones), and Cirrostratus fibratus (a veil with icy fibers in it).
Here they are for your edification (it’s why you’re here, isn’t it; not to read about the Three Stooges?):
12:21 PM. Cumulus fractus, shred clouds, and a Cumulus humilis, just hanging around, not doing much, hardly moving in any direction. Note depth of blue sky, envy of folks everywhere. Estimated cloud height above ground, about 5500-6000 feet because I could also see that they were just topping Mt. Lemmon. Looking over there helps take the guesswork out of it.
1:40 PM. Sky addendum: Altocumulus undulatus, had signs of waves in it. Those shred clouds were motionless, but the Altocumulus were jetting by like a jet from the NW. Could have gotten dizzy watching the relative motion of the stationary low Cumulus fractus clouds and those Altocumulus ones!
6:08 PM. Sunset Cirrostratus fibratus (its got linear features in it, ones aligned with the NW wind of there). Quite nice.
If you looked up at those clouds in the middle and high levels (Altocumulus and Cirrus), you could have gotten disoriented, dizzy, thinking the earth was spinning in the wrong direction, rotating toward the northwest and Seattle. Generally, at middle and high levels, those above around 8,000 feet above the ground, the clouds in them appear to be moving gently, steadily, not RACING along like they were yesterday, because they’re a pretty good distance away, like when you see a commercial jet flying at 600 mph, it doesn’t look that fast from 30,000 feet away. And its always a little odd to see middle and high clouds moving so fast on a fine weather day.
But yesterday, Altocumulus clouds at 12,000 feet above the ground to Cirrus-levels, over 25,000 feet above the ground were racing to the southeast at what appeared to be fantastic velocities. How fast?
Oh, 70-80 mph for that brief mid-day period with some Altocumulus clouds jetting along, and the Cirrostratus? Oh, around ONE HUNDRED TWENTY or so mph! Here’s where the jet stream was at 5 PM yesterday, yep, its red heart right over us!
The 500 millibar map (about 18 feet above sea level, 15,000 feet above ground level here in Catalina, for 5 PM AST yesterday, the 29th. Note red jet core over Catalina.
Gone now, of course. That’s what weather does, just keeps movin’ along. This second part of our two-part storm will bring a lot of needed precip to the Plains States. Feeling good for them.
Is there any more rain ahead for Arizona! this winter?
Yes, “VIrginia”, you know that if there’s a model run out there SOMEWHERE that has rain in it for us here in Catalinaland, Mr. Cloud Maven person is going to find it for you, raise your hopes up!
And here is that widespread Arizona rain for you in this panel of precip from a model run that I just found, “hot” off the press (hmmmm, are presses hot?). The panel below is from last evening’s 11 PM AST global data smash down by our best computers (though ones that are not as good as the Japanese have–a Fujitsu something or other super computer–what have our guys been doing all these years? ((hahahahaha, sort of)):
Global model crunch, valid for Tuesday morning, February 5th at 5 AM AST. Green precip slime (good slime,that is, kind of like good gut bacteria that keeps us from dying from our own waste) has spread over AZ from the SW. Once again, I have helped you locate the State of Arizona on this map in case you’re not that good with geography. The exclamation mark in the word, “Arizona” is because that’s how good a state it is, and everyone should know that. Also, “Arizona!” is intended to be sung to the tune of, “Oklahoma!”, that musical about corn and stuff that Rodgers and Hammerstein did a few years ago.
OK, so we got us some rain coming or not on the 5th. Some model runs don’t have any on this day.
The pattern that develops is exactly like the warmish storm that brought so much needed rain to Arizona a week ago. An upper low sits out over the warm waters off Baja for a couple of days, and then is shoved northeastward across “Arizona!” and “!” Will it repeat exactly with another big drencher? Nope, repeating exactly doesn’t happen. Still, decent rains, ones having an impact on drought, in sizx days from now it looks likely from this precipophilic vantage point . This confidence, of course, derives from our error-filled NOAA “ensembles of spaghetti” plots. Stand by for reality in about six days. Will keep you up to date on those model runs having rain in them, otherwise won’t.
7:34 AM. Coming at you! A line of Cumulus congestus bases briefly passed over Catalina, but only an isolated drop fell out of them before they fell apart. But, for this moment, it was a time to be excited.
Once in the “behemoth-of-the-month” club some 10-12 days ago in the models as a major rain producer this month, and even its timing on the 28th was WELL-predicted as far back as that, yesterday’s storm and powerful trough aloft was ultimately a disappointment, producing only 3 hundredths here. That tiny amount of rain was phenomenally well predicted in the SHORT term, however, with no model thinking it would be anything more than that in Catalina a couple of days away. Still, with SO MUCH bluster aloft, it was disappointing.
For 5 PM AST, yesterday, this 500 millibar map showing the huge system that passed over us yesterday and last night (from the Huskies, purple and gold).
Early yesterday morning, and against the model predictions, as the Cumulus congestus piled up over the Catalinas and to the west through northwest, visions of squall lines danced in my head; surely an arcus cloud with a wall of precip would roll through Oro Valley/Cataina later in the morning or early afternoon with a substantial, if short-lived rain. Maybe we’d get 0.25 inches, not less than a tenth.
Cumulus congestus powered higher into Cumulonimbus clouds for a time to the northwest, giving momentary support to that thought of a rip roaring squall line, maybe some lightning with it.
But no.
They soon moved away and the sky began to change into more stratiform (flat) looking clouds, no congestus to be seen anymore by about 9 AM. The disappointment was huge, kind of like that girl you thought was flirting with you, but then you find out you were deluded, had completely misread the situation. Yeah, it was that painful when the congestus were gone.
Here are a few early shots, ones that created so much early excitement, so much portent, those early bulging Cumulus congestus clouds. Still kind of pretty to look at, like that girl I was thinking of, but I wasn’t good enough for her (actually, that should be plural); maybe they didn’t like all the weather talk, who knows?
8:02 AM. Nice looking Cumulus congestus to the N.8:05 AM. Line of Cumulus congestus to the NW. Congestus everywhere! Nice Cirrus, too.
8:45 AM. Cumulus congestus turning into Cumulonimbus capillatus! Look at all that ice up there on the right. “Here comes that squall line, maybe with a nice arcus cloud”, I thought.9:22 AM. Same view as above 47 minutes later. Need I say anything? Light, Seattle-like rain had just begun to fall, from stratiform clouds, of course. It was a sad moment. Reality was setting in; there would be no squall line, a relationship was not going to be torrid, but platonic, if at all1.10:59 AM. So Seattle! “Platonic” Nimbostratus, but if you really like someone, oops, I mean “rain”, platonic Nimbostratus is OK; its something. This was the emotionless heart of our storm yesterday. Stuck on a theme here…2:47 PM. Hope began to increase that we might STILL get a good shower. But no rain fell on us from this promising scene. Why? No ice in those clouds overhead/upstream.
5:39 PM. While the cloud tops were not cold enough overhead, it was nice to see a long period of light snow falling on the Catalinas where the cloud tops were lifted and did get to ice-forming temperatures.5:40 PM. The sunset turned out to be a muted one in terms of color, but still interesting. Crepuscular rays are seen in the distance. The sky, full of clouds, continued to give promise of rain or snow overnight as new showers developed in western Arizona. They went south of us this morning.
What’s ahead?
This:
You got yer moderately high probability of a low center WAY down off’n Baja, kind of meandering around down there, not sure what to do, in the last night’s spag plots. That low is located just about where our great rains of last Saturday came from. Remember, like your horse, weather has a memory, knows the “trails” you’ve forgotten, and so its not too surprising to see a weather pattern replicate itself in a future forecast map. Gives it a little credibility.
Valid for 5 PM AST, February 3rd. Looks pretty good, eh?
The actual model runs, at times, have had a lot of rain as this system, after fiddling around down there off Baja like the last one, suddenly ejects northeastward across Baja into Arizona on the 4th-5th as the higher latitude westerlies give it a shove. An example, from IPS, and from one of the wettest model runs, naturally, is shown below, the one from last night’s 11 PM AST global data. Presently, the main conundrum is whether part of this meandering, sub-tropical low center will come out on the 4th-5th, before another part combines with a strong Pacific trough on the 7th, kind of a “two for one” situation.
Can’t tell now, of course, which of these scenarios will verifiy, but there WILL be a low in place off Baja soon that, as we like to say, will be “filled with rainy portent” for Arizona again.
The End.
Arrow points to us.
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Did you know that psychologists have a lab standard called, the Passionate Love Scale?
Stage 1 is marked by “obsessive-delusional thinking” (this so funny!), and “euphoria” when things seem to be going right, as in some weather maps I’ve seen.
That’s your weather forecast for today. There’s nothing you can do about it. Why go on about it?
Next, these from yesterday–was under control, only took 127 photos. Every thousand or so shots I take is NOT of a cloud, and yesterday there were two exceptions, which I will post here as an anomaly; a quirk really:
5:48 PM. Sun broke through the Cumulus and Stratocumulus clouds for this orangy foreground as the white light of the sun is burnished orange at low sun angles due to having passed through a denser portion of the atmosphere and the shorter wavelengths (blueish) are scattered out leaving reddish hues to come shining through. Banner cloud remains in the same crevice as yesterday on Samaniego Ridge like a trap door spider or a piece of lint in a corner of the room you haven’t vacuumed for awhile.2:55 PM. Horse demonstrating that the appearance of water in a tributary to the Sutherland Wash yesterday was real, not an illusion. Thanks, horse. The bit of water in the Sutherland Wash itself dried up just down from the private land fence opposite the rusty gate on the east side. (Horse people know where this is.)5:56 PM. Gritty view through wires and a telephone pole of the highlight color in Stratocumulus clouds of yesterday’s sunset. Sometimes I think you’re here only for the eye candy.
Yesterday’s rare ice-forming anomaly
I was hoping you wouldn’t read this far. Something incredible happened, rarely seen here in Arizona. Our slightly supercooled clouds, with top temperatures between -5 and -10 C, formed ice. When I first saw the indication of something falling out of those shallow clouds on the Catalinas, I was beside myself. Here’s what I saw, not taken while driving1:
11 AM. A shopped photo of the ice-fall from these Stratocumulus clouds on the Catalinas to make it look like it was taken from a car, the way you might have seen this ice fall. Note how I cleverly tilted the image to make it look like it was taken in a hurry before the light changed.Same image with writing and an arrow on it to help you out.
I thought it was some kind of fluke since it was indicated just yesterday from this keyboard, based on prior experience in Arizona, that ice rarely forms in our clouds at temperatures above -10 C (14 F). Maybe someone was nefariously cloud seeding I wondered…. Or had flown an ice-producing aircraft through these clouds upwind somewhere. (Its about what cloud seeding would do in marginally supercooled clouds like these, too, not much but something.)
———academic discussion—–
Ice appearance in clouds with tops warmer than -10 C is common in “clean” environments like over the oceans (see the works of Mossop in the Australian Pacific, Borovikov et al in the Atlantic, Hobbs and Rangno in the Washington State coastal waters and the Chukchi Sea offn Barrow, AK, or Rangno and Hobbs in the Marshall Islands) in clouds with warm bases (ones substantially above freezing for the most part) that can be anywhere even in “continental” environments far inland where cloud droplet concentrations are high due to natural and man-produced aerosols (see Koenig in Missouri, Hallett et al in Florida, Rangno in Israel) among many others). We sometimes have those warm-based clouds here in the summer, too.
——-end of academic interlude——–but not really——
These fuzzy very light snowshowers soon ended and the day went on as foretold, no ice in the clouds.While out on Old Jake, shown above, I was taking photos of particularly dark based clouds and was going to tell the story about why they looked so black, and yet did not precip–to warm and cloud top, and drop sizes near the top, too small for ice initiation. Just about every case in which aircraft measurements have been made in such clouds that form ice at top temperatures above -10 C (14 F), inside them are cloud droplets larger than 30 microns AND a few drizzle drops (liquid drops between 100 and 500 microns in diameter, or rain drops. Droplets larger than 30 microns and substantial concentrations lead to collisions where the drops that collide can coalesce into a single drop. Let us not forget Hocking or, later, Jonas and Hocking and the 38-40 micron drop size limits they found for this to happen from lab experiments. Below that 30-40 micron diameter size, the little cloud droplets act like marbles; too much surface tension.
OK, there’s that little discussion preparing you for what comes next. Continuing with the story…was there one? Well, anyway, Mr. Cloud Maven person, riding on his own forecast made that early morning for no ice in the clouds (meaning no rain), decides to also ride on his old horse, Jake, who needs some more of that exercise.
Confidently, though dark Cumulus clouds underlying a broken to overcast deck of Stratocumulus, looked even exceptionally dark in places, Mr. Cloud Maven person smiled at this darkness of the cloud bottoms, knowing that the darkness in the bases of shallow Cumulus only spoke to how high (and small) the cloud droplets were in those clouds; they had to be highly “continentalized”clouds, ones with tremendous droplet concentrations in them and because of that, all of the droplets in them have to be tiny, being so great in number. And, in being a Cumulus cloud with an appreciable updraft, even more droplets are activated in “continental” air than are at the bottom of a layer cloud like Altocumulus.
When the drops are tiny, more sunlight is reflected off the top of the cloud and the darker they get on the bottom, and the more removed they are from producing a drizzle drop, or are in having the precursor droplets to drizzle drop formation, cloud drops larger than 30 microns.
This is what a Cloud Maven person thinks before he gets on a horse….
So, as I am riding along near the Sutherland Wash, these patches of dark bases form nearly upwind…. I watch them for awhile, quite unconcerned, and smiled again, thinking about the other horseback riders, people on bikes out there that likely turned back in fear of a terrific downpour, not really having the knowledge they need about clouds.
Then suddenly I noticed ice streamers coming down NW of Catalina only a couple of miles away! It was falling from the downwind part of these darker clouds, where after a period of time, ice, if it was going to form would be. But, how could this happen?!!!! Before long, the thicker regions of the cloud began to emit stranded precip, a sure sign of graupel up top in the cloud. Graupel in clouds with supercooled droplets only 23-25 microns in size, much smaller than those required for coalescence, and the present of those droplets leads to ice splinters when they are banged by a graupel particle. A coupla graupel (soft hail) and after awhile, (10-30 minutes) a cloud can have a lot of ice, 10 per liter or more in concentration, plenty enough for precip beside the graupel-melting to rain stranded part. Here is a shot of the further, SHOCKING development:
3:06 PM. First graupel strands emit from base of Cumulus congestus. More ice aloft can be seen on the right. Horse, too, noting precipitation in the distance, is surprised by this sight. “It’s OK, Jake, its over there and moving away from us.”3:18 PM. I smiled, a sardonic one, as the drops began to fall (see smudge, lower center). A dark-looking complex of Cumulus topped by Stratocumulus had formed ice upwind of us (see upper right), and now, me and horse were going to get wet.
I had to laugh at myself on the way back, the rain drops wetting us down, when I thought about being quite confident yesterday morning about no ice would form in our clouds. When you have an occupation that tends toward error, its good to have a sense of humor. There’s nothing worse than a humorless meteorologist at a party, one whose likely obsessing over his error-filled life.
So, why ice? The TUS sounding at 5 PM AST did not suggest tops colder than -10 C Z(moisture top was about -5 C is all), but where the moisture ended, the air was incredibly dry, reported as “1 percent” relative humidity. Here is that 5 PM TUS sounding:
Arrows point to main top height, and where the highest Cumulus tops might have gotten to as they momentarily, due to inertia, mounded above the main moisture level. Normally, they plop back down because they get chilled, and the tops are cold relative to the surrounding air.
So, an overshooting top COULD have gotten to -10 C, and certainly, with that incredibly dry air just topside, those drops in those evaporating turrets would have chilled a couple of more degrees C. So, maybe that’s it, in fact, the overshooting moderate Cumulus tops DID reach to, or below, the -10 C normal ice-forming temperature here.
However, the concentrations that developed in these clouds HAD to be due to other processes beyond just the run of the mill ice nuclei since there are so few of them at -10 C, and that where drops larger than 23 microns come into play. Without those, there would never have been showers yesterday, only a very isolated drop or two. Those larger than 23 micron size drops lead to “ice multiplication” where just a couple of initial ice particles can “multiply” like rabbits in clouds because of ice splinters shed when hit by graupel. However, as we speak, the full understanding of how ice forms in clouds with these “high” temperatures has not been pinned down. Some researchers, the present one included, believe that ice splintering alone is not sufficient to explain the rapidity in the appearance the high concentrations (10s to 100s per liter) that develop in clouds like we had yesterday. You probably don’t care about what I think, but rather go with the majority opinion… Oh, well, it always safer that way.
As a test of even deeper knowledge that an aspiring cloud maven junior might have, this question:
What kind of ice crystals and other frozen particles would have been in those clouds yesterday?
No cheating; don’t get out your Magono and Lee (1966) translated-from-a-Hokkaido-University monograph on ice crystals and the temperatures and humidities that control their shape.
Answer1: What is a (hollow) sheath?
Answer2: What is a needle?
Answer3: What is a graupel (more a lump around a pristine ice crystal or frozen drop than just an ice crystal?
Answer4: What is an amorphous ice fragment?
Congratulations and adulation! You are now officially a cloud maven junior. Don’t forget to order that CMJ Tee.
Below, examples from the “ice crystal bible”, Magono and Lee 1966:
Needles, followed by sheaths, followed by “lump” graupel, and then some ice fragments in the last two panels.
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Only a crazy person would take photos while driving, like that crazy woman I once knew whose hobby was taking photos of dust devils while driving! Oh, my.
