Sure, there was a little mischievous wind in the early afternoon, BUT, as a day in late May in Catalina/Sutherland Heights zone of Arizona, wherein the temperature is less than 100 F, well, it was pretty darn great. Another one is on tap today just like yesterday today, too. Feeling sad about the early, northerly ejections of “snowbirds” who thought because of the warm winter, May would be an inferno here and are missing some splendid weather. Doesn’t work that way. You just don’t know.
Lot of interesting clouds yesterday, too, real cold ones. Those Cumulus that formed in the late morning and afternoon started producing ice almost immediately. Wonder if you caught the first ones over there beyond the Charouleau Gap around 11 AM? They did not look as high-based as they were, thus, as cold overall, dad-gum, those cloud bottoms were running around -10 C (14 F)!
How high off the Catalina ground were they? Oh, about 13,000 feet, or about 16,000 feet above sea level (about 550 millibars). I woulda guessed, as you would have, about 8,000 feet off the ground when I first saw them forming (and not looking at the temperature and dewpoints, from which you can make a pretty good calculation of the cloud base height). From the Cowboys at the U of Wyoming, this sounding for TUS yesterday afternoon:
The Tucson balloon sounding for yesterday afternoon, launched around 3:30 PM, ascends at about 1,000 feet a minute.
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Weather Hints for Every Day Use by “Art”: You can calculate the height of a Cumulus cloud base by taking the difference between the temperature and the dewpoint, dividing it by 5, square that number, add the number you started with, and subtract the square root of 2.
DId I get the number you started with?
(Actually, stop at “dividing by 5”, multiply that number by 1000, and you’ll come out just about right. Yesterday, 85 F temp, 20 F dewpoint, leads to 65 F difference, divide by 5, you get 13, and times a thousand is an estimated CUMULUS cloud base of about 13,000 feet above you, not too bad).
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Continuing….. Since bases were so cold, tops were exceptionally cold, too, for shallow Cumulus and started producing ice when they were only about 1,000 to 3,000 feet thick, with cloud top temperatures of -15 C to -20 C (about 4 F to -4 F). Some of the highest tops, all east of us, and mostly on the east side of the Catalina Mountains, were likely as cold as -30 C (-22 F).
You can see yesterday’s small Cu spewing ice in the great U of AZ time lapse movie here. Only plays for one day, though.
You may also have noted in your cloud diary the bifurcation in the Cumulus array of yesterday. Almost no Cumulus west of Catalina, and plenty in the east half of the sky, appearing to be largest in the distance in the east. We were literally on the edge of the moist plume from the south that was hoped to end up been west, with us deeply embedded in it, and where measurable rain might have fallen here as it did east of us yesterday. Oh, well.
Today, with a low center passing over us tonight and a blob of Pacific Ocean air in it, and while that air is cold and pretty dry aloft, it will be a little more moist and so cloud bases today should be a little lower, and warmer, than yesterday’s. That means a little more water condensing in them than in yesterday’s clouds, and a greater chance of sprinkle here. Hoping for measurable, but its probably less than a 50-50 shot at that. Likely will be some thunder in the area of SE AZ, too. And, as always with high cloud bases, gusty winds that arise due to virga and rain falling through the dry air below cloud base. (Yesterday afternoon’s gales in the Sutherland Heights, momentary blasts of 40-50 mph, were NOT due to virga, but a rather to something I didn’t see coming, maybe a smallish low center–nothing really showed up on the maps.)
You will also see in the above loop that our low takes its time moving along, and will keep the skies interesting with Cumulus and weak Cumulonimbus clouds today and tomorrow, along with temperatures below seasonal norms for late May (aka, less than 100 F) ((Snowbirds left too soon; ice still melting off some areas of the Great Lakes!))
From the cloud vault; yesterday’s clouds
10:28 AM. Small Cu with lenticular type tops began forming in the lee of the Catalinas during a horseback ride with a friend, in case you didn’t think someone as cloud-centric as me could have a friend. Calm winds, then, too.11:08 AM. First ice! Can you spot it in the distance? Horse can’t believe that ice is forming already, and is rolling around in ecstasy, thinking about what it might mean for the afternoon.1:43 PM. Approaching low with air moving upward ahead of it, triggers a batch of Cirrus and Cirrocmulus lenticularis (really high lenticularis) upwind of Catalina and above some Cumulus fractus.3:18 PM. One of the more remarkable sights yesterday, were the small Cumulus clouds (humiilis or mediocris) that iced out. Look at ll the ice that formed in this small cloud, exiting on the left side, but dominates the whole cloud from this viewpoint. When you see this, it tells you how COLD those clouds are. First guess should be around -20 C at top when you see this much ice in a cloud this SMALL. Clouds having warmer bottoms, can have warmer tops that look this icy because ice forms in clouds at higher temperatures when the drops in them are larger (see Rangno and Hobbs 1994, Quart. J. Roy, Met, Soc.) Oh, yeah, baby, have some pubs!
6:58 PM. Iced out Cu/weak Cumulonimbus beyond the Gap, the Charouleau one, end the day. Shoot, a slight change in trajectory from the south, and they woulda been here.7:00 PM. Meanwhile, all quiet to the NW, no Cu whatsoever demonstrating the moisture edge we were on.
The weather ahead and WAY ahead
Now what I think is really interesting, which is almost everything to do with weather, is that the models are suggesting a tropical injection again at the end of MAY into early June, with a chance of a decent rain again. As you can see in the plot below from the NOAA spaghetti factory, a trough to the west of us and over California is a virtual certainty now at the end of May. That means the air above us will be, while quite warm, originating from the deep Tropics with the likelihood of clouds and precip coming up from there. Nice. Will keep me posted on these developments, in case no one else is reading this far.
Rained, too, between 3:42 PM and 3:47 PM, actually 273 seconds, if you had your stopwatch out. It was great. I ran around trying to get wet, but couldn’t do it.
3:44 PM. Proof that rain drops did fall yesterday afternoon. Don’t forget to recycle stuff and also don’t forget that this kind of rain is NOT “drizzle”1. Drizzle are fine close together drops that almost float in the air. Tough to bicycle in drizzle if you wear glasses, in fact, I would say its impossible even if you’re wearing a baseball cap and helmet on top of it because the drizzle blows underneath the cap and onto your glasses so you can’t see anything right away. Rain drops fall too fast for this to happen. This from personal experience in Seattle. Always wear a helmet when bicycling.10:23 AM. After a completely clear morning, Altocumulus clouds formed rapidly over and downwind of Mt. Lemmon. Before long, most were shedding ice.11:45 AM. Distant Cumulus cloud forms just underneath some Altocumulus clouds. Here’s where you KNOW that the day is going to be pretty good as far as convection and virga go because these clouds were so cold, and its late March when the sun is strong.1:51 PM. Two hours later the sky was full of glaciating Cumulus clouds, and isolated heavy virga trails, ones heavy enough to reach the ground with a few drops. Looking SW over Oro Valley and toward Marana.2:31 PM. Thunder was heard just a minute prior to this photo, The storm was just west of the Tortolita Mountains.3:29 PM. Part of the cloud mass that brought the sprinkles (coded as RW–) to Catalina. Probably measured below that little streamer, dead center. The virga hanging well below solid young cloud bases told you that those bases were far below the freezing level yesterday. How cold? Sounding indicates that the bottoms of the Cumulus clouds were about -12 C (10 F). The higher tops were colder than -30 C (-22 F)6:36 PM. Residual Altocumulus cumulogenitus containing a lot of ice if you look closely..
Today’s clouds
Still enough moisture for very shallow Cu fractus, Cu humilis, hold the ice (tops too warm). Skies will also be overrun with Cirrus, maybe verging on Altostratus, as part of low and trough barging into northern California today.Will get nice and breezy this afternoon, as the low zips on into the Great Basin and makes its presence known here. Instantaneous puffs might reach 40 mph this afternoon. No rain possible with this system, darn.
However, deeper Sc and Cu with ice in them should be visible up toward the NW-NE horizon today since a little rain and snow is expected on the M-Rim today, this from the U of AZ super mod’s 06 Z (11 PM AST) run, here.
The End.
—————————- 1Here’s the interesting story behind getting THREE public service messages in a single caption/photo: I wanted to both better serve my public by getting some public service messages out there while at the SAME time, documenting some weather singularity, in this case, one of the rare rain events in the Catalina winter of 2013-14. Suddenly, in the midst of the rain I was dancing in, I noticed some shiny drops on the lid of the recycle bin, and things just “came together” you might say for a remarkable photo.
Cloud tops in those deeper Cu reached -30 C (-22 F) yesterday, plenty cold enough for lots of ice, with a few scattered very light showers reaching the ground, even a few drops here in Sutherland Heights a little before 5 PM, qualifying for a day with a trace of rain. Imagine! Rain! What izzat?
Here is that day below (if you want the short version, go to the U of AZ time lapse film department, online here).
Day Summary: Sunny with Altocumulus castellanus/floccus virgae in the early morning, then in the late morning, Cumulus humilis and mediocris, the latter with virga; Cu grew into shallow, but very cold Cumulonimbus capillatus (lots of “hair”-ice), with virga and RWU (rain showers of unknown intensity) in a couple of spots. Sunny again in mid-afternoon, but Cumulus re-developed in mid-late afternoon with more virga and some Cu reaching the shallow Cb stage with sprinkles here and there.
That’s it, in kind of a jumbled form. Hope you logged all these clouds and changes yesterday.
9:55 AM. Altocumulus castellanus/floccus virgae11:06 AM. Cu developed rapidly over and downwind of the Catalinas. Lots of ice at far left, indicating how cold those clouds were, likely around -20 C (-4 F) at cloud top by this time. Bases, too, below freezing by this time.11:10 AM. A classic, gorgeous example of Ac castellanus and floccus (the latter has no base, just a turret). No ice visible here.2:07 PM. Cold Cumulus and Stratocumulus filled in as trough apex was about to pass overhead (wind shift line, one you can see in the movie linked to above).2:08 PM. Rain showers reach the ground toward Marana whose city limit is pretty much everything you see in this photo I think…2:36 PM. Snow on The Lemmon!4:00 PM. Clearing developed for awhile in the mid-afternoon, but then Cu were quickly reforming. Lots of ice again in this one at left, the oldest portion of the cloud where droplets are evaporating, but the ice becomes visible because it doesn’t evaporate as fast as the droplets do. BTW, air flows THROUGH the cloud, youngest portions on the upwind side, oldest portions downwind. You want to know that if you’re flying around with a research aircraft because if you’re only targeting the young portions, you’re not going to find the “correct” amount of ice that developed in that cloud. Some researchers apparently did this and reported in journals anomalously low ice particle concentrations for the cloud top temperatures that they sampled. For the sake of courtesy, I will not mention their names. But this is why at Washington, we always found a LOT of ice because C-M /we knew where to go!14:31 PM. This was probably the deepest cloud of the day, and there is some suggestion of soft hail (“graupel”) falling out as would be an indicator of some higher liquid water contents before it converted completely to ice. Graupel comes from ice crystals or snowflakes that have bumped into a lot of supercooled cloud droplets that then freeze instantly on the crystal, helping it fall faster and collide with more droplets on the way down, a process called “”riming.” Pilots know full well about riming.6:24 PM. Nice sunset color in clouds and on the mountains.
Don’t see any weather ahead that I like, and so not talkin’ about that today.
—————————————- 1One of the many pioneering innovations here at “cloud-maven” is the novella-sized figure caption.
Virga here and there, chance of sprinkles through early afternoon, then blammo, clearing as wind shift aloft makes it way across Oro Valley/Catalina. CLouds will consist of Cumulus mediocris virgae, small Cumulonimbus capillatus virgae. Cloud bases will be below freezing and higher than Ms. Mt. Lemmon, so will be tough to get rain down to the lower elevations, though a virga trail may hit The Lemmon. Tops of Cu, -15 C to -25 C, i.e., cold enough for ice formation, of course. Crystals will be mostly stellars and dendrites with some clustering into aggregates we would normally call “snowflakes.” Some of the very coldest tops will contain some solid columns, maybe some prisms and hexagonal plates.
If you’re having trouble here because you’ve forgotten a few things, you might well want to get your Magono and Lee (1996) ice crystal “bible” and review crystals types and the temperatures they form at. Heck, maybe I’ll just put the first couple pages here for you…Magono and Lee (1966). Everybody had one back then. Very important to have that with you. As a further challenge, I have not rotated two pages to the upright position to make it too easy for you.
I suppose, too, that you COULD hire an small aircraft to go up there and check on these predicted types using the old “black glove” technique of the early 1960s, where a scientist would stick out a black-gloved hand from the passenger side of the aircraft and then report/log the ice crystals he found. Not making this up.
Yesterday’s clouds (something’s “wrong”)
Day started out dusty; ended up dusty.
8:16 AM. Dirt roads ‘n’ dust; that’s who we are. Got some Altocumulus, but they are so high and cold (-30 C) that they transformed into patches of Cirrus (ice) clouds almost immediately. Pretty normal, even at temperatures that low, for a liquid drop to form first, followed by freezing. Weird.
8:23 AM. Here, a real bird, not a fake one, begins to notice something extraordinary; the virga trails from the parent cloud are going the “wrong way”, toward the northeast!8:35 AM. “What’s going on here?”, the photo asks. Well, the virga trail is going FASTER and leading the head or “generating cell” from which it issued, meaning the wind increases with velocity going down, not UP, as usual! Incredible, really! Hardly ever see this. Is it due to global warming/climate change, the polar vortex has maybe turned upside down? I think so. Has annotations on it.
12:07 PM. Then I saw this, a cloud with no name above the Catalinas. Could be the silhouette of a polar bear, eyes and head at lower left looking downard, asking what have we done to it? Its white, too. Can’t be Cu fractus, though a thermal has pushed a damp layer up here, causing the concave shape. You don’t want to fly that small plane in or below this cloud, looking for ice. It would be real bumpy.
Above, through the dust, for some perspective of our ghost “bear.” Pretty cool, huh? I hope there are some left by the time I get done with this blog! Maybe I should check….let’s see what the Canadians (well, one Canadian at U of Victoria) has to say about this dire sitiuation, get informed about stuff. Here’s a link provided by the climate provocateur, and former WA State Climatologist, Mark Albright, who forwarded it to me for my own illumination. I found that post interesting, unexpected…maybe you will, too.
12:39 PM. Iridescence in Cirrocumulus patch. Very pretty for a minute or two, then gone.
3:24 PM. Day ended up cloudy and dusty with some areas looking like sprinkles could have fallen out and reached the ground, but nothing here, and echoes on radar were awful weak when present.
Rain continues to show up on the forecast horizon, which is about 8 days
Best chance of rain, 21st-23rd, mods fuzzy on which day has the best chance. If you love spaghetti, you’ll love this one below. The vast change in the pattern, indicated for almost two weeks now, is just about here. Some mod runs have rain as this “trough bowl” develops, and a strong trough passes through from the west. Seems more likely than not from here that rain will fall as that happens.
Valid for 5 PM AST March 22nd.
The End. (Nice sunrise, lots of Ac cas, Sc, virga around!)
Web crawlers: This is not about Rocky Mountain Silver Bullet Beer1.
Lotta wind last night. Gusts to 50 mph here in Sutherland Heights, stuff all over the yard. I didn’t mention anything about excessive wind coming last night, and so there’s no point in mentioning it now. I’m a cloud-maven, not a wind-maven….
Here’s yesterday afternoon’s sounding from Tucson, around the time we had all that ice pouring out of just about every Cumulus humilis and mediocris around:
The TUS vskkppm sounding, launched around 3:30 PM AST. A quite fascinating finding just now, is that when you type letters on the keyboard when you’re not looking at it, and miss by only ONE letter to the one you are targetting, you get a quite different word. Above, the Polish word, “vskkppm”, which was meant to be “balloon” in English2. The arrows denote bottoms and tops of those small Cumulus yesterday, -17 C and the deeper ones (a km or 3 Kft thick), tops maybe around -25 C,respectively; the bottom temperature exceptionally low for Arizona.
The high cold ones of yesterday afternoon
9:53 AM. Reminiscent of a summer’s day, Cumulus begin taking shape over the Catalinas. At this time, tops are near freezing, too warm for ice. As the day worn on, the bases and tops of the Cumulus clouds both rose, a pretty normal sequence.
1:47 PM. Not much happening yet, though Cu are now reaching “mediocris” in size. Nice lighting on mountains, though.
1:46 PM. Even flatter Cu to the NW-N at that time. I’m thinking, by this time “Where’s is the ice?”
2:40 PM, about an hour later, ice began to appear in several Cumulus clouds. Here in the distance (just above the house), some sprinkles likely reached the ground.
3:52 PM. Hardly a cloud around without a veil of ice crystals around it. Its likely that cloud tops (and bases) rose to temperature below -15 C during the mid-afternoon hours. Here, even Cu humilis are emitting little, hazy-looking ice plumes!
5:25 PM. A snow flurry even touched the Catalinas.
5:32 PM. Iced out! The little cloud that gave out the flurry on the Catalinas in its dying phase, no more liquid water in it, and so all of the ice crystals and snowflakes in it fall out or evaporate and in 20 min, it was gone.6:23 PM. Its not windy at this time. Wind hits just before 9 PM. Here tiny shred clouds, remnants of somewhat larger clouds, show their ice (veil on the right). BTW, its still windy this morning. Should die out during the morning.
There are really no good names for the clouds we saw yesterday. Maybe Cumulus humilis virgae? Cumulus mediocris virgae praecipitatio (to keep the Latin discriminators)? They have all the ingredients of miniature Cumulonimbus clouds, some vertical development, fall streaks and little shafts at times. So, these kinds of clouds, that are COMMON in the interior of the West during the cooler half of the year, really don’t have a good place in our cloud atlases. In fact, you won’t even find one in any cloud atlas! (Tell your friends how special yesterday was…)
The End.
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1 In fact, a legendary beer from Colorado, sung about below by no less than John Denver, or someone who sounds an awful like him, while also describing some football coaching history at the University of Washington Huskies.
2You should try this and see what other languages might be recovered from your keyboard by making just the slightest of errors.
3:05 PM. Classic Cumulus humilis (aka, “pancakeus”). Its not a bad thing to be humilis.4:03 PM. Here you got yer corral, yer horse poop and pee (dark area of soil in foreground), and off on the NW-N horizon, glaciating Cumulus tops; shallow Cbs most likely. Some rain up that way, of course. Don’t needa radar once you detect that ice. You did detect it didn’t you?
In case you don’t believe me again, see below! You can also find a few small amounts here in the USGS network.
24 h radar-derived precip totals for AZy (from WSI Intellicast) denoted by bluish regions. Not much more than a tenth was reported in USGS gauges, which is what’s indicated here by radar.
Today
More bigger Cu, likely some ice/virga visible. U of AZ mod thinks rain will be to the east and south of us. Darn. But, if you’re horny for rain, might be worth a family trip to, say, Douglas, take in a few drops. Nice town, Douglas.
WAY ahead
Big changes still ahead, though lately mod runs haven’t had as big of a wet change here as I would like to see, so not reporting on that.
Lettin’ the past few weather blogcasts about a good chance of snow here in Catalina during the Christmas season ride the old stagecoach into town. Doesn’t seem to be any need to change it… In the meantime this.
A science story for you, while we kill time waiting for some snow
You’ve probably read about snow in Jerusalem and elsewhere in the Middle East. I saw it snow in Jerusalem when I there for 11 winter weeks, January through the middle of March, 1986, on a self-funded cloud investigation. Its not terribly uncommon to see snow in Jerusalem, believe it or not.
I was single in 1986, so I could do stuff like that, quit my job at the University of Washington for awhile (2 years), with no need to ask a spouse, “Honey, do you mind if I quit my job today and spend the equivalent of $40,000 going to Israel to look at clouds for a couple of months, and then spend a year without income working on a publication about ’em?”
Not gonna happen.
I had just sold a house in Durango, Colorado, so had some money to waste; I could be a “gentleman scientist” as in the old days of science before WWII and Vanevar Bush and the onset of big government funding for science, and maybe what some would call the beginning of “careerist” science, that followed WWII and the beginning of the Cold War to propel us forward.
So off I went in early January 1986 to see the clouds of Israel.
Jerusalem was often a city in the clouds during storms; it was so COLD and windy during them, unbelievably so considering what we think of there from Bible stories. I was outside a lot, experiencing the weather and rain, and on one occasion I remember I couldn’t pull the shutter on my old Rolleicord medium format camera, my fingers were so cold.
The three wisemen/magi came in the winter, didn’t they? They don’t seem to have enough clothes on in the Nativity scenes that I have seen, given what the weather can do in the winter there. Below, Jerusalem in the clouds, with 20-30 mph wind, at about 40 F:
Part of the new construction of the Hebrew University of Jerusalem. Might have been a hospital wing. Note leaning cypress or juniper trees.
January 12, 1986. Looking down King David Blvd, Jerusalem, during a storm.January 21st, 1986: sunset over the Med, from the beach fronting Tel Aviv.
I really loved it in Israel. The Israel national weather service (IMS, Y. L. Tokatly, Director) was great to me, letting me have a little research area in their offices after I just showed up on their doorstep, unannounced. Later, in a display of incredible scientific idealism, when the Director learned that the key scientist and I had a falling out about the clouds of Israel after my second week there, he allowed me to continue to use their historical records and my little space in their offices, terming what happened between that researcher and myself, as “merely a scientific dispute.”
Oh, my; where has that pure idealism fled to in the global warming wars?
But I loved the clouds there in Israel the most as they rolled in off the Mediterranean, borne on the cold winds of continental Europe, then boiled upward from flat little guys that they started out as by the warm waters of the Mediterranean into big Cumulus and Cumulonimbus clouds, the latter often spewing lightning, by the time those clouds and cold air got to Israel. It is a gigantic lake-effect situation there in the Mediterranean, the kind that is produced by the warmer waters of the Great Lakes as Arctic air traverses it, such as the storm buried folks in New York recently. Over over the Mediterranean, the air has a chance to really warm up after leaving Europe due to its low to mid 60s late fall and wintertime water temperature.
January 15, 1986. Cumulonimbus calvus marches ashore north of Tel Aviv.February 9, 1986. Skies open up near Nahariya, along the extreme northern Israeli coast near the Lebonese border.January 12, 1986. A moment of “cloud ice” epiphany as the first storm in daylight hours occurred during my visit. I knew with the first two hours of this storm that my hunch about those clouds was right. BTW, showers like these can roll into Israel, and into Lebanon for that matter, for days on end, termed “rainy spells” in that region. Cold air troughs aloft like to “nest” in that region in the wintertime, enhancing the clouds there, and stimulating the “Cypress Low” pressure area at the surface in the eastern Med.
The short of this is, and I COULD write a book, “go long”, was that I questioned, from afar mind you, after I plotted balloon sounding of temperature and moisture from Lebanon and Israel when it was raining, whether the clouds being described by a leading scientist in Israel were correct. In fact, from these plots, I was rather sure they weren’t. But it would, as I knew, be real heresy to conclude that in those days.
Of course, questioning findings goes on all the time in science. Its what makes it better.
A short paper was submitted to the J. of Applied Meteorology in 1983 reporting this discrepancy, and some other problems. It was rejected by three of four reviewers, one being the leading scientist mentioned above. I really was of the opinion I would “get in.” so was disappointed, but not undaunted in the least! Should have taken more than ONE day, July 4th, 1983, to write it, coming into the University of Washington at 6:30 AM, I was so excited to get it off!
I knew what those balloon soundings were telling me, and so after the paper was rejected, it began to occur to me to GO to Israel and see the clouds for myself. After all, by this time (1983) I had been punching clouds with cloud measuring instruments at the University of Washington for about seven years, and had a good idea of what was in them just from their visual (external) appearances. And I was starting to build a list of papers on reanalyzing and commenting on cloud seeding experiments, getting some notice.
So I reasoned that even if I just looked at the clouds of Israel, I would know whether the many journal and conference reports about those Israeli clouds were in error.
Error? What would that be, you ask? Some background, if anyone is still reading.
The clouds being described in Israel by researchers there, ones operating a cloud seeding program, were supposed to get real thick and cold before they rained. That meant the clouds weren’t very efficient and could to be seeded with a substance called silver iodide (AgI) to make it rain sooner, before they got so thick and cold. The AgI would introduce ice, needed to start the rain process going, at higher temperatures than the natural clouds rained at, thus seeded clouds would rain before having to be so thick and cold.
This meant that more would rain when seeded compared to not seeded clouds because not just the taller ones in Israel would rain. More clouds raining would, of course, add hours of rain to storms on seeded days, it was posited, and the researchers evaluating their second randomized experiment reported those very results: seeding, on randomly drawn days, had increased the hours of rain compared to randomly drawn control days. And these increases in rain on the seeded days were statistically significant, as they had been in a first randomized experiment.
So, in not ONE but two randomized cloud seeding experiments in Israel, statistically significant results had been obtained on seeded days, and the scientists reporting these results also had what appeared to be a solid cloud foundation for having obtained more rain by seeding; the natural clouds just had to be too thick to rain, but they fixed that by seeding with AgI. It all made sense.
It doesn’t get better than this for scientific proof, the so-called “gold standard” of science; statistically significant results in two randomized experiments and a solid physical reason why it happened. Due to these attributes, these experiments in Israel were accepted as “proof” of seeding effects by our highest scientific panels, such as the National Academy of Sciences, and every expert in the cloud seeding domain. For a time…..
Representative of this status is a 1982 article in Science magazine; “Cloud seeding: One success in 35 years” That success was the two Israeli experiments en toto.
From the outside, my trip to Israel in 1986 to investigate the clouds would have seemed ludicrous. Why bother; too many peer-reviewed publications documenting the attributes of those clouds, and also in a number of conference papers as well.
Could they all be wrong?
Yep1.
The End, more or less.
Below, an “action shot”:
Yours truly atop the Riviera Hotel, Tel Aviv, January 1986, readying for clouds and storms to blow in from the Med.
——————————————-some final commentary that sort got out of hand after more coffee———–
1The short ending. That answer is not in question anymore. Did that leading researcher allow me to go to either of his two radars to see how thick the clouds were when they were raining?
Nope.
So my publication on those clouds (1988, Quarterly Journal of the Royal Met. Society) had to make inferences about cloud top temperatures based on primitive balloon sounding data. But the results in that paper, that shallow clouds were raining and had MUCH higher cloud top temperatures than had been reported to that time, were confirmed by independent researchers, the best kind, using aircraft and modern instrumentation a few years later.
Spiking fubball now! (Can’t seem to lose that sense of irreverence, even when serious.)
Some final, “human” notes about this chapter of science:
This same leading researcher, in 1972 (published in 1974 in Weather and Climate Modification, Wilmot Hess, Ed, Wiley-Interscience) wrote what may be the BEST, most circumspect review of his experiments, as his second experiment was underway! It is recommended reading for anyone in this field.
So, “something” happened later on when he got his radars to monitor cloud tops and likely learned there was a problem. And you can imagine, I was his nightmare, a smart-ass with a building publication record critical of cloud seeding coming to Israel to question his cloud reports. Ideally, no problem. As scientists “ideally” we want to be the first to know that our results are in error. We care only about truth. (Right.) Ufortunately, our humanity sometimes gets in the way.
The leader of the Israeli experiments died only a year after my visit at the age of 54, aware at that time (1987) that the paper on clouds of Israel was going to be published in the QJ (Prof. Peter Hobbs, the Director of my group, had communicated this news to him after we got word from the QJ that year.) So….we can speculate.
But our meetings were cordial at all times; he was a great story teller, and there was no shouting, even when he firmly asked me to leave his office and never come back (2nd visit when I was telling him about my “findings”, which included a mention of drizzle, something his clouds were never supposed to do).
In fact, I felt bad for him, and still do, knowing the position I was putting him in, how this might end when other researchers began asking more questions about his cloud reports and eventually they would have to be overturned. At one point, on top of the old Hebrew University of Jerusalem, during our first very cordial meeting, I said, “Maybe we can co-author something if I find anything.” Coming from a “newby” like me, I am sure, as cordial as he was, he would have liked to have pushed me off the roof.
Some day I will post the whole technical thing on this experiment, and another one that was its mirror image in the Colorado Rockies. That future post (Cloud Seeding and the Journal Barriers to Faulty Claims: Closing the Gaps) will be piled high with references But this is already too much for now.
An unusual sight yesterday: bulging dawn Cumulus fronted by fog. These Cumulus (not spawned by ground currents) suggest instability aloft, a rapid decline in temperatures with increasing height, which allows the buoyancy of “warmish air” in-cloud surrounded by cooler air to go up, whilst fog1 suggests the opposite; cold, damp, heavy air that can’t go anywhere but down, slip sliding away as it did yesterday because its topped by warmer air, a atmospheric “glass ceiling”. Ground fog like this is colder air that you can see.
7:21 AM. Looking NW from Equestrian Trail Road across Oro Valley. 7:19 AM. Odd multiple layers of ground fog (lowest) and Stratus clouds (“clouds” because they’re not on the ground) with shreds of Cumulus fractus above Samaniego Ridge. 7:07 AM. As above, suggesting a very fine layering of moist air with little temperature caps.
Here in Catalinaland, this kind of layering of cold air, as most of you know, is endemic on clear nights. Those who drive down across the CDO wash from Sutherland Heights or along Lago del Oro from the surrounding higher terrain know. Because of the stupefying amounts of rain in the past three days, the air is damp enough at ground level to form fog and you can see whose colder at night than you are IF you are above it. Also, anyone who walks their dog in the morning passed innocuous looking gullies, is aware of how cold air flows downhill and collects in low places.
The lack of density of this fog indicated that it formed in real clean air, air that didn’t have a lot of junk in it (which would also contain a lot of CCN, cloud condensation nuclei. Pretty hard to get fogs like we had in Bakersfield, CA.
Once things warmed up some, and with Arctic like air up top, Cumulus arose, a couple of which sprouted icy tops and shafts, namely, became small Cumulonimbus clouds, tops around 20-25 kft. Along with these clouds, there was a treasure of sunny highlights and shadows moving across the Catalinas. Here you go:
10:49 AM. Small Cumulus humilis, mediocris begin forming as temperature “warms up” to 50 F (egad).
11:13 AM. There’s water (glinting) on them rocks! One of the prettiest sights we get to see on the Catalinas after some rain. Not enough water was dumped on the mountains during our drought-denting storm to get water into the CDO Wash locally, but the Sutherland Wash developed a trickle. Just too much dry ground up there for much runoff with the relatively steady rains that we had.
12:10 PM. Small Cumulonimbus clouds erupt just north of Saddlebrooke. Thought I heard thunder from this complex later. 2:50 PM. While small Cbs developed to the north, the Cat Mountains were only able to produce Cumulus congestus (“heavy Cu”). Didn’t see any ice; neither did you, or there’s something wrong. But, if you go here (U of AZ time lapse), you WILL see some forming in the downstream portions of clouds over the Catalinas. Sometimes not seeing ice is because the tops are blowing off away from you before they show it, especially when there isn’t a lot.3:48 PM. Last gasp Cu congestus. Will highest turret form ice?3:49 PM. Ice starting to show!3:53 PM. Droplet cloud completely gone. No question now, nice ice plume. You want to target aircraft into densest portions of this ghostly veil of ice; will correlate with densest portions of liquid cloud. Not enough ice for a shaft below the cloud, but someone felt a few drops below it!
Below, one of the attributes of our partly cloudy days and low near-winter sun angle; pretty lighting:
5:19 PM.5:06 PM.3:54 PM.
The weather way ahead, first week in December.
Pile of cold air to drive into West Coast and Rockies during the first week in December. Snow even possible here, the air is that cold, but mainly the cold air will likely lead to the first cold spell where temps drop significantly below freezing. The worst days look like the 5th and 6th right now, after the threat of rain and or snow pass. So, if you have an evap cooler, you’ll definitely want to have it drained before then if you haven’t already taken care of it (like me).
Rain threat at the end of the month/first day or so in December is fading some in mods, but I refuse to give up on it!
The End.
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1Fog is “gof” spelled backwards, BTW. Has a lot of meanings and I avoided the obvious juvenile approach (today), “Think I’ll go goffing today” which I wouldn’t say anyway because I don’t play gof.
A couple of Pima County gauges reported measurable rain yesterday or overnight, but that was about it. But it was a fabulous cloud day yesterday. Heavier spotty rains, one USGS station indicating over an inch, fell in the central and northern mountains, which is good.
Below, a rehash of yesterday’s great variety of clouds.
7:48 AM. Altocumulus lenticularis clouds beyond the mountains to the SE of Catalina. Lenticular clouds indicate a stable layer of air, one resisting being pushed up, the opposite of what the slender Cu below indicated. So, an usual sky for us yesterday morning.8 AM. Towering Cumulus atop Ms. Lemmon indicated how unstable the air was just above mountain top level. Underexposed for dramatic silouhette look. The smooth top on the right would be Stratocumulus lenticularis, again an odd juxtaposition.
10:37 AM. Then you had your Altostratus mammatus/testicularis.3:08 PM. Your Cumulus mediocris topping the Catalinas with a few Altocumulus above; nice shadows and sun quilting.
3:09 PM. And you had your “weak” Cumulonimbus capillatus clouds to the north.
4:19 PM. Here’s a better shot of the Altocumulus perlucidus (here) top side.
4:33 PM. Nice example of glaciating smaller Cumulus remnant north over Saddlebrook. Likely some sprinkles reached the ground under that ice plume. As you know, takes ice to get rain in AZ.4:34 PM. More sunlight and shadow drama due to Stratocumulus and Ac perlucidus above. Was indoors socializing so didn’t see sunset. Hope it was a good one. I am beside myself thinking about how happy you were seeing all these kinds of clouds in one day!
The weather ahead
Models beginning to act quite well now. A little rain is foretold for Catalina and environs on the 21st of November, but Enviro Can make that storm look more significant and slower to move in, on the 22nd. Still two mods, both having some precip? Its all good. First, for your viewing pleasure and because it portends more rain, from Canada, this:
Valid for 5 PM, November 21st. Low and lots of rain shown banging into Cal. Would be here about 24 h later, or on the 22nd.
Also valid for 5 PM AST, November 21st, this depiction of the flow at 500 mb.
An aside: the Canadian model tends to have a westward bias, that is, a storm is foretold to be farther west a few days out than it turns out to be, something I’ve learned since becoming a forecaster yesterday (hahaha, just kidding, if anyone’s reading this far). So you have to figure the Enviro Can depiction of a trough off Frisco, Cal, is really going to be inland that bit. The US mod output shown above, has this same trough going more overland before it gets to us than the Canadian one, and so there’s less cloud water in it by the time it gets here. Root for the Canadian “solution”!
Farther down the road….more illusory water on the hot highway?
And, of course, a heavier rain is once again over Catalina and vicinity as November closes. This model really likes Catalina and SE AZ! Check it out:
We have a monthly rain total that’s not zero! But will there be more this month? Stay tuned until November 30th! (Nothing imminent.) In the meantime, a very pretty blue sky day today pocked with residual Cumulus clouds, maybe some virga. There’ll be nice cloud shadows and sun on the Catalinas again today.
In the meantime, here are the Pima Country reports for last evening’s rain. The heaviest amount seems to be at our end of the Catalinas at Pig Spring, with 0.39 inches. Nice.
Yesterday’s clouds and why
Not exactly the way they were supposed to go, the ice cloud shield WAS on the horizon to the NW at mid-day but didn’t advance over us, but rather fizzled out. That’s OK. What was left of it enhanced a spectacular sunset through the rain.
The Cumulus clouds were the stars of yesterday, doing something in the way that the old rock band, Jethro Tull used to do. The members of JT would come out on stage as roadies, fiddle around with equipment for awhile, then suddenly turn around and began playing! Oh, who can forget Jethro Tull and that Aqualung album that roiled the rock waters back in 1971 by interrupting heavy, driving rock with acoustic interludes and flute playing (!!! )? What were they thinking?
Well, our Cumulus clouds pulled a fast one, too, after hanging around, fiddling around not doing much, then blammo, here comes the ice around 4:30 PM, followed by an eruption into an honest-to-goodness Cumulonimbus cloud with a strong rain shaft, sending forks of lightning to the ground, and pea to grape-sized hail bouncing off the roof with winds gusting to over 30 mph. This spectacular happenstance was triggered by a surge of much cooler air in conjunction with the lifting of air associated with our approaching trough just above those Cumulus tops yesterday afternoon. That steepened the lapse rate; spring-loading those Cumulus clouds as it were, allowing tops to rise and still be that bit warmer than the surrounding air and stay buoyant as they rose. Here are a couple of TUS balloon soundings rendered by the Cowboys of the U of WY:
While cloud fattening and ice was expected late in the day with sprinkles and light showers, the U of AZ mod run based on 5 AM AST data was spectacular yesterday morning in foretelling this larger eruption as that cold air moved over us. But were grape-sized hail stones and LIGHTNING expected? Not only “no”, but “HELL no”.
Here’s your day, reprised below, of which the MOST IMPORTANT part was the first detection of ice, very tough yesterday, but a precursor to the rain that began to fall a few minutes later. You can also reprise your day here thanks to the U of A time lapse films. Watch what happens around 5 PM, if you can read the tiny font in the lower left hand corner.
Here is the pictorial of your cloud day below:
12:06 PM. Flatness.3:49 PM. Clouds fattening, no ice visible anywhere yet. Nice cloud street generated upwind of Pusch Ridge, floating over Catalina. Shows wind direction at cloud level is from that direction.4:01 PM. Nice cloud shadows and sun highlights moving along the Cat Mountains, too.4:34 PM. Something’s definitely happening now. Note turret protruding on the left. Clouds evolving into larger masses to the south, the cloud street having broken up. And, those massing clouds are upwind of us. Still, no ice evident.4:35 PM. Ice! I can’t believe it. Its going to rain! Can you find it? This is REALLY tough. 4:37 PM. Close up of ice. A higher top was breaking off to the NE and was converting to ice.
5:07 PM. By this time, ice had formed in cloud clusters all around Catalina, and this beauty erupted upwind.5:22 PM. About to strike with hail, lightning, wind and rain.5:35 PM. While the rain and hail weren’t done yet, it gave this colorful scene reminiscent of summer sunset color except that the sun would be setting WAY over there on the right out of view.5:40 PM. Second thunderstorm with hail in formation upwind of Catalina.
