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.
Clouds began building early yesterday on the Cat Mountains. Bases initially below Sam Ridge. It was a good sign of a possible “big day” since the lower the cloud bases initially, the more water the clouds will hold compared to a day with bases above Mt. Lemmon.
So, in our CMJ “club”, we look for that moment when clouds to begin form ice above Ms. Mt. Lemmon and her environs as the turrets climb ever higher in the morning and early afternoon sun, log it in our cloud diaries, and maybe compare to other recent days.
9:20 AM. Great portent for great rains. Clouds lining Sam (Samaniego) Ridge! 10:32 AM. Cumulus beginning shooting upward, but tops are far below ice-forming level (around 20 kft above sea level on days like this).
12″24 PM. Turret tops now have ascended to about 20 kft or so.12:28 PM. Same turret a few minutes later. Ice showing (frizzy stuff directly above second car on the road) as droplets evaporate. Unfortunately, those snowflakes, to melt into rain on the way down, have been orphaned from the updraft and are going to fall out into dry air instead of into cloudy air. Few will make it to the ground. That turret to the right has ascended even higher, therefore would be forming ice at this point, and rain to fall shortly. (From the “Not taken while driving collection, BTW). Traffic authorities remind drivers not to take a lot photos while driving.)1:25 PM. An example of the rain that fell from those higher turrets. But again, the top sheared off so that a lot of the rain fell into drier air instead of down through the root of the cloud, and so showers were pretty light.
While CMP was expecting a gigantic blow up any time after this, it only happened in one spot, a sign that the atmosphere was in a suppression mode, that is, was not helping to cluster updrafts below cloud bases yesterday. Those forces can trump great low level humidity, dammitall.
Here’s the ONE behemoth of the many that were expected, based on an eyeball assessment early yesterday:
3:46 PM. Gargantuan Cumulonimbus capillatus incus (has anvil) southwest of Marana Twin Peaks area. Instruction: Estimate 2 inches in the core fall of rain. Overshooting top, barely visible here in the middle of the anvil, indicates extra strong updrafts.7:22 PM. Nice coloration on the Cat Mountains as a cluster of disorganized Cu hover over it, dead anvil over and behind it.
The weather ahead, immediately ahead
Lots of water in the air again today, and since yesterday was a “down day”, caused by some upper level negative feature passing by (often happens AFTER a good day, like the night before last), expect an “up day” today, more showers and thunderstorms. Now, lets see if the U of AZ model says that as well, for support of this SOP (Seat of Pants) forecast…. Yep! Pretty happy right now. Go here to see the U of AZ Beowulf Cluster output for today.
Probably haven’t heard that name in a while. It kind of went along with “Old St. Nick”, “Jack Frost”, the kind of thing that we kids called things.
Well, yesterday in the land of Catalina, we had three separate thunderstorms in about 8 h, all producing nearly continuous thunder, and when you could see it, nearly continuous lightning. Oddly, there were few cloud-to-ground strokes. The lightning, too, was odd, light bulbs going off in small areas of the thundering clouds, and when visible, was a fine, often curly cue thread, seemingly one third the width of “normal” lightning. Thunder was heard at 6 PM, 11 PM, and 1 AM1 in those separate storms. Was a pretty fantastic light show, as you know, since you likely got up to watch it as I did.
All in all, while not a lot of rain fell in Catalina (one core over the Golder Ranch Bridge at Lago del Oro Parkway, presented the gauge there last night with 0.43 inches, though friend, Rick Bowers of Bowers Photo over there on Trotter said he got 0.65 inches, the most in town. Here in the Heights, just 0.24 inches. Still, its ALL good, except maybe for the flying ant swarms that are beginning to erupt.
Here’s the quickest way to look at some rainfall numbers around the region: Pima County ALERT gauges. And here fro the State, from WSI Intellicast’s rendering of radar-derived precip, usually pretty accurate.
The best way to reprise your cloud day, to make sure you logged all of them in your cloud diary, is here, courtesy of the fine University of Arizona Department of Atmospheric Meteorology time lapse film. It was so good yesterday, I put in two links to the same thing. Really is a complicated flow day, one cloud maven person has not seen before.
To wit, there were two layers of ice clouds traveling almost perpendicular to one another. Never saw that before. The height difference must have been huge. You will also notice some Altocumulus tufts at the SAME level as that
Big fat contrail leads to a “heavy” fall of ice crystals at about 9:30 AM, the aircraft flying in the lower ice clouds (where it was warmer, of course, and that means the ice content was higher than in the Cirrus clouds way up top that moved from the west). That higher amount of moisture allowed bigger ice crystals to form and fall out so obviously from the contrail.
And it was an extraordinary event for another reason: contrails aren’t supposed to form at the temperature this one did! You won’t find contrails forming at -20 to -30 C in Appleman’s famous nomogram for contrail formation. No, that’s right, you’re not supposed to get them until about -35 to -40! Could be a publication in this….
IN FACT, what happened is related to the “Hole Punch” and “Ice Canal” phenomenon2 resulting more often from aircraft flying through droplet clouds like Altocumulus, ones that are also very cold, usually colder than -15 C. So, the ground has been tread pretty heavily in this domain EXCEPT that there was NO DROPLET cloud where that strongly precipitating contrail was laid down! Could be a publication, to repeat…some “sci glory” might be down the road….)
Here’s the Tucson sounding that tells all:
The balloon sounding for Tucson yesterday morning, valid at 5 AM AST. Note reversal of winds (west at 40,000 feet or so), then from the east at 25,000 feet or so (above sea level).
Well, got WAY behind in chores following the “vacation” in WA and OR lately, so will quit here. Instead of a cloud shot, I will leave you with this public service reminder about dumping in others trash bins.
Putting stuff in other people’s dumpsters can lead to financial ruin. Don’t believe me? Read the bottom lines (see below).You’ll need a second mortgage to pay the fine! And, why don’t they just make it a million dollars…
More thundershowers on the way here as the Pac NW goes into a heat wave over the next few days. Heat? Hah! They know nothing about HEAT. If its 85 F, they think its really hot!
Forecasting tip: in the summer when the Pac NW gets hot, we’re usually wet. So, lots of great days ahead, and more visits by “Tom Thunder.”
The End.
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1Weren’t we supposed to drink Dr. Pepper at these times?
2Mr Cloud Maven person, yours truly, had his feelings hurt when his paper about his own research aircraft producing ice in clouds at below freezing temperatures, co-authored with Peter V. Hobbs, was rejected twice, but then accepted on the third try (way back in the early 1980s) and in the end, everybody was happy. You can read the whole story here. It starts out, so you can see how bad I felt, “…the reviewers are still unconvinced by these controversial claims.”
What a day, Mr. and Mrs. Catalina, except for that last second “header”:
7:57 AM. Cirrocumulus with exceptionally fine granulation (left center). You might feel a little chop if you were flying in it, but it would be hardly anything. More chop, lower right, where you have something akin to ocean waves rolling along from left to right.
8:04 AM. Pretty Cirrus fibratus (strands are pretty straight in Ci fib).4:47 PM. Pretty Cu humilis and fractus scene near the S-Brooke population complex.5:05 PM. Cu hum and fractus over the Catalinas, Nice shadow bounds the mountains I thought.
The weather way ahead, 10 days and beyond; dreaming green pixels
Rain showing up around these parts beginning overnight on July 3rd-4th, kind of a normal time for a summer rain season onset. This from last evening’s global model crunch. Prior model runs have been dry, so it could be bogus, of course. But, its a hopeful sign. Rains every day after that in this run. Below, the titillating start as rendered by IPS MeteoStar:
Valid at 5 AM AST July 4th. Green areas show those ones where the model has calculated some rain in the prior 12 h.Valid at 5 PM AST July 8th. Raining all over Arizona by this time. How great would that be? Com’on model! Don’t let me down! A feel a really old song coming on about being let down.
Let’s look at some spaghetti and see if the “solution” above has any credibility at all:
Valid at 5 PM July 4th. Note gaps in red lines in Arizona and NM. Errorful mod runs (deliberately so, recall) are therefore pretty confident the necessary ridge of high pressure aloft WILL be centered just to the north of us at this time, extruding all the way from the central Atlantic. So, there is a fair amount of confidence from spaghetti that the summer rain season will start pretty much on time. What’s also supportive is the bulge in the jet stream to the north in southern Canada, as indicated by the bunching of those bluish lines. Pac NW looks cool and rainy with this pattern, BTW. You can enjoy more spaghetti here.
So, right or wrong, you heard it here first because I got up early; summer rain season looks to start on time.
In case you didn’t notice, there was a prolonged street of clouds emanating from possibly as far away as Kit Peak, or maybe just the Tucson Mountains. Lasted for a few hours.Happens only on days with relatively shallow clouds (cloud-topped boundary layer) with a little wind, meaning that the thermals from the surface heating ended up being capped by an inversion or other stable layer, and those thermals form clouds in some places. In this case, a long line of intermittent clouds formed from an initial air bump caused by those mountains far to the SW of us. CTBL is more often invoked as a term by cloud folks when the sky is much cloudier in low clouds than these shots from two days ago, such as when the sky is covered in Stratocumulus clouds.
These kinds of streets occur over the same places whenever a day like this comes along. Think of it, especially here in Arizona, as a row of shady air under which you might like to live compared to those areas on either side of this cloud “street.” In Seattle, where the “cloud topped boundary layer” is almost a daily occurrence, you want to avoid being under the cloud street, where it can block the sun, and instead find the clearer slots!
12:14 PM.1:07 PM.3:19 PM. Barely hanging on now, but still present. Dissipated within about a half hour of this shot.
TUS rawin for June 18th, 5 PM AST (launched about an hour and a half before that).
For those sharpies that day and logged in their cloud diaries that ice formed in those shallow Cumulus clouds, they will be a little chagrined by this TUS sounding. This sounding suggests the clouds around the balloon were topping at -8 C, too warm for ice formation in shallow Cu. Let us begin to explain this puzzle by presenting evidence of ice formation in those clouds on the 18th:
4:13 PM. Virga hangs down from Cu mediocris, maybe only a km thick toward Charouleau Gap. Lots of ice visible.
4:13 PM. Overhead view of likely ice vellum between Cumulus clouds. The clouds themselves may well have a few ice crystals, but too few to provide any visual indication except in the clearings between them. Ice crystals evaporate more slowly than liquid drops when encountering sub-saturated air between clouds, and so can be visible a bit longer if present between clouds in marginal situations like this. Confidence level that this little patch is ice and not just haze is about 70-80 percent.
Simple answer to our connundrum; due to lifting of the air as it approached and went over the Catalina Mountains, the tops of the clouds reached those temperature below -10 C where is begins to form. We would guess even closer to -15 C in that cloud in the distance beyond Charouleau Gap due to the amount of ice. Ice increases with decreasing cloud top temperature, but the temperature at which ice onsets can change on a daily basis; higher onset of ice temperatures on days in which the clouds have larger drops in their tops (a phenomenon originally reported by Ludlam in 1952, then re-discovered by Rangno and Hobbs (1988) who did not, at that time, know of the Ludlam finding, and thus, did not cite it. Pretty embarrassing, really. Was cited later in an update, however.
The weather way ahead
Seasonal rains beginning to show up in southern Arizona now on models beginning around the 4th of July as a big anti-cyclone parks itself over the Four Corners area in the latest model run from 11 PM AST last night. Very excellent run.
Began at 1:15 PM, ended at 1:40 PM. Then, a second round at 3:58 PM. Nothing more on tap today through June. Thought, too, since there’s been a lot of talk about the Southwest monsoon lately in the media, we’d check on that and see how its doing:
This as of June 15-17th (green lines, red lines are normal position. Things are not so good, seems to be running a week to two weeks behind schedule.
Hmmm. Not so well so far. Is this being impacted by the developing El Nino? Our summer rain season, more often than not, has been disappointing as well in El Nino summers. An El Nino is in formation as you likely know.
Your cloud day yesterday, in thumbnails:
A better way would be to go to our University of Arizona time lapse movie here.
5:55 AM. Now I didn’t mention yesterday because I didn’t want you to feel bad, but these crepuscular (aka, “crepsucular”) rays were due to a lot of smog in those clouds yesterday morning. Got mixed out as the day progressed. Likely, from tropical Mexico based on trajectories at cloud base level.5:55 AM. More smog and clouds, some virga. Ugh.6:18 AM. Could be called, I think, Altocumulus castellanus or Cumulus due to the large size of the elements. However, they are not Cumulus arising from warm air near the ground, but rather from the gentle lifting of the air over the Catalina Mountains.6:20 AM. One of the remarkably small, sprinkling clouds that passed over yesterday. To get rain to the ground from about 11, 000 feet there would have to have been graupel (small, soft hail) forming in those little guys. Single ice crystals, or fluffy flakes would never had made it all that way since they would have dried up. Think of how great it would have been for you to non-chalantly, in your morning walk with neighbors yesterday, to have dropped the bombshell that, “Must be hail, soft hail, up there in those clouds for rain to fall on us from so high up.” You can see your neighbors’ jaws dropping in disbelief at that point! But you would then be some kind cloud hero to them, never to be seen the same way again. You wouldn’t say anything more about it; you’d made your point, succinctly I might add, and they’d likely get bored hearing anymore about it. Its best to let them just think about it the rest of the day.
Afternoon…..
12:53 PM. Promising Cumulus congestus are forming over the Catalinas, some already spewing a little ice. Here, about 2 km thick, or something around 6,000-7,000 feet thick, tops already about -10 to -15 C.1:15 PM. Taken just after first thunder heard from this modest Cumulonimbus. Not much shafting yesterday at all, suggesting weak updrafts and modest condensed water in them. No cloud to ground strikes were observed, and the time between thunder was a few minutes, all adding up to marginal conditions for thunderstorms near us, anyway.1:15 PM. One of the signature shots for this website, added to the “cloud base” collection. Here, graupel strands are just barely dectable as they begin fall out.
1:37 PM. Just before the last thunder, this icy top to a cell approaching Mt. Lemmon. Since the transition to all or mostly ice has occurred, this Cumulonimbus would be termed a “calvus.” The outward transition to all ice happens very rapidly, just in a few minutes, kind of an exciting thing to see!1:37 PM. Here’s what the bottom of that top looked like. No major shaft yet, but there will be but out of view.4:02 PM. Second round of occasional thunder in progress. Nice to see a little rain on the Ridge (Samaniego).7:31 PM. After all the excitement, we were left with little rows of Altocumulus perlucidus to celebrate a great day of cloud scenery.
I think ordinary weather, if a bit of a surprise, needs more shouting! Sincerely, Cloud Maven Person!1
A trace of rain has built up here in Catalina in the pre-sunrise hours today, adding to the month’s total that has been received so far, also a trace.
Wow! This was not foreseen, these little sprinkles. Latest NWS forecast for Catalina is “sunny”, no mention of clouds or sprinkles. CMP, too. Wasn’t thinking that the little stream of moisture passing over us would amount to anything but Ac clouds. See U of AZ satellite imagery here to see stream; not a “river”, maybe just a “creek.”
5:31 AM: Moving ahead! Looks like we’re at the end of the sprinkle clouds, don’t see much upwind. BTW, could you see the clouds that produced the sprinkle? Not as easy as you think. You see, the wind is stronger, much stronger where those clouds are up there, and the rain that falls out trails behind them. So you have to look downwind a mile or two to see the clouds what done it! (ANOTHER few drops here at 5:37 AM!) Three sprinkles now! Those drops must be like HUGE water balloons to those ants out there on the pavement!
Here’s what those sprinkle clouds look like, the ones you missed while you were snoozing, but, as usual CMP is there for you:
5:37 AM. Its raining on the camera. See ice coming out, upper center, slightly to the left? That’s what done the last few drops. But now the cloud that done it is a couple of miles downwind. The earlier sprinkle-causer, is the cloud now beyond Charouleau Gap to the NE.
This morning’s Tucson balloon sounding. Shows bases at 600 mb (14,00 feet above sea level), tops at 20,000 feet, and about -15 C, cold enough for plenty of ice.
Below, the same sounding without arrows:
End of rain chances now, darn, looking at withering clouds. (Last sprinkle, hardly noticeably unless you were outside, 7:20 AM, from an remarkably small cloud, ice not really apparent).
(Interrupted by having to get a flat fixed; Philips head screw in it.)
Yesterday’s clouds
Yesterday was a great day to once again test your ice acumen. Here are examples of only those clouds exhibiting ice except that fat Cu over Pusch Ridge, a pic I took during BP2 at James Kreigh Park with ballplaying friend, Patrick.
6:54 AM. Altocumulus. How’s your ice acumen? Never forget how important ice acumen is! Estimate concentrations and cloud top temperature.
1:10 PM. New kind of cloud. Test your ice acumen: Any sign that ice is ice being produced in these clouds? Never forget how important your ice acumen is, repeated in case you skipped over the last caption!
1:56 PM. If you can find the ice here, you will be awarded an honorary doctorate in cloud maven-ness.
2:36 PM, 101 F, at James Kriegh Park, next to CDO HS, this fat little Cu mediocris over Pusch Ridge, as batting practice gets underway. Batting for CMP was “mediocris.” Lefty Patrick hits the ball over those trees from time to time. (This is baseball, not softy ball, we’re talkin’ ’bout.)
Seems U of AZ mod sees this little moist street over us as able to generate Cumulus and isolated small Cumulonimbus clouds this afternoon. Very nice.
The End.
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1Where would Yahoo be today without that “!”?
2It was 101 F during our 2 h session that began at 2:30 PM. Note to baseball people: the ball goes farther when you hit it when the air is less dense. The air is LESS dense when it is HOT, AND when their is moisture in the air (unless the baseball you’re using is hygroscopic, in which case it might absorb water vapor and get that bit heavier and not go as far. So, its great to practice when its above 100 F!
7:35 PM. Curtains of ice droop down from heavy patches of Cirrus spissatus producing an outstanding sunset last evening. Hope you saw it. What kind of ice? Likely “bullet rosette” ice crystals are the ones falling out.The complex ice crystal called a “bullet rosette” for some reason as imaged at 130 mph by an instrument (Cloud Particle Imager) on the University of Washington’s research aircraft high over Barrow, AK. These were at the bottom of Altostratus (thick ice) clouds around 23, 000 feet above sea level. Tops were about 32,000 feet, and was thick enough to produce a gray overcast. The CPI was designed and built by Paul Lawson, a friend who was a starting defensive back on the Michigan State Spartan’s National Champion fubbal team of 1966 or 1967. He formed, and is still the CEO, of Stratton Park Engineering Company, one that makes a lot of high end instrumentation for imaging cloud particles. Likes to meditate, too; just kind of sits there for hours on end like a piece of pottery. I don’t get it. Maybe its related to concussions he might have gotten.
Action shot of the University of Washington Convair-580 research aircraft in flight, in case you wanted to see that. My job was to stand on a little stool (hmmmm, that doesn’t sound right) so my head would be high enough and fit in that little dome and say things about clouds, which as here, was usually too much. Pretty cool, eh?
Wasting time here, filling in with filler material1 since there’s no real chance of rain, though, as usual, pretty clouds and maybe some real nice sunrises llike this morning’s and sunsets. That’s OK. We’ll get by until the Big Boys arrive, those Cumulonimbus clouds of summer, with all their splendor and drama. As reported in the media, a better than average rain season is being foretold by the Climate Prediction Center. How nice is that?
Small Cu today, maybe a CB top way off toward the S or SE…. Have some nice Altocu now, splattered around. No rain in WRF-GFS hereabouts for two weeks, but, as we know over and over again, they can be VERY wrong in that longer view!
The End.
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1Remember when newspapers had “fillers”, interesting little facts punctuating the pages where the columns and such left little spaces after being laid out? They had some fascinating material in them, such as that a certain spider’s web strand, if the diameter of a garden hose, could support TWO 747 jets! (True!)
As the day rolled forward in time as they do pretty consistently, I was really happy for you having so many things to log in your cloud diary and maybe report to neighbors who might not have been so observant as you yesterday; the various types of clouds you saw, fun dust devils here and there spinning their way across Catalina, Cumulus clouds, a couple of which grew into Cumulonimbus clouds, and even produced a thunderstorm way over there in Safford. You could see that one from here, too. And there was a spectacular chances for you to test your ice-in-clouds acuity score.
Let’s go over yesterday’s clouds and make sure you got them right; but remember, don’t feel bad if you missed something. Cloud maven person will always understand and forgive those who might call a cloud by its wrong name. Believe or not, even CMP has done so1.
10:56 AM. Altocumulus lenticularis patches underlain by a tufts of Altocumulus castellanus.11:51 AM. Mostly Altocumulus castellanus and floccus (no firm base, just a tuft). CMP’s cloud chart points out that rain might follow in 6 to 196 h when this form of cloud is observed. It indicates strong instability at this cloud level.11:53 AM. Fun dust devil goes across Catalina. No jumping castles were harmed. CMP used to jump in dust devils when he was kid when they came across the school yard at playtime. Maybe you did, too.1:17 PM. Small Cumulus (humilis) begin erupting over the Catalinas. Portent: moderate.1:54 PM. Cumulus fractus over Saddlebrooke and points NW. Not much going on in the high mountains, either, (as would be seen by tops of Cumulonimbus clouds) suggesting a dividing line in the moist plume over us; drier to the north, more moist to the south.2:24 PM. “Wow!”, you thought, if I may interject one for you that you should have had yesterday viewing this cloud. The real look of our summer rain season (aka, “monsoon”), a tall, thin Cumulus congestus cloud.2:24 PM. And at the same time, a Cumulonimbus capillatus incus (icy anvil) has formed over there toward Safford! Now summer’s on! Safford reported a thunderstorm about this time.2:54 PM. We really haven’t had an Cloud Maven Junior (CMJ) ice IQ test in quite awhile, and so I thought would give you a little surprise quiz today in the following photographic sequence. Here we see, while not driving I might add, that would be crazy, to add that bit more, we see a protrusion from a Cumulus congestus cloud. Will it turn to ice? And if it did, when exactly did you know that?2:57 PM. Ice in the top tuft yet? You have 10 seconds to come up with an answer.2:59 PM. “You are so ice!” Cloud Maven Person got quite excited and has made a call for you, prematurely. See how the finer detail has started to disappear as the droplets evaporate and the slower evaporating ice (in much lower concentrations) begins to dominate the appearance of the little tuft. Compare the newer tuft on the right and its ruffled appearance to the little, detached tuft on the left. In the one of the right, the much higher concentrations of droplets still dominate providing all kinds of visual detail, though ice would undoubtedly be present inside it and about to take over.
3:04 PM. Secret’s out! The little tuft shows its ice. Poor guy has no droplets any more, is just a defunct ice cloud on its way to evapo-oblivion. Note icy fallout from the trunk of the original cloud now. And, you now know that those sharply outlined turrets in the center of the photo have a ton of ice in them, though droplets are also present (soon to be gone as in our icy little remnant to the left).
The End
No further weather ahead of any interest to a CMJ, anyway. Darn.
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1As a kid, I think I once called an Altostratus translucidus an “opacus.” It was pretty embarrassing.
5:30 AM. Altocumulus opacus virgae. TUS sounding indicates the highest tops were about -13 C (9 F), just about where ice would be forming in concentrations of a few per liter, which is likely what the concentrations are in the virga shown in this photo. The thickest portions of the Altocumulus were about 3,000 feet (1 km). In the upper portions of those clouds, droplet sizes would be the largest since that’s where they have been lifted to the highest level. The larger the drops, the higher the temperature at which ice onsets in them. Lenticular clouds, marked by mainly laminar flow, not vertical flow as in these Altocumulus clouds, would NEVER form ice at -13 C since the drops remain extremely small, as an interesting extra note for you.6:30 PM, exactly 12 h later… Nice example of Altocumulus castellanus, no virga or ice visible. Estimated height above the ground, 12,000 feet. Sounding says tops were warmer that -5 C, too warm for ice crystals to form. The highest temperature at which natural ice has formed in clouds is about – 4 C, but those clouds always have drizzle or rain drops that can freeze at this highest temperature. Our clouds, except in summer on a few days with extra “warm” cloud bases (greater than about 10 C, 50 F), do not have drizzle or rain drops in them before reaching the -4 C level.
Today’s clouds
“Dewpoints up!”, akin to “surf’s up!” as said by surfers to one another. 52 F dewpoint here in Catalina, generally, 40s to low 50s throughout southern AZ now. So, we have a good chance for some decent Cumulus and small Cumulonimbus clouds around in the middle of this afternoon and evening. Bases will still be way up there, 14-15 kft above the ground and near the freezing level, so rain at the ground can’t be much, and coverage will be minimal.
Dries out tomorrow, too, so today’s our only hope for a while for rain in the area.
Interaction between Little Crissy Hurricane and the westerlies continues to disappoint as Little Crissy’s moist plume is carried to the south and east of Arizona. There is some indication that that a residual, barely alive low level circulation, as it completely dissipates off Baja around the 19th, might still result in a surge of moist air as a new upper trough moves into the interior of the SW then. More wishful thinking?
Blobs of sprinkle clouds pummeled Catalina yesterday beginning soon after 12 Noon and ending only after 7 PM when an extraordinarily rare “Geo-Astro Meteo Conjunction” (GAMC) was observed due the conjunction of a rainbow, a moonrise exactly over Mt Lemmon, and the top of Mt. Lemmon itself visible through rain. The GAMC “trifecta” scene, is thought to occur only once every several hundred years. The duration of yesterday’s scene was about 3 minutes, the cloud with the rainbow having produced a sprinkle here just prior to the rare scene. Only more rare than the GAMC is a sunrise exactly over the crest of Mt. Lemmon with a rainbow in the direction of the sun.
Three sprinkle periods were recorded yesterday, the longest between 5:43 and 5:45 PM. The others occurred at 12:28-12:29 PM, and 7:26 to 7:27 PM. The rain brought June’s monthly total to a trace, ending the prospect of a completely rainless month.
No accidents were reported due to excited motorists reveling in the “rain” on their windshields, having attention diverted from driving. Local meteorologists explained that higher dewpoints than expected allowed a few drops to reach the ground instead of evaporating completely from the high-level virga that had been forecast earlier. The higher dewpoints allowed cloud bases from which the virga fell, to be 100 millibars, or about 4,000 feet, lower than computer models had predicted. The meteorologists blamed a lack of data far upwind of Catalina for the forecast gaffe.
Below, a rare GAMC, one that you will like not see in your lifetime if you did not see it yesterday:
7:28:26: A truly rare GMAC scene develops toward Mt. Lemmon (the subtle, rounded hump below the moon). This scene can only occur with the rain and sun in proper positions to produce an arc of a rainbow framing Mt. Lemmon, but the rain must be light enough so that neither the moon nor Mt. Lemmon are obscured in any way. Yours, today only, for $1,000,000.
Moving on…..yesterday’s clouds
6:33 AM. Pretty Altocumulus, fatter version of “perlucidus.” Didn’t look to be as interesting a day as it turned out to be. This layer was about 12,000 feet above the ground.12:38 PM. Some Cumulus begin forming underneath the sprinkle clouds (ice/virga visible on the bottoms of the Altocumulus clouds on the left–that made the bottom smooth.)1:17 PM. Gorgeous example of Altocumulus castellanus and floccu (no ice/virga).
5:30 PM. Cloud complex of the day, loaded with sprinkles, CMJs were predicting that sprinkles, and ONLY sprinkles, were about 5-10 min away.5:46 PM. Following the sprinkle, eyes should almost automatically turn to the east for a some rainbow eye candy.7:37 PM. The pretty cloud day closed out with a satisfying sunset.
The weather ahead
Today looks like it will be pretty much like yesterday, lots of mid-level clouds cold enough for virga, as you can see out there right now (just after sunrise), supplemented by afternoon Cumulus. Altogether another pretty day with reasonable temperatures held down by clouds and virga around. We’re on the edge of this mid-level moist plume coming up out of the Tropics, BTW. Rain is foretold by the quite wonderful U of AZ Beowulf Cluster calculator to only fall in the SE corner of the State today. This from last evening’s 11 PM AST data.
The later model runs have had potent Hurricane Crissy’s moist plume missing us to the east now, so don’t really want to talk about it. Winds in Cristina now 145 mph sustained as it rapidly intensified from yesterday’s 75 mph. Should mean good surf along the west coast of Mexico and a certain south-facing southern California beach haunt of CMP, called, “Zuma Beach”, where the acclaimed dramatic series, “Baywatch” was first filmed.
