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.
Looks pretty good…. Two completely different computer models show tropical moisture getting into Arizona in about 5-6 days a resulting preview of the summer rain season. You can find quite a bit of “green pixies” (areas of rain denoted by areas of green pixels) in Arizona here from IPS Meteostar’s rendition of our best model, the WRF-GFS. And, the Smoking Canadians have rain in our area in their model, too. This is going to be the best chance for measurable rain in Catalina since early April!
In the US model linked to above, you can also see the residual low pressure center from today’s Hurricane “Crissy” moving up the coast of Baja Cal in five days. Finally, could we have a month with above normal rain after not having one since November 2013 (or was it 2012?) Might happen, after all we deserve it. So, I will now predict that June will be above normal in rain in Catalina, AZ.
You can keep track of Crissy here. I will be tracking Crissy, that’s for sure.
Below, an example of rain (with drizzle) in case you’ve forgotten what it looks like in a research aircraft with laser beam imagery of all the stuff you’re flying through:
Rain (and drizzle drops) as seen by aircraft instrumentation, arranged in order of small to larger, left to right. The horizontal lines are just about a millimeter apart, so the biggest drops here, one that aren’t breaking up, are about two millimeters in diameter. Drizzle drops, as CMJs know, are those between 0.2 to 0.5 millimeters in diameter, so there are a lot of those. BTW, these were collected while the aircraft was flying at about 160 knots (80 meters per second). Pretty amazing you can image these drops as they go by so fast!
The discerning reader will want to know what spaghetti sez; what are the chances that the steering winds in the middle of the troposphere will steer Crissy toward us as it moves around off’n Mexico. Will those steering winds help Crissy’s moisture get into Arizona and over Catalina?
We seek help from spaghetti and, indeed, the spaghetti shown below is “supportive”, that is, it shows that the “planets are lining up” for rain here, as an astrologer might say, those people we look to for personal guidance in everyday matters; whose forecasts are so important no newspaper can go without them without causing an uproar on the part of their readers.
See writing on figure below for some additional weather interpretation.
Valid for 5 PM AST June 16th. Those red lines suggest that Crissy’s remains (RIP) might indeed be directed at eastern Arizona! Big trough for this time of year foretold along West Coast with high confidence, as indicated by “bunching lines”, perfect for drawing tropical storms northward into the Southwest US. If not us, then those dry areas of New Mexico and west Texas virtually guaranteed for some tropical air.
Yesterday’s clouds
10:53 AM. Mostly Cirrus uncinus, bisected by a contrail.2:38 PM. Cumulus humilis and fractus boiled up out of 100 F plus air at the surface. Tops warmer than -10 C, so no ice, just those thin patches of Cirrus on top.3:08 PM. Cirrocumulus atop Cumulus fractus clouds.
Nice Altocumulus around this morning, but moisture is really confined to that level, not deep enough for rain at the ground. The Cumulus that form this afternoon will have bases around 14,000 to 15,000 feet above the ground. They should be deeper than yesterday, and so ice is likely to form in the larger ones (and we hope that you will log that in your daily cloud diary), but only tantalizing virga is likely, maybe with some brief windy periods near them.
Here you go, the cool season (October through May, 2013-14) rainfall for Catalina, such as it was, updated from 1977-78:
I’ve added a historical note about Biosphere 2, gleaned from one of the tour guides up there. Of course, the full story, one of idealism thwarted by love, jealousy, murder, and ultimately, cannibalism, will likely never be told. Not everyone came out intact. Note, too, that MUCH drier winters than this past one occurred at and just after the turn of the century, which is pretty astounding.
The weather ahead
Nothing in sight, except some interesting high and maybe middle clouds from the deep Tropics in a few days.
Pinching the old Consumer Reports segment, “Quotes without Comment” page from decades ago, for a title. But after that title, I changed my mind and will write a coupla captions.
What drought? This gigantic weed popped up in the middle of an agave plant recently. Spurted up about two feet a day in the backyard! Proabably some kind of wild asparagus. Must be over-watering this year since it sure as hell didn’t come up last year. Wonder if its edible? Cirrus clouds form the backdrop.
Sunset.Morning Cirrus.Cirrus patch trying to be Altocumulus perlucidus, but way too cold for that, its all ice, not liquid at all as an Ac per would be. Sounding indicates our CIrrus clouds are between 35 and 40 KFT above sea level, temps up there between -40 (also -40 F) and -50 C. So, cold air is fairly close by, only a few miles away really.Hot dog. Bubba wanted to go out of the cool confines of the house, and I wanted to stay in to see what the little guy wanted to do, and why, when its 104 F outside. He chose a place on the boiling cement IN the sun, quite happy it seemed, until I brought him in after about TWENTY minutes! Almost as amazing as having a wild asparagus shoot up 40 feet in your backyard for no reason except maybe over-watering.Monster trying to grab something.Sunset (last evening’s).
The weather ahead
Wish it could tell you there was some rain ahead, maybe tomorrow, but…I’d be lying again as I do from time to time. Nothing in sight.
Meteorologists have called stagnant pressure conditions with inflated temperatures “stagflation” for as long as I can remember, which is not that long. Anyway, that’s what we have before us, pretty much the same old thing, day after day, except for some really nice Cirrus patterns in the sky to go with those 100-110 F temperatures we get this time of year. You can see the upper level moisture stream coming over us here, from the Huskies, if you’re interested.
Mind-starting to drift off center now….
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Weather extreme note
If you noted the record-tying “trace” of rain at Vegas back on the 25th and were pretty happy about it, well, you’re going to be put out by this NWS message, passed along by climate guru and mischief maker, Mark Albright, just yesterday. Apparently, the NWS has been concerned over this record tying event for some time:
“RECORD EVENT REPORT…CORRECTED
NATIONAL WEATHER SERVICE LAS VEGAS, NV
1059 PM PDT THU MAY 29 2014
…NO RECORD DAILY MAXIMUM PRECIPITATION WAS TIED AT LAS VEGAS SUNDAY...
DUE TO AN EQUIPMENT ISSUE WITH THE PRESENT WEATHER SENSOR AT THE
MCCARRAN INTERNATIONAL AIRPORT ASOS, A FALSE REPORT OF A TRACE OF
PRECIPITATION WAS REPORTED ON SUNDAY, MAY 25TH. AFTER FURTHER
INVESTIGATION, THIS WAS DETERMINED TO BE INCORRECT. THEREFORE THE FINAL PRECIPITATION TOTAL FOR SUNDAY, MAY 25TH, IS 0.00 INCH AND THE DAILY PRECIPITATION RECORD WAS NOT TIED.
THE ABOVE INFORMATION IS PRELIMINARY AND IS SUBJECT TO A FINAL
REVIEW BEFORE BEING CERTIFIED BY THE NATIONAL CLIMATIC DATA CENTER.
$$”
Hope I didn’t spoil your morning.
On the other hand, you wonder what the NWS meant, “after further investigation…”? What might they have done to remove an extreme weather event, one that tied a record?
Let’s “jump in” and see what we can find out about this record-tying mystery. First, let’s pull up radar-derived precip maps for May 25th and May 26th and see if there is any chance it rained on the 25th. We have to do two maps since the end time of each radar precip map is for the 24 h period ending at 5 AM, whilst the record is for midnight to midnight of the 25th. Below, from WSI Intellicast are those two 5 AM AST maps in chronological order:
:
We can see that it DID rain in the 24 h ending at 5 AM AST on the 25th at McCarran Field, LAS, but not AFTER 5 AM ending on the 26th (map on the right.
But when did the weather observing machine think it rained?
By pulling up the hourly observations in text form below, we can see that the machine thought that rain began at 1519 Central Universal Time (8:19 AM AST) and rained for 11 minutes, ending at 1530 CUT. “RAB” means “rain began, truncated to minutes after the hour).
Looking further, we can also see the text words “SCT” and “CLR” for the time periods in which rain was reported. Furthermore, the the “numbol”, “>120” , means no clouds below 12, 000 feet above ground level.
Can it rain to the ground from clouds higher than 12,000 feet above the ground? Its fairly rare, but it happens, as we Arizona sunbirds know from just the past couple of days when sprinkles fell from such clouds.
However, investigating even farther, we find that the machine is also indicating “CLR” or “SCT” conditions, meaning CLEAR or SCATTERED clouds above 12,000 feet.
Can it rain from CLEAR skies, too few clouds for the sensor to detect overhead? Or SCT skies? It has happened that the machine reports SCT conditions on a RARE occasion when a little Cumulonimbus is passing overhead. I think it was reported from Douglas last summer; thunder, too. Very odd, but not impossible.
But what we don’t see is any “VCRA” report, that is, the coding for “rain in the vicinity” that would be inserted next to the column of “10s” above if there had been any as detected by radar.
So, after a few hours of investigation, we have absolved the NWS of having improperly removed an extreme weather event: the trace of rain was, in FACT, erroneously reported from the McCarran Field weather observing machine.
(Actually the point of this rather tortured writeup is to expose you to a little of our weather reporting language called, METAR. You can read about it here pretty good. You can get those METAR reports from many places, here’s one.
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A hodge-podge of cloud scenes from the recent trace of rain rainy day
(Counted over 100 drops on a wide area of pavement during the many, many sprinkle episodes two days ago; each one, I noticed, dried up in about two seconds, too.)
BTT you read this, rain oughta be falling or near by as the remnants of ‘Manda hurricane dribble into Arizona today. Looks like there’s just enough rain upstream right now (4 AM) to produce, hold your breath, a MEASURABLE amount here in Catalina! Likely will be just a few hundredths, though, as much as two tenths is about the top potential from this. At this point, anything measurable is a fabulous rain!
Mods have been oscillating on whether it would rain here for many days, but last night’s run ended pleasantly with a “correct” forecast of measurable rain. See green pixelation over Catalina below:
Valid for 11 AM AST today. Heart of rainband over us then, mod says. From IPS MeteoStar.
Your Catalina cloud day
(Also, another great cloud movie from the U of AZ here....)
5:15 AM. Cirrus, leaning toward “spissatus”, heavy dense patchy Cirrus.7:42 AM. Cirrus fibratus/uncinus. “Cirrus” will do it.
4:35 PM. What would a day be like without Altostratus? Here, “translucidus” because the sun’s position is visible. When the sun can’t be seen, its “opacus”, like a lot of science can be.
5:27 PM. Walkin’ doggie and this seemed like a nice shot of the rustic neighborhood streets, the Catalinas, and up top, some glaciating Altocumulus, castellanus on the right side; hasn’t gone through the ice forming stage yet, or the ice hasn’t fallen out that’s in it.
7:18 PM, Crepuscular rays show up as the sun sets due to smoke and haze under the clouds. The clouds? A mix of flakes of Altocumulus and Altostratus (the solid blob), some Cirrus on top of it all.
The weather way ahead…
Valid for June 12, 5 PM AST. Not a lot showing up here for mid-June weather, so won’t say anything about that. I suspect it will be warm, though.
7:09 PM. No visible sunspots on the “moon” either. Did you know that a long absence of sunspots, such as in the Maunder Minimum, was coincident with cold weather, such as that during the Little Ice Age, (though only a part of it)? A widely accepted causal relationship between sunspot activity and climate has not been established and findings of such relationships are usually considered controversial.
The tropical fetch coming to Catalina (shown here yesterday) is from the remains of now strong hurricane Amanda, unusually strong for May for that matter, a month in which tropical storms in the Mexican Pacific are pretty rare, let alone have a Category 4 hurricane down there. Has sustained winds of 140 mph now, BTW.
When pointing out the tropical finches yesterday, was not aware that the low down there was, in fact, a hurricane. (Maybe I shouldn’t point things like that out, causing the one reader to lose confidence…. Too late now.) Check out this loop from the U of WA for the “pinhole” signature of strong hurricanes. Really happy to report that rain is on the way as May closes out (29th-31st are best chances for rain here).
Reprising yesterday’s cloud day…
1) Your day began with sprinkles from a cloud deck based at around 12, 000 feet above ground level (remember, too, that you can skip the “added value”, incremental approach below by just going to your great U of AZ time lapse movie. I thought it was really very pretty for yesterday):
5:32 AM. RW– (very light rainshowers) were falling from what could be called a Altocumulus opacus deck with scattered taller turrets embedded in it, ones that produced the sprinkles.
2) clearing from the north:
6:24 AM. The shallow nature of most of the Ac deck is apparent as the backedge moves toward Catalina.
3) once the clearing arrived, small Cumulus began developing on the Cat Mountains and “?”:
9:36 AM. I have no idea. Move along now to the next photo.
4) nice small Cumulus all around, sometimes filling in to make it seem like a Seattle day in spring, with patches of Cirrus on top:
10:16 AM. Cumulus humilis and fractus (those shreds) and that beautiful Cirrus seemingly spreading its icy arms out (spreading likely due to perspective).
5) Was there artwork in the sky? You bet. A niche developed here I immodestly remind you, is that of cloud bottom photography, something I enjoy, and I think you do, too. Below is one of the best ones of the day from the Cloud Bottoms Collection:
10:16 AM. Bottom of Cumulus humilis, maybe mediocris even, that was over ME. You look up, wondering, how deep is it? Will it form ice and rain on ME? Maybe graupel will fall out….since those are the first particles out the bottom of a growing Cumulus that is transitioning to a Cumulonimbus… So much to think about when a bottom is over you. Yours for $1,800, if you call now.
6) Late morning fill in:
11:23 AM. Cumulus and Stratocumulus dominated the sky for a time; looked threatening, but no frizzy ice seen around the edges. No ice; no precip or virga. Pretty, though, with those shadows and sun breaks on the Cat Mountains
7) Smoky sunset (not a western singer, though it would be a good name for one):
7:06 PM. Drifted down from the north. Likely hours old, judging by the striations in it (not well mixed out and homogeneous as would be smoke that’s days old). Could not find source in satellite imagery right off. I see that some of that layer is still visible to the SW this morning.
The End.
5)
6) Wildfire smoke drifts down in a thin layer from the N to spoil our sunset. Note the reddish orange sun, a good sign of smoke and smog particles, tiny ones (typically, if you really want to know, that are 0.01 to 0.1 microns in size) that eviscerate the shorter wavelengths of sunlight so that only the reddish ones get through.
Flash: Very light rain (R–) falling at 5:30 AM! Amazing… Won’t measure though, as thickest clouds are already sliding away. But still, great to see, to smell the scent of rain in the desert, and feel the drops in this little surprise sprinkle!
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Forgetting about that last big bust, namely the last big trough of the season that let us down by producing no measurable rain, let us now consider tropical finches, or rather, FETCHES, since an example is coming soon, one that might well bring rain. (I know what you’re thinking; you’ve heard that before, wrongly, I might add as in the LBT-LBB). Hope springs eternal I guess, though rain is predicted by both the USA and Canadian models, so there is some mathematical backing to this hope. See below, as rendered by IPS MeteoStar:
Green pixelation approaches Tucson-Catalina urban complex on Friday, May 29th at 5 PM,
5:59 AM. Virga falls from Altocumulus opacus. This can also be seen as like a little slice of the tops of many rainy days when cloud tops aren’t below about -30 C or so. As here, those tops are usually still comprised of mostly liquid droplet clouds in which ice crystals form, grow, and fallout. If the air is not rising to replenish the doplet clouds, then you will be left with a patch of ice and virga, a patch that will eventually die. Estimated top temperatures, -12 to -15 C, a little colder than shown on the TUS sounding for yesterday near this time because we are farther into the cold air aloft than TUS is. Also, it would be unlikely that clouds like these would produce ice at the indicated TUS balloon sounding top of Altocumulus at -11 C. With their geerally small droplets, it needs to be colder than that. Egad! This is way too much info! But what kind of ice crystals would you expect in a water-saturated enviroment at around -13 to -15 C? Yes, that’s right, pretty Christmas tree stellar crystals, maybe some aggregates of dendrites. Remember, too, for aggregattes to form that concentrations of the crystals must be more than about 1 per liter. Too, since they are falling through a droplet cloud with droplets larger than 10 microns in diameter, you would expect those stellar crystals and aggregates of dendrites to exhibit some riming, that is, have impacted some of the cloud drops as they grew and fell through the cloud, though keeping in mind that the crystals must attain a diameter of about 200-300 microns in diameter before riming commences, helped by the fact that stellar crystals (planar ones) fall face down like a clown does when he’s trying to make people laugh and trips over something. Also, I think someone in that big house on the right is about to have a baby.9:40 AM. With all the cool air over us, it wasn’t long before Cumulonimbus clouds began boiling upward, giving someone some rain.9:53 AM. While Cu boiled up quickly on the Catalina Moutains, and iced-out a plenty, they never really got the depth required to produce much more than sprinkles and virga. Can you spot the little bit of ice on the right side of this Cumulus mediocris?10:30 AM. Nice example of the tremendous amount of ice being produced by such modest clouds (see right side here–nothin’ but ice).1:01 PM. By early afternoon it was all over, the clouds too shallow, the tops too warm to produce ice even though they were still well below freezing. Just the way it is. Guess warmer than -10 C (14 F) at cloud top when you see a sky like this with no ice.6:47 PM. Sunset so-so as high clouds to the NW blocked the sun so it didn’t under light these clouds. Here, Cu flatten as the heat of the day, such as it was at 85 F, cold for late May, dies away,
Like you, my heart started pounding when that bank of thick clouds on the horizon got close enough to see that there was a rainshaft to the ground with a minor Cumulonimbus on top of it (ignoring the fact that you could’ve been hanging out by the radar all day).
6:47 PM. Cumulonimbus with rainshaft to the ground slowly approached near sunset yesterday. Big dust plume also visible to the right of the shaft a little later.
Today, the heart of the cold air and best moisture are over us and TODAY we will get those local icing-out Cu and small Cbs with sprinkles here and there. Measurable? Not so sure. Will be lucky. LTG in the area likely today, too.
If you’re a low temperature anomaly centric person at this time of the year (in texting, “LTACP”, or just “LTAC” for short), you will likely enjoy today’s 10 degrees or so below normal afternoon maximum, chillier even with outflows from virga and the scattered light showers around.
More later, photos, too… Behind on animal chores now.
Yesterday’s clouds
I thought it was a pretty nice day for you, though a little disappointing due to the late arrival of the minor rain threat mentioned above. You had quite an array of clouds to discuss in your cloud diary, which was good.
Below, I reprise them for you:
6:30 AM. Altostratus, the State Cloud of Arizona I think; Altostratus. We see a lot Cumulus, of course, but sporadically in the winter following a storm or trough like today, and in our summer rain season, but Altostratus we see year round.
8:49 AM. Mostly Cirrus uncinus (hooked, or tufted at the top).10:03 AM. Accas: Altocumulus castellanus. According to my cloud chart, it could rain with 6 to 196 hours after you see these clouds.
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.
