Now for some clouds, ones that spurted up awful fast yesterday. Movie here; still shots chronicling your cloud day below:
U of AZ mod run from last night, surprisingly, has showers around today, but nothing near Catalina. Hmmmm. Can that be right? Hope not. In fact, I am going to wish that it is totally wrong! Don’t forget to check out what Bob says, too. He’s our resident expert on storms, and a Fellow of the American Meteorological Society, a huge honor.
Tomorrow will be better, the model sez.
1“Dusty Ride”? Hmmmm. Once again, another great name for a western singer–I can’t believe how many I have come up with! “Dusty” this, “Dusty” that! The creativity just goes on and on.
As much as 1-2 inches as far south as Ventura County so far, 3-4 inches in the coastal mountains of central Cal as of just now (4 AM AST). Rolling 24 h Cal State archive here. LA area rain here; keep an eye on Opids Camp and Crystal Lake FC. Totals in NW LA County just now going over an inch. Following this drought bustin’ sequence, while just a” two shot wonder”, will be like watching….I don’t know..something really exciting, a weather kind of Olympics, where the favored team “drought” is taken down unexpectedly by some upstart storm. Yes, I will play the Olympics card.
And remember, this is just the lightweight division today; up next, beginning Friday in southern Cal: “Sumo wrestling”, as a 400-lb storm moves in next to push aside “Team Drought” at least for the moment. (Is Sumo wrestling an Olympic sport?) Still expecting some jumbo rain totals in the mountains of southern Cal, such as more than 10 inches at places like Opids Camp in the San Gabriel Mountains.
Speaking of jumbo totals, a friend and expert weather forecaster (and big atmos sci faculty member at Colorado State who now lives part time in Catalina), sent a stunning e-mail to me yesterday expressing his opinion that Catalina will get “1.5 to 2 inches of rain” from the second “Sumo” storm, the one that eases into Arizona late Friday and arrives here by dawn on Saturday, and then continues for around 24 h. Cloud maven here can’t go that high in his guess, doesn’t have the “testicularis” you might say, to go that high; 1 inch max is all I can come up with, but would be ecstatic if in error!
Still, this is going to be FANTASTIC! Saw some perennial wildflower blooms on the trails yesterday (see below), ones in need of a little pick-me-up–actually a big one, and this will be great for them. Fauna, too, will be happy! It may be too late for the annuals…not sure. Poppies are few, and awfully stunted this year, as many of you know.
Don’t forget, too, before our storm; those gorgeous skies! Have camera and pen ready to document and make notes about them in your weather diaries Those skies we’ll be fantastic, too, like yesterday, which was a great day to be on a horse, watching the sky.
Even when its raining the skies will be fantastic!
How many of us, even if we’re from Seattle, are STARVED for low gray, dank and dark daytime rainy skies, clouds chopping off the Catalinas a thousand feet above us, listening to rain pounding on our roofs, then running off roof making puddles, those richer shades of desert green after the rain ends, the glistening, water-covered rocks on the Catalinas in the morning sun after the storm? Its a real treasure when rain falls here.
3:54 PM. A great line of a Ac lenticular advanced over Oro Valley. This shot was about the best I got and its not that great.
On the weather horizon
Mods still have unusually warm weather here in the storm after life, 8-12 days out (cold in the East continues, too). But, then some Catalina rains continue to show up after that hot spell when you think May is already here.
That’s your weather forecast for today. There’s nothing you can do about it. Why go on about it?
Next, these from yesterday–was under control, only took 127 photos. Every thousand or so shots I take is NOT of a cloud, and yesterday there were two exceptions, which I will post here as an anomaly; a quirk really:
Yesterday’s rare ice-forming anomaly
I was hoping you wouldn’t read this far. Something incredible happened, rarely seen here in Arizona. Our slightly supercooled clouds, with top temperatures between -5 and -10 C, formed ice. When I first saw the indication of something falling out of those shallow clouds on the Catalinas, I was beside myself. Here’s what I saw, not taken while driving1:
I thought it was some kind of fluke since it was indicated just yesterday from this keyboard, based on prior experience in Arizona, that ice rarely forms in our clouds at temperatures above -10 C (14 F). Maybe someone was nefariously cloud seeding I wondered…. Or had flown an ice-producing aircraft through these clouds upwind somewhere. (Its about what cloud seeding would do in marginally supercooled clouds like these, too, not much but something.)
Ice appearance in clouds with tops warmer than -10 C is common in “clean” environments like over the oceans (see the works of Mossop in the Australian Pacific, Borovikov et al in the Atlantic, Hobbs and Rangno in the Washington State coastal waters and the Chukchi Sea offn Barrow, AK, or Rangno and Hobbs in the Marshall Islands) in clouds with warm bases (ones substantially above freezing for the most part) that can be anywhere even in “continental” environments far inland where cloud droplet concentrations are high due to natural and man-produced aerosols (see Koenig in Missouri, Hallett et al in Florida, Rangno in Israel) among many others). We sometimes have those warm-based clouds here in the summer, too.
——-end of academic interlude——–but not really——
These fuzzy very light snowshowers soon ended and the day went on as foretold, no ice in the clouds.While out on Old Jake, shown above, I was taking photos of particularly dark based clouds and was going to tell the story about why they looked so black, and yet did not precip–to warm and cloud top, and drop sizes near the top, too small for ice initiation. Just about every case in which aircraft measurements have been made in such clouds that form ice at top temperatures above -10 C (14 F), inside them are cloud droplets larger than 30 microns AND a few drizzle drops (liquid drops between 100 and 500 microns in diameter, or rain drops. Droplets larger than 30 microns and substantial concentrations lead to collisions where the drops that collide can coalesce into a single drop. Let us not forget Hocking or, later, Jonas and Hocking and the 38-40 micron drop size limits they found for this to happen from lab experiments. Below that 30-40 micron diameter size, the little cloud droplets act like marbles; too much surface tension.
OK, there’s that little discussion preparing you for what comes next. Continuing with the story…was there one? Well, anyway, Mr. Cloud Maven person, riding on his own forecast made that early morning for no ice in the clouds (meaning no rain), decides to also ride on his old horse, Jake, who needs some more of that exercise.
Confidently, though dark Cumulus clouds underlying a broken to overcast deck of Stratocumulus, looked even exceptionally dark in places, Mr. Cloud Maven person smiled at this darkness of the cloud bottoms, knowing that the darkness in the bases of shallow Cumulus only spoke to how high (and small) the cloud droplets were in those clouds; they had to be highly “continentalized”clouds, ones with tremendous droplet concentrations in them and because of that, all of the droplets in them have to be tiny, being so great in number. And, in being a Cumulus cloud with an appreciable updraft, even more droplets are activated in “continental” air than are at the bottom of a layer cloud like Altocumulus.
When the drops are tiny, more sunlight is reflected off the top of the cloud and the darker they get on the bottom, and the more removed they are from producing a drizzle drop, or are in having the precursor droplets to drizzle drop formation, cloud drops larger than 30 microns.
This is what a Cloud Maven person thinks before he gets on a horse….
So, as I am riding along near the Sutherland Wash, these patches of dark bases form nearly upwind…. I watch them for awhile, quite unconcerned, and smiled again, thinking about the other horseback riders, people on bikes out there that likely turned back in fear of a terrific downpour, not really having the knowledge they need about clouds.
Then suddenly I noticed ice streamers coming down NW of Catalina only a couple of miles away! It was falling from the downwind part of these darker clouds, where after a period of time, ice, if it was going to form would be. But, how could this happen?!!!! Before long, the thicker regions of the cloud began to emit stranded precip, a sure sign of graupel up top in the cloud. Graupel in clouds with supercooled droplets only 23-25 microns in size, much smaller than those required for coalescence, and the present of those droplets leads to ice splinters when they are banged by a graupel particle. A coupla graupel (soft hail) and after awhile, (10-30 minutes) a cloud can have a lot of ice, 10 per liter or more in concentration, plenty enough for precip beside the graupel-melting to rain stranded part. Here is a shot of the further, SHOCKING development:
I had to laugh at myself on the way back, the rain drops wetting us down, when I thought about being quite confident yesterday morning about no ice would form in our clouds. When you have an occupation that tends toward error, its good to have a sense of humor. There’s nothing worse than a humorless meteorologist at a party, one whose likely obsessing over his error-filled life.
So, why ice? The TUS sounding at 5 PM AST did not suggest tops colder than -10 C Z(moisture top was about -5 C is all), but where the moisture ended, the air was incredibly dry, reported as “1 percent” relative humidity. Here is that 5 PM TUS sounding:
So, an overshooting top COULD have gotten to -10 C, and certainly, with that incredibly dry air just topside, those drops in those evaporating turrets would have chilled a couple of more degrees C. So, maybe that’s it, in fact, the overshooting moderate Cumulus tops DID reach to, or below, the -10 C normal ice-forming temperature here.
However, the concentrations that developed in these clouds HAD to be due to other processes beyond just the run of the mill ice nuclei since there are so few of them at -10 C, and that where drops larger than 23 microns come into play. Without those, there would never have been showers yesterday, only a very isolated drop or two. Those larger than 23 micron size drops lead to “ice multiplication” where just a couple of initial ice particles can “multiply” like rabbits in clouds because of ice splinters shed when hit by graupel. However, as we speak, the full understanding of how ice forms in clouds with these “high” temperatures has not been pinned down. Some researchers, the present one included, believe that ice splintering alone is not sufficient to explain the rapidity in the appearance the high concentrations (10s to 100s per liter) that develop in clouds like we had yesterday. You probably don’t care about what I think, but rather go with the majority opinion… Oh, well, it always safer that way.
As a test of even deeper knowledge that an aspiring cloud maven junior might have, this question:
What kind of ice crystals and other frozen particles would have been in those clouds yesterday?