The “perfect storm”? Well, maybe the perfect rain, and it kept giving fro several hours yesterday after our best model said it should end yesterday before 11 AM. And what a nice rain! 1.18 inches total here in Sutherland Heights, as measured by a CoCoRahs plastic 4 inch gauge. (You might consider getting one, btw, or one from the U of A’s rainlog.org)
Went down to the CDO and Sutherland Washes to see what was up after seeing the gargantuan 4.96 inch total on Ms. Lemmon, and the 3.62 inches at the Samaniego Peak gauge. Below is the resul for the Sutherland, both were the same, nary a drop in them:
8:15 AM. Looking upstream in the Sutherland Wash at the back gate of Catalina State Park. I could hardly believe that there was no flow with so much rain having fallen in Catalinas! But it was good in a sense; all that rain mostly soaked in.
6:37 AM. A photo of drizzle falling from Stratocumulus clouds. Hope you got out and jumped around in our rare drizzle occurrence. Big hat, no bicycle, works in drizzle, too, the tiny drops won’t get on your glasses. Note how uniform the fuzziness is toward Catalina/Oro Valley, only gradually thickens to the left. Took about 2 h to get a hundredth when this was going on.
7:23 AM. Drizzle drops as seen by your car’s windshield after about 1 sec at 1 mph. Note how close together they are. The tiny drops and how close together they are is what differentiates true drizzle from the phony labeling of spares large drops as “drizzle” we sometimes get from our TEEVEEs by semi-pro meteorologists. Sorry to bang on them again, but REALLY, folks, they should know better. Sure, I’m a drizzle-head, but it really does matter since its a whole different process that produces drizzle compared to sparse large drops. Sorry, too, for another mini-harangue on this, but REALLY folks, we should know the difference! Feeling better now, got that out.
8:02 AM. Heading down to the Sutherland Wash on Golder Ranch Drive with temperatures and dewpoints in the mid-60s, there really was a feel for being on the wet side of the Hawaiian Islands, maybe above Hilo, HI, at 3,000 feet elevation, except for the dead grasses.10:20 AM. One of the many dramatic scenes yestserday, this one looking toward the Charouleau Gap NE of Catalina.10:19 AM. While it was nice to see all the water glinting off the rocks on the side of Samaniego Ridge, a deeply troubling aspect was the amount of aerosol that had moved in suddenly it seemed, evident in the crespuscular rays. How could it be this dirty so soon? Seems like a weather oxymoron after such a long period of rain. Also, one wondered if this aerosol loading would stop the warm rain process by providing too many, and smaller droplets in our clouds. Fortunately, that did not happen, and what appeared to be warm rain events, or ice formation at relatively high temperatures in our clouds, also requiring extra large cloud droplets, for the most part, continued intermittently into mid-afternoon.
10:32 AM. Close up of aerosols and sun glints on wet rocks.
12:23 PM. Glimpse of ice-forming top (smooth region above crinkly top). Types of crystals visible here? Needles and hollow sheaths because the top temperature was likely equal to or warmer than -10 C (14 F) and cooler than -4 C, and that is the temperature range that those crystals form under when there is water saturation, as there is in a Cumulus turret before it glaciates. OK, a lot of hand waving, but that’s what I think and I am here mainly to tell you what to think, too.
5:36 PM. The day ended quietly with a little, but pretty scruff of orographic Stratocumulus castellanus on Sam Ridge, the clouds mashed down by the subsiding air at the rear of our little trough that went by yesterday afternoon.
The weather WAY ahead, too far ahead to even speculate about:
NOAA spaghetti plots still suggesting a pretty good chance of rain here around the 23-25th of this month. Nothing before then.
Looked for a time that the rain might be over by mid-afternoon and early evening here in Catalina with only a disappointing 0.40 inches here, but the rains kept coming overnight, piling up a nice 0.98 inches 24 h total for the storm. In the meantime, Ms. Mt. Lemmon has gotten 4.29 inches! Check out these eye-popping totals from the Pima County network, ending at 7 AM AST today (just updated. These are so great in view of last October’s trace of rain:
Gauge 15 1 3 6 24 Name Location
ID# minutes hour hours hours hours
—- —- —- —- —- —- —————– ———————
Catalina Area
1010 0.00 0.00 0.00 0.24 0.71 Golder Ranch Horseshoe Bend Rd in Saddlebrooke
1020 0.00 0.04 0.04 0.28 1.06 Oracle Ranger Stati approximately 0.5 mi SW of Oracle
1040 0.00 0.08 0.12 0.43 0.94 Dodge Tank Edwin Rd 1.3 mi E of Lago Del Oro Parkway
1050 0.00 0.16 0.20 0.67 1.26 Cherry Spring approximately 1.5 mi W of Charouleau Gap
1060 0.04 0.16 0.20 0.83 1.93 Pig Spring approximately 1.1 mi NE of Charouleau Gap
1070 0.00 0.08 0.20 0.59 1.14 Cargodera Canyon NE corner of Catalina State Park
1080 0.00 0.00 0.00 0.31 0.91 CDO @ Rancho Solano Cañada Del Oro Wash NE of Saddlebrooke
1100 0.00 0.12 0.28 0.55 1.06 CDO @ Golder Rd Cañada Del Oro Wash at Golder Ranch Rd
Santa Catalina Mountains
1030 0.00 0.04 0.08 0.55 1.57 Oracle Ridge Oracle Ridge, approximately 1.5 mi N of Rice Peak
1090 0.08 0.31 0.67 1.42 4.96 Mt. Lemmon Mount Lemmon
1110 0.04 0.12 0.12 0.71 1.61 CDO @ Coronado Camp Cañada Del Oro Wash 0.3 mi S of Coronado Camp
1130 0.00 0.24 0.47 1.89 3.46 Samaniego Peak Samaniego Peak on Samaniego Ridge
1140 0.04 0.12 0.24 0.39 1.73 Dan Saddle Dan Saddle on Oracle Ridge
2150 0.08 0.12 0.28 1.14 3.50 White Tail Catalina Hwy 0.8 mi W of Palisade Ranger Station
2280 0.00 0.04 0.12 0.31 1.93 Green Mountain Green Mountain
2290 0.04 0.08 0.20 0.75 2.40 Marshall Gulch Sabino Creek 0.6 mi SSE of Marshall Gulch
Misty drizzle with very low visibilities is still falling here in Sutherland Heights, Catalina, at 3 AM. The Catalina Mountains are not visible from just a couple of miles away. This suggests the clouds overhead are now “clean and shallow” and rain is forming via collisions of cloud drops with coalescence rather than because of ice in the overhead clouds, often called “warm rain,” a rare occurrence in Arizona. You’ll definitely want to log this in your cloud diary!
“Clean” means that the clouds have low droplet concentrations, viz., are not choked with anthro and natural “continental” aerosols but are more “maritime”, almost oceanic in composition, something that easily leads to “warm rain/drizzle” formation. In oceanic clouds far from pollution sources droplet concenrations usually are less than 100 cm-3. They average about 60 cm-3 in Cumulus clouds in onshore flow along the Washington coast, as an example. Cloud appearance should look a little different to the discerning eye, too. With low droplet concentrations, the clouds appear “softer” than usual, not a hard.
Normally, our clouds likely have a few hundred per cm-3 or more and appear darker from below since higher droplet concentrations is also associated with bouncing more sunlight off the top of the cloud1.
With vort max (aka, curly, or curling, air) still well to the west of us at this time (3 AM AST) as seen here. This sat imagery also shows plenty of shallow clouds upwind of us, so it seems like the very light rain and drizzle will continue well into the morning, likely adding a few more hundredths to our generous totals. Remember that the air likes to slide upward as curly air approaches, that is, produce a lot clouds, and today, a last bit of precip. Did pretty good last night, too!
Honestly, you really want to get out and experience our misty, drizzly rain (drop sizes mostly between 200 and 500 microns in diameter; a few human hair widths), before it ends; the kind of precipitation that makes riding a bicycle even with a big hat impossible. You might even try the near impossible trick of photographing the drizzle drops, too, as they land in puddles, see if you can catch the tiny disturbance made by drizzle drops. That would be great photo! I know, too, that experiencing real drizzle will give you a bit of a chuckle as you think of all those less informed folks, some of whom are even on TEEVEE, who call a sparse fall of raindrops, “drizzle.” Oh, my, WHAT has happened to our weather education?!
Yesterday’s clouds
Lots of gray cloud scenery yesterday, including a stunning example of Nimbostratus (Ns), the steady rainmaker (at least here we had that, anyway.) In other places, Cumulonimbus clouds were also contained within that rainy cloud mass and dumping an inch or so in an hour in TUS with LTG (weather text for “lightning2“), as you likely know. Didn’t hear thunder here, but coulda happened since I was off to the new Whole Foods market at Ina and Oracle as the steady rain from Ns moved in it because it said online that they had Brother Bru Bru’s African Hot Sauce which I had been looking for for a long time but when I got there they didn’t have it! The grocery manager apologized profusely and then we started talking about haloes and the ice crystals that cause them. So, you never know when your cloud mavenhood will come in handy in everyday conversations, maybe make that friend you’ve been looking for:
7:14 AM. The many layered remnants and distant rain creeping toward Catalina from the southwest are evident soon after dawn
7:34 AM. New round of rain begins on the Catalinas. Shafting here implies mounding cumuliform turrets on top, likely glaciating. From up there they would probably look like soft Cumulonimbus capillatus clouds, ones with weak updrafts.
8:34 AM. One of the prettiest sights around here can be just a tiny little cloud (Stratus fractus) like this one when a glint of sun falls upon it. It looked so CUTE! Imagine, you could be up on that little knob and run in and out of it, maybe play hide and seek with your friends, except that being a “clean” cloud, the visibility would be pretty good inside it, not like the shallow, impenetrable fogs you sometimes get around Bakersfield, CA. There, in one of those, you could play really great hide and seek! I’m guessing that if you’re reading this far, you may not have a lot of friends. :}1:23 PM. In the midst of our mid-day light rain, a clear example of Nimbostratus with underlying Stratus fractus and Stratocumulus. Remember, its not the LOW clouds that are raining, its the deep Ns layer above them. However, it is OFTEN true that the lower clouds ADD to the rain because as the rain falls from the Ns layer, those drops often collide with the floating drops in the lower clouds thus making a raindrop bigger. That’s one main reason why rain and snow are so much more on the upslope side of mountains just due to that collection of non-precipitating cloud drops! Its so cool! Away from mountains, you likely won’t have so many low clouds at the bottom of Ns, and the rain is less.
2:50 PM. After the rain ended, suddenly this lower cloud line formed representing a wind puff from the west. It headed toward the Catalinas, but then, within a few minutes, pooped out with no precip having fallen out. It was quite a bit fatter before this photo, too. That dissipation indicated that whatever wind source had produced had died out. But anyway, when you see a cloud line like this, think “windshift.”
4:57 PM. Expansive deck of Stratocumulus with spots of very light rain in the distance promises, along with the curly air feature (an upper level vortex) being so far to the west of us at this point, promises that the rain is not over.
The weather way ahead
Dry for almost two weeks. However, a crazy NOAA spaghetti factory plot suggests rain in about two weeks, around the 23-25th, as you can plainly see here:
NOAA spaghetti factory plot (aka, “Lorenz plot”, after chaos scientist, Edward N. Lorenz–he would really like THIS plot!) valid for 5 PM AST Oct 23rd. Rain is hinted at by the loopy lines in Arizona dipping down to the south. Will keep you posted on that, but not very often.
The End. Its really amazing how much information I have passed along today! Most of it correct, too!
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cCoCoRahs gauge, not Davis tipping bucket which seems to have a problem of late.
1This is the concept behind kooky schemes to defeat potential global warming which hasn’t happened for 18 years or so by polluting oceanic clouds, making them “brighter” on top, darker on the bottom by inserting extra aerosols into them. Ghastly thought! Haven’t we polluted enough?
2Recall that weathermen and women were WAY out in front when it came to what we now call “texting”, as in “2KOLD4me” that kind of thing.
Let me give you an example from the 50s when we were rocking around the clock: “M8BKN15OVC2R-F68/661713G24989 R-OCNLY R”, a text phrase that would take a paragraph to unravel, to paraphrase language maven, Noam C3,4., except in those days we had our own private symbols which I can’t duplicate for “BKN” (a circle with two vertical parallel lines in it) and “OVC” (a circle with a plus sign in it). Weather typewriters and teletypes came with those private symbols!
3Wow, a footnote in a bunch of footnotes! Breaking ground again I think! What Noam C. said: “takes a phrase to tell a lie; a paragraph to unravel it.”
4Factoid, one not having to do with weather: Language maven, NC, really liked Pol Pot and his “restructuring” of society back then until he learned about all the millions of skulls were piling up along with that “restructuring.” You can hear about Pol Pot (and hypocrisy) here in Holiday in Cambodia, one of the defining songs of the 1980s IMO, as interpreted by The Dead Kennedys featuring lead singer, Jello Biafra. (You remember Jello don’t you? Ran for president a while back. Kind of surprised we didn’t elect him…)
The obvious often makes a good headline: “National debt HUGE; more on way!”
With Simon’s decrepit, but juicy remnants on the way, and swept in our direction due to a little upper trough of the southern Cal and Baja coasts, significant rain is likely here. The heaviest reported amounts from the USGS and the Pima County ALERT sites (as of 4 AM) are already a little over an inch in the Green Valley area and near Bisbee. Likely more has fallen in the data sparse SW part of AZ. Will have to depend of radar-derived amounts there, but some of those will surely be over an inch as well.
Oddly, the Yuma radar doesn’t see much to the east of them, which is quite incorrect, but the PHX radar does see something akin to what was predicted the evening before last; a narrow band of heavy rain starting near the border near the Organ Pipe Cactus NM.
Overdoing the radar discussion but continuing anyway, the PHX radar is too far away to really see what fell at the ground down there by the SW border, but it did have that band of heavier rain shown in their storm total loop near Organ Pipe.
Our own TUS radar is also too far away to catch what’s going on that far to the west of us. However, it does show several hot rain accumulation spots already over an inch at of 4 AM AST to the SE-SW of us, validated by those larger totals around Bisbee and Green Valley mentioned above.
Radar-derived rain totals through 4 AM AST October 8th. Yellow areas denote those where the radar believes more than an inch has already fallen.
Today
Now here’s the excitement plan for today: Check this out from OUR very own University of Washington Huskies’ Weather Department, one of the highest ranked publicly-funded universities, not at all like Stanford U. which gets huge amounts of funding from big billionaires:
A forecast of the locations of curly air (red areas) at 5 PM AST today. The model run was based on global data taken at 5 PM AST last evening.
Red curly air, always in low pressure troughs, can organize storms. Looking at this, one would expect that as the red curly air moves toward Arizona in the trough that was off southern Cal but passes over us tonight, that storms will get organized and move through our area later today as it approaches! Because they’re organized, one tends to think, if its me, that there will be a nice line of thunder rain, and the rain duration would be several hours, heaviest at first, then tapering off to steady rain that gradually decreases, much like in our winter cold fronts.
The use of “curly” here, BTW, means those locations aloft where the air has relatively high vorticity, or rotation, as in around a center, as in the inside of a low; check out the “red curly air” in that low south of the Aleutians on this map). The approach and passage of “red curly air” (as it is shown in this color scheme) over you is associated with upgliding air motions that assist in the formation of large cloud shields; helps organize rainbands. So, a depiction like this, showing that southern Cal trough passing over us, combined with all the tropical air that has come into the State ahead of it during the past 24, portends some heavy rains in the State today with the cores of the heaviest cells. That’s, of course, what the models are anticipating, too, though going “blind” at this point, haven’t checked ’em, which is kind of silly. OK, checking now as a rational weatherperson would do…. OK, here goes:
Accumulated rain between now and 4 PM AST tomorrow afternoon from the 11 PM AST U of AZ Beowulf Cluster model run by the U of AZ. Now this is pretty exciting since it shows that twixt later today and tomorrow that something around an inch will fall here, and an inch and a half to two in the Catalina Mountains!
Yesterday’s clouds
Not a really exciting day, though a great sunrise due to Altocumulus, just more Altostratus and Altocumulus clouds as we had the day before. By mid-afternoon, some exciting towering Cu began to appear over the Rincon Mountains and to over the Santa Rita Mountains indicating the lower level moistening of the air approaching us.
6:15 AM. Under lit Altocumulus with a higher vale of Cirrostratus above. TUS sounding suggests the Ac was about 19,000 feet above the ground as seen from Catalina. BTW, during our (U of WA) research, we found that Altocumulus clouds, via pilot reports obtained directly from the local ATC Center1 and in our own flights were often higher than usually thought of as “middle level” clouds).
7:49 AM. Band of Altocumulus with Cs above. No virga here.11:40 AM. Virga to the west from an Altocumulus castellanus buildup, but in this case some of the virga was reaching the ground as a sprinkle-not-drizzle, a great sight because that showed how moist the air was all the way to the ground.4:36 PM. Dense Altocumulus clouds with considerable virga spread over the sky late yesterday. By this time, sounding data indicated that they had lowered from 19,000 feet above the ground to 13,000 feet.
Hoping to report at least half an inch by this time tomorrow morning.
The End.
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1 In those days of the 1980s and 1990s, it was possible to call the ATC Center in Auburn, WA, and ask if they had an aircraft taking off from or landing at Sea-Tac, and get the height of an Altocumulus layer when it was intercepted by that aircraft! Imagine, being able to call some guy working the planes and getting that info (for our research on aircraft-produced ice)? It seems totally amazing now.
While waiting for the remnants of former H. Simon to pass over us during the next couple of days, bringing some rain, starting overnight, got distracted while looking to see how many rainfall measuring stations they have in Baja Cal, and found this about the Great O from NASA. Its a pretty fascinating read I thought, which you will also find fascinating. Sure, intense hurricane O’s floody remnants missed us here in Catalina/Tucson, but it did produce some prodigious rainfall on its path across Baja and points northeast from there into NM. NASA’s Tropical Rainfall Measuring Mission (TRMM) radar estimates that over the ocean off southwest Mexico that about 33 inches fell over a ten day period while O was meandering around down there with some other disturbances, probably raising sea level that bit. And up to 5 inches per hour was falling in rainbands as it entered Mexico from the Gulf of Cal! O was deemed the strongest hurricane (tied with 1967’s Olivia) to ever hit southern Baja since sat images became available.
You will also see reprised in the “Diary of O” the huge rainfall totals that were expected in the TUS area but rains that missed us, the sad part of the story for some folks, who we will not mention. But, as Carlos Santana said, “Those who do not know history, are doomed to repeat it.”
For that reason, in view of the prodigious rains predicted in southern AZ again, but to the west of us, I thought we should be prepared for disappointment by recalling O’s “terrible” miss for TUS.
Here are some graphics from our very fine U of AZ Weather Department’s Beowulf Cluster computer outputs from just last evening at 11 PM AST, ones that can be found here, in case you don’t believe me again, a seeming theme around here. First, when the computer model thinks it will start raining, Figure 1, and in Figure 2, the expected gigantic totals expected along and near the US border where we really shouldn’t go unless you 1) go in an armored vehicle of some kind, 2) make prior arrangements with the appropriate ruling Mexican drug cartel for that part of the US that you just want to visit some rain, nothing more:
Figure 1. Valid for 2 AM AST tonight. The leading edge of the rain has reached Catalina. You might want to stay up for that. That wet desert aroma as rain begins is so awesome!Figure 2. Valid for 3 PM tomorrow afternoon. One small, mountainous area around Organ Pipe Cactus National Monument is forecast have more than TEN inches by then, likely slowing the amount of incoming drugs. Organ Pipe Cactus NM is a US national park that you are warned not to visit, or if you do, you might be shot or have some other untoward happenstance if you go hiking. So you probably shouldn’t drive down there to see this once in a century rain. How sad is THAT?
Right now, as of 4 AM AST on Thursday, this model thinks Catalina and vicinity will get less than half an inch. Be prepared for more, though, rather than less. Note the streamer of heavy precip associated with Simon in Figure 2. Well, recall that O’s heavy precip streamer was going to be right over us, but then shifted eastward in the models and in real life at the last minute. The above prediction would only have a bit of a “westward bias” (the real streamer is EAST of where its shown now) to give TUS and vicinity a memorable, drenching October rain. This is what occurred with O’s streamer of torrential rain which was expected to pass over TUS, but ended up a little east of us. So, anyway, given all the little uncertainties in model predictions at this point, the watchword here is “watch out” which is actually two words. The view from here, incorporating a positive rain bias as you know, is somewhere around an inch for Catalina. The grassy green is gone, most annuals in serious wilt or crispy now, but could an inch bring some green back? Clueless on that score.
Yesterday’s Clouds
6:06 AM. Nice Cirrus sunrise, maybe some Cirrocumulus at far right, and off on the left horizon.
5:05 PM. Altostratus translucidus with an Altocumulus layer on the horizon.
5:07 PM. A “classic” view of Altostratus translucidus (sun’s position can be discerned through it), and here, an all ice path to the sun. Liquid cloud elements would appear as dark flakes, or would obscure the sun’s position. Sounding indicated that this layer was 26 kft above the ground in Catalina!
Remember last October we didn’t get nothing, we got a trace instead, which is almost nothing. This October, with a juicy tropical storm remnant headed our way, I predict something more than nothing which is quite something. Remember it was foretold here just a month ago that rain would fall in September in Catalina…
TS Simon, about to be a remnant low by tomorrow, the NOAA hurricane folks say, is beginning to send in the clouds to Arizona with promises of rain, “real” rain, at least a tenth of an inch. Here’s Simon as seen by NOAA’s NexSat just a few minutes ago, and do we really need all that lighting?:
Satellite image of Simon as of 6 AM this morning.
Today
Overcast to broken Cirrus is all most of the day, likely thickening into Altostratus at times, thinning at other times–you can see that sequence approaching us in the sat image above.
As you cloud folk know, Altostratus is a Cirrus-like cloud that’s much deeper with tops at Cirrus levels as a rule, but bottoms in the middle levels, between roughly about 8,000 and 22, 000 feet above the ground. Altostratus, a layer cloud that covers much or all of the sky, has gray shading which Cirrus can’t have (with the exception of one patchy variety, Cirrus spissatus). Like Cirrus, As clouds are usually all ice. Maybe some Ac later, too. So, not a REAL interesting cloud day for you.
The Catalina Water Year Record Updated through 2013-14
This is probably the only worthwhile part of this blog. Actually our total, from a Davis Vantage Pro Mark IV Extra Deluxe Personal Weather Station “tipping bucket” gauge located here is probably a little low. A chincy CoCoRahs gauge always had more, including 4.63 inches on the Sept 8 true monsoon day, whereas the tipsy bucket couldn’t apparently keep up, reporting “only” 4.18 inches. The actual water year total is likely just over 15 inches.
Will be resting mind here for a few days; its kind of depleted of creative sophomoric (AKA, “lame”) humor and expert cloud talk for awhile after the long summer of clouds.
Just going to lay back and enjoy the storms in the next couple of days, not think about cloud stories. Thanks to both of you for your patience.
6:20 PM. Cumulonimbus calvus pileus. Hope you had your camera. This would have been a good example to add to your collection. “Calvus” or “bald” is a short-lived period when a Cumulus congestus top is converting to a fibrous (“capillatus”) appearance. That left bulge is clearly loaded with ice. The pileus forms in moist air being pushed up by the rising turret below it. I wanted to be inside that cloud so bad! There’s real magic going on when the droplets are being converted to ice, along with the appearance of hail and/or its soft, squashable version, graupel.
Fantasy storm of the day
….popped out of the WRF-GFS run from 12 Z yesterday, rendered, as we say, by IPS MeteoStar. Tropical storm “Q” is shown in the Gulf of Cal/Sea of Cortez racing north into Arizona. Pretty cool, huh?
A map configuration like this hasn’t been back yet, and wasn’t there in any run before this one, so we can throw it in the trash pile of bogus model predictions so far, though the models DO have a strong hurricane “Q” in the works. Mods now show it going NW and out to sea off Baja. Still its fun to see how much fantasy rain can fall in Arizona. Kinda reminds one of the track of infamous Tropical Storm Octave, October 1983, almost passing over Tucson on the same day 31 years ago. You remember “Octave” I am sure. You can read about it and a very similar eastern Pacific hurricane season to this one here.
Valid Wednesday, October 1st at 5 PM AST. Flooding rains from tropical storm “Q” move into Arizona.
The Cumulus ahead
Whilst CMP was glumly anticipating the end of Cumulus clouds, tropical ones on a daily basis anyway, due to the onset of westerly winds aloft, it has been pointed out by more astute forecasters, like forecasting legend, Mike L, at the U of AZ, TEEVEE ones, NWS, etc., (i e., namely, everyone else who knows anything at all about weather) that tropical air will still be feeding in enough from the east below the westerlies to keep some Cumulus going here and there, some even becoming Cumulonimbi with rain! Your errorful CMP was actually glad to be “informed”, glumness disappearing.
Also, we got that cold front coming on the 27th or so, with another chance of rain as humid air is drawn northward ahead of it. So, another coupla chances to make this a decent water year, one that ends on September 30th. We’re just surpassing 15 inches now; the normal, computed from 37 years at Our Garden here in Catalina, is a little less than 17 inches.
Had another rainbow from those cloud “warriors” we call Cumulonimbus on the Catalinas. But, “If traces are your thing, Catalina is king!” as we recorded but a trace of rain again while soaking rains poured down just a couple of miles away on the Catalinas, to form a sentence with too much punctuation and a sentence within a sentence1.
More interesting perhaps to some, this modest rainbow formed just after 5 PM yesterday toward the Charouleau Gap, as seen from Catalina, and was still in almost the same spot after 30 minutes. Have never seen that before since both the sun and the showers are drifting along and so the rainbow should change position.
First, in today’s cloud story, the strangely believe it rainbow part:
5:12 PM. Rainbow first spotted toward the Gap. Cumulonimbus cloud not sporting ice at top; ice is below flat top due to weak updrafts that allow the ice crystals to subside while the top remains mostly liquid appearing. The smoothness on the side of the cloud above the rainbow is due to ice particles5:42 PM. While the observer has moved some few hundred yards, the rainbow has stayed pretty much where it was after 30 min. A course in optics would be required to explain this and that’s not gonna happen (accounting for the sun’s movement, the rain, and the observer’s movement).
The whole day represented several phases, the early, spectacular eruption of clouds on the Catalinas as it started to warm up under clear skies, those low bases topping the mountains again indicating stupendous amounts of water are going to be in them when they grow up, the rapid appearance of “first ice” just after 10 AM, the heavy showers and cooling on the mountains and here (little thunder heard), the clearing due to the cooling, the warming, the rebuilding of the Cu on the mountains, and new showers–the rainbow was part of the second growth phase, and then the gradual die out of the Cu as sunset occurred.
Huh. I just realized that what happened to our temperatures yesterday was like a mini-sequence of the earth’s climate over the past 200,000 years or so, the prior Ice Age in the morning temps, the warm Eemian Interglacial as it warmed up, the last ice age when the cooling wind from the mountain showers hit, then the warm Holocene when the clearing and warming started up again in the afternoon! Cool, warm, cool, warm. Below, the Catalina temperature record that emulates earth’s climate over the past 200,000 years, beginning with next to last “ice age.” I can’t believe how much information I am passing along today! What a day you had yesterday!
Mock climate change for the earth’s past, oh, 200, 000 years or so as indicated in yesterday’s Catalina/Sutherland Heights temperature scale. But, we have a LOT of days like yesterday’s in the summertime, but only now after 7 summers has it hit me how it mimics our earth’s “recent” past climate.
Cloud Alert: Yesterday might have been the last day for summer rain here. U of AZ mod from last night has plenty of storms, but we’re on the edge of the moist plume, and those storms take place just a hair east of us it says. So, while they may be on the Catalinas today, unless we get lucky, they’ll stay over there. Drier air creeps in tomorrow, too.
Here is the rest of our day in clouds, from the beginning, even if its not that interesting. In the interest of efficiency, you’d do a lot better by going to the U of AZ time lapse site to see all the wonderful things that happened yesterday, instead of plunking along one by one as you have to do here. (PS: Some functions in WordPress not working, would not allow some captions to be entered as usual.)
9:21 AM. This tall, thin Cumulus cloud was a reliable portent for yesterday’s early storms on the mountains. It just shot up!
11:57 AM. Thunder and downpours are widespread on the Catalinas.
2:46 PM. After the long clearing, Cumulus begin to arise on the Catalinas again.5:46 PM. A pretty, and isolated Cumulus congestus with a long mostly water plume ejecting toward the NW. Some ice can be seen falling out of that ejecting shelf. Now here’s a situation where an aircraft measuring the ice output from such a cloud can miss it because its formed as the turret subsides downstream, and most of the ice is substantially below its top, and under the shelf. If you cruised along the top of the shelf, you would miss most of the ice and measure ice particle concentrations that are much lower than what the cloud put out.6:17 PM. This same quasi-stationary cloud with its long shelf, still shedding ice just downwind of the cloud stem, is about to disappear. Note, too, that the ice fall quits after awhile going downstream even though cloud top temperature is the same for quite a distance. The ice was actually formed at lower temperatures in the protruding turret, not at the temperature of the shelf, which apparently were too high for ice to form. Also, cloud droplet sizes shrink from those in the protruding turret as evaporation takes a stronger hold. Larger droplet sizes are associated with greater ice formation at a given temperature.6:12 PM. Like aspen leaves in the fall, but every day, our clouds change color as the sunsets. Here’s another memorable site, not only due to the color, but how tall and thin these Cumulus clouds are, showing that the atmosphere was still extremely unstable over the depth of these clouds, probable 2-3 km deep.
The End.
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1Hahah-these are just a couple of the grammatical gaffes I actually know I’ve done!
The sky was packed with tropical Cumulus congestus and a few Cumulonimbus clouds in the distance at dawn yesterday, an unusual sight for Catlanders. A few of those Cu around the Catalina/Saddlebrooke/Oro Valley area grew overhead into “soft-serve” Cumulonimbus clouds with heavy, tropical-feeling showers you could hike in with great comfort; no lightning/thunder observed.
Up to an inch likely fell out of the core of the largest ones yesterday morning, but only .09 inches was recorded here in the Sutherland Heights. The Golder Ranch Drive bridge at Lago del Oro got 0.28 inches, Horseshoe Bend in Saddlebrooke near one core got 0.71 inches, Oracle, a half inch. Due to the exceptionally warm cloud bases, about 60 F again, warm-rain processes were certainly involved with those showers, though glaciated tops were usually seen, too. In warm base situations, they can act together.
Now here’s something interesting of me to pass along to you, something you might want to pass along to your friends when the opportunity arises: ice doesn’t seem to make much difference in the rainfall rates of true tropical clouds in pristine areas, only a little “juicier” than the ones that we had yesterday. Early radar studies in the 1960s1 indicated that the rainrates of tropical clouds peak out BEFORE the cloud tops reached much below freezing, a finding that has been confirmed in some aircraft studies of rainrates in tropical clouds2. Icy tops going to 30 thousand or more really didn’t do much but add fluff. All that really heavy rain that developed before the cloud tops reached the freezing level was just due to collisions with coalescence (AKA here, but nowhere else because its too silly, as “coalision.”) So, “coalision” can be an extremely powerful and efficient way to get the water out of clouds and onto the ground!
Scattered storms beautified the sky the whole day in the area. More are expected today, as you likely know. Have camera ready! Hope you get shafted!
Cool snap, maybe with rain, virtually guaranteed now for about the 26th-27th. Should make a good dent in the fly season, if you got horses and have been battling them all summer you’ll really welcome this.
Your Cloud Diary for September 19, 2014.
We start with an early morning vignette, down there somewhere:
6:32 AM. Overcast Stratocumulus (likely with bulging tops) and the distant top of a Cumulonimbus, that bright sliver, lower right. 6:33 AM. Cumulonimbus top NW of Catalina, an usual sight since it had arisen from such low based clouds in the “boundary layer”. Usually this only happens due to heating by the sun later in the morning or in the afternoon, of course.
Vignette: When this cloud bank above Sutherland Heights (shown above) darkened up, looked more organized, and with Cumulonimbus tops visible and showers already nearby, I made the not-so-surprising comment to two hikers about to leave on their hike hour long hike, “Watch out for these clouds overhead!”
They got shafted, see photo below; came back soaked, their dogs, too.
But, I had done my best. True, it was early morning, and after all, those hikers were likely thinking, “it doesn’t rain much here in Catalina in the early morning” (unless its FOUR inches like two weeks ago).
7:30 AM. Heavy rain falls S of Sutherland Heights, on hikers who had been warned about a dump; produced a warm feeling.
8:14 AM. Those showers moved off into the Catalina Mountains and the early morning sun provided a spectacular scene. (From the “Not-Taken While-Driving” Collection, though certain attributes here suggest that someone just pointed a camera in any old way and got this shot. Pretty clever to make it look that way, kind of adds an “action: attribute to the shot.
Cloud of the Day:
1:47 PM. I meet a friend, southbound, on Equestrian Trail. I advise her that if she drives under this cloud, she will get dumped on. She continues on. There is no outward sign of ice, and no shaft, however.
1:49 PM. Thunder begins to grumble repeatedly from this cloud only two minutes later! The conversion from a droplet top to an ice (glaciated) one is clearly in progress. My friend has disappeared over the horizon, which isn’t that far in only two minutes.
1:58 PM. Kaboom! I was actually a little late getting the fallout to the ground. Will have to look at the video to see the shaft plummet down. Produced a nice little haboobula, too, on the left side, where the shaft is densest. I wondered if my friend had gotten “shafted”, as we say here when folks are under the rain shaft.
2:57 PM. An isolated Cu congestus thrusts three turrets out. Who will it turn out to be?2:53 PM. Stable layer halts growth of the two outer turrets and they begin to flatten, but caulifower top in the middle shows that further growth will occur. Will those wings develop ice? Beginning to look like a rocking horse, I see…Look! Its Snoopy with wings! (Ice seen on the right, also on the left, but less obvious).4:31 PM. Pile of Cumulus congestus clouds weighs down the Catalina Mountains again as they did the previous evening. Had to pull off the road this time, jump out car to get this grand scene, well, to me anyway. Hungry passengers a little annoyed at the pre-dinner delay. You know, had to complain a little.6:18 PM. Another sunset reason why we live here and love it so much.6:20 PM. Late storms continue on The Rim, toward Globe
The End, enjoy our last couple days, it would seem, of our summer thunderstorm season. Oh, me.
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1Saunders, R. M., 1965; J. Atmos. Sci.
2Cloud Maven Person with Hobbs, 2005, Quart; J. Roy. Met, Soc.
Yesterday, in the wake of TD Odile, it was about as Hawaiian a day in Arizona as you are ever likely to see. First, the high dewpoints, ones that replicate those in HI, mid and upper 60s (69-70 F in HNL right now), cloud base temperatures of around 60 F, and with misty, even drizzly warm rain around at times. The only thing we didn’t see was a rainbow, so common in HI they named a sports team after them.
If you thought the clouds looked especially soft-looking yesterday, I thought they were, too. That soft look that also characterizes clouds in Hawaii and other pristine oceanic areas arises from low droplet concentrations (50-100 per cc), characteristic of Hawaiian clouds.1 Both low updraft speeds at cloud base, and clean air result in low droplet concentrations in clouds.
The result of these factors?
The droplets in the clouds are larger than they would be forming in air with more aerosols (having “cloud condensation nuclei”, or CCN) and stronger updrafts at cloud base. Yesterday, you could have remarked to your neighbors late yesterday morning, as the rain and true drizzle began to fall from that Stratocumulus deck out to the SW-W, that the droplets in those clouds, “….must’ve exceeded Hocking’s threshold” of around 38 microns diameter. Lab experiments have demonstrated that when droplets get to be that large, which isn’t that large at all, really, that they often stick together to form a larger droplet, which in turns, falls faster and bumps into more droplets, and collects them until the original droplet is the size of a drizzle (200-500 microns in diameter) or raindrop (greater than 500 microns in diameter) and can fall out the bottom of the cloud.2
6:10 AM. Light drizzle or rain due to collisions with coalescence rather than due to the ice process falls from yesterday morning’s Stratocumulus deck (fuzzy, misty stuff in the center and right; eyeball assessment). Quite exciting to eyeball. 9:46 AM. So clean and pure looking, these clouds during a brief clearing yesterday morning. These might well have been seen off the coast of Hawai’i. 10:23 AM. One of the Hawaiian like ambiance of yesterday was both the low clouds, the humid air, and the green texture on the mountains highlighted by the occasional ray of sunlight. Fantastic scenes!
11:31 AM. Being a cloud maven, I wasn’t too surprised to see drizzly rain start to fall from our Hawaiian like Stratocumulus clouds, but I was excited!
11:41 AM. Stratocumulus clouds mass upwind of the Catalinas. Hoping for a few drops at least.
12:07 PM. An especially tropical looking scene I thought, with the very low cloud bases, the humid air; the warm rain process likely the cause of the rain on Samaniego Ridge.
6:08 PM. As the day closed, this fabulous scene on Samaniego Ridge. Clouds might be labeled Stratocumulus castellanus.
6:25 PM. As the air warmed in the clearings to the southwest and west of us, King Cumulonimbus arose. Expect some today around us.
Mods still coming up with cold snap at the end of the month, even with rain as the cold front goes by. How nice would that be to finish off September? Still have a couple of days of King Cumulonimbus around as tropical air continues to hang out in SE Arizona. Hope trough now along Cal coast can generate a whopper here before that tropical air leaves us. Am expecting one, anyway, in one of the next two days, probably our last chances for summer-style rain.
Speaking of Odile….
the thought that inches of rain might fall in Tucson, something we all heard about two eveings ago WAS warranted by the gigantic amounts that occurred as Odile slimed its way across extreme southeast AZ. In modeling terms, the error in its track was pretty slight, but the predicted amounts that we COULD have gotten were pretty darn accurate. I did not see these amounts until after writing to you yesterday. Note those several four inch plus values around Bisbee, and the one in the lee of the Chiricahuas. That one 4.45 inches over there suggests to me that the Chiricahuas like got 4-6 inches. Check’em out:
24 h rainfall ending at 7 AM AST yesterday for SE AZ (courtesy of the U of AZ rainlog.org site).
The End
———————— 1Except those affected by Kilauea’s “VOG” which have much higher concentrations, and look a little “dirty.”
2A thousand microns is a millimeter, in case you’ve forgotten, and that’s only about 0.04 inches in diameter. Most raindrops are in the 1000 to 3000 micron diameter range, though the largest, measured in Brazil, the Marshall and Hawaiian Islands, can be about a centimeter in diameter.
