Yesterday was as rare a day in Catalina, Arizona as seeing the marbled murrelet in Olympia, Washington.1
Why?
Our bit of rain (0.12 inches in Sutherland Heights) was only due to that formed by the collision-coalesence process, some times called the “warm rain” process, or more technically, non-brightband rain2.
No ice needed.
Usually clouds at inland locations like Arizona have so many droplets in them , a few hundred thousand per liter or more, larger drops that can collide and coalesce don’t form because the condensed water is spread over so many of them.
So I could feel the excitement out there as that frontal band got closer. Perhaps you saw the drizzle-mist rainbow on the Tortalitas, looked at cloud tops, and saw no ice. If you said you saw some ice yesterday you were mistaken or lying to impress your friends.
Let us review yesterday in clouds:
7:36 AM. Looking toward the Tortolitas at the line of Cumulus congestus approaching Catalina. Can you see the little piece of rainbow just below those low,low cloud bases? Go straight above the white dot marker in the road (Oracle). Cloud bases were usually hot yesterday morning, 15-17° C, and, thus. our clouds were loaded with extra water. The warmer the base, the greater the amount of water that condenses above cloud base. That means drops is bigger, and can reach sizes where bumping together leads to sticking, not rebound as is normal. The usual cloud base is around 5-10° C this time of year. Photo, of course, not taken while driving; that would be crazy. Is just “shopped” to look that way to provide an “action” setting.7:40 AM. Such a pretty scene! Can you see the little bit of lower hanging cloud below the line of Cumulus? It looked like our windshift, cold front line might be on the doorstep. Waited until afternoon to get here, though.7:45 AM. Here’s a closer look at those lower windshift indicating clouds to the NW yesterday. Now you KNOW the front and “FROPA” is getting close. Very exciting scene. But would it rain? No ice was visible anywhere around.7:44 AM. In the meantime, Stratocumulus clouds gathered upwind of Catalina with light rain visible just above the horizon SW/ Was looking for an icy top. to extrude above the Stratocu, but didn’t see one. You didn’t either.7:49 AM. In the meantime, not much is going on over the Catalinas. Notice how much shallower the Stratocu are than just over there by the Tortollitas. Really showed that the lifting zone of the front was so close!8:22 AM. Suddenly, it was raining! If you don;t believe me there are drops on the camera lens in this photo. All this misty rain developed while the author, cloud maven person, wasn’t paying attention. Did that Stratocumulus develop rain, or did that bit of rain above the horizon move in? Maybe this can be answered at the next club meeting.8:25 AM. Starting to lose photo control here, as things closed in, prettyness getting enhanced be passing rays of sun on the greenish Catalina Mountains. How can you not record this? Well, maybe you can go ho-hum, but no cloudcentric person could.8:33 AM. By this time it was all over and 0.05 inches had been logged. Here, those raining clouds zip off to Oracle State Park and vicinity over the horizon. Still looking for icy tops, but haven’t seen any, such as in those Cumulus tops, horizon left. Photos now being taken almost every minute, certainly within every five minutes. Wondering if I need a doctor….?8:47 AM. Rain begins to form on Pusch Ridge from low-based Cumulus clouds. The misty look, lack of a shaft, has you thinking “warm rain” all the way, Maybe of Hawaii, too.
Skipping a LOT of pretty scenes now…..
9:47 AM. Think how special you would think you were when this ray of sunlight bathed you for those few seconds, darkness all around.9:48 AM. Pretty much the same scenes as you’ve already seen over and over again, but this one has a bird in it for the sake of variety.10:33 AM. A little break allowed some nice scenes of the Cumulus congestus on the Catalinas. Notice how low the base is. You could have been hiking in congestus bases yesterday! Very few people get to hike in the base of a Cumulus congestus clouds. You still haven’t seen any sign of ice, either.10:44 AM. Something in the way of a shaft out there over Marana/Oro Valley probably made you start to wonder, “maybe there is some ice up there?” It dissipated quickly before it arrived dropping only a few drops. Still has hard as you and I looked, we couldn’t see any as it came and its remains went. U of AZ computer model soundings at this time had the tops way above freezing. In case you don’t believe me again here is a sample:
Valid for 10 AM, yesterday. Output was from the 11 PM AST model run, a diagram with a lot of writing on it.
11:50 AM. Major windshift line and fontral passage (FROPA) now beginning to make progress toward Catalina along with a line of deeper clouds along it. Was thinking ice might be seen somehwere up there at this time, but nope.11:52 AM. When looking for ice, you want to look at what’s ejecting from the tops of the clouds. Here, that little flat cloud above the Cumulus clouds is the “ejecta” from those showers just starting to hit the Tortolita Mountains. As you can see as a cloud maven person, it does not have a fibrous look, nor are there fine strands of ice dropping from it, as would be the case if ice was present. SO it was another piece of circumstantial evidence that ice was not involved in even those dark clouds toward the Tortolitas, ones that would eventually give us our final bit of rain here in Sutherland Heights, Catalian. This kind of cloud has sometimes been called a “water anvil.” This was a really exciting moment, though most folks would find that hard to fathom.12 Noon. A hard shower has popped up over there toward Marana. Now here’s I would have guessed these must be some ice at cloud top from the narrowness of the shaft indicating a higher cloud top than in the other nearby shower-producing clouds. Does anyone out there have an aircraft and can fly IFR? It would be great to be on standby like days like this and go take a look at cloud top heights.12:38 PM. Stratocumulus, in one of its better presentations; lumpy and widespread.
The rest of the day was overcast, cool with a period of light rain around 2 PM, with the temperature dropping to a remarkable 58° F here in Catalina.
The last TUS sounding seemed to confirm this unusual rain day, indicating that the stratiform tops near and over the site were at 0° C.
Here’s pretty much what the balloon went up through: The TUS rawinsonde, launched around 3:30 PM yesterday. Cloud tops would be where the two lines, temperature and dewpoint temperature, separate.4:04 PM. Looking toward Pusch Ridge and Tucson.
Our final rain total in Sutherland Heights was a respectable 0.12 inches from a rarely observed event. 0.47 inches fell on Ms. Lemmon for the highest amount around.
Might add more later, but am quitting now to go “lunge” and ride a horse..
PS: I have added more, re-written some not so great “formulations”…
The End
1If upon reading that sentence you would like bail on reading about clouds and rain here in Arizona and read about that bird, please consult:
2When steady rain is occurring, returns have a bright band, or a augmented return from the layer in the atmosphere where snow is melting into rain. On days like yesterday, throughout the Tropics, along the West Coast, among many places, non-brightband rain is fairly common. Typically it falls from clouds with tops warmer than -5° C. Ice usually onsets at temperatures between -5° and -10° C in such clouds. Hawaii is a good example where “warm rain” produces most of the prodigious rain totals there on the windward slopes, such as that at Mt Waialeale on the Island of Kuwai where the average rainfall is more than 450 inches!
Former Hurricane ‘Newt’ brought some real humidity, low clouds with unusually warm bases (around 15-20 ° C) to Tucson and Catalina yesterday as its remnant center passed just about over us.
Old Newt was “dragging” here as a tropical storm, aloft it was pretty strong still, brought near hurricane force winds on isolated, high, mountain tops. Mt. Hopkins reached 59 kts from the ESE before the “eye” passed nearby and the winds turned to the west. And in the Rincon Mountains a gigantic 6.39 inches was logged, and a site on Mt. Graham reported 6.43 inches. (Thanks to Mark Albright for these reports.)
While Sutherland Heights received only 0.29 inches in that all day rain, there were eye-popping totals in the Catalinas. Take a look at some of these, Dan Saddle near Oracle Ridge, nearing 6 inches in 24 h! Below, 24 h totals ending at 2 AM this morning, which pretty much covers Newt:
0.28
Golder Ranch
Horseshoe Bend Rd in Saddlebrooke
0.59
Oracle Ranger Stati
approximately 0.5 mi SW of Oracle
0.24
Dodge Tank
Edwin Rd 1.3 mi E of Lago Del Oro Parkway
0.35
Cherry Spring
approximately 1.5 mi W of Charouleau Gap
0.79
Pig Spring
approximately 1.1 mi NE of Charouleau Gap
0.47
Cargodera Canyon
NE corner of Catalina State Park
0.31
CDO @ Rancho Solano
Cañada Del Oro Wash NE of Saddlebrooke
0.39
CDO @ Golder Rd
Cañada Del Oro Wash at Golder Ranch Rd
4.13
Oracle Ridge
Oracle Ridge, approximately 1.5 mi N of Rice Peak
4.25
Mt. Lemmon
Mount Lemmon
1.61
CDO @ Coronado Camp
Cañada Del Oro Wash 0.3 mi S of Coronado Camp
2.17
Samaniego Peak
Samaniego Peak on Samaniego Ridge
5.91
Dan Saddle
Dan Saddle on Oracle Ridge
3.54
White Tail
Catalina Hwy 0.8 mi W of Palisade Ranger Station
3.66
Green Mountain
Green Mountain
1.77
Marshall Gulch
Sabino Creek 0.6 mi SSE of Marshall Gulch
Your cloud day yesterday; we don’t talk about today. That’s for tomorrow.
The day began with one of the great examples of Nimbostratus, that technically a middle -level cloud greeted us at daybreak in what was one of the great examples of the phantom cloud, the true precipitator, usually hidden from view by lower clouds such as Stratocumulus. But, yesterday morning, there it was, “Ns” naked as could be. I know many of you have been looking for a good shot of Nimbostratus to add to your cloud collection for a long time and I could feel the joy out there when I saw it myself. I only took a couple of shots myself, wish now I had taken more of an extraordinary scene.
6:49 AM. Nimbostratus! Note how high the bottom is, a bottom marked mostly by falling precip, usually snow because steady light rain is so relatively transparent.6:52 AM. Looking NNW toward parts of Saddlebrook/Eagle Crest developments. Notice the nice, relatively uniform, blurry gray, the “blurry” look due to falling rain, the perceived bottom, at the melting level, snow is melting into rain. In winter, therefore, the “bottom” or base of Ns, absent lower clouds, appears lower to us because the snow level is lower.
Then, as the light rain here moistened the air hour after hour, low clouds, such as Stratocumulus and Stratus fractus began to form along the mountains, producing some interesting “tracers” of the chaotic air movement over there by the Catalinas under nearly calm conditions. Newt disappointed in his wind accompaniment.
1:41 PM. Stratus fractus clouds lined Samaniego Ridge, Stratocumulus or weak Cumulus topped it, with a higher layer of Stratocumulus above that, That highest layer was once the much deeper Nimbostratus, but now has lost its deep part, so its no longer “Ns” since its not precipitating.1:42 PM. The deep stratocast has departed, the remaining clouds in the foreground are Stratocumulus. The darkening bases on the horizon southwest of Pusch Ridge are where Cumulus and Cumulonimbus clouds filled with rain are piling up, likely due to the light winds coming together down there, maybe in the low center that was once “Newt.”
Later in the day, as the highest, coldest cloud tops associated with those beautiful Nimbostatus clouds moved off to the NE, and our cloudscape became a mix of deeper Stratocumulus with Cumulus and isolated Cumulonimbus cells, they produced true drizzle and misty, visibility-reducing “warm rain”, that rare type of rain that falls here from clouds lacking in ice, began to be observed producing Hawaiian looking rain on our mountains, delicate shafts of rain whose small drops slanted away from the base.
2:32 PM. Misty drizzle and very light rain! When did this transition happen?2:32 PM. Hard to tell the difference here in a photo between the pure, naked Ns, and this lower drizzle,misty rain producing cloud likely topping out well below the freezing level. I’ve seen these transitions before, but I missed this one, where a Stratocumulus deck starts to look a little fuzzy on the bottom as the drizzle, very light rain starts to come out (due to tops rising, drops at the top getting larger, at some point crossing over the “Hocking” droplet threshold of larger than about 38 microns in diameter, where they begin sticking together when they hit). Here, the transition from non-precipitating Stratocu to I-don’t know what has already taken place during between the photos at 1:41 and 1:42 PM. Should drizzly, relatively shallow clouds like these now be termed, Nimbostratus? Or Stratocumulus praecipitatio,to emphasis the shallowness? A question definitely for the cloud philosophers to haggle about. No member of the cloud maven club would be punished for calling this scene one showing “Nimbostratus.” However, the drizzle and very light misty rain should have told you it was from a far different cloud structure than that associated with true Nimbostratus, always a deep cloud with ice in it, often topping out at Cirrus levels.
Here, you might well erupt with, “This doesn’t look like Hawaii, but Ocean Shores, Washington, or some other coastal location along the West Coast on a spring day having Stratocumulus with drizzle!”
You would be correct in that eruption.
Below, an example of drizzle drops on your car’s windshield:
3:50 PM. The tiniest drops you can make out on the window are drizzle drops. I focused on them and you’ll have to click on it to get the full size to be able to see them. I was so excited to see some more of them!
Later, it was to look little more “Hawaiian”, but if you’ve been to Hilo, you know its mostly cloudy all day.
“Warm rain” or rain due to the colllision-coalescence process, is also mainly associated with “clean” conditions, ones low in aerosol particles that can act as cloud condensation nuclei. The fewer the “CCN” the fewer are the droplets in clouds, and the larger the individual cloud droplets are when saturation and cloud formation occur. So, by yesterday afternoon, certainly, it was doggone clean here, no doubt aided by washout in that light rain we had.
Particularly heavy rain with low visibility fell just south of Catalina yesterday afternoon around Ina and Oracle just after 4 pm. However, that rain did not have those HUGE drops that we see from unloading, deep, Cumulonimbus clouds making this observer think as heavy as it was, it may have been due to a Cumulonimbus topping out at less than 20,000 feet, where the temperature would have been too warm for ice. The 500 mb temperature yesterday was a tropical-like -3.7° C on the TUS sounding, almost unheard of with a rain situation here. This, another sign of tropical Newt, since tropical storms/hurricanes have warm cores.
lacking in those huge drops we see in our thunderstorms, this rain likely formed from the “warm rain” process except maybe in the very heaviest rain areas. It was a special day.
You probably noticed how quiet it was; no thunder around, for one thing, indicating the updrafts in the clouds were not very strong, and that was another indicator that the clouds may not have contained ice. Without ice, hail and graupel, soft hail, you don’t have lightning.
The lack of lighting, the all day off and on rain, such as you might experience at Hilo, Hawaii, on the windward side, made it seem like you were in Hilo, Hawaii, or one of the other wet spots on the windward side of the Island.
3:27 PM. Another, to me remarkable misty scene reminiscent of oceanic and coastal Stratocumulus with drizzle and light rain3:52 PM. In the meantime a much deeper cell had developed to the SW of us, down around Ina and Oracle, where an inch and a half of rain fell. Look how the bottom is so close to the ground, like at a temperature near 20° C, about as warm as a cloud base can be here! And the warmer the base, the more water is going up into that cloud! Very exciting scene! Well, they all are to people of cloud maven persuasion.4:24 PM. Into the bursting cloud. Still, drops were not HUGE, as you would expect, but extremely numerous, rain rate over an inch an hour in the heaviest parts. Was taken I around Oracle and McGee, and of course, not while driving. That would be crazy. Only looks like it.6:32 PM. One of the more Hawaiian looking scenes, fine trails of rain dragging along the Catalina Mountains. The slope of the rain coming out absent much wind down low tells you the drops are small, probably near drizzle sizes. And the “shaft” if you will, is diffuse, indicating the small drops are spreading out due to the little turbulence there was making it fuzzy around the edges. Maybe, anyway.
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.
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.
————————————
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.
Odile passed to the S and E of Cat land, leaving only 0.13 inches here in the Heights, the Sutherland ones. Didn’t even get the half inch I hoped for. Oh, well, we can be happy for the droughty areas of New Mexico that got the brunt of that tropical system as did portions of extreme SE AZ. You may know that for many days in advance and up until 11 PM the night before last (shown here), our best models had O practically passing right over us with prodigious rains indicated.
Unfortunately, we meteorologists often “go down with the ship” when this happens due to model forecast consistency. Only in the last minutes, so to speak, did the model runs get it right (but too late to be of much use) and finally indicated that the true path of the heaviest rain was NOT going to be over us, as was already being discovered via obs. O was such a cloud mess, the mods may have been off in locating where the center was. Not sure. Will have to wait for the panel report.
Seems to be preciping on the Cat Mountains right now, though doesn’t show up on radar, so its likely a RARE “warm rain” event here in AZ where the rain forms by collisions between larger cloud drops to form rain drops and the cloud tops are low1. Maybe that’s O’s legacy; tropical air and a warm rain day sighting.
BTW, whilst Catalina and most of Tucson didn’t get much, it has continued to rain steadily in our mountains over the past 24 h with Dan Saddle, up there in the CDO watershed, leading the way with 2.09 inches in 24 at this hour (5 AM) and its still coming down lightly, as noted. Its been a fantastic rain since it was steady and soaking up there over that whole 24 h period, much like in our winter storms. Below, some totals from the PIma County ALERT gauges. You can see more totals here.
Gauge 15 1 3 6 24 Name Location ID# minutes hour hours hours hours —- —- —- —- —- —- —————– ——————— Catalina Area 1010 0.00 0.00 0.00 0.00 0.16 Golder Ranch Horseshoe Bend Rd in Saddlebrooke 1020 0.00 0.04 0.04 0.04 0.20 Oracle Ranger Stati approximately 0.5 mi SW of Oracle 1040 0.00 0.00 0.00 0.00 0.12 Dodge Tank Edwin Rd 1.3 mi E of Lago Del Oro Parkway 1050 0.00 0.00 0.00 0.00 0.16 Cherry Spring approximately 1.5 mi W of Charouleau Gap 1060 0.00 0.00 0.00 0.00 0.16 Pig Spring approximately 1.1 mi NE of Charouleau Gap 1070 0.00 0.00 0.00 0.00 0.04 Cargodera Canyon NE corner of Catalina State Park 1080 0.00 0.00 0.00 0.00 0.20 CDO @ Rancho Solano Cañada Del Oro Wash NE of Saddlebrooke 1100 0.00 0.00 0.00 0.00 0.08 CDO @ Golder Rd Cañada Del Oro Wash at Golder Ranch Rd
Santa Catalina Mountains 1030 0.00 0.04 0.04 0.08 1.73 Oracle Ridge Oracle Ridge, approximately 1.5 mi N of Rice Peak 1090 0.00 0.00 0.04 0.04 0.75 Mt. Lemmon Mount Lemmon 1110 0.00 0.00 0.00 0.00 0.43 CDO @ Coronado Camp Cañada Del Oro Wash 0.3 mi S of Coronado Camp 1130 0.00 0.04 0.04 0.04 0.31 Samaniego Peak Samaniego Peak on Samaniego Ridge 1140 0.00 0.08 0.28 0.35 2.09 Dan Saddle Dan Saddle on Oracle Ridge 2150 0.00 0.00 0.04 0.08 0.71 White Tail Catalina Hwy 0.8 mi W of Palisade Ranger Station 2280 0.00 0.04 0.12 0.16 1.02 Green Mountain Green Mountain 2290 0.00 0.04 0.04 0.04 0.47 Marshall Gulch Sabino Creek 0.6 mi SSE of Marshall Gulch
BTW#2, true CMJs (cloud maven juniors) will want to photograph the rain from these shallow clouds, this rare, Hawaiian-like rain event2, lining the Catalinas this morning as soon as its light enough. It would be like photographing a parakeet on your bird feeder here in Catalina, one migrating from South America. I think that’s where they come from. Anyway, your cloud-centric friends from other part of the world would be quite interested in seeing your photos of this.
Is the summer rain season over?
No way! (But you already knew that, though it sounds more exciting to put it that way, in the form of a question like the TEEVEE people do)
Now we get into some interesting weather times as we go back into the scattered big thunderstorms feeding on the moist plume that accompanied O. That moist plume will be around for the next few days. These coming days, with their thunder squalls, may well be the most “productive” ones for rain here compared to the piddly output of O here in the Heights. We have upper air goings on that are likely to make storms cluster more into big systems a time or two during the next few days instead just the one over here and over there kind of days, the ones you hope you get lucky on to get truly shafted. So, “fun times at Catalina High” ahead, to paraphrase something.
Yesterday’s clouds
11:15 AM. The look of a stormy sky: Stratus fractus lining Samaniego Ridge, orogrpahic Stratocumulus topping the Ridge, overcast Nimbostratus producing R– (very light rain).4:56 PM. By afternoon the deeper clouds were gone leaving Cumulus, a couple of distant Cumulonimbus clouds with their rain shafts, and an overcast of Stratocumulus or Altocumulus, no precip coming out of them.6:28 PM. The sunset, while OK, like O was a little disappointing since more clouds could have been lit up by the setting sun but weren’t.
The weather way ahead
Cool weather alert: based on model consistency, which I have already discredited earlier, there are cold snaps now appearing for the end of September and early October. They’ve shown up in a couple of runs now. They have some support in the NOAA spaghetti factory plots.
The End.
—————————–
1There’s a nice description of “coalision” , the warm rain process not involving ice, in Pruppacher and Klett (1998) if you really want a nice book about cloud microphysics in your library.
2Mostof the rain that falls in Hawaii falls from relatively shallow clouds with tops at temperatures above freezing, no ice involved, contrary to the usual situation here where ice is necessary.
First, a tedious note about the Big One of two days ago.
While the Davis Vantage Pro 2 tipping bucket gauge registered a whopping 4.18 inches, a smaller plastic gauge from CoCoRahs here had 4.63 inches, after subtracting some rain (half an inch) I forgot to dump due to a brain cramp. A neighbor a couple hundred yards away here in Sutherland Heights, measured 4.65 inches in her gauge, and I now think that the 4.63 inches is the correct amount of rain for this spot. This goes with two other reports of 4.48 inches at Our Garden, and another one of 4.50 inches just a bit on the west side of Lago del Oro Parkway, and the 4.59 inches at the Samaniego Peak ALERT gauge just E of us. We seem to have been in the heaviest band of that storm! (Makes up for all the misses during the summer.)
The Vantage gauge is mounted above the ground, and some loss occurs due to wind, and also when the rain falls too hard, the tipping bucket can’t keep up. The CoCo gauge is ground mounted, and is protected from wind by surrounding natural desert vegetation (aka, “weeds”).
Below, from the University of Arizona’s rainlog.org, is a map of rain totals in our area and the northern areas of TUS. (The Our Garden and Samaniego Peak totals of 4.48 and 4.59 inches, respectively, don’t show up because they are not members of rainlog.org but probably should be so’s we can get all the rain we want to see in one site! I have added those values
Rain totals for September 8, 2014. The green values are for Our Garden and Samaniego Peak, along with the revised total for Sutherland Heights. Recall a neighbor here measured 4.65 inches!
In the meantime, from CDO at Wilds Road videos I took in heavy rain as the Sutherland Heights rain started to eclipse 3 inches, this larger wave that formed. I think it could have been surfed.
10:55 AM. From a frame of a video taken at the CDO wash and Wilds Road intersection, this monster. Must have been 6 feet high in total height! So, you CAN “surf Arizona!”
Yesterday’s clouds
First of all, it was real disappointing to see so much haze in the air after so much rain! Not sure where it came from yet, will have to do some back trajectories to find out, but later…
6:14 AM Sunrise Cumulus6:54 AM. Crepuscular rays outline a Cumulus turret.6:54 AM. Distant Cumulonimbus offers hope for a similar scene later in the morning over the Catalinas, a scene that was NOT realized.8:17 AM. A great example of crepuscular rays and bad air.12:53 PM. Promising Cumulus congestus that really went nowhere.2:03 PM. However, it was not a completely rainless day, as can be seen, “dead ahead.” Some clouds got thick enough to rain lightly. In this Arthur’s opinion, this rain was due to the collision with coalescence rain process, not the ice one which I deem with a 51% confidence level.4:26 PM. Kind of losing interest in the whole day now as Cu disappear in favor of an Altocumulus opacus deck, one originating right out of Norbert if you saw the satellite imagery.
The weather ahead
Still pretty confident in more summer rains and tropical air after the current dry spell of a few days, this partly associated with the next tropical storm, likely to be named “Opal” or something like that with an “O” as it takes shape. Of course, we could look up what name it will be, but it will be named soon enough, so why bother?Its already a numbered tropical depression (a weak area of low pressure) down there off Guatemala now.
Today will be a special one in the desert. Cumulus bases are going to be really LOW for summer, maybe only 3-4 kft above the ground, and likely warmer than 15 C (50 F). Maybe 50 F doesn’t sound special, but it is. A base temperature of summer clouds that warm is rarely observed here. And with that, and all the posts here about the temperatures that ice forms (around -10 C, 14 F) are out the window. Ice will form at much higher temperatures than usual.
This is because on a day when the Cumulus bases are that warm, rain forms by collisions between droplets before clouds even reach the -5 C (23 F) level, the highest temperature at which Ma Nature can produce ice. Rain mgiht even form in our clouds today even before the freezing level itself!
This is so exciting for an Arizonan who has studied ice-in-clouds development over the years because today ice will form in clouds around the -5 to -10 C level, and the mechanism of Mssrs Hallett and Mossop will be heavily involved as well as other lesser understood mechanisms to form ice in clouds today. And, along with that high ice-forming temperature will be categories of ice crystals that are rarely seen here, needles and hollow sheaths, ones that form at temperatures in clouds warmer than -10 C! You can see how excited Mr. Cloud Maven Person is. For comparison, it would be like a bird watcher seeing a _________, something pretty rare go by.
Dewpoint temperatures are running in the upper 60s and was 70 F (!) at TUS earlier this morning! Indicative of a really, really moist day from a cloud standpoint even now is that line of Stratus fractus cloud halfway down on Samaniego (Sam) Ridge. And this is BEFORE rain has fallen. Not too unusual to see something like that AFTER a good rain, but before, its pretty rare.
All in all, a very tropical day ahead, very “Floridian” I would call it, and that means more water in the clouds above us ready to fall out, and more “fuel” to send those warm plumes of Cumulus turrets spaceward. That’s because heat is released to the air around cloud droplets as then form, and the more “condensate” the more heat. The warmer the cloud bases, the more condensate that occurs. Its quite a feedback loop.
The last time we had bases this warm and low, some “lucky” areas got “Floridian” dumps of rain, that is, 3 inches in an hour. (Three inches in an hour is pretty common in Florida in the summer.)
However, need some heating and/or a good symoptic situation to gather up the clouds today if we are to get more than just high humidity from Norbert’s remains. Last night’s model run from the U of AZ was not real supportive of a great day because while the humidity is here, and upper level situation is going in the wrong direction, is not going to help much. A lot of what we needed was expended over night in huge storms that are raking central and northern AZ now, with some sites in PHX reporting up to 2 inches since midnight! And as that upper air configuration responsible for their great rains moves away, what’s right behind it up there, will try to squash clouds.
So, while we have the ingredients down low for an exceptional rain day, its not in the bag. What’s worse is that drier air is now foretold to roll in from the west by tomorrow, further diminishing (not eliminating, though) the chances for a decent rain here in Catalina. “Egad”, considering all the promise that “Norbert” once held for us!
So, in sum, a bit clueless here as to what exactly kind of day we’re going to have. “Truth-in-packaging” portion of blog. I see rain has formed just now (6:41 AM) on Samaniego Ridge, AND to the S-SW, very good sign!
—a note on air quality—as inferred from visibility in a humid situation——–
Another thing you will notice is how clean the air is. We have tremendous humidity, and unlike smog-filled air back east, the sky will be blue, and the visibility good. If you’ve ever been back East, you’ll know that in most areas the sky between the clouds on humid days is pretty white, and horizontal visibility is reduced in the moist air, say ahead of a cold-cool front in summer. This is due to large haze particles that have become droplets before water saturation has been reached, a phenomenon called deliquescence. Its horrible. Really ruins the sky back there on humid days.
Enough semi-technical blather. We’re mostly about pretty cloud pictures here.
Yesterday’s clouds
There were some spectacular scenes yesterday, even though it was disappointing as a rain day, only a late afternoon trace here in Sutherland Heights. Here are some of the best.
6:34 AM. Altocumulus lenticularis hovers over and a little downwind of the Catalinas.10:03 AM. First Cumulus begin to form on the Catalinas, later than expected. I will using the words, “expected” and “unexpected” a lot today.1:21 PM. First ice seen, lower left top of blue sky and cloud border. Can you see it?1:24 PM. Soon after the first ice is seen, out pops the rain, that very faint haze in the center of the photo.2:12 PM. Mt Lemmon receiving 0.79 inches of rain in about an hour from this little guy. Note that the peak is TOTALLY obscured by this rain shaft.12:24 PM. Cumulus clouds kind of muddled around up there when yours truly was expecting a sudden eruption at any time. Really did not happen yesterday.12:26 PM. Mostly just a pretty scene, the blue sky, the Altocumulus perlucidus, and the Cumulus congestus erectus.4:17 PM. It was especially gratifying, after kind of a non event day, to have this unexpected late eruption of a Cumulonimbus NW of Catalina. Meant chances weren’t quite over for nearby developments.5:03 PM. Cumulus cloud street trails off the Catalinas. Will it do anything?5:21 PM. The ragged edge of the higher layer leads to a series of crepescular rays in the falling rain, while the Cu congestus turret sends a long shadow Catalinaward, A gap in the clouds allows the sun to shine on the rain falling in Oro Valley then. Can you imagine how great the rainbow was on the other side, say from the Tortolita Mountains? The rainbow isn’t seen in the forward scattering direction because its due to reflected light back toward the sun from within the raindrops.5:22 PM. Nice lighting on Samaniego Ridge, rainbow imminent,5:24 PM. Magnificent, the lighting, the rainbow. How lucky we are to be here!6:56 PM. Just when you thought the day was finished, this surprise. Well, it was to me, that’s for sure!
6:58 PM. Ghostly-like late blooming Cumulonimbus calvus and Cumulus congestus clouds rise up against the falling temperatures. Pretty neat sight.[/caption]
6:58 PM. More unexpected strong developments to the west after sunset.
The End!
Heck, if I worked on this much longer, the answer to what’s going to happen today would be in!
I wonder if you caught it? Fell between 8:10 and 8:12 AM. Very isolated, and pretty small drops. If you weren’t driving in it, or outside, you would never have known this happened. But observing and reporting events like this is what makes us who we are, you reader of CM. We take pride in seeing and observing what others don’t.
8:12 AM. Photographic documentation of the total rain event on a car window, zoomed view. The largest raindrops are about 1 mm in size.
Before the rain hit, some two or three RW– (weather text version of “very light rainshowers”) began to fall to the SW of us from that deck of Stratocumulus clouds. Must have been where the tops were higher than anywhere else. Here’s the first sign, and upwind of Catalina, that you, as a CMJ (cloud maven junior) know to pull your car out of the garage. (BTW, thinking about having a CMJ cookie drive next month…so look around for your best recipes.)
7:42 AM. A full 30 minutes before the trace event in Catalina, a weak shaft of rain is observed on Twin Peaks, part of a broken line of sprinkles-its-not-drizzle rain.
It may seem strange, a non-sequitor, for those blog passersby to be talking about taking your car out of the garage or carport if a slight amount of rain might occur, as was the case yesterday. Here’s the “skinny”, as we used to say in the last century when we were young and could do things: a “clean” car, one that been wiped of all evidence of prior rain drops, but one having a thin coating of dust (you don’t have to apply a thing dust layer, its goes with the territory here) is great as a “trace detector.” And for us, CMs and CMJs, observing a trace such as yesterdays, when ordinary observers miss it (fumble the ball), is like hitting a low outside slider from former Husky pitcher Tim Lincecum, for a game winning touchdown. Or Boise State beating Oklahoma in a bowl game.
Why not just use the radar instead of parking your car outside and if the 24 h depiction of precip shows an echo over you, just mark yourself down as having a “trace”?
That would be cheating! Besides, some echoes seen on radar are only aloft.
And what if you’re in a “data silent” zone, where the radar beam is blocked by terrain, or is too far away? You’re adding unique information with your trace. Sure, nobody around you really cares if you had a trace or not, but, what the HECK.
8:01 AM. Heavy looking cloud produces sprinkle on the Tortolitas. Looks so dark partly because of the time of day, and partly because there was a fair amount of aerosol in the air. When higher aerosol concentrations get into clouds, it causes the drops in them to be small, and when small, they reflect more light off their tops and the bottoms appear darker. But it also indicates that the clouds are thicker than surrounding clouds, there’s a mound on the top. Still, among those higher droplet concentrations must have been drops large enough to collide and stick together and become small raindrops.
Did the tops reach -10 C or so to form ice and cause this shower? Nope. Capped out at 0 to -5 C, so almost impossible to have had ice form to cause our sprinkles. Check this sounding from the WY Cowboys, who are off to a good season BTW.
The Tucson sounding for 5 AM AST yesterday morning during our cloudy conditions.
In examining this TUS sounding closely, its good to remember that we are NOT Tucson, but in Catalina. We are 14 miles from the city limits; have a road sign that sez so. “Hey”, we aren’t even on the same side of the mountains as is “Tucson.” In fact, you have to go through the city limits of Oro Valley to get to Catalina! Only the Post Office thinks that Catalina is in “Tucson.” OK, got that in…
And, during the cooler season when troughs go by, as yesterday, the temperature profile from Tucson balloon is not accurate for us here in Catalina; its always that bit colder to the north and west of the balloon launch site for days like yesterday. So, like a chef, adding that bit more of butter or garlic, OUR sounding should be tweaked from the TUS one to show slightly higher and colder cloud tops, probably near – 5 C, not at ZERO or slightly cooler in overshooting Cumulus/Stratocumulus tops as would be expected from the Tucson sounding. Also, since it sprinkled at 8 AM, and not 5 AM, its also likely that clouds tops were going up some as the trough from the west approached yesterday. So there are lots of possibilities.
Sure wish we’d had a PIREP! (Texting form of, “Pilot report”). Any CMJ’s out there have an aircraft that we could take up and kind of poke around up there, see for sure what really happened instead of “hand waving”?
Absent aircraft reports, I am going to say that almost certainly yesterday’s sprinkle was a case of rain formed by “collisions with coalescence, or via the “warm rain” process (called that because it doesn’t have ice), sometimes called here, “coalision” rain. Very unusual in Arizona and, you can see that if you have to park your car outside to see how much came out of a cloud producing rain through “coalision”, it doesn’t amount to much.
You know, this is a great story for you. First, you observe rain that no one else did, or even cares about, until maybe you tell them it was almost certainly caused by collisions among cloud droplets, and then watch their eyes bug out!
Had some spectacular highlights again on the Catalinas, and also evidence of the aerosol loading as we say, in the crepuscular rays (colloq., crepsucular) shown below.
8:03 AM. Evidence of smog, maybe some dust, too, aka, aerosols that were getting into our clouds yesterday.8:04 AM. Gorgeous highlights continuously moved across the Catalinas. Hard to stop watching, snapping photos like mad, HD filling up, not much room left, gasping for more empty sectors now.
1:39 PM. Its all over. Only a field of small Cumulus (“humilis”) are left. Photo taken from inside a horse corral to give it a western flavor, make it more accessible to reader, maybe make you feel more comfortable after a heavy dose of “science-hand waving” today. Note rust on panel piping; adds artistic content. “Rusty corral and Cumulus humilis”; yours today only for $2,000.
Since there is STILL no rain indicated for the next 15 days in the models, just dry (for now) trough passages, I may have to discuss yesterday’s sprinkle again tomorrow. Thinking of a title even now: “That sprinkle; more insights on what happened.” Yeah, that should do it.
Maybe they sneaked up because I wasn’t looking. After posting yesterday just after 5 AM, went out side and looked at the Catalina Mountains, that is those parts I could see through the thick rain shafts, and said, “WHAT!!!?” I was STUNNED to see them; had not even looked at the radar imagery for a couple of hours. Really was asleep at the keyboard.
And then the hour or so of rain that followed, with no lightning! Rain is so rare here om the morning in the summer, and it was so substantial. If there was a disappointment, a slight one, it was that Cargodera Canyon (NE corner of Cat State Park) with 0.87 inches, and the bridge at Golder Ranch Dr and Lago del Oro (0.71 inches) got so much more than we did here in Sutherland Heights in the past 24 h (0.38 inches). They were hit harder, too, by that late afternoon Cb that drifted off Pusch Ridge, again, a heavy shaft of rain with no lightning–how often have you seen that in a summer afternoon?
For a roundup of Pima County rainfall totals, go here.
It was, with its high concentrations of drops, a rain reminiscent of coastal Washington State in the early fall when offshore waters are still pretty warm, or Hawaii, for that matter, the latter location where most of the rain forms without ice. Our high concentrations of rain drops was also likely due to forming, at least partly, through the “warm rain” process, one that does not require ice, and is VERY rare in Arizona. Requires really warm cloud bases, and we had them yesterday, with bases around 60 F, 15-16 C, not too much cooler than you would find hovering over you in New Orleans or Miami, or Merida, Mexico, etc., places where warm rain develops routinely along with ice in the deeper clouds.
Here are some scenes from our huge, and low based, soft-looking, “soft serve” Cumulonimbus clouds, ones that looked that way because updrafts are weak for such deep clouds. You will see that updraft weakness in these photos.
This will seem strange, but I thought yesterday, with its absence of thunder until around dark to the NE, was one of the most unusual days I have experienced here in the summer, so reminiscent of the clouds in the Marshall Islands near the Equator that we (the U of Washington’s research aircraft) flew into during a ’99 field project down there; low, warm bases, high visibility under them, and clouds with weak updrafts and little lightning (the plane was only struck twice during the program):
11:44 AM. After the rain, this gentle giant. No anvil, frosty glaciated slides that kind of slope upward, all indicative of relatively gentle updrafts, a situation that limits the amount of electrification that can build up in them. I was in awe of how pretty this was, and how unusual its appearance was, too. Had to stop, jump out in the mud and grab a shot.
11:46 AM. A closer look. I am just beside myself at how tropical this scene is, so I took another shot. Took too many photos yesterday, too.2:31 PM. Another tropical-looking scene on the Samaniego Ridge. Cloud bases are running about 15-17 C here, 59-62 F. Coulda been taken in the hills around Luzon, Phillipines. Note itty bitty rain shaft. Without doubt that from drops colliding and sticking together (“warm-rain process), no ice needed for those clouds to start raining yesterday. I hope you enjoyed this unusual day as much as I did! It was like being transported to a REALLY warm and humid climate, and yet, here we are in a desert!3:06 PM. Maybe the “Dump of the Day”. It was beginning to fade at this point, and as it approached Catalina, I listened intently for thunder, but none was heard. This, too, made it so “tropical oceanic” since those huge clouds with their weak updrafts, hardly ever have lightning. But I have never seen a shaft like this in the afternoon here sans thunder, making the day that bit more unusual, and special. I will never forget you, August 29th, 2013.6:43 PM. Just the condensation of the water, and the accompany release of a little heat was enough even in the evening to send small clouds shooting upward, another sign of warm based clouds. The warmer the base, the more water is contained in the droplets that first form, and the more heat that is given off to the air next to the droplet. Those clouds were magnificent last evening on the Catalinas! There was yet another Cumulonimbus beyond the mountains, too.6:45 PM. Just two minutes later, I was thinking about that curry dish with mushrooms. I guess it shows how flexible the human mind is, going from this to that.
Well, that’s about all we have time for, kids, and the hour of the exede.com choke hold, 5 AM approaches, and its too frustrating to be on the Web after that. May dredge up a Kwajalein shot at some later point, for comparison purposes, though.
——Today——-
Dewpoints are still running very high, even several 70s in the state (68 F here in the Heights). And so, with luck and no drying and no appreciable changes evident, we’ll have another day in the Phillipines, or the Marshall Islands, or Puerto Vallarta, New Orleans, Miami, Panama, etc. Enjoy.
