The first t yesterday, from growing clouds topping Mt; Lemmon was at 9:30 AM, the earliest such event of the summer. Cumulus that grew immediately into Cumulonimbus clouds, then one cell after another in a continuous stream came off Mt Lemmon with no breaks in the dark bases above the spawning area. Had never seen that before. Usually there are breaks between cells, a brief clearing on even the most active days. And those cells really must have sprouted upward around 11:10 AM when, finally, a second blast of thunder occurred. After that grew much more frequent, and by early afternoon, it was almost continuous. Very exciting, as steady rain fell here.
Here in Catalina Sutherland Heights, we were the beneficiaries of the more stratiform (flat, dissipating) part of those Cumulonimbus that stayed rooted on the mountains. Those flat portions provided a more or less gentle rain amounting to 0.18 inches here. However, more than an inch fell in the Mt. Lemmon and Samaniego ALERT gauges. You can see more rain data here from the U of AZ rainlog. org home page. It is a certainty that some mountain sites got considerably more yesterday if you saw the repeated dense shafts of rain S of Samaniego Peak, where 1.10 inches fell. Guessing the peak (but non-measured total) was more like an 1.5 inches. This should recharge many of the normally dry creeks and streams on the Catalinas, and keep the green coming.
Another aspect, making yesterday one of the best visually pleasing days was the absence of haze and smoke. The sunlit Cumulus clouds that were forming away from the mountains and over Oro Valley were especially, pristinely white and gorgeous; took your breath away to see them piling up so high, and so purely, brilliantly white, so clean looking.
Here are some shots from yesterday, beginning with some “morning castellanus”, which were nice to see, too:
7:50 AM. Always a hopeful sign, Altocumulus castellanus float lazily to the north of Catalina.8:27 AM. Altocumulus castellanus growing into sizes that they would now be called, Cumulus clouds. Those very flat bases tell you that they are not from plumes of warm air from the ground, but are associated with a moist layer that’s being gently lifted. Its clouds like these that produce our dawn thunderstorms and showers from time to time, and indicate there’s a disturbance in the area lifting the air. It was another hopeful sign of a significant rain. These clouds, unlike the ones that were starting to grow over our mountains, tend to dissipate lin the morning hours after the sun comes up and burns them off.8:12 AM. In the meantime, actual, ground launched Cumulus, from the slight amount of morning heating, were already starting to puff up from Ms. Mt. Lemmon. This was really unusual. You can tell that these are “real” Cumulus because such ground plumes of warmer air produce more irregular bases and scattered shred clouds, show more turbulence (movement) when you watch them than Ac cas clouds, the latter seeming to be almost motionless. Bases of these starting Cumulus not too much different in height than the castellanus clouds in the prior shot. Looks like today will be a big day for captions, if nothing else!
9:25 AM. The first Cumulonimbus is about to announce its presence with a thunderblast. No precip evident here, but aloft, next shot, is the “ice” in the overhanging anvil.9:25 AM, overhead view showing that this buildup had already deepened upward enough to form ice, and was about to let go of some precip. See arrows.9:31 AM. Seconds after first, and completely unexpected thunderblast. Didn’t look big enough. Top of Mt. Lemmon is obscured in heavy rain.
11:13 AM. Finally a second blast of thunder occurred in this cell, though one rain shaft after another drifted across the Catalinas, fading away as they continued across Catalina and Oro Valley.11:14 AM. A look at the downwind part of these storms where only the deep, flat portion remains. Yesterday we were lucky since it is often too dry underneath these portions for the rain aloft to reach the ground. Steady light rain was occurring at the time of this photo, while deluges were taking place on Samaniego Ridge. Rain from these Cumulonimbus portions shown here is mainly due to melting snowflakes while the strong shafts are produced by melting hail and or graupel,that began as as frozen drops or ice particles that subsequently get heavily rimed (coated with ice) as they collide with supercooled drops in the vigorous rising portions of Cumulonimbus clouds, finding their way down as the updraft weakens or collapses entirely. I can;t believe how big these captions are getting, but it can’t be helped.11:27 AM. While things were “humming” along from the Catalinas, Cumulus arose elsewhere in a hurry, producing this gorgeous scene. This cloud is a Cumulonimbus calvus, that short-lived stage when a congestus begins to form ice in its top, but has not gotten to an obvious fibrous stage. That ice is present is seen in the rainshaft already pouring out of this cloud. Can you see that the very top is ice?
6:52 PM. As with many active days, yesterday ended with “debris” clouds from the many Cumulonimbus clouds that formed early in the day, providing a comfortable, overcast evening. The clouds are Altocumulus, at two different levels, with an Altostratus overcast above. Who says Arizona is unbearable in July? Some of the most pleasant days of the year are now.
Today is supposed to be another early starter as well with rain on The Lemmon before noon, the model runs at the U of AZ from last night say. However, the longer term model runs indicate a break in the summer rain season for a few days after today. I guess that’s when our weather can be that bit unbearable here in July. Phooey.
Cloud bases were very warm again yesterday, 15-20 C (59-68 F) paving the way for thunderstorm rainfalls similar to those seen in the Southeast US, inches in an hour or so. Didn’t happen locally, but just to the north of us toward Park Links Road and up toward the Florence area, likely happened as one giant cell after another formed between Saddlebrooke and Florence.
Those were the only clouds that produced thunder yesterday. Less vigorous clouds rained, but didn’t have the ingredients to be thunderstorms, stronger updrafts, apparently. Also, at times it appeared some of the rain, to this eyeball, was “warm” rain, rain formed without ice, a rarity here in Arizona (something that happens all the time in Hawaii, and over the oceans.)
And if you were sharp, you saw something happen yesterday that is also quite rare; the clouds erupt in our vicinity into Cumulonimbus by 9 AM from surface heating (they weren’t those nighttime showers that tend to fade as the sun comes up). That was exciting because when they took off, it seemed like a day destined to have giants here.
But then something happened, drier air began to move in from the east, and pretty soon, the ONLY large clouds were to the west and north, a sure sign a disturbance aloft was moving through and less favorable conditions for rain would follow it, the normal “couplet”, or sequence.
Sure enough, the clouds over the Catalinas, after such an auspicious start, struggled to grow into Cumulonimbus clouds, as they did elsewhere to our southern flank, while we watched one magnificent Cumulonimbus after another rise up to the north.
Fortunately, a moistening and destabilizing regime of air is moving this way from Texas across northern Mexico toward Douglas, and so our day here in Catalina should be more enlightened, by lightning.
Yesterday’s clouds
6:15 PM Cumulus congestus forms over Oro Valley in smoky air. Died away in 20 min. Nice, isolated example of that cloud, anyway.1:42 PM. Another one of the large Cumulonimbus capillatus clouds forms just north of Saddlebrooke.1:36 PM. Looked like a promising sign that the clouds on the Catalinas might still erupt into Cumulonimbus after the brief shower an hour earlier. But no. Looking like someone exulting over a three-pointer, hands raised, it turned out to be a case of cloud erectile dysfunction. It flopped back down in minutes. HELL, we can talk about things like that because we hear about them all the time during our favorite TEEVEE shows! BTW, “TV party tonight!”12:27 PM. The very most hopeful part of yesterday. Forming over Charoleau Gap was this beauty. I thought I was going to see the first strands of large drops/and graupel pour out of it at any moment. I was so happy then. But then, only misty-looking rain fell out, no strands, filaments, suggesting maybe that it was rain due to drops colliding together rather than from ice/hail mechanism. Well, did get measurable rain, but only 0.07 inches.10:55 AM. What a behemoth this was, dumping its inches, producing the first thunder of the day, north of Saddlebrooke.9:13 AM. First Cumulonimbus forms out of the growing field of Cumulus clouds. Can you see the ice shield peaking out on the left?8:26 AM. To see real (ground launched) Cumulus sprouting like this so early in the morning was incredible; hopeful signs of “big day.”
3:32 PM. Severe thunderstorm comes roaring out of TUS and, we hoped, “up around the bend”, as the song says (Pusch Ridge). But it didn’t happen. Did dump a whopping 1.93 inches in one hour at an Avra Valley gauge a bit later. Note light gray, lower “arcus” cloud in the center, the sign of strong winds pushing outward from the cell. Very Floridian looking.
Ealier yesterday, a very nice cell traversed the Catalinas dropping a half and more on Ms. Lemmon before sliding down toward the southwest. Here’s what it looked like at its peak:
1:32 PM. Great to see more water landing on those mountains, feeding those washes and creeks.
Other notes: Yesterday morning was the coolest in weeks here at 71-72 F. Perfect.
More storms and mayhem today. Take a look at how low the clouds are on the Catalinas and Samaniego Ridge, always a great sign when they are are low as this for powerful storms and big rain areas, though we missed them yesterday, they were all around.
Don’t really need to explain this NOAA “ensembles of spaghetti” map anymore, so thought I’d just post it. Made me feel real good thinking about all the summer rain ahead in the next two weeks and how green it will be around here then. The second greening of Arizona; its so great!
Valid at 5 PM AST, August 3rd. I think it would make a great summer “I ‘heart’ spaghetti” T-shirt for you, too, maybe sleeveless using dry-fit cloth. Still working out the details, of course. When you want to make a LOT of money off a T-shirt, you want to get it right.
Yesterday’s clouds, in cast you missed them, especially the great sunrise:
5:27 AM. Altocumulus opacus.
5:28 AM. Unusual -for -summer Altocumulus lenticularis near the tops of the Catalina Mountains.11:30 AM. The perfect example of Cumulus humilis, those little acorns destined to grow into moderate-sized Cumulonimbus clouds with light-to-moderate showers yesterday afternoon. What was particularly great about yesterday was that we had our usual absolutely stunning visibility due to an absence of the early July smoky skies we saw day after day.3:27 PM Light showers (Code 2 rainshaft; transparent one) drift across the Catalinas. Cloud too shallow here for lightning.3:51 PM. Growth of those clouds continued as they moved SW toward Marana. The denser shaft means tops were far higher than they were for those clouds over the Catalinas. “Code 3” shaft, horizon barely visible through it.
The End.
Useless note: Might have been 0.02 inches of rain early this morning, but then again, the tipped buckets might have been due to condensation this coolest morning (71 F) in the past few weeks. Radar did have tiny echo going over….still, not sure it was “rain.” But, heavy dew is good, too! Non-recording gauge also had 0.02 inches, so I guess its was real “rain” not dew! Mystery solved.
First, check out these eye-popping totals from the Pima County ALERT network, led by Ms. Lemmon with 4.33 inches!
Yesterday was a day when cloud/storm watching can be kind of fun. Here’s the scene in the early evening, storms over Marana and southern Oro Valley are bypassing Catalina. We only have moderate Cumulus clouds drifting off the Catalinas. You might have been quite sad to see that the storms were missing us, and those friendly folks down there were getting a good rain again. You’d feel good for them, but sad yourself. Maybe we wouldn’t have any summer wildflowers and greening up around Catalina, you began to think, with another miss at hand.
But you would have been “too fast on the mental draw” and should have envisioned the following scenario:
Those strong rainshafts down toward Marana, Twin Peaks area were going to push a mighty blow of wind up our Oro Valley and toward Catalina, and like the miniature cold front it is, would push air it ran into upward and launch the moderate Cumulus overhead and slightly upwind of Catalina into Cumulonimbus cloudzillas.
And you’d have been right.
Imagine telling your neighbor, looking at our so-so clouds, “Wow (be very excited), this is GREAT!” Look at all that rain falling down there toward Marana! Now we’ll get a good rain, maybe a trmndus one!” You’d be so excited, you might start speaking in “text.”
If the following events wouldn’t have made you the neighborhood weather guru for life, probably nothing else would except telling strollers by your house that they had three minutes to raindrops, big sparse ones, like I did yesterday around 6 PM. Those strollers got good and drenched, which was GREAT, too! They kept going outbound with doggie even AFTER I screamed at them about those drops coming. The cloud bottom overhead was just starting to unload.
Oh, well, there’s only so much cloud and weather gurus like us can do to help people.
It was the push from the south toward us that made last evening’s torrents and power outages possible (oops). Lets give those Marana Cumulonimbi a hand, an “assist”, really, like in baseball or basketball!
5:05 PM.
Here are some dramatic, memorable scenes, the big rainbows, etc, for you. These will be thumbnails because when take more than 200 photos in one day, you can’t post them all… I wish I had a gigantic web site where you could do that, and you with a gigantic wall monitor so that you could enjoy them in life sizes, because they would ALL be there for you to enjoy. Its all about you, again.
They’re going to be a little messed up in the post because, “haven’t time for the pain” (of posting them nicely) as the song said.
The End. Today? Let’s see what happens! Still light rain around even now!
5:06 PM. Cu to be energized by Marana outflows.
5:35 PM Marana storm expands northward, outflow winds reaching south Catalina.5:53 pm. Arc of uplifted clouds due to Maran outflow winds extends from Cat Mountains over Catalina and Oro Valley.
5:57 PM. A nicely shaped cloud bottom begins to let its contents out almost over ME!
6:20 PM. Core of first cell passes just east of Catalina, but still unloaded 0.22 inches.6:30 PM. What’s this?! A new base forming overhead upwind! Did not see that coming, first rain dropping out now!
6:38 PM. In the middle of a 0.45 inches dump!
6:54 PM. One of the brightest rainbows you’ll ever see finishes off a great rain day, totaling 0.67 inches. Or did it?6:54. Closer look at same rainbow that ended storm, or did it?
7:03 PM. Parting rainbow; certainly won’t be any more rain after a wonderful 0.67 inches…or not.
7:20 PM. What? New, firm cloud base forming upwind. Surely there can’t be more coming. It was, a lot more.
We accumulated just 0.01 inches of rain here from those overhanging anvil clouds from thunderstorms centered on top of Ms. Mt. Lemmon early yesterday afternoon but they drenched Ms. Lemmon with 2.28 inches! Details from the Pima County ALERT rain gauges can be found here. The next highest amount was on Samaniego Ridge with a nice 0.79 inches. Both good.
You may have noticed something odd, too, the thunder from those cells was continuous for a long time while Lemmon was getting pounded, quite remarkable, indicating, as you would guess, highly electrified clouds, unusually so.
The last time I experienced continuous thunder without break was in Oklahoma City during the El Reno tornado-producing complex of Cumulonimbus clouds, ones with huge mammatus formations that just ERUPTED from the overhanging, approaching anvil cloud repeatedly. An example of that dramatic OKC scene, FYI:
May 31, 2013, 3:34 PM above ASA Stadium, Oklahoma City. Thunder from in-cloud lightning, as here yesterday, was continuous, not the least break, as the rain approached and tornado sirens went off. Yep, Mr. cloud-maven person was there and took this shot. The former company team, the Washington Huskies, had made it to the WCWS. and me and the missus used to go to the Husky games in Seattle.
Oddly, like that OKC situation, where there was almost no cloud-to-ground lightning as the storm approached, and not so much during the 5-7 inches of rain that fell there that night. Neither was there much C-G LTG around here yesterday with OUR continuous thunder; I saw not ONE cloud to ground strike in the several thunderstorms which developed on top of Ms. Lemmon, nor from the continuous thunder-producing cell toward Charoleau Gap around 7 PM. Here are views of our contrasting thunderstorm and overhang from that at OKC looking toward the Cat Mountains. Below that, the remarkable-to-me, anyway, the continuously thundering cell with a modest rainshaft toward the Gap in the evening hours:
12:34 PM, soon after nearly continuous thunder began from the Cumulonimbus that erupted on top of Ms. Lemmon.7:03 PM, looking toward Charoleau Gap at a moderate-sized Cumulonimbus ALSO emitting continuous thunder! No cloud-to- ground strikes were seen over about a half hour’s time. And the thunder ended abruptly, like a light bulb that had been unplugged. That was odd, too, since usually LTG tapers off as the conditions producing it slowly change (well, over minutes, anyway.)
I really expected to see some rogue cloud-to-ground strokes coming out of that overhang over Catalina yesterday (middle photo), as often happens here, dangerous ones because they can be quite removed from the rainshaft and so you don’t expect them.
Have only seen one or two days like yesterday before, absent cloud to ground strikes but a lot of electricity up there in Catalina over the past five summers. So if you thought it was an unusual day, you were right.
Today
More showers and TSTMS are expected in the later afternoon and into the nighttime hours according to the U of AZ model run from 11 PM AST last evening. Still hasn’t finished crunching numbers, but goes through tomorrow morning. Again, the flow is from an easterly direction and so the early bombardment of Mt. Lemmon should have us in the trailing overhand again until evening when cells are likely to form away from the mountains today.
A real odditiy is that upper level low from back East (Virginia) that is headed to Catalina land! You can see its progress over the past few days here from the U of WA map makers here–you’ll need a big pipe to see all 64 of these frames in a reasonable time., Here from San Francisco State, these 500 mb maps, starting with the low over West VIrginia and SE Ohio, ending this morning with the low now over the Texas-Oklahoma border! Amazing.
July 12 at 5 AM AST. Low too be here forms over Ohio and West Virginia! Oh, my, this is so funny.5 PM AST, July 14th. The SAME low is now moving from OK into Texas and toward US!Valid for July 18th at 5 PM AST. Remnant of low moves into SE AZ.
So if something like this happens, we’ll have a DISTURBANCE to cluster our Cumulonimbus clouds into real monsters, ones bigger in area, and ones that last longer, maybe make up some rain deficits around here.
Of course, with such an odd track, lots can go wrong, but its something to keep in mind.
We live in interesting times. As with so many days since June 30th, thunder almost rules the day, going on intermittently for hours, as it did yesterday. And yet, only a little rain, just a few drops from an anvil overhang just after 2 PM, can find its way here to my house here in Sutherland Heights, Catalina. I know areas down toward Golder Ranch Drive and just south of there have gotten brief hard rains this July, but not here. What is going on?
Or what is NOT going on? Not enough heating I guess, only the very highest terrain participated in Cumulus and Cumulonimbus production yesterday; those cloud bottoms just could not work their way off the mountain tops, and so only the middle and higher dissipating portions dribbled over Catalina land. No disturbances to group them either, regardless of temperature, like two mornings ago when the line-cluster of thunderstorms came through.
Lets just hope that upper low that used to be over Virginia a coupla days ago can get here and be that needed “disturbance.” You probably didn’t know that weather moves from Virginia, or even Ohio, to Arizona…..well, its happened, and no doubt due to climate change where weather is backward from what it usually is, this low is , now over MO, continues moving west and south, reaching AZ by Wednesday the 17th.
It is a little unusual to see that and here’s what real convective-severe storm weather guru Bob (lives in Tucson, BTW) is saying to a weather folk group in Albany, NY:
“Ed and Greg – the current forecasts looked familiar to me. Check out the 500 mb analysis
series from 00Z 9 August 2003 through 12z 16 August 2003. Short wave in westerlies
over Ohio morphs into an inverted trough in the easterlies. The IT moves SW across the
southern Plains and ends up near the Four Corners on the 16th. It was associated with
a widespread thunderstorm outbreak across Arizona on the 14th. Bob Maddox”
“On 7/12/2013 11:25 AM, Edward Szoke – NOAA Affiliate wrote:
Greg – we remarked about this up at the CIRA weather briefing yesterday in Fort Collins. We see westward moving systems in the sub-tropics, but this far north and heading so far west does seem rather unusual. It looks like quite an outbreak of convection in OK come Sunday presumably as the cold pocket aloft moves over that area. Maybe it will keep moving west, close off and deepen over the 4- corners and bring us the seldom-seen but often talked about July snow! (OK – heat has made me go goofy – hope all is well at the Wx Channel). ed”
End of filler material from experts to get you a little excited, as we all will be if this comes to fruition as now foretold in models.
Yesterday’s pretty castellanus:
5:57 AM. Altocumulus castellanus spire under a higher layer of Altocumulus perlucidus.
5:57 AM. Looking west toward the Tortolita Mountains at a large grouping of those lower castellanus clouds. This, I thought, was one of the best shots I’ve taken of those clouds.6:28 AM. As sometimes happens with these clouds, they can group together and morph into true Cumulonimbus clouds based at high levels capable, as yesterday, producing lightning and brief heavy rain; they’re not caused by heating at the ground like our afternoon and evening storms. This is a common situation in the Plains States during winter when moist Gulf of Mexico air overrides cool winter air masses at the ground.
Our afternoon clouds, ones springing off the heating slopes of the Catalinas, dribbling overhang with sprinkles on Catalina once or twice:
1:30 PM. Cumulonimbus over Ms. Lemmon, middle and upper portions hanging out over Catalina.4:06 PM. Got pretty excited when this behemoth sprung out over the Cats. But, faded quickly after a lot thunder.
Oh, well. Day ended up with a nice multi-cloud layer sunset, always the best ones:
7:38 PM. Why we love the summer rain season and would never go to places like Michigan to avoid it.
Today is supposed to be about like yesterday, but hopeful that more rain can dribble off the Cat Mountains.
At least it wasn’t predicted the day before, but how nice to see a “mesoscale convective complex1” (a bunch Cumulonimbus clouds clustered together) come roaring over the Cat Mountains yesterday morning. Here it is, in case you missed it and want to see it again, from the beginning when what was going to happen was in doubt:
11:00 AM. Major rainshaft, and accompanying dark base where updraft is forming new precip approaches Catalina area.11:47 AM. The dramatic backside of this cluster, resembling those seen in the Plains States; good mammatus, too.
It was great, too, to see some evidence of water on the ground, and several natural livestock ponds form due to the storm. Its been too long since puddles formed. I like puddles, BTW2.
11:18. Evidence of significant rain; a puddle has formed.4:38 PM. Calves inspect newly formed livestock pond on Equestrian Trail Road. Mom not impressed.
Go here to see some regional rainfall totals from the Pima County network and here for the U of AZ network.
What was best was the clarity of the air after the rains washed all that smog, and we had our brilliantly white clouds against that deep blue sky back:
4:10 PM Cumulus mediocris over the Catalinas.
Today:
First, right now (6 AM) we have some of the best Altocumulus castellanus around I have ever seen. So pretty!
U of AZ 11 PM mod run expecting afternoon showers/TSTMS over Cat Mountains today, trailing off to the NW and near Catalina proper. Showers and lightning now to the S-SW, expected to die out before reaching us. So, happens, look for bases launched in the late morning and early afternoon to drift overhead–often a street of clouds forms over the southern portions of the Cat mountains about where that dark base in the first photo is, and if we’re lucky, will dump in this area. Look toward Table Mountain and a stream of clouds from around there headed this way.
————
1It would be great if you used this term with your neighbors when talking about yesterday’s rain: “That was a great MCS that came through yesterday morning! Hope we get another one today, though rain in the morning here is rare, but anyway…..” Neighbor “A what went through?” You: “Oh, sorry, I meant a nice cluster of thunderstorms. ” You continue: “As a cloud-maven junior, I’m learning a lot incomprehensible jargon that I can use to impress neighbors. Hey, have you heard of the ‘diffusion domain’? That’s when you’re flying in clouds and you can’t see either the ground or the sun! The next time you fly and that happens, tell the passenger next to you…..”Hey, I think we’re in the diffusion domain.”
2Photographed a lot of puddles on a trip to Death Valley in 2005 (wettest rain season there in 75 years). It was a lot of fun for me.
Yesterday was a disappointment. Oodles of water up there above us, as represented by cloud bases somewhere around 15 Celsius (59 F) yesterday morning, early Cumulonimbus activity–one was up toward Oracle by 10:37 AM–Oracle got 1.06 inches yesterday, but while the skies darkened over Catalina several times, they didn’t “unload.” Maybe only once or twice before in six summers have I seen this darkening to the level we had yesterday, without a rain shaft soon falling out of it. A couple of examples from yesterday:
1:29 PM. A Cumulus congestus takes shape over Cat State Park, and heads toward Catalina. Only sprinkles fell.2:40 PM, looking toward Charoleau Gap. It doesn’t get more “portenful” than this. I was SURE a shaft would crash down, and with it, the WIND from the north, the clouds then building over ME to the south, as happens so often when heavy rains pour down on the Gap. Didn’t happen, at least not until too late, long after it had moved farther north. Got pretty dejected.
So, what went wrong? Why were the clouds SO DARK, even shallow ones like Stratocumulus, let alone the Cumulus congestus, but with so little “emitting power”?
The darkness of these clouds was surely due to the high smoky aerosol content of the air that led to unusually high droplet concentrations in these clouds. The higher the droplet concentrations, the darker the bottom of the cloud, say holding cloud depth constant. So, a moderately deep cloud, but one too shallow to rain, can look like these, like the normal darkness on the bottom from which blinding shafts of rain fall. So, most likely we were looking at smog-laden clouds, the kinds of ones in our future around the world because that’s what we do, produce smog and smoke, well, us and lightning.
And, as we recall from Squires and Twomey (1967), smoke inhibits the formation of rain in clouds. I am sure most of you remember that article about smoke and sugar cane fires in Australia, and how those smoked up clouds did not rain like the ones around them that were “clean.” This phenomenon has been reported on numerous occasions since, like how in LA it helps reduce drizzle (mist rain) occurrences.
However, as we know, even smoked up clouds can rain IF they get high enough to reach the -10 C level here because then copious amounts of ice, soft hail and snow will form aloft, and down it will come! That only happened in isolated places, like over Oracle where they got that inch of rain (at least around here). So another cause of dark clouds lacking in downspouts was that they were not QUITE deep enough for the tops to reach -10 C. up around 20,000 feet above the ground yesterday–those tops were SURELY so close, though!
Back to smoke effects. With bases as warm as 10-15 C yesterday, there should have been rain formed without ice, and almost certainly a little did (these eyeballs detected some yesterday afternoon on the Catalinas). However, this is the type of rain that smoke inhibits most. This is because with so many cloud droplets competing for a given amount of condensation, they all stay too small to collide and stick together (requires drops bigger than 30 micrometers in diameter (let us not forget Hocking and Jonas (1970)…. So, we lost some rain due to smoky skies there, too,
Next, it can be relatively cool with tremendous amounts of rain IF there is a good disturbance to cluster the clouds together, forcing converging air near the ground, taking it away at Cirrus levels. We didn’t have a “disturbance”, a trough or a low to help out.
Finally, without the help aloft, we needed, as you can all guess by now, that bit more heating at the ground, maybe just a few degrees was all to launch some really large but isolated storms.
Today?
U of AZ 11 PM mod run has Cbs developing over the Catalinas by noon, and during the afternoon some of those showers trail to the northwest over Catalina. I think one will. So, once again we have a day with rain around, and maybe today a little cell will bombard us with a quarter of an inch. Should be warmer, today and that will help since again we have no trough help. Still smoky, as you can see here at sunrise by that orange-brown layer below this morning’s Cirrus. So, once again, the clouds may look a bit darker than they “should” when we have clean air.
The End except for this nice morning shot of Ac perlucidus undulatus I would call it. Very nice!
6:54 AM. Altocumulus perlucidus undulatus, if you care.
Stratus fractus on the sides of the Catalina Mountains:
5:54 AM this morning.
This tells you how wet it is out there, if per chance you haven’t walked around in it, and also tells you that moist air has some depth. These are the lowest clouds yet of our summer rain season. CUmulus cloud bases later this morning and this afternoon should also be lower than any prior day, and that means more rain gets to the ground, and likely the cloud clusters are large.
Fingers crossed for half an inch or more today here in Sutherland Heights-Catalina area.
BTW, some points in the Catalinas, such as White Tail, got 1-2 inches yesterday. Douglas way in the corner is already over 4.6 inches or about 160 % of their whole July normal. Excellent.
