Oh, well. Was expecting at least 0.25 inches a few days ago, and thought maybe a heavy shower last night might pull that expectation out of the trash bucket. Monthly total now up to 0.70 inches (updated after reading NWS-style and CoCo gauges here), still significantly below average (0.96 inches). Not much else elsewhere, either. Double dang.
Mostly Cumulus humilis and flat Stratocumulus yesterday. Was looking for ice as the temperatures aloft cooled during the afternoon and evening, and only as the sun went down was a slight bit of virga visible to the west. That Stratocu deck over us was deepening upward, and began reaching the magic point where ice begins to form, probably around or a little below -10° C (14 °F) in clouds such as yesterday’s. Let’s look at a sounding from the U of AZ (as displayed by IPS MeteoStar) and see what it says about those evening clouds and see if the above is just a bunch of hooey (I haven’t seen it yet, either):
The TUS sounding launched about 3:30 PM from the University of AZ campus. Suggests the cloudy air on that side of the mountains was indeed reaching to -10° C and likely a hair lower in the slightly higher cloud tops. Our tops especially a bit later and being a little northwest of there, were surely a bit colder.
Yesterday’s clouds
9:31 AM. Nice scruff of maybe Stratocumulus lenticularis topped Ms Lemmon, and indication of the lower level moistening that took place overnight with a dry front going by, with another one on the doorstep. Gee, camera lens is dirty.2:45 PM. Not much going on, just a few Cu hum, “two riders were approaching and the (cold) wind began to howl.” Bob Dylan, in “All Along the Watchtower” by Jimmi Hendrix. Nobel Laureate Bob wrote a LOT of songs about weather!2:47 PM. The Mighty Fraidy Cat Zeus, waiting for the weather to change, the Cumulus clouds to fill in. Today’s blog is particularly boring so thought I would spice it up with a [icture of a large (16.2 hands) horse that saw a tire leaning up against a horse fence, twirled around and at a full sprint, as though being chased by a Tyrannosaurus rex, plowed into a clump of tall cat claw acacias and mesquite bushes. The first second of that bolt was really exciting and fun, the second second, not so much. CMP was knocked off in the midst of them, racking up a broken rib, and a lot of scratches that bled profusely. However, with all that blood on his long sleeved shirt as he walked the mighty Zeus back to his corral, also chalked up quite a few “man points” when passersby saw him, I am sure. Well, there was one passerby who didn’t seem to notice as he drove by and I had to scream, “I’m OK! Its nothing, really!”2:48 PM. Nice lighting. I don’t know how many hundreds of these shots I have posted here. I just never get tired of sunlight and shadows on our mountains! Clouds still not doing anything, but its only been a minute since the last report.3:11 PM. Now we’re talking! Those Cumulus clouds are beginning to expand, fill in, transitioning to a Stratocumulus broken to overcast sky, a Stratocast (nomenclature unrelated to Fender guitars), as expected as the next front and trough approached. This was exciting. But when will the ice form in them to give us the first virga and precip?3:53 PM. Looking SW over the Oro Valley. This is really looking good. In situations like this, the clouds are forming as they travel upslope toward the Catalinas, and while they’re not preciping now, its fairly common in the situation we had yesterday for them to start preciping as the tops get chillier and chillier, often with the clearing remaining in place to the SW. That’s what I thought might happen. Things were changing fast at this time.5:15 PM. Virga and light precip were occurring on the horizon NW-NE, and these heavier Stratocu began to virga a few minutes after this. The anticipation? A nice period of light to moderate rain during the early nighttime hours as this deepening and filling in continued. That didn’t really happen. The clouds began to rain lightly here, but it didn’t measure. It was a another band coming through before midnight that produced the 0.08 inches.5:24 PM. I know a lot of you like to see pictures of the sun, so I thought I would post one today. Looks pretty round, a little bigger than usual. Don’t see any sunspots (defects) on it. That’s probably good.5:30 PM. Just after sundown the virga began to emit from this layer just beyond the Tortolitas. Really thought this would lead to a generous rain with continued deepening. Guess that didn’t happen. Probably only the best virga detectors among you saw this little curtains starting to descend from this cloud deck. I’ve added arrows to where those two patches of virga are.
Still looks like a chance for some light showers before the month closes out, but will be hard to get enough to bring the total to an above average value. Dang.
Will update my reader on December’s early cold outlook as new information that agrees with my assessment comes in. Right now, that information is not available.
Every once in a great while, we have days where fairly thick clouds do not produce even a sprinkle, even though their tops are a little below freezing, but not quite cold enough for natural ice to form. Yesterday was one of those days.
And it was a day you, a cloud maven junior member, could likely have done something about it: rented a small plane or helicopter capable of flying up to around 15,000 kft ASL, taking a bag of commercially available dry ice pellets, then drop them into the fattest, highest Cumulus tops you saw while nipping them in VFR flight mode, and, “violet!”, ice would have formed along the path of the falling dry ice pellets!
So what were the ingredients that made yesterday so special for a little renegade cloud seeding?
The clouds that did not rain were pretty thick for ones that didn’t rain naturally, maybe 5,000 to 6,000 thousand feet thick in their maximum “overshooting” tops, and temperatures at top were a little below freezing, but warmer than -10° C. At lower top temperatures ice would likely have formed naturally. Here’s the annotated TUS sounding from yesterday afternoon from IPS MeteoStar:
The 00 Z (5 PM AST) rawinsonde from TUS, typically launched about 3:30 PM AST. The upward pointing arrow shows what the in-cloud temperature would have been like. The lapse rate, from aircraft measurements is virtually never along the “pseudoadiabatic temperature line (one of which is where the horizontal arrow heads are), but somewhere between that and the dry adiabatic temperature lines that show the temperature drop in a rising dry parcel of air (one of which is where the upward pointing arrow begins). Cumulus protrusions carry the boundary layer air from the surface, that air that forms the Cumulus clouds, into the stable,, and warmer overlying air. So, protruding tops sink like a stone; don’t stay long at their lowest temperature, also hurting the chances that ice will form. That’s why you have to do it.
Here’s how it works: the dry ice pellets, themselves at -72° C, will chill the air it comes in contact with to -40° C, resulting in the formation of jillions of tiny ice crystals in each pellet’s wake, which are then spread over a wider region in the following minutes due to turbulence in the cloud. In essence, each pellet is creating a tiny, vertical “contrail” in that cloud, as least in those upper parts of the cloud below freezing. (Bases yesterday were a little above freezing, around 2° C, while the highest afternoon tops locally appeared to run between -5° and -10° in clouds that were forming in more haze and smoke than usual (wonder if you noticed that?) Haze and smoke tend to reduce droplet sizes, and in doing that, make it harder to form ice and rain, especially in marginal clouds for that, such as we had yesterday.
What happens next is that the “supercooled” water in the cloud evaporates around those crystals due to the dry ice bombardment, while the crystals take up that evaporated vapor. When the crystals get large enough, they may collide with some remaining cloud droplets, if there are any around. Usually all those crystals that have formed will not left too many droplets in their vicinity.
As the crystals grow in size, and because they are in such high concentrations, they will bump into one another and form clusters of ice crystals we call snowflakes. Cloud Maven Person has, along with Professor Doctor Lawrence F. Radke, the latter the “Flight Scientist” in those days with the University of Washington Huskies’ Cloud Physics Group1 in the late 1970s, made snowflakes the size of pie plates (fluffy light ones without a lot of water content) in Cumulus clouds like yesterday’s here.
IMO you would have created not something of much importance, but rather just an annoying sprinkle or very light shower for those out hiking, horseying around on their horses, biking the trails, on an otherwise perfect day for outdoor activities.
One of the problems, long known about in such seeding experiments as could have taken place yesterday, is that the cloudy air is moving THROUGH the cloud, exiting at the downwind location. That is, lower clouds in particular, move SLOWER than the air itself2.
So, you drop some dry ice in a nice turret, the air you dropped it is, along with that turret’s air, will be moving downwind and is going to go out into clear air eventually. So, if the crystals don’t stay in a turret and upward moving air, but goes out the side of the cloud or into “shelf clouds” like yesterday, those crystals/snowflakes aren’t going to grow much, and will remain “light and fluffy” even though they could be huge because they are like “powder snow” not a lot of water mass in them. When they melted at cloud base, they might end up being just drizzle-sized drop (less than 500 microns across) or very small raindrops. So, that’s why you would likely have gotten just a sprinkle or very light rain shower had you done some unlawful, renegade cloud seeding yesterday. Remember, just like when you hike in the State Land Trust areas, you need a permit to seed legally.
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Yesterday’s clouds
7:02 AM. Tall, but not so tall to form ice, Cumulus clouds boil up off the Catalinas. Made you think some Cumulonimbus clouds might form later on. They didn’t.10:26 AM. Disorganzied Cumulus still lurking on on the Catalinas, but the main thing here is how much smoke was in the air when you might have been expecting a very clean morning due to the previous evening’s thunderstorms and rains. Very upsetting to this smoky scene.10:27 AM. Looking NE at some Cumulus congestus, no ice evident from this view, but I would not rule it out, Forgot to check radar to see if there was an echo with this cloud.2:10 PM. By mid-afternoon skies started to look a little threatening with a Cumulus congestus having formed over and extending downwind from the Tortolita Mountains.2:14 PM. Looking for ice to appear in the oldest top portions, now evaporating, top of photo. None seen.2:39 PM. Someone needs to get up there on top of this Cumulus congestus, drop a little dry ice in it. Nothing came out, though I thought I would feel a drop at any moment! Some sort of birds can be seen, lower right.3:19 PM. Looking downwind at part of the base of this Cumulus congestus cloud line that sat over Catalina for awhile. The top has the base, to the left is the “shelf cloud of Stratocumulus spreading out from other tops and drifing downwind. If precip falls out of the shelf cloud, once part of a turret, you can see I hope that it would fall out of a thicker column of dry air.
4:01 PM. The scene before a lot writing appears on this photo.The same photo with a lot of writing on it.
The weather way ahead
While warm weather returns to AZ over the next week to12 days or so, there is now, and this goes with climo, a big trough that barges into all of the West Coast in two weeks.
When I say climo, I mean that there is a noticeable tendency for this to happen in mid-November in the longterm upper air records so that in some areas of California, for example, there is a modest increase in the chance of rain in mid-month over other times in the month. These kinds of things in weather are termed, “singularities” like the supposed, “January thaw” back East. This mid-November annual trough passage may be related to the increasing speed of the jet stream in the Pacific as winter approaches, something that changes the spacing between the troughs. Pure speculation.
But in any event, be on the lookout for a major change in weather here between the 17th and 20th of November. Something like this is starting to show up in the models.
The End
——— 1Later renamed the Cloud and Aerosol Research Group.
2Something that was even noticed in small tradewind Cumulus in the Pacific in the 1950s by Joanne Malkus (later, Joanne Simpson) and her colleagues.
We’ve waited a LONG time for a rain day. It was so nice, so photogenic as well. I hope you enjoyed it as much as I did.
Also, you may have seen the Froude Number1 in action as Cumulus congestus and Cumulonimbus clouds developed and went around the sides of the Catalina Mountains instead of developing over them and dumping big shafts of rain on them. The heaviest rains yesterday were due to streamers of showers and with an OCNL TSTMS that were north and south of us, Oracleville, Bio2 area, and Marana, Avra Valley where over half an inch was logged in some places.
Still , we managed a third of an inch here in Sutherland Heights, the first appreciable rain since I don’t know when, though, I could look it up. Too long, though, even for Catalina.
Some regional totals, 3 AM to 3 AM: Precipitation Report for the following time periods ending at: 03:19:00 11/04/16 Data is preliminary and unedited. —- indicates missing data Gauge 24 Name Location ID# minutes hour hours hours hours —- —- —- —- —- —- —————– ——————— Catalina Area 1010 0.08 Golder Ranch Horseshoe Bend Rd in Saddlebrooke 1020 0.12 Oracle Ranger Stati approximately 0.5 mi SW of Oracle 1040 0.08 Dodge Tank Edwin Rd 1.3 mi E of Lago Del Oro Parkway 1050 0.16 Cherry Spring approximately 1.5 mi W of Charouleau Gap 1060 0.16 Pig Spring approximately 1.1 mi NE of Charouleau Gap 1070 0.24 Cargodera Canyon NE corner of Catalina State Park 1080 0.20 CDO @ Rancho Solano Cañada Del Oro Wash NE of Saddlebrooke 1100 0.16 CDO @ Golder Rd Cañada Del Oro Wash at Golder Ranch Rd
Santa Catalina Mountains 1030 0.04 Oracle Ridge Oracle Ridge, approximately 1.5 mi N of Rice Peak 1090 0.16 Mt. Lemmon Mount Lemmon 1110 0.16 CDO @ Coronado Camp Cañada Del Oro Wash 0.3 mi S of Coronado Camp 1130 0.28 Samaniego Peak Samaniego Peak on Samaniego Ridge 1140 0.08 Dan Saddle Dan Saddle on Oracle Ridge 2150 0.16 White Tail Catalina Hwy 0.8 mi W of Palisade Ranger Station 2280 0.04 Green Mountain Green Mountain 2290 0.16 Marshall Gulch Sabino Creek 0.6 mi SSE of Marshall Gulch
Santa Catalina Foothills 2090 0.04 TV @ Guest Ranch Tanque Verde Wash at Tanque Verde Guest Ranch 2100 0.16 DEQ Swan Swan Rd at Calle del Pantera 2160 0.08 Sabino @ USFS Dam Sabino Creek at USFS Dam 2170 0.24 Ventana @ Sunrise Ventana Canyon Wash at Sunrise Rd 2190 0.16 Al-Marah near El Marah on Bear Canyon Rd 2200 0.04 AC Wash @ TV Bridge Agua Caliente Wash at Tanque Verde Rd 2210 0.00 Catalina Boosters Houghton Road 0.1 mi S of Catalina Highway 2220 0.04 Agua Caliente Park Agua Caliente Park 2230 0.04 El Camino Rinconado El Camino Rinconado 0.5 mi N of Reddington Rd 2240 0.04 Molino Canyon Mt Lemmon Highway near Mile Post 3 2390 0.24 Finger Rock @ Skyli Finger Rock Wash at Sunrise Rd
Yesterday’s Clouds
6:50 AM. “Shape of things to come1.” “Nothing could change the Cumulus shapes of things to come” yesterday, to paraphrase here, as evident in this Cumulus shedding ice in the downwind decaying end on the left.7:35 AM. Look at this little guy, so full of ice. Another harbinger of the ice-filled clouds about to arise, and with ice, precipitation, snow aloft, graupel (tiny soft snowballs), and even some hail (solid ice). You could guess here from how shallow this Cumulus cloud is that the bases must be at near the freezing level, and tops must be at least as cold as -10° to -15° C, cold for such a small cloud. But what would we call such a small cloud? Cumulus congestus praecipitatio or virgae (since the present of ice absolutely means some precip up there, not likely reaching the ground though. Shoot from the hip estimated depth 2 km, or around six thousand feet.11:37 AM. Sure enough, as it got warmer, Cumulus congestus/small Cumulonimbus clouds arose trailing ice northwestward in huge plumes of ice. Note to airborne researchers: be sure to sample the older parts of the turrets that have trailed downwind and turned completely to ice even though that trailing portion doesn’t look much like a Cumulus cloud. It you only sample the newly risen portions, you will cheat the cloud out of how much ice it can produce since it takes a little time for all the ice to form. Lotta early airborne researchers made this error, reporting too little ice, but, of course, if they were in the cloud seeding business, they wouldn’t mind at all since they could report that clouds needed more ice, that from their seeding activities!11:37 AM. Oh, so pretty, those dark blue skies punctuated by a little muffin Cumulus cloud. Aren’t you glad you live here?1:25 PM. Showers and weak Cumulonimbus clouds trail off the Catalinas north of Bio2.1:25 PM. In the meantime, stronger Cumulonimbus clouds and showers track westward south of Catalina toward Avra Valley while the clouds over the Catalinas dissipate or remain disorganized while heading toward us.2:33 PM. A voluptous Cumulus congestus in the process of transitioning to a Cumulonimbus calvus (ice is visible but top stil pretty firm and round looking), then Cumulonimbus capillatus (fibrous top) AN older turret, looking all ice, leans to the left. Precip was already dropping out the bottom of this fat cloud. What kind would it be? Grauple, without doubt since so much supercooled liquid water would remain in this cloud amid the ice crystals forming inside. Those ice crystals, nice and pristine when they first form, would have their pretty forms obliterated by droplets that would freeze instantly on them, making them little snowballs, falling faster and faster, collecting more droplets.2:46 PM. Moving rapidly away from Catalina, of course, that cloud has now become a Cumulonimbus capillatus (hairy, fibrous top a,most completely composed of ice–some liquid may still arrive at cloud top in new turrets before quickly converting to ice.) A portion of a rainbow can be seen at almost ground level.2:48 PM. In the meantime, pretty strong storms, now having thunder, rage S through W of Catalina.3:14 PM. While we didn’t have any great clouds near us, at least we had some nice lighting (not LTG) on the mountains from time to time.3:41 PM. Finally, the dramatic skies were shifting northward and measurable rain was on the doorstep. Looking SW toward Pusch Ridge and the Tucson Mountains.4:43 PM. Took awhile, but a decent Cumulus with a nice base now transitioning into a Cumulonimbus plopped some big drops and hail down. Streak at right is a hail particle with its fall distance in about 1/400 of a second.4:47 PM. The hail got a little bigger and I took a picture of one of the stones, a little smaller than pea-sized in case you don’t believe me that some hail fell, too. Sometimes I think people don’t believe what I write, especially in footnotes….5:02 PM. While the sunset was dramatic, it didn’t bring the color hoped for, but this line of dark clouds presaged another bit of rain for Catalina.
Except for a morning or afternoon sprinkle, no rain in sight, just a warm up back to above average temperatures. Dang.
The End
———————-
1The young fluid dynamicist, Richard Penniman, fascinated by the flow around mountains, and who later became known as the rock and R&B entertainer, “Little Richard”, first brought the Froude Number to public attention in his song, “Tutti Froude-e.” The title, after an early release failed to capture the public’s imagination, was later revised for greater “accessibility”, to the song we know today as, “Tutti Frutti.”
2Who can forget “Max and the Storm Troopers” and that great song? I would submit, “everyone.” Of course, few know that after 1968 they changed their name to “Led Zeppelin.” And that, my friends, is “the rest of the story”, as Paul Harvey might say if he was lying about something anyway.
“Too many pictures, for one site…”, a continuing theme here1, to paraphrase “? and the Mysterians1“.
Two stations near Picture Rocks reported 1.25 and 1.35 inches, respectively, so some major rain fell fairly close to us. You can see the amount arounds around the State or here at the Banner U of AZ rainlog,org site.
Below your October 8th, 2016 cloud day, a Saturday in which the author’s former company fubball team, the Washington Huskies, spanked the Nike University of Oregon Duck, 70-21, ending years of futility against the billionaire’s sports teams. Too bad Washington multi-billionaire Gates is more interested in saving the world instead of helping the Huskies get better in sports like Phil Knight does with The Duck there in Duckville, OR….
Oh, well, off task there for a minute. I’m back now!
7:06 AM. Pretty Cirrus uncinus (tufted ice clouds with the larger ice crystals falling out where the wind is not as strong as where the head is) with a few Altocumulus over on the left.8:43 AM. The really sharp-eyed cloud maven junior person would have noticed these little icy trails in a sliver of Altocumulus or Cirrocumulus. These supercooled clouds were converted to ice along the path of the aircraft. The brighter one is the most recent one and is so white due to the extremely high concentrations of tiny (order of 10s of microns) germ-like ice crystals. Concentrations would be something like 10s of thousand per liter. Once formed, they compete for the available moisture, some evaporating, some able to grow larger and fall out just as ice crystals do in Cirrus clouds. The less white trail is older and is one where the crystals are spreading out and also evaporating so the concentrations are much less. Presently it is believe that the air going over the wing of a jet drops the temperature to below -39° C where crystals form spontaneously and can survive and grow within a supercooled water cloud egad this is getting to be a long caption.
Now, here where the excitement begins. Recall Mike L. and Bobby Maddox, both super experts concerning convection, called for severe storms and large hail today due to what the models were showing in the vertical wind profile and the amount of moisture available. Below, we start yesterday chapter of convection, and see where it leads.
3:47 PM. Beginning to think Mike L and Bobby M are going to be wrong. Cumulus in the heat of the day have only reached moderate, “congestus” sizes around here, though Cumulonimbus cloud tops can be seen off in the distance.2:50 PM. Another pretty sky scene with an ineffectual Cumulus congestus there north of Saddlebrooke. Looks like is has a little ice ejecta on the far right, middle. But see how any rain would fall out not within the main cloud body but out the side away from the base. More evaporating of any drops would occur. This is happening due to the moderate southwesterly winds higher up, with slower winds from the south below. Thinking about taking a nap….2:51 PM. On second thought, maybe I should see how the septic repair is going…. Looks OK. Wonder how many thousands it will be?2:58 PM. Even though it looks like Mike and Bob are still going to be wrong, at least someone’s getting some good TSTMS (weather text for “thunderstorms” in case you do that, but don’t do it whilst you’re driving, a public message from your CMP. Some cloud science: On the right is a turret that’s climbed up beyond the level of “glaciation” but still contains tons of water. Center left, is a complex of turrets a little behind that one that are taller, and in those tops you woud find little or no water, just ice crystals. Can you see the difference in texture between the rising turret full of water (though graupel, hail, and small ice crystals are likely inside it)3:58 PM. Septic crew was asking, “where’s the hail you said would happen today?” I corrected them by saying that Mike and Bobby told me that, I didn’t personally make that forecast. I told them, hang on, things are starting to happen. And, about this time, the NWS started to issue severe TSTM alerts for Cochise County due HAIL and high winds! Still, it didn’t yet look that great for us here in Catalina, Oro Valley area. The Cbs shown here are that “tough.”4:27 PM. Still kind of bored, think I’ll take picture of an interesting shadow pattern.4:34 PM. Gads, looks awful out there. Only the anvil is left of a former thunderstorm toward Twin Peaks as the wind shear aloft rips from it from its root base. Not too bad there on the left, though. Still looks like a dud day for us in Catalina anyway at this moment.4:55 PM. Modest Cumulonimbus forms in the lee of the Charouleaiu Gap. Notice here that looking to the NE you can only see the rising turret part of this Cumulonimbus. The anvil is trailing downwind away from you, some of that anvil can be seen at the far right,just above the ridge. But you can clearly see some precip is falling out of this, Code 1 (transparent shaft) likely because as we saw earlier, the precip is not falling through the whole depth of the cloud but is falling from a higher portion of the cloud that has been blown off toward the NE before the precip got going in it.5:01 PM. Yikes, when did this happen? Must have been between commercials during football viewing. You can only go outsie during commercials so you miss some things. Bobby and Mike are going to be correct for our own backyard! Hope we get something, and it appears to be upwind of Catalina!5:06 PM. Just because it was pretty. Cumulus congestus tops, brilliantly white (that higher one in the back).5:31 PM. More commercials allow a quick trip down the road to get this. Of concern, the shafting is shifting rightward and away from us. What’s upwind is now the Code 1 transparent rain. BUT, the base in the middle of the photo, and close by, looks great! Perhaps some stupefying dump will emerge from that and grow more good base material exactly upwind of us!5:58 PM. Another discouraging day of promise gone unfulfilled here in Catalina/Sutherland Heights. Feelling sad, though I would take a funny picture of my shadow whilst walking the dogs at half time, makes me look bigger than I really am. made me smile amid the dismal sprinkle that started to fall, giving us yet another “trace” of rain day.6:06 PM. There goes our complex of rain, thunder and lightning off into the distance. Still, the scene was great.6:08 PM. Day ended with some dramatic, colorful scenes, something said here alot, but true.
The End.
1If you don’t believe ? said something like that, go here
Kind of getting tired of gorgeous rainbows every day, ones without a lot of rain here in The Heights. But, here they are again:
5:44 PM5:54 PM.
Upwind Cumulonimbus clouds faded as the trudged toward Catalinaland yesterday, bottoms evaporating, raining out, leaving only a big patch Altostratus cumulonimbogenitus way up (at least ten kft above the ground) there with rain drops just big enough to survive evaporation and reach the ground just before 3 PM.
2:18 PM. Heading for Catalina, right side will maintain–note nice flat base, left side of heaviest shaft is a gonner. So, hope is on the right (not a political statement, but rather referring to the part of the cloud you want to be heading for you, which is not the shaft itself due to the short lifetime of shafts, but the new parts where new shafts will emanate. No renewing base/updraft over there on the left. You hope that segment isn’t exactly heading for you. We shall see in just a few minutes of yesterday time.2:24 PM. OK, we’re done as far as rain goes in Catalina from this. The updraft and solid base are propagating to the right, meaning that nice appearing rainshaft will be what targetis us. But the lives of shafts are so short without renewal, and that renewal is going to slip to the west of us. Notice how in six minutes the shaft on the left is almost completely gone.2:48 PM. Hard to believe that this is all that’s left of that pleasant Cumulonimbus cloud, an Altostratus translucidus cumulonimbogenitus , maybe with praecipitatio as well with it since you can see a veil of preicpitation is reaching the ground. Note the sun is shining through larger ice particles like snowflakes, its disk cannot be made out, though its position can. If this cloud was a thin droplet cloud, the sun’s disk could be seen as a sharply outlined disk.
In the meantime, all the excitement, possibly spurred by the gusty outflow winds that accompanied the above seen, was happening almost overhead to the NW-NE, as a great line of Cumulus bases blackened. They were already passed us, but if they unloaded and sent a pulse of wind out and toward us, then we might end up in a wind clash zone, with huge clouds forming overhead. OK, was dreaming again, but here’s what was going on, which ultimately led to another major dump on the CDO watershed.
2:20 PM. Dark Cumulus bases mass over Saddlebrooke and north. No precip trails yet, but they were virtually assured. Started videoing this scene about now.2:28 PM. In just eight minutes this has become really menacing, possibly a major dump on Saddlebrooke with more golf balls flooding down into the CDO wash as happened the previous day. Now looking for the first strands of the largest hydrometeors (likely hail or graupel) to drop through the updraft, which is looking very substantial at this time due to that well-formed base.2:30 PM. Here’s a close up of that base over Saddlebrooke, now placed in the “Cloud Base Collection” series that we offer to readers from time to time. We’re hoping ot get into a gallery soon.2:37 PM. “Thar she goes!” This is really hard to see, but at top center the rain/hail/whatever is just starting to show out the bottom. Some of these, likely gigantic drops, are already reaching the ground. Notice the slight dimming of the Cumulus clouds in the background. That would be the developing rainshaft is going to be.2:39 PM. Now even little teeny babies can see the shaft dropping out.2:42 PM. For all to see now….just three minutes later.2:44 PM. Just another two minutes later. Its pretty remarkable how fast these things collapse. The whitish strands are likely hail/graupel shafts, often located on the upshear/upwind side of thunderstorms.2:49 PM. Soon the plop of all that rain push enough air out of the way that the shaft extruded outward toward the west. Note that rain would be falling on people from a raining cloud some mile or three away. The heaviest rain seen in the ALERT gauges from this event was only 0.79 inches at Pig Spring, near the Charouleau Gap. The peak rain was probably in the 1-2 inch range.
Hiked over to see if the Sutherland Wash, east of the similarly named housing development, Sutherland Heights, had a good flow from our “Mighty Kong” of prior day. It had:
3:45 PM. The Sutherland Wash scene showing that it flowed bank-to-bank as did the CDO here in Catalina.
The weather ahead
Seems Remnant Roslyn will spit out another snippet of moisture ahead of our fall-like cold front passage late Sunday or early Monday bringing clouds, and with clouds, a slight chance of measurable rain. Don’t hold your breath for measurable rain IMO. Hope I’m as wrong as the prediction I made to a friend that the Stanford Cardinal would trounce the wildly overrated Washington Huskies fubball team last night.
Just back from a horsey ride with Zeus the horse. Rode into the CDO to see the surprising view that it had run bank-to-bank last night after that mighty cell passed by along the foothills. In the wash, were golf ball-sized golf balls scattered throughout the wash, indicating that it hit the planned community of Saddlebrooke with it many golf courses very hard. No golfers were found.
The Pima County ALERT gauges really did not call out that such a flow would occur from precip data around here, the greatest amount being barely over an inch, and its likely that such a flow in the CDO, bank to bank would need 2-3 inch dump in its watershed.
This morning around 10 AM in the CDO south of the E Golder Ranch Drive bridge,
———-end of updated material unless I get more updated——
After an afternoon of “steady-state” Cumulus congestus and small Cumulonimbus clouds trailed northward from the Catalina Mountains, the “Mighty Kong” erupted about 5 PM providing one of the most intimidating, yet majestic and beautiful scenes of the summer rain season; this or any.
Cloud Maven Person was indoors drowning his sorrows concerning what appeared to be a a grotesquely failed forecast of a good rain day (“about half an inch”) here in Catalina in flavorful Indian cuisine when the unexpected began to take place outside. So, the photo record is incomplete for this event. “CMP” had given up on the day.
Just measured in NWS-Style 8-inch gauge and CoCoRahs gauge:
0.12 inches was our total here in the Heights.
And, the photos aren’t quite as good as they should be, slightly out of focus since CMP didn’t adjust his camera for the dark scenes his was seeing. Oh, me. Missed the great sunrise, too, due to not having memory stick in the camera! Oh, me.
6:48 AM. The day started propitiously enough with a ton of clouds, and a line of weak Cumulonimbus heading for us from the SW -W. horizon. A small Cb ahead of this line can be seen on the left.7:14 AM. Looking at this scene, and pondering a day and evening of these, “CMP” is wondering just how many inches of rain we might have,
However this line faded, bringing only sprinkles, a trace of rain to Catalina, and was followed by a huge clearing and sunny skies, thought to be a good thing at the time. Soon, gigantic Cumulonimbus clouds would erupt to over the mountains all quadrants… Nope. By mid-afternoon, only Cumulus congestus had formed with an occasional bit of ice and rain visible, all to the north.
2:08 PM. Cumulus congestus repeatedly formed in the lee of the Catalinas. Occasionally one produced a shower. The clouds are moving from right to left in southerly flow, probably pinching together in the lee of the Catalina Mountain “sky island” as happens in the lee of real islands.4:21 PM. Another nice Cumulus congestus, but where’s are the Cumulonimbus clouds, that big line of them coming in from the S and SW? Pretty much threw in the towel, gave up except to document for purposes of training a little conversion from water to ice visual lesson in one of these turrets that climbed just high enough to convert.4:25 PM. Thus in a series is just 5 min long. Shows how fast the liquid looking cloud can convert to one that is all ice and droplets evaporate due to incursions of dry air, and their molecules race over to that ice crystal next to them. When water and ice are together, its supersaturated with respect to ice, and water molecules head toward any ice around, accumulating as a solid on the ice (a process called deposition), racing over there as a vapor.4:27 PM. A very slight change has taken place. The tight cauliflower look due to liquid water “cells” (such as those on the left side where a new turret is rising up) are disappearing, Its not very obvious at all, but you should be thinking even with this little bit of change, “There she goes! It made it to the “glaciation level” today.”
4:28 PM. Underneath this converting turret are ice particles that are just starting to fall out. Can you see the little fibers of ice? Since they don’t have a long water path to fall through, these would be pretty pristine ice, maybe only lightly “rimed” covered in frozen cloud droplets. Notice to here and in the next shot, that they are sloping a bit, indicating they’re not heavy ice particles at all. If you’re really good, you can see that the whole turret has changed, no longer looks “watery”; that tight, hard, cauliflower look has “mellowed”, the crenelations have mostly disappeared. What is a “crenelation” anyway? Better look it up….4:30 PM. Its a gonner here, no liquid water is left in that turret. The question we still struggle with is how this conversion happens so fast?
This was the last photo I took until walking out of a local Indian restaurant and exclaiming, “What? When did this happen?” It was so clear to the S-W with the exception of a single dissipating Cb that it didn’t even seem worth a photo.
6:04 PM. Hope for that great, meaningful rain in Catalina, though I am in Rancho Vistoso when shooting this.6:04 PM. Looking over the Catalina Mountains as much as I could. Look at that nice, solid base!6:08 PM. Luxurious shafts of rain begin to pour out of solid cloud bases. And look at the one protruding outward toward Rancho V. THis is looking incredible for something humongous to happen. Not sure why this happened? Was there a trigger aloft that was going over this late in the day?6:11 PM. Now, a rainbow to boot! This shot from Honeybee Canyon Park.6:13 PM. This is becoming something memorable. Losing control, photos every minute or so, but ISO level too low!6:14 PM. In the meantime a shelf of clouds, Stratocumulus I’d say, spreads westward from the storm. Would they, could they erupt, too? No, as it turned out.6:16 PM. As darkness fell at Honeybee, and the rainbow faded, it was now becoming evident that this odd late eruption was becoming something special. The rest of the time was spent racing home to be there when it hit Catalina/Sutherland Heights.6:26 PM. Got this kind of crummy shot waiting at the light at Rancho Vistoso Blvd and Oracle Rd. By this shot, I am thinking, unbelievable what has happened! This has become the “Mighty Kong” of summer storms, and its spreading away from the mountains toward Sutherland Heights!6:33 PM. Car was blasted going down Golder Ranch Drive by not blowing dust but blowing gravel as outflow winds slammed down Golder Ranch Drive. Estimated gusts 60 mph. Afraid to look at front of car this morning. Also look at how firm, solid that leading base is, telling you that there is a strong updraft feeding into it. More cells will develop downwind. That’s Jenny and Matt’s house shining in the sun on the hillside.6:33 PM. Looking from Golder Ranch Drive toward Samaniego Ridge, obscured in rain.
Well, as it turned out it was a near hit, only 0.06 inches fell in a violent few minutes of huge drops at my place in Sutherland Heights. From what I saw going by, and needing 0.44 inches on yesterday morning’s forecast of 0.50 inches in Sutherland Heights. about 500 yards farther west for this remarkable, dramatic storm would have given us that amount easily. 1.06 inches was recorded at Cargodera Canyon, NE corner of Cat State Park, and several sites in the foot hills of Catalina toward the mountains area had more than half an inch.
A quickie take on a U of AZ model run from last evening’s global data, has Cumulonimbus clouds developing to our southwest and rolling across Catalina in the afternoon. This would be, appropriately, considering the definition of the end of our summer rain season as September 30th, very appropriate.
Should be some good rain today in Catalina, FINALLY! Thinking maybe half an inch or so over the next 24 h, something decent, as tropical air drains o northward and over us out of tropical storm remnant, Roslyn (“Rozzi”).
Clouds and weather interruption:
Due to the name of our weather-affecting tropical storm, Roslyn, I am now reminded of a profound, life-altering “Hallmarky” chapter of life when I was in HS, involving another Roslyn (aka, “Rozzi”). In an another attempt to increase blog readers, those really not interested in clouds and weather anyway, I have inserted this story about a 15-year old, shy boy and his incapacitating crush on a Rozzi R as a junior in HS I suspect it is a fairly common one in some ways, although this one leads to the formation of other people with a different classmate. The Story of Rozzi R
This story was passed to Rozzi, who had no idea who I was, only in 2009, btw. She seemed to like it, and told me about her life, family and three kids. I think its OK to share it.
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Back to weather, at 7:11 AM, one pulse of rain is within a half an hour or so. (Later, we only got sprinkles out of that first pulse).
Yesterday’s clouds
Nice rainbow last evening; nice sunset, too:
6:26 PM. Altocumulus and patches of a higher mostly ice cloud (Cirrus spissatus or Alstratus?) provided quite a nice sunset yesterday evening. Back the other way, were rainbows galore.6:11 PM. Rainbow under a more or less stratiform remnant of a Cumulonimbus cloud.6:17 PM.
The Prodigal Storm yesterday afternoon
Yesterday afternoon had quite the dump and something of a little ‘boob from the outflow winds, so much rain came down initially around Oro Valley/Marana, west Tucson, south of Pusch Ridge. Was heading this way, too, with nice big, black, solid-looking base. Started a video of it, thinking about the gush was to strike Sutherland Heights/Catalina.
Here it is, in all of its glory and subsequent dissipation:
3:09 PM. Outflow from TUS storm builds ledge of Cumulus base S-SW of Pusch Ridge.3:20 PM. Only 11 minutes later that new base has unloaded its load on Oro Valley. ).59 inches at the CDO and Ina Road intersection yesterday, but likely an inch fell out of this in the peak rain area. Note how the winds are pushing rain and dust west and northwest.3:25 PM. She’ll be comin’ around the mountain when she comes. This was looking so good for us. Why? Look at that great SOLID base coming at us ahead of the rain! The lower scruffs of cloud are called “pannus” and in this case they are created by the nose of the outlfowing winds from this storm. What you want is for those outlfowing winds to keep generating new, fresh Cumulus bases, ones that explode upward into Cumulonimbus clouds. Without the new, good base and the updraft that goes with it, all of the rain can fallout in less than half an hour from the ones already raining. Its a supply thing, you have to keep it going. What if there were no new people born? Well, after awhile the supply of people would run out.3:31 PM. By this time, you’re getting worried about this incoming system. Look what’s happening to the formerly solid base. Its beginning to get “lumpy” looking with dark and lighter spots telling you the updraft is getting broken up, fallling apart, maybe due to the blockage presented by Pusch Ridge. But there’s still hope, the updraft MIGHT reassemble itself….and there are still a couple of pretty good base “hot spots” where the updraft is still good.3:37 PM. “Its is finished.” What;s heading toward Catalina is that transparent veil of rain on the left of the shaft. We now have no chance for a major dump. Maybe it will measure though, a few hundredths…3:44 PM. Need more be said? Sprinkles occurred here, it did not measure. Warning: A sprinkle isn’t drizzle, a continuing theme here. Look at the “crapulent” bases now! Oh, me. I wanted to go in the house and never come out again, it was SO DEPRESSING to see this happen. Lots of storms make it past Pusch Ridge, too, but not this faker.3:44 PM. As usual, major shafting occurred AROUND Catalina, and not on it, pretty much like this whole summer has been. This is looking north toward Bio25:16 PM. Nice interplay of rain and sun.
Models, with spaghetti support, show a strong, but dry, cold front coming through next week, and fall will be in the air as nighttime lows drop into the 40s in our colder, lower spots, like at the bottom of Catalina State Park, in the CDO wash, etc.
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!
A very few small, isolated drops fell between 4:50 and 5 PM here in Sutherland Heights from what appeared to be nothing overhead. You’d have to be really good to have not been driving, and to have anticipated the possibility (by recognizing ice in upwind clouds) and then having observed it. You would be recognized, given some extra adulation, at the next cloud maven junior meeting if you did observe it, that’s for sure.
So, a long blog about anticipating and observing a sprinkle of rain (RW—, “RW triple minus” in casual weatherspeak or text).
We start with some nice, but inapplicable to our main story photos from yesterday.
3:14 PM. Another one of those, to me, memorable, dramatic shots just because of cloud shadows on our pretty mountains caused by Cumulus humilis and mediocris clouds; Cirrus uncinus on top.3:15 PM. Pretty CIrrus uncinus, “Angel’s hair.”3:15 PM. Looks like a cloud street off the Tucson Mountains, one that streamed toward Catalina. Hope you were “unbusy” enough to notice it. Its a pretty common one here when the lower level winds are out of the SSW, and the clouds shallow.3:50 PM. Shadow quirk. The cloud shadow follows the terrain line. Wow. Never seen that before, but I suppose if you had an infinite number of monkeys watching, they’d something like this all the time. Maybe they’d type out some Shakespeare as well in time.3:54 PM. While busy watching the cloud-sahdow dappled mountains, some honest-to-goodness Cumulus congestus arose in a line to the southwest! Not at all expected! Looks like they’re tall enough to form ice, but don’t see any. Will take too many photos to see if any develops though.3:56 PM. That poor turret that first extruded from this line (center raggedy one) is being ravaged by “entrainment”, that cloud killing process wherein the surrounding dry air gets in and kills off the droplets. Pretty sad when you think about. It also shows you just how friggin’ dry the air was just above the main tops. No ice visible here.3:56 PM. Let’s zoom in to be sure. Anyone saying they can see some ice in this is either an ice-detecting genius or just plain lying. BTW, that turret on the left, partially visible, is much taller, so its got a good chance to convert to ice.
3:58 PM. Now even little tiny babies can see the ice that formed in that now dessicated turret. This means some rain fell out of it! Wow, did not see that happening today.3:58 PM. Pulling back to grab the whole scene, those Cumulus congestus clouds converting to small Cumulonimbus clouds that will bring those few tiny drops to Catalina in an hour even as the dry air up there wasted them. Real cloud mavens would be thinking about the possibility of rain here, seeing the ice form in clouds upwind of us, that right at that time! Congratulations!4:09 PM. Doesn’t look that great now, but areas of ice visible, and its heading this way with a light shower falling out of it! Maybe we’ll pick up another trace! But what cloud name would you put on this scene? Well, its kind of embarrassing to call them “Cumulonimbus”, but we do have a suitable moniker for weakly-producing Cumulus ice clouds with a little precip, Cumulus congestus praecipitatio. Yep, that’s the name I would use here since the rain is reaching the ground (is not just producing virga).4:30 PM. Code 1 rain shaft, a transparent one. We’re going to a LOT of trouble for a trace of rain here! But, you should have been really excited by this time. The possiblity of rain is just minutes away, but you’ll have to be outside to notice it!4:40 PM. Drawing back to look at the whole scene, which is not that great. Bottom of sprinkle cloud has evaporated leaving that big patch of ice, left side of photo. Can the sprinkle heading toward us survive? Your heart probably was really pounding at this point since you wanted to see some drops so BAD, report that trace the next day, one that maybe only you would have noticed.4:47 PM. Three minutes to first drops, though here no drops would be reaching the ground from the condition the cloud is in now, its too high, just really anvil ice, and the ice crystals too small, The drops that are going to be intercepted are surely the last ones reaching the ground, the top of the sprinkle shaft, above which there are no more drops.4:55 PM. Drops are collecting on the windshield a few hundred yards from the house with almost no cloud aloft at this point! A trace of rain has been logged!
The End
(What about those gorgeous Cumulus congestus and Cumulonimbus calvus clouds over toward and well beyond Charouleau Gap about this time? Maybe later or tomorrow.)
The day started with some nice Altocumulus “pancakus”, some lenticulars and breezy conditions, reminding one of fall day with a cold front approaching. Small Cumulus appeared quickly, but with the wind, you wondered if they would get enough heating to power upward into Cumulonimbus clouds.
By noon you had your answer as a large Cumulonimbus complex settled in just beyond the Tortolita Mountains west of Catalina. And it pretty much recurred there and over the Tortolitas all afternoon. In the meantime, passing light showers dotted this side of the Catalinas, but that was about it. No “Code 4” shafts on those mountains yesterday. Rain totals were less than a half inch, and most less than a third. On the other hand, would guess that parts of the Torts got well over an inch. The cores missed us again, with Sutherland Heights logging only 0.03 inches.
Developing showers passed over Catalina dropping occasional very large, sparse drops, but shafts generally fell out of those clouds after they had passed off to the northeast.
Late in the afternoon, the line of recurring showers finally approached Catalina, but as dry air encroached in the middle levels, at the same time, catching up to that standing line, all those great mushrooming clouds were no more. The cloud story board is below:
(by Chad and Jeremy but with photos of Peter and Gordon with whom the former were often confused with, the site notes! How funny is that?)
Oh, well, yesterday might well have been the end of the summer rain season here in Catalina as far as rain goes, so an ending point song seemed appropriate.
6:16 AM. Altocumulus with a underlying Altocumulus castellanus.6:16 AM. Another view of Altocumulus with an underlying line of Altocumulus castellanus.8:06 AM. Altocumulus perlucidus translucidus (real thin).10:55 AM. Altocumulus lenticularis clouds provide the real look of a fall day with a significant jet stream overhead. Cumulus begin to form on the Tucson Mountains in the distance.12:56 PM. The idea of a fall day is quickly dispelled by the rapid growth of a narrow Cumulonimbus calvus cloud.12:57 PM. Wow. At the same time, there’s been an explosion of Cumulonimbus clouds to the west through northwest of Catalina. This looked REALLY promising for a dump here, since it would surely expand southward (to the left) from the rain shafts in progress.1:30 PM. Line of thunderstorms reaches the Tortolita Mountains. This is looking extremely good for Catalina though the thunderstorm is moving left to right rapidly, not toward us. Why does it look good for Catalina? Because you expect winds pushed away by all that falling rain to blow back against the sotuhwest winds and generate new Cu congestus and Cumulonimbus clouds upwind of the shafts, and more in line with Catalina. Summary: it didn’t happen though there were numerous times it looked like it was verging on doing this. So, all those thoughts you had out there that this was going to happen were in considerable error. This was probably because the southwest wind against which the outflow was clashing, was too strong yesterday, limiting how far upwind new clouds could develop.1:34 PM. This was looking so great! Bases massing there on the right side, pretty much upwind of Catalina.1:43 PM. Tortalitas now obscured by water.1:49 PM. Showers are developing farther upwind of the main blast over the Tortolitas as expected and near to upstream of Catalina! Gloating here. Was SURE now we’d get a tankful of rain within the hour.1:53 PM. In only a few minutes its looking so much better for us, and those showers and thunderstorms are racing this way! Looks like the whole line is drifting east, too. In the meantime, the thunderstorms moving away from the Tortolitas and toward Saddlebrooke Ranch and points north have sent out a blast of northerly winds into Sutherland Heights, pretty much like yesterday. The clouds overhead begin to respond to that uplift caused by this blast of north winds.2:06 PM.2:16 PM. That first nice cloud base waited until passing by to drop its load, but another promising one appeared upwind!2:17 PM. In the meantime, another ferocious thunderstorm is dumping on the same area of the Tortolitas as the prior ones!2:21 PM. A closer look at the Tortolita blast. Expect wind from this to reach Catalina.2:22 PM. WIth the north wind blowing you’re looking for something to erupt upwind of us as the nose of that north wind pushes into Oro Valley. But here you see that the organization of the cloud bases is poor, too many little light and dark areas, no broad base indicating a strong updraft. This was a depressing shot but I took it anyway.2:27 PM, The severe thunderstorm over the Tortalitas has moved NE. Here you see the kind of cloud base you want to see just upwind of you, not that mess in the previous photo.2:29 PM. Only a few minutes later, but look at the change that has occurred upwind of us! That north wind scooting down into Oro Valley has finally triggered a massive base just upwind of us We are going to get pounded!2:33 PM. But that great cloud base moves to the west of us, adajacent to yet another blast on the Torts. Ugh. Just can’t get this right.2:36 PM. Some lightning for you in case you don’t believe me that these were thunderstorms.2:49 PM. Yet another promising base, more in the upwind direction passed over, only to leave some enormous drops. Compare splash marks to that mesquite pod on the sidewalk. Sounded like hail at first. But the main load fell downwind. I thought we were going to really get shafted right then, too. Not.3:03 PM. An example of poor cloud base structure upwind of us.3:04 PM. Curtains of heavy showers continue to bombard the Tortolitas, Amazing how many cells passed through that area as this zone of converging winds remained stationary instead of advancing toward us as I believed it would.3:18 PM. As skies cleared overhead, some of the prettiest scenes of the day were of these brilliantly white Cumulus congestus clouds over the Catalinas.3:20 PM. Ice detection drill… Can you tell that those two turrets in the last photos are now mostly ice?3:28 PM. Can a scene be more beautiful? The turret on the far left has converted to ice.3:29 PM. A single strand of hail or the largest drops have plummeted out of this base. This suggests that they were either very large particles, or that the updraft had a minute weakness that allowed some of the load aloft to escape in something of a narrow chute. And, of course, its part of the line still pounding the Tortolitas!3:47 PM. FINALLY the line appears to be shifting east toward Catalina, but the tops aren’t as high, there are no giant cells any more, an indicating that both drier air is moving in and that the instability aloft is changing to less favorable for large storms. Oh, me. This was a discouraging scene.3:55 PM. While not as heavy as prior showers, there is still hope that the line will produce measurable rain in Catalina as it drifts east.4:05 PM. By this time, its looking like the slowly advancing line will die before it gets here.5:24 PM. That line: Done and done.6:39 PM.
