Woke up to Cumulonimbus clouds NW-N of Catalina. Hmmm. Here’s the unexpected, pretty sight just after sunrise:
7:24 AM. “Pretty, but will likely die much after sunrise.” Cumulus and Cumulonimbus clouds along a windshift line moving toward Catalina continued to develop throughout the morning while getting closer.9:34 AM. Odd line of Cumulus congestus growing into Cumulonimbus clouds with major rainshafts is getting closer still. “What’s keeping this going so early in the day?”
10:00 AM. “Upon closer inspection….”, a windshift line is detected via photography! Arrow point to shred cloud below base of the turret at left. This is a great example of how clashing winds build clouds. Above the shred clouds is that vigorously growing turret trying to reach the glaciation level.10:06 AM. It made it! (to the glaciation level) Maybe it means that the line of fat Cumulus-Cumulonimbus might make it here to Catalina and rain on me! I’m getting excited. Arrow points to icy top, though as cloud maven juniors you would already recognize that icy top, so I left the arrow out since I forgot add it anyway. These are the best kinds of icy tops to study with an airplane because they near the threshold temperature where ice forms in clouds on this day. That threshold level changes from day to day, strangely believe it, and the warmer the BOTTOM of the cloud, the HIGHER the temperature at which ice forms, strangely believe it#2. Even stranger, Mr. Cloud-maven person thought he had discovered this interesting fact back in 1988 and then he found that this guy, the Englishman, Frank Ludlum, one of the best we’ve ever had in cloud studies, and I should have known better, had reported the SAME THING 36 years earlier in 1952! There is nothing new under the sun, Ecclesiastes said, and I guess I found out first hand. Darn. I laughed bitterly when I saw that Science mag cartoon about stuff like this, posted below because it won’t fit in this caption. Darn. You can see I still have some feelings about having something to report but then finding out that it had already been reported. I thought maybe I was gong to be famous, perhaps win a prize of some kind, but no. (See second cartoon)
Well, the end of the story (told in the captions) is that a windshift producing this line of heavy Cu and a Cb or two and it “struck” Catalina about 11 AM; the wind turned from the SW to the N, but the heavy line of clouds riding it were nowhere to be seen at that time; the last Cumulonimbus cloud disappearing beyond the Charoleau Gap. Tough to take after hopes up.
Only in the early afternoon did a gift of a few drops from a towering Cumulus directly overhead produce the final surprise. The drops fell from 1:22 PM to 1:23 PM. I rushed outside to see what the heck was doing it and here that cloud is (last two photos) from the bottom up.
1:23 PM. Its raining! 1:23 PM also. Arrow points to ice, showing that this little guy got to the ice-forming level, and would have been another great subject for an aircraft study of ice formation.
4 AM to 4 AM 24 h totals ending today, ones that catch that morning rain (except where noted):
2.12 inches near Chrysotile, AZ, NE of Globe.
2.06 inches Wet Beaver Creek, Oak Creek Canyon area.
1.85 White Tail, just west of Palisade RS off Catalina Highway.
1.39 Oracle Ridge near Oracle in Cat Mountains
PHX set daily record ending at midnight last night, 0.80 inches.
Here’s the AZ radar-derived rain from 5 AM to 5 AM from WSI Intellicast:
Catalina? A crummy 0.07 inches. Well, no rain is technically “crummy”.
Good chance that some or all of that rain yesterday morning fell from clouds not having any ice in them, that is, formed rain due to the “warm rain” process, a rarity in AZ. But, without an aircraft, its a dicey call.
1 PM Catalina temperature and dewpoint: 86 F and 73 F. Miami, FL, at the same time: 90 F, 72 F. Warmer and dryer in Miami at the same hour. Our dewpoint was higher here than in Miami, quite something. Our high dewpoints were helped by all the rain water evaporating yesterday against a background of already very moist tropical air.
The air was extremely humid here, but not hazy like back East on humid days. Interpretation? The air was very clean.
Its not the end of summer rain season even though a few dry days are ahead after today.
Cloud bases in the morning clouds were running 16-17 C, about 62-64 F, which means those clouds had about as much water condensed in them near their tops as any cloud could possibly have here.
AZ mod (here) thinks it can rain here in the late afternoon today. Excellent.
Some of my big fat Cumulus cloud shots from yesterday, ones that were just like ones in Florida and Gulf Coast this time of year.
7:24 AM. Warm-based Stratocumulus clouds with embedded Cumulus build ups produce intermittent rain along the Catalina Mountains.9:36 AM. As the Stratocumulus layer dissipates, gigantic, low-based, Florida-style Cumulus clouds begin arising NW of Catalina.9:48 AM. I can hardly speak, these clouds are so HUGE! How many inches of rain might fall from them? Note glaciated tower protruding above the mass; top, right of center.10:04 AM. Larger yet! Note low scud clouds, seemingly just above Saddlebroke rooftops.10:09 AM. While these were wonderfully tall and low-based Cumulus congestus clouds, something was going wrong. Why weren’t there Cumulonimbus clouds, anvils scattered here and there to the SW-W?11:15 AM. It was getting worse. It was clear that drier air was moving in aloft and dessicating growing clouds. Cumulonimbus were still peppering the area just NW of Catalina, but they were shrinking in size as cloud bases rose.1:23 PM. The Cumulus congestus clouds lined the tops of the Catalinas, and occasionally produced a glaciated turret, but nothing gigantic as had been expected earlier in the morning.1:32 PM. Glaciated turret (center) pokes up behind Cu congestus tops over the Catalinas. Would have been raining like “heck” under it.2:26 PM. Though a big rain did not come through as I thought it might, it was a fabulously photogenic day with scenes of our now green desert topped by those puffy, roiling Cumulus clouds dotting the sky, ones providing thoughts of rain.
Just about. Ended up taking more than 300 photos yesterday (!), first 100 plus of the greenery next to the CDO wash (“its a jungle out there”) during a horseback ride, and of those spindily Cumulus clouds that were rising off Ms. Mt. Lemmon so early in the day (and oddly, with a lower, scattered layer of Stratus fractus clouds along the side of Sam Ridge). Those early skinny towers were full of portent about the day ahead, and those lower St fra, told about the unusually high humidity if you didn’t go outside!
A couple of photos from along the CDO wash and an example of those “stalagmite”-like Cumulus:
Along the CDO near Spirit Dog Ranch.Along the CDO. With the new wetter climate, perhaps new life forms are already arising inside this jungle.Morning glory blossom along the trail, almost a “Husky purple” I thought as the college football season nears and the summer sports malaise ends (hahahah, sort of). In that regard, former Washington Husky pitcher, little Timmy Lincecum, SFO Giants, can’t find himself–we thought for a time he would win the prestigious Cy Young Award every year– but has been a real disappointment this season for those of us who used to watch him throw at Husky Ballpark on Friday nights, so who cares about him or baseball anymore?
The spindily early Cumulus
These were an incredible sight on that early morning ride, truly, because of what they suggested for later on.
You can really get an appreciation for these guys puffing off “Smokestack Lemmon” from the U of AZ time lapse movie, as well as the power that was unleashed in those gorgeous, if volcanic, Cumulonimbus clouds later in the afternoon. I don’t believe I have seen as strong a convection day as we had yesterday before.
One measure of horrific convection, horrific updrafts in clouds is that little or nothing comes out of them. These kinds of Cumulonimbus are well known in the Plains States where giant clouds can form spewing anvils out that can cover much of a whole state. But, then, there is no rainshaft, or its very tiny.
Here’s an example from South Dakota of what is called a weak radar echo, or “echo-free vault” (the Cb seems to be “hollow” with no echo to great heights. sometimes in the middle of it).
The updraft in these severe storms is so strong that almost nothing can fall out, well maybe softball-sized hail; instead the all the water is transported high into the troposphere where only tiny ice crystals form at very low temperatures (liquid drops can be transported to temperatures below -30 C!) in updrafts of 50-60 mph or more in these situations (the measured record is about 100 mph). When this happens, too many ice crystals form and none can grow large enough to fall out until many minutes later, but then are 40,000 feet and can never reach the ground. That appeared to have happened here yesterday.
The South Dakota Cumulonimbus cloud shown was memorable because, like yesterday’s severe thunderstorm west of Catalina in the late afternoon and evening (shown below in its early stage), there was continuous lightning and thunder from overhead, high anvil; no cloud-to-ground strokes anywhere nearby in both situations. Those were likely occurring far off in and near the shafts on the horizons.
Parkston, South Dakota, 1976. This gigantic anvil was rumbling continuously from overhead and to the southwest. Note the tiny rainshaft from the parent Cb on the horizon. Yep, I took this photo WAY back then. I loved South Dakota…in the summertime!5:36 PM. By the time of this shot of this vertical giant, toward the Tortolita Mountaintas, had been thundering continuously from the upper half for over half an hour before this tiny rainshaft FINALLY emerged. It was remarkable, something I had not seen happen here before. It was a measure of how strong the updrafts were in this cloud and many others yesterday. Don’t know for sure whether it had an “echo-free vault.”
Rain amounts
The ALERT precip reports are here. White Tail, by Palisades Ranger Station on Catalina Highway, got another 1.50 inches yesterday and last night. It received 2.44 inches last Friday, and had another 1.25 inches on Sunday for a few day total over 5 inches now. Other local data can be found here and here.
Here in Catalina, we only received 0.08 inches, and that from some steady light rain overnight. Maybe today….
Today?
Well, no surprises for any met man, another strong day of convection. It will be interesting to see if there are more “low echo” Cumulonimbus clouds, ones with lots of high lightning, and a delayed emergence of a shaft, an emergence long after ice has proliferated aloft.
The late afternoon yesterday was like a Carpenter’s song, i.e., “easy listening” interrupted by Metallica, Megadeath, Slayer, Black Flag, Helloween, The English Dogs (“She Kicked Me in the Head and Left Me for Dead”), etc.
A day filled with moderately promising Cumulus congestus and brief area Cumulonimbus clouds, was suddenly overrun by a black steam roller with a watering tank behind it, and also having a big fan, to wind up a semi-ludicrous metaphor, coming down out of the northeast bringing an early nightfall, blinding rains, and winds of 60-70 mph. It was an astonishing change, and if you weren’t watching, but rather watching TEEVEE: “Ka-blam! What the Hell?” (More on TEEVEE later; see last caption.)
Some rain totals, ones up to 2.64 inches (!) can be found here in the listing of Pima County ALERT gages. More results will be available during the morning from the U of AZ network here, and from the CoCoRahs network. BTW, if you haven’t joined up, it would be good if you joined up with both of these latter “rain gangs.”
Of course, neurotic-compulsive cloud-maven person was watching for you. I only wish I had a huge microphone yesterday evening so that I could have alerted the people of Catalina, “CDP”, to its impending weather doom.
Non-weather side note: “Catalina: its not a town”, but rather, a “Census Designated Place” (CDP) where people are clustered, according to the Census Feds. Namely, we’re Catalina, CDP, Arizona, 85739. Its quite amazing the kinds of things you might read here, and its usually right after I find them out myself.
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Enough collateral information.
The day, had a tranquil but portentful beginning filled with potentiation, with those low, warm cloud bases. However, with the rising temperatures, ones into the mid-90s, so, too, did cloud bases rise. This is normal. As the daytime relative humidity falls, the cloud bases form at higher and higher levels. I hope you didn’t get upset seeing that the afternoon bases were above the top of Ms. Lemmon. Still, those higher, cooler bases did mean that the rain had farther to fall through dry air, not as good as having them down on the Sam Ridge line.
10:23 AM. Turrets begin shooting upward from bases topping Samaniego Ridge. This is good.1:37 PM. Weak Cumulonimbus (Cb) finally forms in the area. Getting a little concerned at the lack of “progress”, and much higher bases now.1:56 PM. Another weak Cb forms over the Tortolita Mountains.
3:43 PM. Another weak Cb forms this side of the Tortolita Mountains. That promising dark base above Catalina unleashed a sprinkle! (Sarcastically spoken).3:18 PM. Finally, something close! Looks promising, but fizzled out.4:14 PM. Not looking good. The Catalinas are back to producing shoots, not Cbs.
5:25 PM. Then “The Man” showed up, a gigantic Cb, one like the model had been suggesting would occur in the prior evening’s run.6:28 PM. The “black steamroller” appears, about to blow over lawn furniture everywhere.6:56 PM. Rolling into Sutherland Heights above Catalina, CDP, this 30-minute “incher”. I wonder who was watching TEEVEE, perhaps planning a TEEVEE party tonight, and not watching?
For a great movie of yesterday’s clouds from the U of AZ, go here.
Oddity
An as yet inexplicable odditity to yesterday’s stupendous storm. The lack of cloud to ground strokes; I didn’t see ONE, and I was looking. Second, the frequency of lightning was as high as it gets. In the dusky light, a new flash within the Cb in less than ONE second at the peak. Its was remarkable. That same kind of activity could be seen last night as the storms receded from us with almost continuous in cloud lightning, but no strokes to the ground (at least during the time I watched.
Today?
Still humid, still unstable aloft. Mods say another active day, so watch it (not teevee)!
7:12 AM. Action shot of bird with morning Altocumulus perlucidus translucidus.11:50 AM. Clouds topping Samaniego Ridge. Get ready for sprouts!12:38 PM. Amid the Cumulus “rubble” a glaciated top has emerged representing a Cumulonimbus calvus. Can you find it? Only the BEST cloud-maven juniors will be able to locate this tip of a tall cloud. Maybe you’ll get that special badge… If you don’t believe me that there was an extra tall top in this photo, you can go to the movies and see it here: http://www.atmo.arizona.edu/~leuthold/yesterday.mov.4:23 PM. While it was pretty and placid here, ominous Cumulonimbus clouds pile up on the S-WSW horizon.6:49 PM. Closer, spectacularly tall and pretty, but still over there, not here.7:05 PM. Time to give up and go to bed. Finely granulated virga from Cirrus/Altostratus deck was a bit of a treat. Suggests tiny cells of rising currents within that layer that produced tiny areas of larger ice crystals now falling out after the “updraft” (maybe 1ft a minute) weakened. The crystals? Likely “bullet rosettes”, of course, to extend the guesswork.
OK, enough of yesterday, a bit of a disappointment unless you looked at the models and saw that there wouldn’t be much here.
But TODAY….oh my. Those models have a MUCH more active day! Be ready; have camera charged, video as well. Don’t forget, you loggers out there, to note the time of your first Cumulonimbus sighting.
Should be a “fun” day with once again our very warm cloud bases (topping Sam Ridge now as I write at 6:02 AM) giving us, in essence a cloud travelogue to normal condtions in tropical countries near the Equator.
How much rain can fall from in these tropical boys? As we saw two days ago, 2 inches in an hour can fall; three is possible. 2-3 inches in an hour? Happens all the time in Florida in the summer. And with our upper sixties and low seventies dewpoints this morning, we are one with them (taking into account our higher elevation).
Heard thunder for about 12 h it seemed yesterday, but little came of it. Even the rainshafts looked anemic for the most part for the second day in a row.
Current 24 h rainfall totals from the Pima County ALERT gages here. U of AZ network here. “Coco” for Pima, here.
Got hopeful after a disappointing afternoon when an evening shelf of Stratocumulus with buildups spread westward from the northeast, shown in the first photo. Rain shafts began to appear in the upwind direction as the sun set with occasional cloud to ground lightning strokes, ones that continued until after dark. Those showers grew and then were almost dead by the time they passed over Catalina. So another disappointment. Seems you end up saying that a lot when you’re living in a desert and wanting some rain…
6:58 PM. Looking north6:59 PM. Looking NE.7:33 PM. OCNL LTGCG NE (weather texting example for “occasional lightning cloud-to- ground northeast”).4:48 PM. Got hopeful here, too, looking at this dramatic sky toward Charoleau Gap. But no; instead it went down the Catalinas, didn’t spread southwestward.5:27 PM. This is the same complex, now moving away into TUS. Dumped nearly an inch on the wealthy Catalina Foothills district where they probably don’t even need it because they can afford so much irrigation. It had missed us completely. I included this one with lightning because sometimes it seems like you are a people that enjoys fireworks more than a lecture about how graupel forms.
That Enviro Can model isn’t going to win a Gold Medal, another clever play on the Olympic Games now underway in London, with its forecast track for Hector-Ernesto. In our last episode, the Enviro Can mod had H-E drifting northward in a timely manner, and it had been that way in model run after run, so that portions of its remnant produced significant rains in southern Arizona.
The medalist in the H-E track forecast? The USA! WRF-GFS model. It had tropical storm Hector-Ernesto staying far away until it was dead, drifting glacially northward off Baja until it disappeared (as it is shown to do today) with only modest effects here. That USA forecast was better forecast all along.
We just did not get that upper level trough along and off the West Coast, required to steer H-E rapidly northward before it faded over the cool waters off Baja.
The good news is that there is no real droughty days ahead either, which means a steady diet of scattered thunderblusters for another week or so, and if we can get the cloud bases down from 14,000 feet above seas level to 8000-9000 feet (at the top of Ms. Lemmon), we could be back in the 1-2 inch rains in those scattered intense rainshafts. This morning’s sounding from TUS suggests they will be a couple of thousand feet lower than yesterday! Yay!
A quite active day is forecast for us today, beginning in the early afternoon rather than mid to late afternoon as has been the case. The first shower/Cumulonimbus cloud is forecast to form today on the Cat Mountains is by 1 PM, hours earlier than prior days. That would go along with the 5 AM sounding just in which has is more moist than previous days. Note that last night’s model run would not have had this new data.
So, chance of a hard rain in the afternoon if we’re lucky. But what could be really nice is that rain (in the model) continues here off and on overnight at a moderate rate, pretty unusual.
Fingers crossed that the “initial conditions”, the starting point for lat night’s run, are accurate, one of the biggest bugaboos in our models.
Another day with hours of thunder, but with those high and cold cloud bases, not much rain reached the ground. Also hurting the rain situation, too much ice. An afternoon sprinkle, a very close, rogue lightning strike, followed by an early nighttime “chaser” storm that, with all of its bluster, wind and vivid lightning, produced only 0.02 inches here, but a lot more at Sutherland Heights, a robust 0.39 inches (new knowledge, gained after dip sticking gage up there at around 7:30 AM) To see how remarkable that Sutherland Heights rain amount is, go here to the U of AZ rainlog network.
Here’s a smaller, but typical example of yesterday’s generally “low output” Cumulonimbus clouds:
5:24 PM. Starting to let go.5:32 PM Maximum strength.5:45 PM Almost gone.
Here’s another quite bad cloud (shown below), though it was good one one hand, because it was an early afternoon, frequently thundering cloud which gave promise of rain later in the day. But that rainshaft? Pitiful.
1:55 PM. At least some rain is getting to the ground amid all the thundery bluster by this cloud, thunder heard about once a minute at its peak output.1:47 PM. Small, former Cumulus congestus dissipates into an icy mass, no shaft was ever visible. Poor cloud.
It was also a forerunner of the kinds of storms we would have. Again, with high and cold bases (and oddly to me), there seemed to be an awful lot of lightning for the size of the Cumulonimbus cloud at 1:55 PM, much of it in vivid cloud to ground strokes. You may have seen a another example of that last evening around 9 PM on the Catalinas when there were a series of frequent and spectacular cloud-to- ground strokes, but little rain. The most that fell up there was 0.28 inches at Oracle Ridge. Map here. BTW, you can see the “1:55 PM”
Cb in the U of AZ time lapse movie at the far left beginning around 1:40 PM.
Well, how high were cloud bases? Rendered by the Cowboys, this 5 PM sounding for Tucson:
Reading this sounding, it makes bases appear to be around 16,000 feet Above Sea Level (subtract our elevation for above ground level) and a few degrees C below freezing. With bases that high and cold, the amount of water condensing at the bottom of the cloud is less than on days with bases, say, at 5 C and at 10,000 feet ASL.
So, less condensed water input means less rain coming out the bottom later.
If there is “too much ice” for the amount of water coming into the bottom of the cloud as we saw yesterday, its like a glass of water filled with ice cubes in which only a tablespoon of liquid water can be contained in it. The analogy is only somewhat representative since with “too many ice crystals” competing for the available water vapor, you end up with high concentrations of smaller crystals that hang in the sky rather than fall out.
So you get big anvils and debris clouds with little rain to the ground even in the peak stage of the storm.
Since the best rains in the shafts we see are due to melted graupel and hail, icy particles that generally start as an ice crystal at high elevations in the cloud, if there is little “supercooled” water there isn’t much graupel or hail, the type of precip that can make it to the ground from high bases (melting snowflakes wouldn’t from bases as high as we had yesterday because they’re essentially like Rice Krispies, there’s not much mass in them).
Well, this is pretty boring, so will end here with a sunset photo from last evening:
Today?
The U of AZ WRF-GFS rendering of rain in the State of AZ sees early afternoon Cumulonimbus clouds breaking out over the Cat Mountains today.
Why not?
Starting out with pretty similar sounding this morning, but a bit more moist than last evenings above 600 millibars (about 14,000 feet ASL).
Longer view?
Hector marches slowly toward the Southwest (Canadian model outputs), promising an enhancement of August’s meager rains so far in southern AZ.
The End.
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1Reminded one of summers in Durango, Colorado, where high, cold cloud bases and “too much ice” is normal.
Yesterday’s surprise thunderstorm, rolling off the Catalinas, provided relief with 0.22 inches here. More rain tables/maps here and here. This sight in the first shot, showing it in the formation stage yesterday, was cause for joy:
2:12 PM
Due to global warming-induced extra heat over the past few days here, as all extra heat must be automatically assigned (go here to a critical commentary on recent claims like mine above by a still-employed University of Washington Atmo Sci. prof.–wonder how long he’ll last?) combined with a break in the summer rains, our grasses, amaranth, pig weed and such were looking pretty stressed out; wilted, turning yellow due to global warming. One felt helpless to see the green of summer fading so fast due to global warming. (Want to make sure I am on the RIGHT side of this issue, you can’t be too careful these days about what you say in this domain; who might be watching.)
Then, after a near miss to the north yesterday around noon, an initially small thunderstorm that dumped on Saddlebrooke, moved off to the NW, multiplied, and became a real giant on the north side of the Tortolita Mountains, this new, large cloud base (at left) began forming over the Catalinas upwind of us. Time for hope.
Rain was already falling out of the downwind leaning upper portions of the cloud (arrow), shown in the second shot. You might recall that rain that falls out like this is not going to be what it could be, all that it could be.
Y?
Imagine dropping a cup of water out of that cloud where the bottom is (arrow), to drift away from the main discussion for a second. What will happen? Since the humidity must be less than 100 % all the way to the ground after it leaves the cloud, a lot of that water from that cup will evaporate. If you could capture the water that originally came out of that cup, it might be 10% of what came out.
How high was that “base” that’s not really a base but an overhang (above arrow in second shot)? Probably at the freezing level, or about 12,000 feet above us. So, if you’re storm chasing, and want to collect the most rain, avoid rain from overhangs!
The next shot shows where you want to be to get the most rain, and in a hurry. Those dark bases managed to hold together and keep reforming as rain fell on the Catalinas. A new strand of rain has overcome the updraft associated with new dark bases, and is beginning to fall out this side of Samaniego Ridge. An arrow has been added to point out this new rain streamer. It reaches near the ground beyond the dead yucca stalk in the foreground. This is where you want to be to collect the most rain, should you be trying to do so.
Y?
This time, pouring out a cup of water at the same height as in overhang rain, but inside the cloud, several thousand feet above the bottom, means that there will be no evaporation, and MORE IMPORTANTLY, the cup of water will grow in volume until near the very bottom because the falling drops will bump into and collect floating cloud drops that got in the way. So, if you could collect that water somehow, there would be more of it than what you dropped originally. So, those rain streamers, forming high in the cloud, are doing the same thing, pulling water out of the cloud on the way down, growing in amount.
This was a heartening sight since this new shaft, and the movement rate of the storm as a whole, meant that it would reach ME and Catalina in general) before it dissipated. As it turned out, probably another such shaft dropped right on top of us, judging by the low visibility in the intense rain. Air, rudely pushed out of the way by all that water, created winds to estimated 50-60 mph for a brief time, followed by an almost instantaneous reversal to 5-10 mph. That reversal was really something, as was as the lightning strike back behind me about 100 yards.
Today?
Expected to be dry. End of story. I really don’t enjoy talking much about dry air.
What about Hector-Ernesto, that schizophrenic tropical storm that has come all the way into the eastern Pacific from a birth place in the West Indies, home of calypso music, some weeks ago?
The Canadians think Hector-Ernesto is going to end up as a big rain producer southern Cal, with some rain enhancement here as well. The USA! models think its going to drift north and die before getting much past Baja, where it drifts off to the west. Due to a rain bias, I am only showing the Canadian model result with a tropical storm approaching San Diego and a huge crescent of rain over the Southwest, including over ME (oops, I mean us).
Yesterday’s higher based Cumulonimbus clouds were hyper-electrified for some reason. Their bases were running about 11-12 kft above the ground over Catalina at 5 C (41 F). Here’s are two examples of the tiniest thunderstorms I have ever seen (and I seen a lot of ’em, having chased them in the southern Cal deserts in the late 1950s and early 1960s, and for a few days here in the summers of 1964 and 1965. (Egad, you’re thinking; me, too.)
Here are those “tiniest thunderstorms” in the first two shots.
3:13 PM. Thunder in progress, slight rain shaft to the ground.3:41 PM. Thunder from this seeming marshmallow (two rumbles I think there were). Glaciated tip top of this guy, center.
At this point in mid-afternoon, even though the temperature was a baking 104-105 F here in Catalina, hot enough to send plumes of warm air into the ionosphere you would think, the cloud situation for rain was not looking so great upwind toward the northeast.
But those big rollers came, didn’t they!
What these little thunderstorms were telling us about the big boys that grumbled in from the NE eventually, and the ones that developed near us later, was that they were going to throw a lot of electricity at us.
They did not disappoint, though we only received 0.04 inches here in Catalina at this site.
The frequency of cloud to ground strikes was incredible, I think the most frequent I have seen. Here are some shots, in case you were inside watching TEEVEE and Olympics’ beach volley ball from London, which is somewhat understandable:
5:08 PM. Here they come, puffin’ up, shootin’ sparks, like drunken cowboys in some western movie!5:25 PM. Looking towards Charoleau Gap.
6:02 PM. Looking toward Saddlebrooke. Got an inch of rain from this just northeast of SaddleB.6:34 PM. Strike across the Oro.
Some rainfall tables for you to peruse for yesterday:
“Cocorahs” for Pima County, another, but national rain collecting network
Why were our Cumulonimbus clouds so hyper-electrified?
The simple answer is, I don’t know.
We know that electrification is related to updraft speeds in clouds and separation of hail/graupel (soft hail) and smaller ice crystals like dendrites, which leads to separation and build up of charge centers in clouds because, after bumping into one another, they collect in differents areas of the clouds. They build up charge and spark to one another, and to the ground. I am really oversimplifying this, but that appears to be the main source of cloud electrification, and why stratiform (“flat”) raining clouds and clouds that produce rain without ice, do not spark.
There was nothing in the lapse rate from the TUS sounding yesterday afternoon to suggest higher updraft speeds would develop that I could see. Was it the extreme heat that drove this occurrence? Also, crystal type in the clouds may have something to do with it.
Idle speculation: It has seemed to this observer, that the warmest based Cumulonimbus clouds have not been highly electrified here, at least, not like the ones yesterday. Warmer bases lead to different collections of ice crystals in the clouds, such as huge concentrations of columnar types (rods) called needles and sheaths (hollow columns). At lower cloud base temperatures, these do not occur except at very great heights, and very low temperatures, not in the middle of the cloud as needles and sheaths might.
The weather ahead…
Today: I could not find a single model that had rain here in Catalina today. It’s supposed to dry out due to dry air invading from the east. You can see that here in this water vapor loop from the U of WA Huskies. That dark area in New Mexico and extending into the central Plains is how the imagery represents dry air as seen by a satellite. You can see that while we are moist air right now, i.e., dewpoints are high, we have mid-level Altocumulus castellanus around, distant Cumulonimbus clouds to the WSW as I write, this moisture over us will thin. Still, I have to think we’ll see something in the way of a Cb off somewhere, probably not here, though.
Tomorrow: About the same as today, the mods say. Darn.
Why would such skinny, towering clouds be filled with thundery, gushing portent? Its really hard for a cloud to be tall and skinny. Why? Because too much dry air comes in as it rises, both from the tops and sides, and if that air is dry, it can’t go far without evaporating. Too, the drop in temperature with height has to be larger than normal for clouds like yesterday’s to shoot up to well beyond the level where ice can form (glaciate). But they did off and on all day. Mt. Lemmon functioned as a smokestack for Cumulus and even skinny Cumulonimbus, clouds all during the late morning and into late afternoon. There was some thunder here as ONE got big enough to rain that bit toward Charoleau Gap. So, you do get to record a TSTM (thunderstorm) in your log book. No rain fell here.
If you missed those bulimic clouds, here’s yesterday’s movie from the U of AZ. If you watch that time lapse, you will see some of the tallest turrets shooting up awfully fast; I thought they were rising about fast, at times, anyway, as any turrets I have seen in these movies, a marker for how rapidly the air cooled with height yesterday.
Also, here are a few shots of those skinny clouds from this angle here Catalinaland.
11:34 AM.11:36 AM. Skinny over yonder as well! Look at the behemoth behind it!
1:26 PM. “Smokestack Lemmon”, the old folk singer, still puffin’. Wonder if Sara smoked?
1:50 PM. This next puff showing more “calories”… Uh-oh. Head coming off, chopped off by dry air in the middle. Dammital.2:03 PM. The gruesome sight of a chopped off head of a Cumulus cloud that reached the ice-forming level. At least it had ice in it this time, showing the the puffs were getting taller.2:43 PM. Best one of the day, a Cumulonimbus cloud, was producing thunder at this time. A slight, transparent rainshaft was evident on Cat Mountains to the left of this shot. Notice that head of this cloud drifted away from the root or body. That means the rain falling out is going to pretty light, maybe as here, a hundredth or two.
OK, quiting visual cloud displays here. You’ve seen enough disappointing clouds, ones that did not live up to their potential like so many of us.
You would have thought massive clusters of Cumulonimbus clouds were about to roll in, spawned over the Rincon Mountains or from the high terrain near Pie Town, NM, rolling westward to pummel the townlet of Catalina again. Some of our more gigantic area storms have been preceded by morning “long tall sallys” like these.
But no.
Looking at today:
The boys in the weather club, like Bob and Mike, were talkin’ good storms today based on their very great and decades-long experience. I, too, am riding the Bob-Mike wave.
Way out ahead; major rain joy, maybe…
I am more excited about the longer term view, one in which when it gets here, will remember what I said with enthusiasm now. Remember our logo, one just like the big TEEVEE stations have:
“RIght or wrong, you heard it here FIRST! Live!”
What “first”?
Tropical storm remnant has been probably unreliably, but hopefully, forecast to come into southern Arizona in 192 h or so. Could be worse; what if it was a forecast that was 360 h from now?
Here it is, courtesy of those folks at IPS Meteostar who have rendered the 00 Z (think Olympics Time Zone) time maps for us. Here’s the low, shown on the first map, on Baja coast. The next map shows that the ENTIRE remnant has moved into AZ! Could be great.
What gives this storm a better chance of getting here than some? The upper level steering is set up to draw tropical storms northward should they drift too far northwest, like a bug getting caught in a spider web; the spider then hauling the bug to its hiding place. Gee, I never thought I would write about spiders here, but there it is; it just kind of popped out.
But, you ask, how do we KNOW, have any CLUE, that the steering, as by an upper level trough, is going to be properly placed to draw tropical storms northward so that they get caught up like a bug in a spider web which after being caught in the web, the spider comes down and takes it back to its hiding place. I really liked that metaphor. We are like that place where the spider is hiding!
Of course, you say, we go to the NOAA spaghetti factory and try to discern how likely it is that a trough will be along the West Coast, positioned to draw storms up thisaway.
The last image is a spaghetti plot of trough contours using what be called, “the bad balloon” approach. Hard to imagine, but the starting points for the model is deliberately altered a bit just to see how wild a few of the contours get. The wilder they get, the less reliable a longer term forecast is.
Valid for August 15 at 5 PM AST. Note all the green, denoting rain that fell in the preceeding 6 h.
NOAA “spaghetti plot” valid for the SAME time as the first map, 5 PM AST, August 15th. Shows that a trough along the West Coast is virtually assured. But the “devil”, the storm here, is in the details. While it is a necessary condition, it is not sufficient, since the flow might not exactly draw a tropical storm right to ME. Oops, “us.”
Well, the end of the story (told in the captions) is that a windshift producing this line of heavy Cu and a Cb or two and it “struck” Catalina about 11 AM; the wind turned from the SW to the N, but the heavy line of clouds riding it were nowhere to be seen at that time; the last Cumulonimbus cloud disappearing beyond the Charoleau Gap. Tough to take after hopes up.
