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.
A horse photo will always enhance a blog about clouds. Expecting a little uptick in readership due to this ploy, maybe will break out of the single digit column.
Not much happened early on, a thin film of Cirrostratus covered much of the sky, delaying the expected development of convection, as would be evidenced by the formation of Cumulus clouds, until mid-afternoon.
But they did form, mostly to the S through W of Catalinaland, upwind of us, and eventually rumbled in on their last legs as weak thunderstorms with gushes of sprinkles and gusty breezes, maybe ones over 15 mph!
Over there in Marana and Avra Valley, those places upstream of us, some spots got more than half an inch. But, i it seems this year that storms die when they move toward Catalina, and especially, toward MY house and its many raingauges (3).
Still, it was nice to feel cool breezes, air chilled by falling rain, even if elsewhere.
Here are a few dull and disappointing cloud shots from yesterday, including one with a horse:
10:56 AM. Horse looks ahead, examining the vellum of Cirrostratus cloud overhead, wondering if it means anything. If this was Seattle, such a layer would thicken and lower into a steady rain within hours 70% of the time. Pretty true for most higher latitude locations in the cooler time of the year. (This was horsey’s first true trail ride, going up and down rocky gullies with loose rocks along side the Sutherland Wash. Previously this horse had spent most of its 14 years in a small corral so this was all pretty new to him; rider tension high.)2:49 PM. A soothing gray of Altocumulus undercut the layer of Cirrostratus. Building Cumulus clouds can be seen toward the Mexican border on the horizon. Pusch Ridge is in the foreground. As you can see, no virga is falling from those Altocumulus clouds, so they must be pretty “warm”, warmer than about -10° to -15° C at cloud top.3:38 PM. Looking suggestive of rain here in Catalina. However, these storms were in the late, dissipating stage. Note too how the anvils have merged with the Cirrostratus layer and lean far out from the storms toward us, helping to cool the ground, ruin the chances of new Cumulus buildups ahead of them.4:19 PM. Not much going on over the Catalinas. Notice how broken up into light and dark patches these otherwise dark looking lower clouds are. Shows there’s no hope for any buildup out of them, though, lower clouds like these under precipitating Altostratus cumulonimbogenitus (that higher cloud here which is really the result of anvils) can help sprinkles get to the ground. That’s because drops or snowflakes falling out of the higher cloud, won’t evaporate while falling though these clouds (representing saturated air with respect to water).4:33 PM. Nice shaft, some cloud-to-ground lightning strokes toward south Tucson, but who cares? Wasn’t moving this way, and would be mostly dissipated by the time it got here anyway.4:57 PM. Some rain with an occasional lightning outrage did reach the southern parts of the Catalinas, eventually making it all the way to Ms. Mt. Sara Lemmon where 0.24 inches was recorded. SPKLS fell in Catalina.5:42 PM. Last gasp, last chance for rain here, dying shower with some new bases to the right, offer another slight hope that the new stuff will develop into showers like this one. It didn’t.
Still have rain chances last few days of Oct into early Nov.
Many of you probably were gasping for air after having seen the WRF-GFS model outputs from last evening’s 5 PM AST global data.
A large hurricane, really more the size of its typhoonic big brothers in the western north Pacific, and one that also dwarfs the late tropical remnant, “Newton” , that came through here a week or so ago, is shown to move along the SAME path as Newton into Arizona in about 13 days from now.
For those few of you who did NOT peruse the 00 GMT, CUT, Z output, here are the fantastic fantasy hurricane depictions that this model, with all of its calculating power, shows entering AZ on the 26th. Kind of fun to see even if it is bogus because it indicates that such a strong tropical cyclone could come through here one day.
Below, from IPS MeteoStar, these, maybe the best fake AZ hurricane depictions I have ever seen. Note all the isobars, i.e., lines of equal pressure with this tropical cyclone in AZ, and then remember for all its rain, little Newton had virtually no signature on pressure maps! Hell, the pressure didn’t even fall at Nogales as Newt approached. Pitiful.
But it wouldn’t be like that in this fantasy hurricane. Tremendous pressure falls would occur as it entered AZ giving your microbarograph quite a workout as the pressure plummeted and then went up as the center passed by.
You do have a microbarograph don’t you? If you don’t, think about it.
“Invalid” (haha) for 5 AM AST September 25th.Invalid for 5 PM AST September 25th.
Next, you’re curious, though, about what steering pattern caused this hurricane, previously shown to stay far offshore and dissipate over some jellyfish and plastic particles way out in the Pacific in the models.
Let’s look, again from IPS MeteoStar at the steering situation at 500 millybars, or in around 20,000 feet or so:
Here the configuration. You’re breathing a sigh of relief, maybe even chuckling: “That’s not gonna happen.” Ludicroous really, though withing the slightest realm of possibility, maybe one in a thousand. Like kicking a field goal that goes through the uprights after bouncing off an opposing player’s helmut. I mean, it could happen, like a golf shot at Carmel that bounces off a stunted cypress and goes into the hole from 500 yards out, or…. OK, enough of that.
What you need to have any confidence is a big trough along or just offshore as we had with Newt, not a slight little itty bitty eddy aloft that has to be in exactly the right location at EXACTLY the right time. I mean, its like a ball that goes for a home run after it bounces of the center fielder’s head1 …
Hold your cash on the sand bags.
Finally, there’s really nothing from the spaghetti factory that supports this. Boohoo. What you need in spaghetti is strong support for a trough along the coast, not the below:
Valid at 5 PM AST September 25th.
Yesterday’s clouds
Spectacular Altocumulus castellanus and floccus (no virga) passed overhead during the morning. I hope you documented them with a few photos.
9:11 AM, on the trail looking at a superb example of Altocumulus floccus. Estimated height, 12,000 feet above ground level. No ice visible, so tops likely warmer than -10 C. The bases of these clouds evaporated almost as soon as they formed, but the tops not so much, rose steadily after bottom disappeared. Tallest ones were likely more than 1,000-2000 feet tall.12:16 PM. By this time, which was good, smallish Cumulonimbus clouds recurred over the Catalina Mountains mostly east of Ms. Lemmon. Nice stages of ice development in the tops from newly risen, no sign of ice (right side here), to frizzy all ice remains (left side here), over and over again.
Horse story
Have to depart from clouds and weather to tell this tale. Yesterday I stopped here to let the mighty Zeus rest a little. I let him graze “off leash” on some of the still-green nettle grass in a gravel parking area next to our cottage. I then went to get a pail of water for him, the pail being on the north side of our house. When he saw I was leaving, he immediately followed me like a dog. It was kind of cute.
But as we got to the gravel outside the north porch of our house, our two dogs, Banjo and Emma were going nuts at the sight of a horse outside the north windows.
Zeus got distracted by all of the commotion in the house and went onto the porch to look in one of the windows to see what was up, or maybe he saw his own reflection and thought it was another horse? Here is the hilarious scene:
2:21 PM yesterday. Zeus looks in to see why the dogs are barking so much.
The End
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1This actually happened in South Dakota, at Mitchell’s Cadwell Park, during a baseball game I played in ’72. I was catching in those days for Mitchell Commercial Bank. Our center fielder, a track star, ran to get a scorching line drive to medium depth center, and racing to his left, reaching up to grab it, the ball instead bounced off his noggin and went some 40 or 50 feet over the fence! He was OK. We had no “concussion protocol” in those days. Had a chance to bat against the legendary Canova, SD, pitcher, Lee Goldammer in that game. Whiffed on three pitches; was maybe at bat for 30 seconds.
0.02 inches of it, anyway, as the core of the jet stream at 18,000 feet or so passed by Catalina yesterday afternoon. Keep your eye on the orange and reddish streak in these progs from IPS MeteoStar yesterday morning beginning at 5 AM AST and how it slides over us as the clouds began to ice up:5 AM yesterday. Jet at this level races across central AZ. 11 AM yesterday. Maximum winds getting closer! Tiny Cumulus clouds begin to appear over the Catalinas and on the west to north horizon.
11:40 AM.
The jet separates deep cold air on the left side, looking downwind, and deep warm air on the south side. The deep warm air prevents Cumulus clouds from getting very deep due to inversions and stable layers where the temperature does not change much with increasing height, or even rises. The temperature at 500 millibars or 18,000 feet above sea level dropped from -17.7 °C to -21.1° C over TUS yesterday between 5 AM and 5 PM, while the temperature about which ice begins to form in our clouds dropped about 400 meters during that time. With the temperatures at the ground rising into the mid-70s as the colder air moved over us, Cumulus clouds deepened, reaching the ice-forming level between 1 and 2 PM.
Also with patterns like this, the cyclonic rotation (vorticity) in the air above us is increasing like mad, and that leads to a gentle upglide motion in the atmosphere, one that also helps cool the air aloft and usually produces sheets of clouds like Cirrus, Altostratus, Altocumulus and NImbostratus. But yesterday the air was too dry for sheet clouds to form.
First ice was noted just after 1 PM. Can you find it?
1:11 PM. Looking N toward the Charouleau Gap. Tiny puff of ice ejects from a Cumulus humilis cloud based at about 8 thousand feet above ground level. Bases were running about -5 °C
2:31 PM. Cumulus and Stratocumulus clouds launched off Pusch Ridge and the Tucson Mountains stream toward Catalina. The sky begins to fill in rapidly.3:44 PM.3:49 PM.3:57 PM. A horse eating as it clouds up.4:33 PM.5:09 PM. Light rain falls in Catalina/Sutherland Heights.6:04 PM. RW- (light rain showers) continue in Oro Valley.
5 PM yesterday. Just passed! B y this time, Sutherland Heights had 0.02 inches as the tops of Cumulus and Stratocumulus complexes continued to cool and ascend. The sounding from TUS at 5 PM AST (launched about 3:30 PM AST) indicated the coldest tops had reached -20 °C or so, plenty cold enough for ice, virga, and light rain showers. Too bad the bases were so high since we could have had some real rain if they had been lower.
But, we were “lucky” to get that. Even the great U of AZ model had no rain anywhere near us late yesterday afternoon when it fell! THAT does not happen very often.
Looking ahead….today:
Nice Cu, ice, too.
Farther out:
Substantial rains, maybe half an inch or so, still on tap between May 6th-8th as previously foretold here. Yay! May averages 0.38 inches here in Catalina. More rain likely after that episode, too. So an above normal May in rain is pretty much in the bag now. Could be an especially great May, too.
I was really happy for everyone out there when the skies were dotted with so many perfect examples of Cumulus humilis. It was like a numismatist finding a perfect Indian head penny. If you were like me, and I suspect you are, you were just going CRAZY taking pictures of those flat little pancake clouds. Those clouds were pretty much limited to about 1,000 feet (300 m) thick at most
Not cold enough for ice in them, of course, since the temperatures at Cumulus cloud tops were only around -3 ° to -5 °C (28 ° to 23 ° F, respectively). Around here, ice USUALLY does not appear in clouds until the temperature is lower than -10 °C at cloud top.
Yesterday began with some light snow falling on Mt Lemmon…well, it was falling downward TOWARD Ms Lemmon, actually. Fell out of some thick Altocumulus clouds up there around where the cloud top temperature is… what? OK, silly question for you, probably lower than -15 °C (5 ° F).
Let’s check the sounding to be sure, remembering that the launch site (University of AZ) was downwind of air flowing from the NW yesterday that went over the Catalinas, so a sounding at the U of AZ might suggest higher temperatures than this cloud was actually at since the air was probably descending before it got there.
Indeed, as just seen by me, the TUS sounding indicates that layer, up around 14 kft above sea level, 11 kft or so above Catalina, not a city, but rather a Census Designated Place or CDP, was “only”at -10 ° C.
I reject that as the temperature of the virga-ing cloud over Ms. Lemmon! Its a little too warm IMO.
8:41 AM. That white haze under the Altocumulus clouds is composed of ice crystals, concentrations probably a couple or less per liter of air. Likely stellar or plate crystals, ones that form at temperatures less than -10 ° C. Almost certainly no aggregates of crystals; concentrations too low to form “snowflakes” which are aggregates of single crystals. Snowflakes form when higher concentrations of crystals collide and get locked together, as in stellars, and their cousins, dendrites, that grow in a similar temperature regime. Dendritic crystals are usually seen in deeper clouds than these because those crystals have time to grow extensions in various directions, are not just “planar” ones. If the cloud is thin like this one, not much growth can take place in the droplet cloud and simpler crystals like hexagonal plates and stellars (Christmas card crystals) fall out. There is a lot of hand-waving here….10:20 AM. A horse named “Zeus” looks to see if any Cumulus clouds are forming over the Mogollon Rim to the NE, or, maybe he’s fixated on the horses in that corral below…
By afternoon, the skies over Catalinaland were spotted and dotted with spectacular Cumulis humilis examples. (The littlest shred clouds are Cumulus “fractus.”)
I’ve left the time of the photos off today. After all, there was only one true time yesterday, “perfect humilis time!” or as we like to say, “PHT.” Immerse yourself.