Definitions – Page 97

Trace King; how to be one

Had a trace of rain yesterday, August 5th, in Catalina as a few drops fell just after 5 PM, and again just after 8 PM. If you weren’t outside or driving in the neighborhood, you wouldn’t have noticed.

I always felt recording a trace of rain was important, but the recording of traces is definitely human influenced: there are outstanding trace “reporters”, and those who aren’t so diligent. An example, discovered while looking at rainfall data for my hometown Los Angeles. For decades it seemed, Sam Miller, was the Weather Bureau (now NWS) “statistician” reporting to the newspapers the amount of rain or other climate data of interest from the Los Angeles official climate site, downtown. Sam NEVER missed a trace, whether it was a summertime sprinkle (sparse larger drops that fall rapidly) from mid-level clouds, or drizzle (fine, close together drops that almost float in the air) from low, maritime Stratus clouds prevalent in mornings in the Los Angeles basin during the spring and early summer. During Sam Miller’s regime, Los Angeles averaged about 20-25 traces a year. When Sam passed in the mid-1960s, he was replaced by an observer that was not so vigilant. The number of traces fell to just several a year!

At the time, being a little naive, I thought I had discovered an air pollution effect. It had been reported that smoke from cane fires in Australia had reduced rainfall from relatively shallow clouds. I thought maybe that the notorious Los Angeles smog had reached a level where it had turned off the Stratus drizzle machine (mid-level clouds would not be affected). I got excited, but it wasn’t long before reason set in and the “heterogeneity” in the data was found to be due to human influence.

Even today, I take pride in detecting “traces” of rain, recalling Sam Miller. A “trace” tells you, when you see it in the climate data, that rain was in the area. And especially here in the summertime, perhaps even heavy rain that missed gauges. So, while hoping for a “dump” from a promising cloud base almost directly overhead (first pic) I waited outside for many minutes so I could “detect” it first hand. A heavy shaft of rain was already drenching the west slopes of Samaniego Ridge.

I waited outside for the first sparse fall of giant drops the size of silver dollars, those big boys that fall through the updraft overhead first before the collapse and main rainshaft falls out. Didn’t happen. The shaft from the cloud base overhead developed that bit too late and all we got is a few, spares medium drops, more or less having been blown our way by the wind as the main shaft that eventually came down. Oh, well.

Evidence of those drops having fallen, in nearly 100 F temperatures, was soon gone. If I hadn’t been outside watching as this base developed overhead, I might have missed it, or at least when it fell. However, I do have a “trace detector”, our oldest car which is parked outside. That car is always aquiring a new layer of dust, and, at the same time, I clean the windows every day. With the inevitable dust, overnight “traces” of rain are NEVER missed! I deem myself therefore, the “Trace King.” I’ve noticed that many people do not park their cars outside for the purpose of detecting traces of rain, and so that’s why I EASILY surpass others trace reporting because so many night events are missed. Its great to be at the top, I have to say, to be good at something anyway, if nothing else. An example of the detection of a trace from an overnight event below (2nd photo) Note small mud balls where drops and mud congealed. What a great sight! Got me another “trace” for the records!

I hope now that many of you will now appreciate the meteorological importance of parking your car outside, 24/7, refreshing its surfaces each day for that new, possible trace, to help you be that bit better weather observer you always wanted to be. Soon, you could be the “Trace King” of your domain!

The End

In case you missed it…

yesterday’s lightning criss-crossed rainbows over Catalina/Oro Valley. Couldn’t capture the lightning, but two strokes occurred while this glorious rainbow was in progress. Once again, being from Seattle, I have to say, “Never seen that combination before.” I now really wish the University of Washington had had a branch campus in the Tucson area–go Huskies! The first shot was taken at 5:49 AM, about the same time as the rainbow fragment in an earlier post. You can see that the other part of yesterday’s rainbow is in EXACTLY the same position as that colored highlight shown back then. It was odd, too, that there still was lightning with this very weakly, raining, and dissipating Cumulonimbus, and in particular, a cloud-to-ground strike. Seemed to continue the regime of unusually electrified clouds in the past 24 h, ones that seemed ordinary, or even weak, yet produced prodigious amounts of lightning, and continued to flash long after they seemed “dead” as clouds. That is, no new updraft areas apparent, just virga and weak rainshafts as shown here). Hmmmmm…..

Nice, unexpected thunderstorm this morning with an extremely close strike here about 3 AM. Total rain only 0.07 inches, but with an interruption of the summer rains predicted for several days, the mods say, any rain is welcomed!

Sunny, with rain and close lightning strikes

Good grief, what a last 12 h or so. First, the smallest thunderstorm that produced the most vicious cloud-to-ground strikes that I’ve experienced developed overhead just before 5 PM LST yesterday. Took the photos below looking in several directions because, as the heavy rain fell for a few minutes and the lightning bolts were striking all around the house, it was SUNNY! Somebody musta got a good rainbow shot! Take a look; the following photos were taken amid close, cloud-to-ground strikes and pouring rain (amounting to 0.13 inches in a few minutes):

Here’s the cloud what done it, just as the “festivities” got under way. Truly amazing!

We all know small (Cumulonimbus clouds) can produce very small shafts of rain, but it was how highly “electrified” this small cloud was that made it special. And that phenomenon continued into last night as that huge complex moved in from the SE after 10 PM last night with about as much lightning as I have seen over such a wide area. Its still producing lightning to the NW-N. Sadly, we only received another 0.01 inches overnight to bring the 24 h total to 0.14 inches. But somebody got a pounding overnight. Let’s check with our friendly ALERT gage reports. Not much around here or on the CDO watershed, darn! Still hoping for a Sutherland and CDO wash run before summer is out. Last year they were running on July 30th. These dogs were pretty happy about it back then, too; here a scene from the Sutherland wash last year. But, I nostalgiate. (What a great sight that is, water running in our washes!)

Most of yesterday’s appears to have been to the S and SW of us. Oh, well. As Scarlet said, “Tomorrow is another day”, except that now its “today is another day.” Mods tending to dry us out in the days ahead. Drat.

The End.

Anyone for sprouts?

Man, I wanted some sprouts so BAD yesterday afternoon! But, no, it looked like there weren’t going to be any. The air seemed to be too dry near the tops of the small Cumulus clouds that populated our sky until 3:30 PM LST. But then, voila, sprouts! Little acorns grew into huge cauliflowers! And then, voila#2, those sprouts reached the “glaciation level” and well beyond it, where the tops suddenly transformed into ice, meaning that there is hail/graupel and snow that will fall out of the bottom of those clouds and melt into RAIN!

While we didn’t get any here in Catalina yesterday, it was still a spectacular sky for us to enjoy. Here are some examples, in case you missed them, which, if you are in Colorado, Montana, or New Hampshire, or somewhere like that, you CERTAINLY did and will want to see this. First, a failed cloud. Tried to sprout as best it could, but didn’t have what it takes. Sky pretty discouraging at this point because it was 100 friggin’ degrees and the Cumulus clouds were acting like they had cold bottoms; they weren’t sprouting in response to the ovenly weather, to continue a theme.

But then, when I wasn’t looking and had really kind of given up, voila#3, here was this “glaciated” tower (3rd photo)! It was stunning! I missed this because, as a man with feelings, I was preoccupied with the vets “rassling” with our horse, trying to poke him with huge needles (photo included as a human interest diversion in case you’re already tired of seeing cloud pictures.)

Off we went, with more cloud sprouts and glaciation! The Cumulonimbus “calvus” shown on the right (5th photo, the one after the horsey shot) with palo verde tree in foreground, virtually went “volcanic”; a huge cloud explosion ensued after this shot, 16 minutes later (4:44 PM LST). You can really see this happen at the movies here, presented by the University of Arizona Department of Atmospheric Meteorology. “Two thumbs up.”

And, of course, we had another memorable sunset to clog our already overloaded brains.

The End.

The “boys” are back in town; those Cumulonimbus ones

Who can forget “Thin Lizzzy”? I guess everyone. A reminder of their one hit below:

“Guess who just got back today?

Them wild-eyed boys that had been away

Haven’t changed, haven’t much to say
But man, I still think them cats are crazy”

After some English language deviations above, it was great to see for the past coupla days some of them fat Cumulonimbus clouds we been missing of late. Lotta lightning, too, which was fun to see. At this point, I would like to point out that some residents of Catalina habitually leave in summertime so’s that they don’t experience our storms, colorful sunrises, sunsets and warmth. Such a pity, wouldn’t you say? Some go off to the White Mountains to their second palaces and villas up there, but at least these weather refugees remain in our State where you could drive up to see them if you really wanted to. Others go off to such far away weather refugee centers as….Colorado, Montana, New Hampshire (?, really inexplicable), etc., to escape our photogenic storms and sunsets.

Besides, they got smog back East, smog so bad you can barely see the blue sky overhead on a humid day, just the kind of day where interesting clouds might be around! Its awful. Here’s an example from a University of Washington field project in Virginia, the view from the ground and then on top during a research flight. Ghastly! Certainly this kind of thing extends all the way up to New Hampshire on humid days and you have to wait for a cold front (they get a lot of them up there) for the air to clear out. Ugh!

Below is what we in Arizona see on a humid day; these from yesterday. Of course, for some little climate babies, maybe the temperature is a little too high here for them (100 F yesterday). I guess that is pretty high… But you can see 100 miles off in the distance as well! Look at those (Code 4) rainshafts out there. “Code 4”? Nothing visible behind rainshaft. This is so COOL!

You may have noticed a southwest wind picking up here in Catalina soon after this complex of rain and lightning appeared, and a bit of a ‘boob off to the southwest, marked by a dark line of dust just above the horizon. That outflowing wind got here and gave a nice upward shove to the otherwise innocuous clouds over us. Watch what happened to this moderate Cumulus cloud as the SW wind began to hit. #4, rain begins to fall out, the best time to be underneath and experience the biggest drops or hail.

Well, it pretty much missed us, only got 013 inches as this spread to the north some later. But, it all helps. Leafy desert vegetation looking stressed before the last two days of rain, now totaling 0.32 inches here in Cat land.

Lastly, since I have too many cloud photos here, a picture of a horse grazing on somebody’s weeds. Hypothetically speaking, perhaps the owner is in New Hampshire (today’s location theme) and would want to know that her horse is being exercised even after I fell off the day before.

The End.

The color of rain

In case you missed it last evening…. Don’t forget, too, that if you are standing in sunlight AND rain, that you are IN somebody’s rainbow. In fact, whereever the sunlight is hitting the rain is somebody’s rainbow. You can only see the one the laws of physics combined with drop sizes allow you to see. So, in a sense, the rain you standing in is brilliantly colored; you just can’t see it. Kind of cool, when you think about it.

Here’s the post mortem on yesterday.

First, morning Stratocumulus clouds topping Samaniego Ridge. 2) The occasional “sprout” of deeper Cumuli out of that mass.

But along with that, the Cumulus clouds elsewhere remained pretty flat (3), indicating there was something above the tops holding them back. That would be some sort of “stable” layer that would have to be overcome by more heating before any of these could surge upward farther and produce rain. Below, taken at 2:15 PM yesterday afternoon. With only occasional “sprouts” over the Catalinas that withered and died (4) instead of blowing up into thunderstorms, there was some reason for concern at this point. In fact, NOTHING sprung up over the Catalina mountains. Rain fell yesterday evening for a few hours, but we had to be “saved” from a dry day by a thundery mass, mostly the fading remnants of strong storms that marched westward from the White Mountains. The last photo, (5) shows that “stratiform” cloud mass (with Cumulus underneath it) that brought the steady light rain and rainbows. This photo was taken as the first drops began to fall.

Our rainfall was only 0.13 inches, but considering these masses often run out of rain before getting here, I was grateful for that.

Less color, more filling…

of raingauges wanted. It was another spectacular sunset yesterday evening after another dry day here in Catalina. You hate to see a completely dry day go by during our peak of the summer rain season, July 5th through August 20th.

Below, the best we could do over Mt. Sara Lemmon in the way of Cumulus clouds, a “medicocris” one is what I would call it, followed by a couple of shots of that great sunset. That Cumulus was pretty pathetic I thought, though it was trying as hard as it could. You really don’t want to be a Cumulus mediocris in life, but there it is, and that’s as “important” as that cloud got, to the “mediocris” stage. Really hoped for more yesterday, too, since the morning Altocumulus cloud bases were a bit lower than the prior dry day. Some remnants of the morning Altocumulus are there above that Cu med.

If you caught the remnant of the moon yesterday morning through those Altocumulus clouds, you saw something a bit unusual. You couldn’t detect any cloud movement. In fact, the relative movement of the moon toward moonset almost seemed faster than the cloud movement! That’s not good for storms either, since its better if there is a bit of wind shear, turning and speed increases with height, not virtually calm all the way up. If you want to read a little more deeply about this sort of thing from one of the world’s best experts on convection, Bob Maddox, who lives right here in Tucson, go here to Maddweather. Has a great web page on our weather, and storm structures.

Learned something, too, yesterday. I did not think you could have Altocumulus lenticular (sliver) clouds with virtually 2 kts of wind. But, there they were in these sunset photos. An old weather saw, obviously a bit flawed, is that lenticular clouds require appreciable wind.

The models are wetting it up here over the next few days, and we’re not that far from conditions that produce large storms. In this last photo. taken at 7:02 PM, you can make out a Cumulonimbus cloud on the SW horizon, and the huge gray shield to the S was the remnant of a large cluster of storms near the border. So, get ready, and dust your gauges off!

The End.

Last, after The End, is the NWS sounding (courtesy of the U of AZ Dept Atmos. Sci.) for yesterday around 5 PM LST. Where the green line pinches in toward the white line is where the two cloud layers shown in the sunset photo were located. On the far right are the wind “barbs” showing how light the wind was, less than 7 kts.

Watching rain come out of the Arizona summer sky

Here is a sequence of photos showing the development of a rainshaft from a prior “doing nothing” cloud base. For a long time, it appeared that these dark clouds, bottoms of Cumulus clouds, were too raggedy, not contiguous enough in a nice, large and dark region indicating a wide updraft, one that might push cloud tops to the “glaciation” level where ice forms magically and spreads throughout the cloud top. Our Cumulus clouds, at this warm time of the year, must climb to about 20,000 feet or more above sea level, or to the -10 C (14 F) level, before the liquid cloud drops in them will freeze to ice, and then only some cloud drops do. Those first ice particles, surrounded by drops that have not yet frozen, become hail or “graupel” (aka, “soft hail” you can mash between your fingers) as they collide with those unfrozen drops as they begin to fall out.

So, no rainshaft, no tops to 20,000 feet or more, no matter how dark the clouds may look. At least for a long time yesterday, they did nothing. You’re thinking, “What a waste!” and, “So close!” (to precipitating). I did, for sure, as I thought a chance for rain in the area was going to be missed.

But then, there it was (look hard, straight above the tree near the middle of the 2nd photo) ! A thin strand of rain dropping out of those dark bases, a strand that quickly became a downspout, then a huge rainshaft clobbering, maybe Saddlebrooke! Very nice, dramatic to see.

Here’s the main sequence of that. First the line of non-raining cloud bases is shown, and then the cloud base area where the shaft began to fall out. After that, it lengthened, broadened into a full rainshaft. Notice the curvature to the left as it went down toward the ground, showing the N wind underneath cloud base. This is SUCH an exciting time because you’ve been waiting and waiting for something to happen and begin to wonder whether it will at all.

We only got a trace, a few drops. But the air cooled nicely, followed by another fabulous Arizona sunset producing that little bit of paradise.

Why was there a line of clouds like that shown over Cat land yesterday evening?

Clash of the “outflow” winds from thunderstorms in the area, that were meeting below that line of cloud bases. That wind clash passed through this location at 6 PM LST when the wind shifted from the southwest to the north. Above these kinds of clashes, the air is forced to rise and enhanced clouds, or a line of clouds forms. Some areas got over 2 inches yesterday between Colossal Cave and Benson. Check these amounts out here.

Here’s one of last evening’s sunset, for a little color, “Arizona gold” in here to break up all the gray:

Yesterday’s Catalina-centered blast dump: 0.83 inches; 0.53 in 16 minutes

Nice weather we’re having lately. Nice desert greening we’re having now, too.

What a day yesterday was! Look at the sunrise view of Altocumulus at the start of the day. And, too, how about some neat patterns before all the mayhem. What a day, to repeat.

Yesterday’s blast and dump that struck just after 2:30 PM yesterday can be seen in a side view here, courtesy of the University of Arizona Wildcats Department of Atmospheric Meteorology.

Watch those dark cloud bases move over the southern portions of the Cat Mountains at 2:30 PM in this time lapse film! Pretty dramatic, and also see how fast a cloud can drop a load of precip its been carrying in some of those around Tucson yesterday.

Below is what those same clouds looked like rolling over the Cat mountains toward us from our Catalina vantage point. This was pretty darn exciting to see! Why?

First, that dark line of bases was streaming toward Catalina from Table Top peak. Next, the bases are pretty large, meaning a there is pretty large area of updraft, and 3) MOST importantly, the bottoms looks solid, no bright spots interspersed among the dark base telling you that the updraft has holes in it. A solid, contiguous base like this suggests a good AND contiguous updraft, and a LOT of water is being condensed above those bases.

Can things change and holes develop even at this point?

Yes, have been horribly disappointed a time or two when that has happened, and when it does, its kind of like the beginning of a love affair you thought was going to be a good one but goes “south” all of a sudden because you made some assumptions based on too little “data” and other misinterpretations due to wishful thinking and delusions and then you find out that those assumptions and perceptions were incorrect and you REALLY were delusional cum laude. How painful is that? But then you have to “man-up”, as we say today, and pretend that nothing happened…or you’ll lose face. Yes, I have had to do that with some cloud bases that have let me down.

Or taking another tact here for sports fans, a cloud base that falls apart is like a seeing a running back breaking into the open, with a clear field ahead. Everything LOOKS good until he trips and falls at the 10 yard line. You’re so upset, you go down to the Golden Goose thrift shop and buy a pair of ladies’ used tennis shoes and send them to the miscreant running back as a way of pointing out your displeasure. You don’t want to admit you were wrong in your “a priori” assessment that a touchdown would surely be scored.

Well, you get the idea. It can all go bad just from looking at the cloud base and making an “exterior” assessment because you really don’t know what’s happening “above” (as in people). So, you have to “hold back” your emotions just that bit to keep from being hurt by a nice “cloud base.” Was I talking about weather somewhere in here? OK, back on task.

But that cloud base yesterday did not fall apart; it did not disappoint! Rather it remained solid until that magical point that all that water/hail/graupel up there above the bottom of the cloud begins to shoot down, often in strands or filaments. The strands or filaments are almost always due to hail or graupel shafts. Hereabouts they are likely to have melted into large drops on their way down. (When flying through these kinds of clouds, as the writer did for many years with the U of WA Cloud and Aerosol Group, flying through those miniature shafts of hail/graupel (soft hail) was like someone throwing a handful of rice at the pilots window. They were only tenths of a second in duration, maybe 10-30 yards (meters) wide. Its still not clear what cloud “microstructure” and circulation leads to such tiny strands within large clouds. Uh Oh, getting deep here.

Check out the next couple of photos, especially number 2 and 3. For maximum precip excitement, I would have, and I am sure you, too, wanted to have been about 1 mile farther toward that base as the bottom drops out. That’s where the largest raindrops, hail or graupel are going to be. Of course, all that water is going to shove a lot of air out of the way, and that’s why we saw those momentary blasts of wind to 50-60 mph, at least right here.

Here’s a map of the local area rainfall, thanks to the U of A rainlog organization. It will show you how well we did relative to the rest of Tucson.

The End.

“Back in Black”, cloud bases, that is

Few people know that Angus Young, lead singer for AC/DC, was quite the weather nut and many of his songs, such as “Back in Black”, are actually about clouds and storms. Thought you’d like to know so that when you get your old AC/DC albums out, they’ll have a little more meaning to them… What about the AC/DC song, “Hell’s Bells”, you ask? Its interesting that you have asked me about that. Here’s the story behind that one: well, that was about a forecast of rain that didn’t materialize there in Australia. Its mostly desert there, like here. Mr. Young was pretty upset about it, apparently.

Some cloud bottoms for you from yesterday. Nice to see the return of the summer rains. Only 0.07 inches here, but I was quite happy to see that heavier showers fell elsewhere, all around me, in fact, and perhaps in droughty areas that needed more rain than I do (face turning red, fist pounding table). No, it REALLY was good to see others get more rain than me, and watch the summer “spectacle of the rainshafts” way off in the distance underneath those Cumulonimbus clouds. I like spectating rather than participating, that is, being inside those rainshafts (face turning red, fist pounding table).

On with the picture show:

That sunset scene last evening; the slot of clearing that allowed the yellowish sunlight to bath the rocky faces of the Catalinas, followed by sunset color in the underlit clouds overhead. Can one’s thoughts not shift away from self and problems, to the joy of being here in this special place?

The End.