Beginning to wonder, with all the middle cloud thickness out there over and SW of Baja that’s headed this way if we won’t get sprinkles that produce a little measurable rain later today or overnight….
7 AM AST. Look at all those clouds over Baja and to the west of there.You can see this whole loop from the Washington Huskies here.
Models beginning to wetten things up here as well, like that Enviro Can model that sees our tropical surge high and middle clouds passing over us now, as deep enough for measurable rain later today and overnight. Huh. U of AZ mod, the best one for us, is still dry around here except on mountain tops. Our larger scale model, however, also has some very light rain in this area now, later today into tomorrow morning.
What’s intriguing is that a little jet core at 500 mb (up there at about the height of middle clouds) passes south of us as this happens, key for precip here1 in the cool season. The major jet stream is far to the north.
As you know, we have a bit of an El Niño going, both a “Classic Niño” as well as the “New Niño” going, and El Niños strengthen the southern portions of jet streams in the very way that we’re seeing in this situation.
They do that because its warmer than usual in the central and far eastern Pacific tropics due to heat in extra big Cumulus and Cumulonimbus clouds that pump away down there over that extra warm water, and that rising warmth produces a greater than usual difference in temperatures throughout the troposphere between the tropics and the mid-latitudes. Since jet streams are the products of temperature differences between warm and cold air around the globe, so unusually deep warmth in the tropical eastern Pacific gives a little strength tweak to jet streams coming into the coast2.
SInce there are two of these lower latitude “waves” traveling along in the southern branch of the jet stream, there are TWO chances for slight rains including that for later today. The next one barges in on the 6th of December. Will again be dense middle and high clouds with virga at its worst, like this one, though again a hundredth or two could happen.
Next real rain chance, and major front passage with air that’s too cold for us, will be on the 12th. Spaghetti folk, or “Spaghetti Busters”, those who can make sense of these balls of yarn, can EASILY see that trough on the 12th and a cold front with are “in the bag” even though that’s ten days away. Rain occurrence is more dubious, since the trough may land a bit too far east to produce rain, only a lowering of temperatures. Here is that plot from last evening. Enjoy.
Valid at 5 PM, December 12th. Pretty clear a nice trough will be in the area then.
Your yesterday’s clouds
11:44 AM. Up and down, up and down, those wavy air motions that produced this interesting line.3:37 PM. Classic Altostratus translucidus (sun’s position is visible).5:20 PM. Sunset Altostratus (ice clouds) and Altocumulus (droplet clouds).
BTW, for horsey people, the Cement Trough had water in it yesterday after being completely dry ten days ago:
11:44 AM. At the Cement Trough headed to South Gate.
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1See Rangno, 1973, unpublished manuscript and figures for the whole US using only the horizontal shear in jet stream at 500 mb as a definer of precip occurrences. Its really quite something, though, I guess you can’t see it.
2This was figured out by the Great Jacob Bjerknes of the Norwegian School of Meteorology while he was cruising into retirement (“Emeritus” status) at UCLA in the 1960s, though Chuck Pyke3,4, his grad student, did most of the work. Did a lotta work on the big “Classic” El Niño of 1957-58, which, per chance turned out to be an International Geophysical Year with a lot of extra observations! How lucky wazzat?
3Chuck, as you may recall was in the National Guard whilst at UCLA and was sent to Biloxi, MS, for two weeks of training and while there, was “gifted” with the passage of the eye of Hurricane Camille, one of the strongest of the century. Later the remnants of Camille, to go on and on, produced 31 inches of rain in 6 h in Virginia.
4Chuck P, who now lives in Arizona, also was very thorough in his evaluations of rainfall in his other studies concerning the seasonal timing of rainfall throughout the West. He once told me when I visited UCLA once to get Bjerknes autograph5 that he had gone to every rainfall measuring site in his study! Now some people go to every baseball park in America, but going every rain gauge site would be more interesting to cloud mavens. He further told me he found one that had not moved for 30 years, but the rainfall had been decreasing. When he went to that gauge, he found that it was being overgrown by a tree! This is why you have to check things.
5I failed. He was “Emeritus”; too good to be in his office that day. You see, your Catalina cloud maven was a strange person even then, wanting an autobgraph by Bjerknes rather than one by Mickey Mantle, though one by Mickey M would be worth a lot more today.
(Formerly titled: “Storms lining up for Catalina in early December”)
Things change.
Confidence was never real great in the spaghetti plots we rely on for hints about the reliability of our longest range “wishcasts,” as a friend puts it. Now it seems we’ll only see high (Cirrus) and middle (Alftocumulus and Altostratus) clouds on the edges of the rain areas that move across California, maybe the NW corner of Arizona, too, during the first week in December. Oh, I suppose there could be some virga with a sprinkle here from the thickest of those middle clouds, but that’s about it now.
But, on the happy side, we’ll see our usual array of stunning sunrises and sunsets under warm conditions when those high and middle clouds begin arriving about Saturday, the envy of many northern “climers”, or “northlats” this time of year. (Starting to see those Illinois, Minnesota, Ohio, license plates now, aren’t we?)
Our next chance at rain after that is not good but revovles, and the air does, around a cutoff low that gets stuck out of the mainstream here in the SW in mid-December. Those, unless you’re in the exact right position, or are gigantic like that one back in ’67, often have limited amounts of moisture. If you’ve never seen a cut off low, here’s what they look like in the middle troposphere, a forecast valid for this Monday afternoon:
From the University of Washington Huskies Weather Department, this example of a cut off low at 500 millybars, or around 18,000 feet above sea level. They kind of meander around not doing much, then eventually dissipates/”opens up” into just a bend in the winds up there, as this one does as it begins to move eastward and then northeastward (the killer for us) as it comes into the Cal coast. Most of the jet stream, as indicated by numbers of contours, is far to the north, something that allows lows like this to pretty much have a mind of their own for awhile. The bulging northward contours over us mean that it will be toasty and dry here, maybe some Cirrus clouds around..
So, it would kind of lucky for us to get something out of it. And, when you’re in a droughty period, as we have been in for the past EIGHT weeks, things like that don’t usually work out in your favor. Its like being a football team that loses the close ones but also gets blown out in other games. Since we’re talking about sports now, a pause for a sports exultation: Washington1 volleyball somehow beat No. 1 Stanford on Wednesday!
Special Scientist, Bob Maddox, who is an actual expert and does a superb weather blog for this area, has passed me a long range forecast from the CPC (Climate Prediction Center) recently that I will share with my reader:
A wet mid-winter in the Tucson area been forecast!
How wet? 2 inches in December, 4 inches in January, and a colossal 6 inches in February. Wow. There would certainly be flooding at some point later in this period.
These results derive from a longer range forecast model the CPC runs. Although the fantasy factor is high here, still, something to hope about. With a bit of an El Niño in progress, and this forecast resembling the tendency for El Niños to act up in aiding wetness in the Great Southwest in the mid-winter to spring, there is some SLIGHT credibility here.
Too, such forecast amounts resemble the great El Niño winter of 1992-93 that helped ruin the Biosphere 2 experiment, then in progress because there were too many clouds and not enough sunshine to make it “work.” Imagine.
OK, already getting too worked up about this. Will quit here.
The End
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1The writer was employed in studies of clouds by the University of Washington’s Cloud and Aerosol Group, and quickly adopted the company teams as his own, one of the signs of a great employee, one who wore Washington this or that sports Tees in the off hours, no doubt helping to enhance Washington revenue streams.
I wanted to add some suspense to this blog today, and to enhance readership beyond one, I would do like TEEVEE news and weathercasters do who get people to hang around by saying silly things like:
“Will it rain for the Arizona fubball game tomorrow? We’ll tell you at 11”
when an answer consisting of a single word would do.
These are one of the dumbest, outrageous and annoying lines that weather and newscasters come up with over and over again, and I hope I am NEVER on TEEVEE and have to say something like that unless I am making a LOT of money, and then I might say almost anything! (Haha, just kidding, I think, but not positive.)
Valid for 5 PM AST Thursday, December 4th. The location of Arizona and Catalina on a map of the United States is shown. Areas of rain are generously pointed out by arrows to help the reader comprehend this map.
Well, since the supercomputer calculations, these based on earth data from last night at 5 PM AST (00 Zulu, Greenwich Time, Central Universal Time, etc.) continues to show early December rains in Catalina (see illustrative figure above), we need to have some spaghetti to see if a trough in the middle troposphere has much chance of being here:
Also “valid” for 5 PM AST, Thursday, December 4th, corresponding to the storm map above from NOAA, and also based on earth data from last evening at 5 PM AST. Areas of high confidence and cluelessness are pointed out, FYI. The yellow lines are what the model actually predicted. (Hint: doesn’t match up that well with itty-bitty error-laden runs, one that try to account for “chaos” in the atmosphere (where itty-bitty things like a single thunderstorm mislocated in the initial run can cause the forecast to go bad; and, of course, real errors in measurements. Sometimes this strange plot, deemed a major advance in weather forecasting, is called by CM, anyway, a Lorenz Plot, after E. N. Lorenz who liked to publish papers on chaos. OK, as you can see, I hope, not a lot of confidence is suggested for a storm on December 4th at this time; mods will continue to see it come and go. Here, you will only see those forecasts that have a storm for Catalina.
Went on a hike yesterday morning, about 4 h worth up the Baby Jesus trail to the Deer Camp trail and back down again. Here are some scenes from later November from a desert having a lot of rain in September and October. Octotilloes are blooming here and there! Amazing! Morning glories hanging on, too. Cement trough, though, was dry. Boohoo. Didn’t expect that.
Ocotillo in bloom, November 22nd, 2014.Arizona fall color as evidenced in a coral bean bush.More Arizona fall color in something, maybe a wild cotton bush. Was hiking with the Cottons, too.Some kind of green grass. Most of the grasses, though, were dried up.Morning glories still abound!Typical riparian scene seen on the hike. Crossed this wash several times, and all of the views were as good as this.A weed. Burrowweed in bloom. Kind of pretty, I thought, but who cares what I think?Expected to see water here at the old “Cement Trough” where water is often counted on by horsemen and horsewomen.People from all over gather at the Cement Trough scenic area for a hike respite.Two stage arrowhead.
6:52 AM. Altocumulus cloudlets over and east of the Catalinas.6:52 AM. Sprinting to the other side of the house, this spectacular scene of virga falling from Altostratus. Breathtaking!6:53 AM. To the NW, the virga roiled downward into mammatus bulges under lit by the sun.6:54 AM. The color was fading just in a minute or two, but it was still a breathtaking panorama I thought you should see.
Some additional commentary about these scenes. One of the remarkable things about clouds, a real unknown, is how clouds such as Altocumulus (1st photo) can get so cold, colder than it was this mid-November in Wyoming, and can remain all or mostly water drops, which is what you are looking at in those cloudlets over and beyond the Catalinas. Pretty amazing. This phenomenon has been known about for decades, but not fully explained. We expect to see a lot of ice in clouds with tops colder than -30 C (-22 F) as you might imagine.
Here’s the sounding near the time of these photos, with writing on it:
———-Begin learning module———————————-
The Tucson balloon sounding, launched around 3:30 AM AST yesterday morning.
As a CMJ, you need to be armed with explanations if, on a morning walk, your neighbor, at first overwhelmed by the morning beauty, but then instead of being quiet, goes on to ask, “Hey, aren’t those clouds composed of droplets; they must be pretty low and warm?”
Since you’ve already seen the TUS sounding for the hours just before this, you know those cloud bottoms are real cold and high, -26 C, and 19,000 feet above you here in Catalina, and tops are really cold, about -32 C (-26 F), you cringe. What to say? How do you explain clouds that can sit there at -32 C and develop little or no ice, while knowing that Cumulus clouds, ones whose tops have never been colder than -7 C, can be completely composed of ice just after reaching up to that temperature?
—————-End of learning module, such as it was———————
Here’s another example from yesterday of extremely cold clouds with few ice crystals:
9:36 AM. Altocumulus perlucidus opacus (sun’s position is not detectable). The TUS sounding for the morning would not be valid at this time since the cloud bases were slowly lowering but they would still be about -20 C at this time, height about 17,000 feet above ground level. And, at this temperature, such clouds are ultraripe for ice production by aircraft that may flay threw them. See next photo for a POSSIBLE aircraft production of ice in these cold clouds.
10:43 AM. Of course, all of you were looking for some aircraft perturbation I’m sure, and this seemed “too linear, too uniform, the crystals too small (as deduced by the sloping lines of virga underneath this line for the ice to be natural. No other virga looked like this having straight fine lines underneath, the thing typical of contrails. However, its not the typical ice canal, either, with clearings beginning on the sides. In fact, the cloud seems thicker here where an aircraft may have traversed it, posing an explanatory challenge. Also counter to reason, why would an aircraft fly so far in what would have been light rime icing conditions in those Altocumulus clouds? Lots of questions, no really good answers.
11:07 AM. Linear feature passes over Catalinaland. Was hoping for a drop so I could claim it had rained in November, even if it had been a phony rain.
11:32 AM. Looks phony to me! Not a real cloud. I think we’re looking now at the tube of high concentrations tiny ice crystals that slowly settled out from that Altocumulus layer after an aircraft went through it–this tube to me appears to be BELOW the general layer, due to settling out after a few larger ice crystals fell out first. Am about 60 % sure that’s what happened and caused that linear feature. Getting pretty worked up about, too.
Well, Shakespeare said it: “Much ado about nothing,” so it must be important if he said it.
Had some really nice cloud scenes after the big clearing came through in mid-afternoon:
3:38 PM. Our typical spectacular lighting on the Catalinas scenes as storms move away.
4:49 PM. A dramatic finish to the day; light showers hit south and southwest of Tucson, but faded before arriving here.
There were some light showers that produced as much as 0.20 inches of rain in the south and east parts of Tucson late yesterday afternoon and evening. Nice for them.
The weather way ahead
Nothing in the way of rain in the immediate future. Have to wait until December for any real chances. See this bad boy for December 6-7th, this panel only 360 h from now1!
Valid at 11 PM AST December 6th. Note that the heaviest rain in Arizona is over Catalina! These are totals that accumulated in the 12 h prior to 11 PM AST. Hope I made you that bit happier showing you this. It’s a pretty cold system, too, might be a close call for snow here.
The End.
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1360 h in advance, even using our best model, is about in time like the distance to Betelgeuse in light years. Hence, caution when the writer says, “only.”
Started out clear yesterday. Below, an example of that completely clear sky in case you missed it.
10:06 AM. Clear skies are evident as we look in the general direction of Baja California. HOWEVER, note shallow smog plume exiting Tucson and flows northwestward across Continental Ranch over there by Twin Peaks where fellow University of Washington meteorologist, Mark Albright, lives.
I think it is interesting that Mark would chose to live as a snowbird in a smog plume rather than here in Catalina where that Tucson smog plume rarely strikes. Its pretty regular down there because the normal morning wind in Tucson is from the southeast and that wind shoves the urban smog over to Mark’s house on many cold mornings. Pretty funny, really.
Yesterday’s clouds
In the mid-afternoon, a stream of patchy Cirrus was beginning to creep over us. If you don’t believe me, you can see it in the University of Arizona time lapse film for yesterday.
And, in those leading Cirrus clouds were some spectacular, stupefying really, complex patterns of cloud formation and and holes in them, ones like CM had never seen before except maybe that one time in Durango back in the 1970s. Here are some examples of those odd that were up there:
3:14 PM overview of Cirrocumulus and Cirrus clouds with oddities.3:14 PM Close up of previous cloud scene. Note all the weird stuff going on.3:22 PM. More oddities. Going crazy trying to understand what the HECK is going on!3:23 PM. Close up of rectangular “fringe.”
Started to breath a sigh of relief when this melange of complexity moved off rapidly worrying that someone might call and ask me to explain it. So, when some Cirrus uncinus and/or the rarely seen Cirrus castellanus came by I started to relax, feel confident again. Here are some of those pretty shots of little, icy clouds trailing light snow showers, likely, to repeat again, crystals called bullet rosettes. The ones in the part of the cloud from which they spew are likely tiny prisms, side planes, and tiny solid columns, thick, but tiny hexagonal plates with little fall speed, so those hang up there, while the favored ones in the best tiny updrafts in these clouds that resemble tiny glacial Cumulus clouds grow from those kind germ crystals into bullet rosettes, complicated crystals with multiple tiny columns sticking out of them. If you would like to read all about the crystals that form in high icy clouds like these you should spend some time browsing this paper, co-authored by the great John Hallett1 I really like footnotes–yes, of the Hallett and Mossop riming and splintering mechanism, discovered by them in 1974. Helped explain why there was a LOT of extra ice in clouds that shouldn’t have it.
Here’s one more weird scene in Cirrus before moving on to something explicable:
3:43 PM. Holes, plops of downward moving air amid the Cirrus/Cirrocumulus. But why so round?
Thankfully, here’s what transpired next at Cirrus levels:
4:02 PM. Cirrus uncinus (one with tufts or hooks at the top and long streamers of ice below them) followed the strangely patterned sky.4:03 PM. Look at all the larger ice crystals pouring out these little guys! Its amazing. Notice how FINE those strands are. Airborne work we did indicated that the cores were only a 5-20 meters wide!4:20 PM. Reminded me of a ballet the way the clouds and the streamers were arranged around one another.4:17 PM. Just a little before the dancing clouds came by, there toward the Gap was this CIrrus castellanus mimicry of a full grown Cumulonimbus capillatus (tuft in center of photo). Look, it even has a tiny anvil spreading out, to use the word “tiny” for the 18th time! How fun was that to see!
Of course, with all the patchy Cirrus around we were guaranteed a nice sunset and it did not disappoint:
5:29 PM. Sunset.
Today’s clouds
Heavy ice clouds, several kilometers thick at times. We call that kind of fray, often full sky-covering layer, Altostratus. Likely some Altocu around, too. Will look now and see if I see any of those latter ones. Oops, too dark.
With clouds kilometers thick, tops at Cirrus levels, you can expect to see virga, and the chance of a few “sprinkles-its-not-drizzle” later in the day. The whole progression of clouds can be seen from the U of AZ model output from last night in these forecast soundings for Tucson. As per usual, the bottoms get lower and lower as the day goes by, but are still up around 13, 000 feet above Catalina by around sunset. So, will be tough to get a drop to the ground before then. U of AZ mod thinks all measurable rain will be to the south of us. Oh, me.
BTW, and this is an embarrassment, it was asserted by this keyboard that rain would fall in November at the outset of the month. This is the last chance for that! Egad. But forgetting that possible gaffe, moving ahead anyway to what’s going to happen in December (of this year).
The storms way ahead, that is, ones in early December.
Those early December storms for us are coming and going in the WRF-GFS runs. But I am counting on rain here in early December myself due to an interpretation of those weird in so many ways, “spaghetti plots.” I think they’re showing, and continue to do so, significant troughs coming through the Southwest in early December.
The End
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1Later after the referenced paper above, and this is quite interesting, the great Hallett was to claim that me and Pete Hobbs had embarrassed2 the entire field of airborne researchers due to a paper published by us way back in 1983 (J. Hallett, 2008, communicated by him during his presentation at the Pete Hobbs Symposium Day of the American Meteorological Society, New Orleans.
2But it was a good embarrassment, not a bad one due to incompetence, I think.
Been away from you for a couple of days, wanting to see how you do on your own, perhaps see you grow in your cloud watching obsession, namely, that you want to name everything you see, as though you were Luke Howard himself. Hope you logged all cloud genera, varieties and species, 27 all told, over the past 48 h. You can bring your photo log books to the next meeting and CM will go over them with you.
Measurable rain chance still pretty reasonable for the window of Nov. 20-21st, too, as we have purported for some time here, but it will be pretty minimal.
The weather way ahead; a promise of substantial rains
However, as often happens, on the horizon is a substantial storm for Arizona, ones that have a habit of disappearing it seems as the foretold event gets closer. Here it is depicted below in plots from our cherished NOAA spaghetti factory:
Valid at 5 pm AST, December 2nd. Pretty cool, huh?Same spaghetti plot, annotated. Recall that these plots are ones where the model input has been deliberately errorized to see how big little errors make in the outcome of the model. Why do that? Because we know at the outset that our measurements are not perfect, and have all kinds of actual little errors in them. These plots are a way of seeing how robust a predicted pattern is, and those areas where the forecast is pretty reliable, is indicated by bunched lines (key contours of the airflow at 500 millibars, or around 18,000 feet above sea level in the mid-latitudes, lower near the poles, higher near the equator. Why do we use a pressure level instead of the pressure at a height? Go here. CM would like to see as well, in the 21st century, maps of constant altitude (3 km, 5 km, etc.) with the high and low pressures on them as we have on our sea level maps! Is anybody listening? (A google search just now could not locate, constant altitude pressure maps….)
While the above forecast of contours is two weeks away, and numerical models are often unreliable at those long horizons, we see that the red lines (not to be confused with political markers) have dipped down in great bunches over the extreme eastern Pac 12 Ocean, and continue all bunched up across Baja Cal and thence into Texas. In the plot above, the red lines represent a 500 mb height of 5760 meters, one that’s on the southern periphery of the jet stream. So, when its well south of us, our chances of rain are engorged. Recall, too, that the 5640 meter contour, just that bit lower in height, is associated with leading edge of rains in the central and southern California area–remember Brier and Panofsky, Some Applications of Statistics to Meteorology? Well, in that book you will learn that contour is what the LA weather service used to use as crib for when rain would occur in southern California.
I am sure you remember two things, maybe more than two. We have an El Nino in progress, not a great one, but an OK one, AND that El Niños strengthen the southern jet stream in the eastern Pac and across the southern latitudes to the east. So, we expect to see this pattern, one of a stronger jet stream in the sub-tropics carrying stronger disturbances as a result, evolving as the winter develops, that is, more disturbances in the lower latitude band of the jet stream (sub-tropical part). The plot above is a classic one for predicting that kind of regime, maybe with a bit of a split in the J-stream with northern and southern branches being pretty vigorous at this map time, and before, for that matter.
Valid at 5 AM AST, Monday, December 1st. Colored regions are those in which the model has calculated that precipitation has fallen in the prior 12 h.
The plot above, it has laid a foundation of credibility for what is show below, from IPS Meteostar’s rendering of our WRF-GFS forecast model output based on the 5 PM AST global data. It shows 24 h of substantial Arizona rains, including here in Catalinaland, at the beginning of December. You’d be pretty cool to inform your friends about this, ones who might be heading back somewhere after a TG visit to sunland1. (Besides, they won’t remember what you said anyway by the time December gets here.)
Valid at 5 PM AST, Monday, December 1st. Colored regions are those in which the model has calculated that precipitation has fallen in the prior 12 h.
Today’s clouds
Lots of pretty Cirrus.
The End
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1By the way, the Great Lakes are freezing over already, a month earlier than normal due to some astounding cold back there, so TG visitors from back East, upper Midwest, may look for reasons to stay longer. Well, at least until the rain and cold hit here.
This was pretty neat, this forecast map from yesterday’s 11 AM AST WRF-“GOOFUS” (GFS) run. Look at all the rain barging into Arizona and Catalina!
Plenty of rain here in southern California AND Arizona! Valid at 11 AM November 20th.
What’s remarkable is that the ensemble runs made yesterday’s prediction of rain, one discussed here, quite the “outlier” of the rest of the “members” of the spaghetti plots, so one wouldn’t be expecting to see any rain for Catalina again!
But, here was that rain again, and this whole storm complex along the California coast falling mostly within that time period where over the decades there has been a tendency for storms to strike the more southerly locations between the 10 and 20th of November, something that was mentioned yesterday as a bit of a conundrum. Rain, though not as much, was shown again in the next run based on 5 PM AST global data, and due to that prediction of less rain, I am not showing it.
Below is a comparison of how the ensemble outputs (shown as “spaghetti” plots of a couple of key contours at 500 mb (around 18,000 feet above sea level) have changed since yesterday. To this observer, its been an unusually large change in where the grouping of those key contours are in just 24 h (they always change some, of course).
Notice how the blue (contours of flow pretty much in the heart of the jet stream) and red lines (periphery of it) have been shifted 10 degrees latitude and more southward from the first plot to the second, latest spaghetti plot, indicating that we’re going to be more in the storm track at that time, and the likelihood of a rain threat on the 19th-20th is more credible, less subjectively based as was yesterday’s take. Maybe subjectivity in forecasting isn’t that bad afterall…
Valid at 5 PM, Wednesday November 19th. Note how the red and blue lines bulge northward along the West Coast, suggesting a fair weather pattern.
Also valid at 5 PM AST, Wednesday November 19th. Blue lines (contours along which the wind blows from left to right) are now much farther south, and the red lines are now so far south they’re almost not in the map domain. Also, those red lines now do not bulge northward anymore, but rather are suggesting a broad trough along the West Coast at lower latitudes, completely different than the plots just 24 h earlier.
Finally found some rain for you. Took awhile. Came from the 11 PM AST global data from last night using the WRF-GFS model, our best. The rain falls around the 19th, “only” 11 days from now and during the “sweet spot” for southern California rain in mid-November, 10-20th, which gives it a few more percent of credibility than it otherwise would have.
BTW, there is virtually no support for this pattern from the NOAA spaghetti factory. So, all of the discussion below about an upcoming rain in Catalina might erroneous, based on a personal hunch about an outlier model run being the correct “solution”, one based on experience, and to HELL with spaghetti1, a study in forecasting subjectivity, etc.
Got that Bay Area rain timing info originally from C. Donald Ahrens, the big author of Meteorology Today and Essentials of Meteorology, both of which have about 400 editions out by now, while he and I were at San Jose State College University.
Don, a grad student then, and me, and undergrad, worked and sang together to Top 40 songs radiating from KGO-FM 2,3 in a little corrugated metal building there by the San Jose State football stadium back in the late 60s, and it was somewhere between songs that he told me about his findings.
Don had done a rain frequency study for the Bay Area for a local insurance company and it turned out that he found that it was somewhat more likely to rain in the middle of November than earlier or later in the month. That rain fell more more often than earlier was no surprise, but more often than later in the month was. Later I found that it was also true for southern California.
Sometimes oddities like these are referred to by big professors of weather, like Reid Bryson at the U of Wisconsin Badgers, as “singularities”, a weather pattern that tends to recur year after year around the same time of the year, like the so-called “January thaw” in the East which I don’t think happened last year.
So, ever since Don told me about the mid-November peak of rain in the central and southern parts of Cal, I have looked for it year after year and it seems to turn out quite often, and this November seems to be no exception, though the models were resisting this pattern for quite awhile before “giving in.”
Well, anyway where was I? It seems that the southern California rain is now being foretold for around 18th of November, and a day or so later it trudges on into Arizona. From IPS MeteoStar, a Sutron Company, whatever that is, this wonderful map:
Valid the night of November 19th-20th. Colored regions denote those areas where the model thinks it has precipitated during the PRIOR 12 h. So, storm has arrived here during the day on the 19th.
Some clouds
we have known over the past few weeks while CM was re-hydrating mentally:
Some ice for you on a warm fall day.Some ice for you on a warm fall day (virga from Altocumulus castellanus and or floccus)Pretty iridescence (or irisation) in a Cirrocumulus cloud.Pretty sunset, Altocumulus featured.
The End
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11The non-supportive spaghetti plot from the 00 Z (5 PM model run from last evening):
Valid at 5 PM AST Wednesday, November 19th. Arizona is in a low amplitude ridge, according to most of the “members” of the repeat model runs with itty-bitty errors deliberately put into them. I have rejected this plot and look for validation of this action around the 19th of November. You will not hear about it further if I am erroneous in this action!
2An odd, almost mysterious Frisco FM radio station with no commercials featuring, “Brother John.” We’d sing along to the Four Seasons, The Five Americans’, “Western Union” (about telegraph, the way people used to communicate before the Internet).
3 We both had quite a talent for falsetto it seemed at the time.
Looked for a time that the rain might be over by mid-afternoon and early evening here in Catalina with only a disappointing 0.40 inches here, but the rains kept coming overnight, piling up a nice 0.98 inches 24 h total for the storm. In the meantime, Ms. Mt. Lemmon has gotten 4.29 inches! Check out these eye-popping totals from the Pima County network, ending at 7 AM AST today (just updated. These are so great in view of last October’s trace of rain:
Gauge 15 1 3 6 24 Name Location
ID# minutes hour hours hours hours
—- —- —- —- —- —- —————– ———————
Catalina Area
1010 0.00 0.00 0.00 0.24 0.71 Golder Ranch Horseshoe Bend Rd in Saddlebrooke
1020 0.00 0.04 0.04 0.28 1.06 Oracle Ranger Stati approximately 0.5 mi SW of Oracle
1040 0.00 0.08 0.12 0.43 0.94 Dodge Tank Edwin Rd 1.3 mi E of Lago Del Oro Parkway
1050 0.00 0.16 0.20 0.67 1.26 Cherry Spring approximately 1.5 mi W of Charouleau Gap
1060 0.04 0.16 0.20 0.83 1.93 Pig Spring approximately 1.1 mi NE of Charouleau Gap
1070 0.00 0.08 0.20 0.59 1.14 Cargodera Canyon NE corner of Catalina State Park
1080 0.00 0.00 0.00 0.31 0.91 CDO @ Rancho Solano Cañada Del Oro Wash NE of Saddlebrooke
1100 0.00 0.12 0.28 0.55 1.06 CDO @ Golder Rd Cañada Del Oro Wash at Golder Ranch Rd
Santa Catalina Mountains
1030 0.00 0.04 0.08 0.55 1.57 Oracle Ridge Oracle Ridge, approximately 1.5 mi N of Rice Peak
1090 0.08 0.31 0.67 1.42 4.96 Mt. Lemmon Mount Lemmon
1110 0.04 0.12 0.12 0.71 1.61 CDO @ Coronado Camp Cañada Del Oro Wash 0.3 mi S of Coronado Camp
1130 0.00 0.24 0.47 1.89 3.46 Samaniego Peak Samaniego Peak on Samaniego Ridge
1140 0.04 0.12 0.24 0.39 1.73 Dan Saddle Dan Saddle on Oracle Ridge
2150 0.08 0.12 0.28 1.14 3.50 White Tail Catalina Hwy 0.8 mi W of Palisade Ranger Station
2280 0.00 0.04 0.12 0.31 1.93 Green Mountain Green Mountain
2290 0.04 0.08 0.20 0.75 2.40 Marshall Gulch Sabino Creek 0.6 mi SSE of Marshall Gulch
Misty drizzle with very low visibilities is still falling here in Sutherland Heights, Catalina, at 3 AM. The Catalina Mountains are not visible from just a couple of miles away. This suggests the clouds overhead are now “clean and shallow” and rain is forming via collisions of cloud drops with coalescence rather than because of ice in the overhead clouds, often called “warm rain,” a rare occurrence in Arizona. You’ll definitely want to log this in your cloud diary!
“Clean” means that the clouds have low droplet concentrations, viz., are not choked with anthro and natural “continental” aerosols but are more “maritime”, almost oceanic in composition, something that easily leads to “warm rain/drizzle” formation. In oceanic clouds far from pollution sources droplet concenrations usually are less than 100 cm-3. They average about 60 cm-3 in Cumulus clouds in onshore flow along the Washington coast, as an example. Cloud appearance should look a little different to the discerning eye, too. With low droplet concentrations, the clouds appear “softer” than usual, not a hard.
Normally, our clouds likely have a few hundred per cm-3 or more and appear darker from below since higher droplet concentrations is also associated with bouncing more sunlight off the top of the cloud1.
With vort max (aka, curly, or curling, air) still well to the west of us at this time (3 AM AST) as seen here. This sat imagery also shows plenty of shallow clouds upwind of us, so it seems like the very light rain and drizzle will continue well into the morning, likely adding a few more hundredths to our generous totals. Remember that the air likes to slide upward as curly air approaches, that is, produce a lot clouds, and today, a last bit of precip. Did pretty good last night, too!
Honestly, you really want to get out and experience our misty, drizzly rain (drop sizes mostly between 200 and 500 microns in diameter; a few human hair widths), before it ends; the kind of precipitation that makes riding a bicycle even with a big hat impossible. You might even try the near impossible trick of photographing the drizzle drops, too, as they land in puddles, see if you can catch the tiny disturbance made by drizzle drops. That would be great photo! I know, too, that experiencing real drizzle will give you a bit of a chuckle as you think of all those less informed folks, some of whom are even on TEEVEE, who call a sparse fall of raindrops, “drizzle.” Oh, my, WHAT has happened to our weather education?!
Yesterday’s clouds
Lots of gray cloud scenery yesterday, including a stunning example of Nimbostratus (Ns), the steady rainmaker (at least here we had that, anyway.) In other places, Cumulonimbus clouds were also contained within that rainy cloud mass and dumping an inch or so in an hour in TUS with LTG (weather text for “lightning2“), as you likely know. Didn’t hear thunder here, but coulda happened since I was off to the new Whole Foods market at Ina and Oracle as the steady rain from Ns moved in it because it said online that they had Brother Bru Bru’s African Hot Sauce which I had been looking for for a long time but when I got there they didn’t have it! The grocery manager apologized profusely and then we started talking about haloes and the ice crystals that cause them. So, you never know when your cloud mavenhood will come in handy in everyday conversations, maybe make that friend you’ve been looking for:
7:14 AM. The many layered remnants and distant rain creeping toward Catalina from the southwest are evident soon after dawn
7:34 AM. New round of rain begins on the Catalinas. Shafting here implies mounding cumuliform turrets on top, likely glaciating. From up there they would probably look like soft Cumulonimbus capillatus clouds, ones with weak updrafts.
8:34 AM. One of the prettiest sights around here can be just a tiny little cloud (Stratus fractus) like this one when a glint of sun falls upon it. It looked so CUTE! Imagine, you could be up on that little knob and run in and out of it, maybe play hide and seek with your friends, except that being a “clean” cloud, the visibility would be pretty good inside it, not like the shallow, impenetrable fogs you sometimes get around Bakersfield, CA. There, in one of those, you could play really great hide and seek! I’m guessing that if you’re reading this far, you may not have a lot of friends. :}1:23 PM. In the midst of our mid-day light rain, a clear example of Nimbostratus with underlying Stratus fractus and Stratocumulus. Remember, its not the LOW clouds that are raining, its the deep Ns layer above them. However, it is OFTEN true that the lower clouds ADD to the rain because as the rain falls from the Ns layer, those drops often collide with the floating drops in the lower clouds thus making a raindrop bigger. That’s one main reason why rain and snow are so much more on the upslope side of mountains just due to that collection of non-precipitating cloud drops! Its so cool! Away from mountains, you likely won’t have so many low clouds at the bottom of Ns, and the rain is less.
2:50 PM. After the rain ended, suddenly this lower cloud line formed representing a wind puff from the west. It headed toward the Catalinas, but then, within a few minutes, pooped out with no precip having fallen out. It was quite a bit fatter before this photo, too. That dissipation indicated that whatever wind source had produced had died out. But anyway, when you see a cloud line like this, think “windshift.”
4:57 PM. Expansive deck of Stratocumulus with spots of very light rain in the distance promises, along with the curly air feature (an upper level vortex) being so far to the west of us at this point, promises that the rain is not over.
The weather way ahead
Dry for almost two weeks. However, a crazy NOAA spaghetti factory plot suggests rain in about two weeks, around the 23-25th, as you can plainly see here:
NOAA spaghetti factory plot (aka, “Lorenz plot”, after chaos scientist, Edward N. Lorenz–he would really like THIS plot!) valid for 5 PM AST Oct 23rd. Rain is hinted at by the loopy lines in Arizona dipping down to the south. Will keep you posted on that, but not very often.
The End. Its really amazing how much information I have passed along today! Most of it correct, too!
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cCoCoRahs gauge, not Davis tipping bucket which seems to have a problem of late.
1This is the concept behind kooky schemes to defeat potential global warming which hasn’t happened for 18 years or so by polluting oceanic clouds, making them “brighter” on top, darker on the bottom by inserting extra aerosols into them. Ghastly thought! Haven’t we polluted enough?
2Recall that weathermen and women were WAY out in front when it came to what we now call “texting”, as in “2KOLD4me” that kind of thing.
Let me give you an example from the 50s when we were rocking around the clock: “M8BKN15OVC2R-F68/661713G24989 R-OCNLY R”, a text phrase that would take a paragraph to unravel, to paraphrase language maven, Noam C3,4., except in those days we had our own private symbols which I can’t duplicate for “BKN” (a circle with two vertical parallel lines in it) and “OVC” (a circle with a plus sign in it). Weather typewriters and teletypes came with those private symbols!
3Wow, a footnote in a bunch of footnotes! Breaking ground again I think! What Noam C. said: “takes a phrase to tell a lie; a paragraph to unravel it.”
4Factoid, one not having to do with weather: Language maven, NC, really liked Pol Pot and his “restructuring” of society back then until he learned about all the millions of skulls were piling up along with that “restructuring.” You can hear about Pol Pot (and hypocrisy) here in Holiday in Cambodia, one of the defining songs of the 1980s IMO, as interpreted by The Dead Kennedys featuring lead singer, Jello Biafra. (You remember Jello don’t you? Ran for president a while back. Kind of surprised we didn’t elect him…)
6:20 PM. Cumulonimbus calvus pileus. Hope you had your camera. This would have been a good example to add to your collection. “Calvus” or “bald” is a short-lived period when a Cumulus congestus top is converting to a fibrous (“capillatus”) appearance. That left bulge is clearly loaded with ice. The pileus forms in moist air being pushed up by the rising turret below it. I wanted to be inside that cloud so bad! There’s real magic going on when the droplets are being converted to ice, along with the appearance of hail and/or its soft, squashable version, graupel.
Fantasy storm of the day
….popped out of the WRF-GFS run from 12 Z yesterday, rendered, as we say, by IPS MeteoStar. Tropical storm “Q” is shown in the Gulf of Cal/Sea of Cortez racing north into Arizona. Pretty cool, huh?
A map configuration like this hasn’t been back yet, and wasn’t there in any run before this one, so we can throw it in the trash pile of bogus model predictions so far, though the models DO have a strong hurricane “Q” in the works. Mods now show it going NW and out to sea off Baja. Still its fun to see how much fantasy rain can fall in Arizona. Kinda reminds one of the track of infamous Tropical Storm Octave, October 1983, almost passing over Tucson on the same day 31 years ago. You remember “Octave” I am sure. You can read about it and a very similar eastern Pacific hurricane season to this one here.
Valid Wednesday, October 1st at 5 PM AST. Flooding rains from tropical storm “Q” move into Arizona.
The Cumulus ahead
Whilst CMP was glumly anticipating the end of Cumulus clouds, tropical ones on a daily basis anyway, due to the onset of westerly winds aloft, it has been pointed out by more astute forecasters, like forecasting legend, Mike L, at the U of AZ, TEEVEE ones, NWS, etc., (i e., namely, everyone else who knows anything at all about weather) that tropical air will still be feeding in enough from the east below the westerlies to keep some Cumulus going here and there, some even becoming Cumulonimbi with rain! Your errorful CMP was actually glad to be “informed”, glumness disappearing.
Also, we got that cold front coming on the 27th or so, with another chance of rain as humid air is drawn northward ahead of it. So, another coupla chances to make this a decent water year, one that ends on September 30th. We’re just surpassing 15 inches now; the normal, computed from 37 years at Our Garden here in Catalina, is a little less than 17 inches.
