Category Archives: Cirrocumulus clouds

Ice optics extravaganza; Cirrus uncinus fallstreifen going in different directions!

What a day, Mr. and Mrs. Catalina!

Not as good as a rain day with lightning, but yesterday did have its moments in the sky, enough to make the astrologers  on Mt. Lemmon jealous with displays of parhelia (“sun dogs”, or “mock suns”), faint haloes, a rare parhelic circle, something you don’t see but once every year or two,  and fallstreifen (fall streaks) from Cirrus uncinus clouds going in almost opposite directions, an extremely rare sight.

The rare “parhelic circle” is a local brightening often extending out from a parhelia (sun dog) at a sharp angle, which I just learned about here1.  Usually you don’t see a whole circle, just part of one.  

These optic displays are caused by ice crystals, of course, ones not too complex, but rather simple ones like prisms, short solid columns, bullets, and hexagonal plates.  Some examples of these can be seen here.

The bottom of yesterday’s moist layer was just above 30,000 feet at a temperature of -35° C and extended all the way up to about 40,000 feet above sea level where the temperature were around -65° C.

Ann 2016102800Z_SKEWT_KTUS
The balloon sounding launched around 3:30 PM AST yesterday from the Banner University of Arizona.

Some photos documenting the excitement of yesterday

5:30 PM. Cirrus uncinus crystals heading in two very different directions. Wow. Notice the fibers from the contrail that are starting to fall out are going in the "correct" direction, back toward that west.
5:30 PM. Cirrus uncinus crystals heading in two very different directions. Wow. Notice the fibers from the contrail that are starting to fall out are going in the “correct” direction, back toward that west or southwest.
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3:04 PM. Parhelic circle erupts in mostly Cirrus uncinus clouds.
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3:06 PM. The astounding sight continues, but fades away just after this.
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3:33 PM. Local brightening at the position of a sun dog suggests these are tiny ice crystals or possibly even droplets that have just formed, the sizes too small to allow refraction into color normally seen in sun dogs.
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3:32 PM. A zoomed view of that little bright spot. Sure looks like it may have been droplets. Droplet clouds have been reliably reported to temperatures as low as -44° C. Of course, wouldn’t stay liquid long!  I thought this was a pretty exciting shot!  Hope you got it, too.

 

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3:42 PM. Amid all the optical excitement was this ghost-like halo. Can you make out the faint circle around the sun? In ascents through thick ice clouds having complicated ice crystals like bullet rosettes down below the tops, as you climb to the top of such clouds, amazing haloes can be seen where the crystals are newly formed and quite simple in structure, allowing the refraction required for a halo. So, this halo was likely at the top of these thicker Cirrus and Altostratus (dense portions) clouds, though no one would penalize you if you just said they were all Cirrus clouds.

 

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3:59 PM. Another spectacular bright spot at the sun dog location (which is also at the 22° halo location, faintly evident here).
3:59 PM.
3:59 PM. Zoomed view of this sun dog/parhelia. Lots of fine structure evident, which is not usually the case with parhelia.
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4:25 PM. Another finely structured parhelia/sun dog suggesting the ice crystals were newly formed. Fine structure like this can’t last long with the usual turbulence, and so that’s a sure sign this feature has just formed.  I don’t recall seeing so many atypical sun dogs in one day!
5:09 PM. The normal, amorphous sun dog. No really fine detail can be seen here.
5:09 PM. The normal, amorphous sun dog. No really fine detail can be seen here.

Below, examples of cold Cirrocumulus, ones that quickly transition to Cirrus clouds.

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5:19 PM. This group of CIrrocumulus clouds appeared very quickly almost overhead. The tiniest elements are those that have just formed. These are composed of ice crystals in extremely high concentrations, perhaps 10,000 per lilter. Once that ice has formed, its gradually spreads out, much like a puff of smoke would, thinning, some crystals growing large enough to start fall steaks.
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5:19 PM. Some elements are still forming, but the spreading of the older ones is well underway, producing a “blurred” look as the elements merge and thin out.
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5:28 PM. Off to the southwest of Catalina, a promising intrusion of lower moisture indicated by these approaching Altocumulus clouds. Will there be enough today for a sprinkle somewhere?  Not looking so good now, clouds did not lower much overnight.   Well, maybe if it doesn’t sprinkle, maybe we’ll get to see some nice virga and dream about rain…

 

The End

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1I was going to call it something else.  Egad.  Let us remember the words of the B-52s:  “Before I talk, I should read the book.

Cirrus, Cirrocumulus and Altostratus day closes with a painting-like sunset (now updated even more!)

No rain in sight for Catalinans, to get that over with.

However, if you’re bored and are thinking about a quickie storm chasing vacation with the family, monster storms, likely to produce newspaper headlines will be smashing the Pac NW in the next few days.  Expect to read about flooding and hurricane to 100 mph winds on the Washington/Oregon coast sometime.  Also, Tofino, British Columbia, along the SW coast of Vancouver Island, would be a great place to head for, watching giant waves crash up against the coast and around that lighthouse they have around there, pounding rains…

The long fetch with these storms in the Pacific guarantees some monster waves.

3:49 AM, 14 Oct:  Mark “WeatherPal”  Albright informed me that a 94 mph wind was observed last evening (the 13th) near Astoria, OR.

The next low,   a “regular low” but one energized by leftover moisture from Typhoon Songda,  looks to be even stronger than last night’s low.  This one comes  in  moving really rapidly tomorrow evening while deepening (central pressure is dropping further) as it passes over the Washington coast.  Looks like that one will be a “blow-down” storm;  good-bye timber.

The synoptic pattern (placement of jet streams and lows) is       “Freda-esque”, that is, similar to that of October 12, 1962, the infamous Columbus Day storm where a remnant of Typhoon Freda zipped in as a regular low that deepened explosively as it raced up the Pacific NW coast bringing winds of 100-200 mph and blowing down BILLIONS of board feet of timber as well as weather pal, Mark Albright,  mentioned above,  when he was a kid1

Well, we sure hope its not THAT similar!

Yesterday’s Clouds

Lots of interesting patterns and complexities in yesterday’s skies. If you didn’t see them, here they are, though its kind of a much ado about nothing, really:

1:23 PM. Icy Cirrocumulus. As a solid band of high and middle clouds approached, the first things we saw as the moisture began to increase aloft were some spectacular patterns in isolated high clouds as it approached. Probably most of the Cirrocumulus we see is composed of droplets, but here, it appears to be composed of ice, possibly starting as droplets at the upwind edge,
1:23 PM. Icy Cirrocumulus. As a solid band of high and middle clouds approached, the first things we saw as the moisture began to increase aloft were some spectacular patterns in isolated high clouds as the solid band  approached. Probably most of the Cirrocumulus we see is composed of droplets,  and never glaciates, but here, it appears to be composed of ice, though likely started as droplets at the upwind edge (middle of photo).  At the top of the photo, the tiny “granulets” are fibrous, clearly ice, and strands of ice crystals are starting to make their way down.
1:23 PM. Got excited and thought you might like a zoomed view of this patch in case you didn't get one.
1:23 PM. Got excited and thought you might like a zoomed view of this patch in case you didn’t get one.
1:30 PM. I thought this was kind of a strange and fun pattern for you. Look how the youngest cloud elements are over there beyond the Catalinas and the oldest ones with strands of ice crystals falling out are overhead. Besides perspective giving you a sense of radiating lines, one would normally guess that the wind way up there (about 30 kft above the ground) is heading toward you, newest parts back there, oldest ones arriving overhead, which would be from the south in this shot. But the wind was from the west-southwest at this level, perpendicular to this scene. Can't say either of us has seen this before, quite the "Tom Foolery" in a cloud scene.
1:30 PM. I thought this was kind of a strange and fun pattern for you. Look how the youngest cloud elements are over there beyond the Catalinas and the oldest ones with strands of ice crystals falling out are overhead. Besides perspective giving you a sense of radiating lines, one would normally guess that the wind way up there (about 30 kft above the ground) is heading toward you, newest cloud (Cirrocumulus, maybe lenticularis)  back there, oldest ones arriving overhead, which would be from the south in this shot.  But the wind was from the west-southwest at this level, perpendicular to this scene. Can’t say either of us has seen this before; quite the “Tom Foolery” in a cloud scene, a real knee-slapper.  Clouds do that a lot where we think we know what is going on, but, as they say, “upon further review”…..
1:32 PM. Confusion? Strands of ice and waves in this cloud seem to run in various directions.
1:32 PM. Confusion? Strands of ice and waves in this cloud that produced lines seem to run in various directions.  Some lines are perpendicular to the wind, blowing from the lower right to the upper left side, representing little bumps in the air, ones resembling sea swell rolling in to the shore,
1:40 PM. Pretty much unfathomable, too complex to even begin describing, which makes it worth photographing. We can make out some icy Cirrocumulus though, here and there, with that lenticular-looking backside beyond the mountains, though perspective may be bunching it up to look that way.
1:40 PM. Pretty much unfathomable, too complex to even begin describing in less than a page, which makes it worth photographing. We can make out what CMP deems as some icy Cirrocumulus though, here and there, with that lenticular-looking backside beyond the mountains, though perspective may be bunching it up to look that way.  I’ve already taken too many photos in just eight minutes!
2:10 PM. Breathing easier now, here, "simple" Cirrus fibratus, lined Cirrus clouds with mostly non-curving fibers,
2:10 PM. Breathing easier now, here, “simple” Cirrus fibratus, lined Cirrus clouds with mostly non-curving fibers,
Also 2:10 PM. The scene upwind of that "liney" Cirrus. Also "fibratus" except overhead there looks to be "uncinus" as evidenced by those thick regions likely trailing ice strands back toward the viewer.
Also 2:10 PM. The scene upwind of that “liney” Cirrus. Also “fibratus” except overhead there looks to be “uncinus” as evidenced by those thick regions (upper right hand corner) likely trailing ice strands back toward the viewer.
2:18 PM. Pretty soon the heavier masses of CIrrus began to appear, with lower, but still very cold droplet clouds just below them.
2:18 PM. Pretty soon the heavier masses of CIrrus (Spissatus) with some gray shading began to appear, with lower, but still very cold and at least momentarily,  Altocumulus droplet clouds  (above bush on the right) began to appear just below the Cirrus.  Clouds almost always lower in time, even when they don’t lead to a storm.
2:18 PM. More patterns. Here we have a mush of Altocumulus, very fine granulation of Cirrocumulus (top) and CIrrus clouds passing overhead. You can tell if clouds are at different levels by looking to see if they are moving all at the same rate. Here, if you looked really carefully, the little white tufts of Altocumulus clouds were moving in a slightly different direction than the Cirrus clouds were. How important is this. Not too much.
2:18 PM. More patterns. Here we have a mush of Altocumulus, very fine granulation of Cirrocumulus (top) and CIrrus clouds passing overhead. You can tell if clouds are at different levels by looking to see if they are moving all at the same rate. Here, if you looked really carefully, the little white tufts of Altocumulus clouds were moving in a slightly different direction than the Cirrus clouds were. How important is this. Not too much.
4:18 PM. Skipping ahead, the full boatload of this band, consisting of a thick Altostratus, was passed over at this time. The clearing on the right told you there was going to be a nice sunset in a couple of hours. This was the lowest level the moisture got to. somewhere in the 22-25 kft above the ground, according the the TUS sounding though the darkness of it may make it look lower.
4:18 PM. Skipping ahead, the full boatload of this band, consisting of a thick Altostratus, was passed over at this time. The clearing on the right told you there was going to be a nice sunset in a couple of hours. This was the lowest level the moisture got to. somewhere in the 22-25 kft above the ground, according the the TUS sounding though the darkness of it may make it look lower.
6:01 PM. Almost could have been a painting. The gradual ascent that produced the heavy line of Altostratus is now being broken up by patches of downward moving air, leaving holes and streakiness in the former solid cloud shield. But who cares when you can just sit and take scenes like this in!
6:01 PM. Almost could have been a painting. VIncent Van Gogh himself could not do this scene justice.  If you’ve seen his work, like “Starry Night“, you’ll know how bad he was at capturing the sky.  But for him to try to capture this scene, it would be beyond “bad”, but rather a total and complete travesty,.  The gradual ascent that produced the heavy line of Altostratus is now being broken up by patches of downward moving air, leaving holes and streakiness in the former solid cloud shield. But who cares when you can just sit and take scenes like this in!
6:06 PM. The moon amid CIrrus spissatus and other varieties of Cirrus. Notice that the disk of the moon is just a bit blurry, out of focus. That blurring is due to ice crystals in those Cirrus clouds. If it was a thin droplet cloud, the disk would appear crisp and very sharp.
6:06 PM. The moon amid CIrrus spissatus and other varieties of Cirrus. Notice that the disk of the moon is just a bit blurry, out of focus. That blurring is due to ice crystals in those Cirrus clouds. If it was a thin droplet cloud, the disk would appear crisp and very sharp..

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1Mark. like most kids who are blown over in a windstorm,  wanted to be a meteorologist right after that.   Its pretty traumatic and life changing when you’re blown over by wind.    CMP’s life was traumatized and changed forever when it snowed a few inches in the San Fernando Valley of southern California when he was six year’s old.  Not sure you’ll find this information in the latest Diagnostic and Statistical Manual of Psychiatric Disorders #5, however, but its a well-known phenomenon in the weather subculture.

Some cloud scenes from yesterday; a forecast map gone awry?

0.07 inches here in Sutherland Heights yesterday afternoon. Much more SW-NW of us, as the photos below show.

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A predicted super hurricane?

I now direct your attention to the forecast maps below, produced by the WRF-GFS model last evening’s global data, courtesy of IPS MeteoStar, the usual.  The aforementioned extremely strong hurricane foretold in the models 24 hours ago, has acheived in this latest run, mythical strength, possibly a Category 6 or 7 (which don’t yet exist).

We presume the model went berserk, so its kind of fun to imagine how intense, how low the pressure in the center of such a goofy predicted hurricane could possibly be in the panels below.

First, the jaw-dropping -to-weather-nerds like the current writer, predicted height of 540 decameters height of the 500 millibar pressure level!  For the pressure of 500 millibars in the atmosphere to be reached at a level that LOW in warm tropical air means that the sea level pressure must be astoundingly LOW to begin with.  In warm air, the pressure doesn’t change as rapidly going up as it does in dense cold air.

I don’t believe, in viewing many weather maps with hurricanes that a height that low has ever occurred at 500 millibars.  Thus, the pressure at sea level, for whatever reason, must be incredible in this predicted hurricane SW of Cabo.  Surf will be up!

The record measured low pressure at sea level is 870 mb in one of the super typhoons (Typhoon Tip) in the Pacific some years ago where winds were estimated at about 200 mph.  It is thought that recent devastating Super Typhoon Haiyan, 2013, had a lower pressure, 858 mb, or the equivalent of the density of air at 5,000 feet elevation was thought to have occurred at sea level!

Valid at 5 AM AST, Sunday, July 19th.
The heights of the 500 millibar pressure level predicted for 5 AM AST, Sunday, July 19th.  The center of the hurricane SW of Baja  is shown to be 5400 meters (540 “decameters”).
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Valid at the time of the above map. The surface pressure lines are too packed to display, but the center pressure would certainly be less than 900 millibars, and in such a tight center, winds, maybe 200-300 mph, tornado-like. Kidding only slightly.

OK, enough fun with a crazy model prediction, though this hurricane will be extremely strong, and the models are still bringing its pathetic, but wet, remnant into California a couple of days later.  Many July rain records, though they are not much to begin with, will be broken if this remnant does make it to Cal.

What we really hope for is some aircraft reconnaissance reports during the life of this strong hurricane instead of satellite-derived estimates of strength (though the latter are quite good).

We still look quite wet during this period, too.

 

The End.

Cirrus enigma; medium-sized Cumulus clouds snow away

First, you should always begin your day, not with the breakfast of champions, but by reviewing the prior day’s clouds in the University of Arizona time lapse movie.    Here’s what you will see:

Lots of Cirrus, varies species, Altocumulus, Cirrocumulus, a high temperature contrail go through some Cirrocumulus just after 4 PM, and flocks of medium-sized Cumulus clouds emitting ice.

First, one interesting, but inexplicable Cirrus scene.  I know you were likely going to ask Mr. Cloud Maven Person, “Hey, what gives here?”  I get a lot of calls like that1.

1:15 PM.  That tuft of Cirrus on the right seems to have trails of ice falling out then coming together.  There is no explanation for this since the wind has to blowing 1) from the same direction at the head, and then changing direction/speed ("shear") at the same rate underneath the cloud.
1:15 PM. That tuft of Cirrus on the right seems to have trails of ice falling out then coming together, almost like they missed each other and want to be together as snow trails until evaporating away.   There is no explanation for this2 so I will next post a distraction. (Remember, when you can’t explain something, and this is a life hint, you can either talk around the question without answering it,  beginning with, “I’m glad you asked me that question…..” when you’re lying and really NOT glad, or launch a distraction.  Here, we launch a distraction.

“I don’t know how that happened; let look at a flower instead”:

Seen yesterday morning on a dog walk.
Seen yesterday morning on a dog walk, evening primrose.  Pretty restful image; problems gone…

In the meantime, after being flustered over a cloud in the early afternoon, those Cumulus clouds aroiund, only two or three thousand feet thick were beginning to snow away, first way off to the south of us, then downstream of the Cat2 Mountains.

Here is the rest of your interesting and learningful cloud day yesterday:

7:17 AM.  Riff of Altocumulus castellanus/floccus to the north.  Remember in Cloud Maven's Person's poster-sized cloud chart it says when you see this cloud it could rain in 6 to 196 hours, as it does for all the clouds in it.
7:17 AM. Riff of Altocumulus castellanus/floccus to the north. Remember in Cloud Maven’s Person’s poster-sized cloud chart it says when you see this cloud it could rain in 6 to 196 hours, as it does for all the cloud formations in it.
7:18 AM.  Iridescence in a patch of Cirrocumulus, indicating that the droplets comprising it were very tiny, less than 10 or so microns in diameter (one tenth the diameter of a human hair).
7:18 AM. Iridescence in a patch of Cirrocumulus, indicating that the droplets comprising it were very tiny, less than 10 or so microns in diameter (one tenth the diameter of a human hair).  It could rain in 6 to 196 hours when you see this cloud….
9:43 AM.  Cirrus, various species, overspread the sky.  Blockage of some Cirrus by a bird of some kind, lower center.
9:43 AM. Cirrus, various species/varieties overspread the sky. Blockage of some Cirrus here by a bird of some kind, lower center.

Moving ahead…..

1:14 PM.  The cloud-maven cloud indicator blimp was positioned to draw your attention to some building Cumulus clouds southwest of us.  No ice evident.
1:14 PM. The cloud-maven cloud indicator blimp was positioned to draw your attention to some building Cumulus clouds southwest of us. No ice evident, but was soon after this shot.

 

2:47 PM.  Cumulus complex shows no ice, but its up there inside, as you would have known from looking at other similar-sized clouds.
2:47 PM. Cumulus complex shows no ice, but its up there inside, as you would have known from looking at other similar-sized clouds.
3:02 PM.  Droop der it is!  Virga, there it is, downwind end of cloud stream.
3:02 PM. “Droop,  there it is!” Virga, there it is, drooping out just below the farthest cloud bottom downwind end of this cloud stream.
3:17 PM.  Virga's pretty obvious now.
3:17 PM. Virga’s pretty obvious now (above that protruding tree in the distance.  Cloud that produced this virga likely no thicker than the white backed one at the start of the cloud stream, etimated depth, 2000-3000 feet.  Bases, however, were about -8 to -10 C (18-14 F)!  Tops, of clouds even that shallow,  were really COLD, maybe to -15 to -20 C (down to 4 F)!  But you would have guessed this anyway based on the amount of ice coming out of such shallow clouds.  Sorry to insult your Cloud Maven Junior intelligence..
3:23 PM.  Getting excited here so zoomed in for you.  A sprinkle of rain was likely reaching the ground
3:23 PM. Getting excited here so zoomed in for you. A sprinkle of rain was likely reaching the ground.  Here you can see how cold the cloud bases were since that whiteness in the shaft is snow.  Where it has completely melted into rain drops is where the bottom of that whiteness ends,  The freezing level is typically about a thousand feet higher than where than whiteness ends below cloud base in steady, not too heavy precip, which is what we have here.  Small clouds can’t precip too much.  That snow is hanging down about 3,000 feet.
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4:34 PM. A streamer of shallow clouds forming ice heads out from the south toward Oro Valley from Tucson. Estimated depth, 2000-3000 feet is all.
4:34 PM.  Zoomed view of some of the ice in this cloud with an education module inserted into the photo, wrecking it some.
4:34 PM. Zoomed view of some of the ice in this cloud with an education module inserted into the photo, wrecking it some.  Concentrations here likely around 1 per liter of ice crystals.  If depth correct, the crystal habit will be stellars  (“Christmas card” crystals) and dendrites, ones that form between -13 C and -18 C.
The TUS balloon sounding (AKA, rawinsonde for technophiles) launched around 3:30 PM AST yesterday afternoon (from IPS MeteoStar).
The TUS balloon sounding (AKA, rawinsonde for technophiles) launched around 3:30 PM AST yesterday afternoon (from IPS MeteoStar).  Sounding calculates a cloud base of about -9 C, at about 10,000 feet above the ground (over Catalina).   That is cold!  Cloud base is just about where the two lines come together at the bottom.
5:46 PM.  Mock sun or parhelia; couldn't tell if is was due to the lower ice cloud, or a Cirrus way above.  Caused by hexagonal (six-sided) plate-like crystals falling face down.
5:46 PM. Mock sun or parhelia; couldn’t tell if is was due to the lower ice cloud, or a Cirrus way above. Caused by hexagonal (six-sided) plate-like crystals falling face down.  What a great optical phenomena day it was for you, starting out with a nice iridescence!
6:25 PM.  Sunset photos continue to get later and later.  These shallow clouds continued to produce virga into the evening hours.
6:25 PM. Sunset photos continue to get later and later. These shallow clouds continued to produce virga into the evening hours.

There’s still water in the Sutherland Wash.   Its been running now since the end of January!  Amazing.

The End

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1FYI,  this is a lie.

2I suppose someone could posit that “Dark Magic”, oops,  “Dark Energy” may have caused those trails to “come together over me” , by Lennon and McCartney.  “Dark Magic”, OOPs. “Dark Energy”, dammitall, is invoked to explain a lot of impossible things, like how the Universe blew up from something smaller than the head of a pin (!) and was 200 million light YEARS across in the tiniest fraction of a ONE second.   Clearly impossible without magic, oops, Dark Energy.   This impossibility was deduced on cosmic microwave radiation measurements at the farthest edges of the Universe as we know it.

However, instead of checking their measurements, cosmos (not Cosmos Topper of early movie fame with Carey Grant, but cosmos scientists that study the cosmos  invented Dark Magic, oops, Dark Energy, dammitall again,  to explain how something that’s impossible happened.

Recently, cosmos scientists retracted that finding and said their measurements in retrospect were likely compromised by cosmos dust.  How funny izzat?  Sure, I am a weather man and make a LOT of errors myself,  but that cosmos one is pretty big.

Just kidding, cosmos guys,  the cosmos is tough.  Science mag reported that only 4 % of the visible Univserse is made up of  known stuff, 96% (gasp) is made up of Dark Matter (23%), and 73%, of “Dark Magic”, oops again, “Dark Energy”, that stuff that is still thought to be behind the increasingly rapid expansion of the Universe3.   That is, 96% of the Universe is composed of stuff we’re clueless about.

3It was originally posited that the expansion of the Universe should be slowing down until around the 1990s, when measurements indicated it was speeding up.  Hmmmmm.  Will there be a retraction of that claim, too, in our future?  Stand by for more measurements.  Just kidding, cosmos guys.  Try being a weatherman….

A nice cloud yesterday, not a great cloud yesterday; dramatic day ahead

The clouds were somewhat of a disappointment yesterday, not the stupendous photogenic day CM was expecting.

Maybe CM is total fraud, gets Big Oil funding and should be investigated by Rep. Grijalva as other weather folk are,   like the great Prof. and National Academy of Sciences Fellow,  Dr. Judy Curry,  a friend, and about whom I say on a link to her blog here, and from this blog’s very beginning, “The only link you will need.”  I said that because Judy2 is a top scientist, and is eminently fair in this polarized issue.

I am in real trouble!  Will remove that link immediately1 before our very own  “climate thought enforcer”,  Demo Rep. Grijalva, AZ,  finds it using a spy bot!  No telling how far down the influence chain it will go, maybe all the way down to here, where there is virtually no influence!

Back to clouds…….

Only late in the day did the delicate patterns expected to happen ALL DAY appear, again, with iridescence, always nice to see.

Here is your day for yesterday.  Its a pretty interesting movie.  Two thumbs up!

Oh, today’s weather?

The media, Bob,  and our good NWS, of course, are all over the incoming rain in great detail.  In fact, it will take you half a day to read all the warnings on this storm issued by our Tucson NWS.

So why duplicate existing information that might be only slightly different than the prevailing general consensus on the storm amounts, and then maybe be investigated for going against a consensus?   No, not worth it.   Best to be safe, not say things against The Machine.  (OK, maybe overdoing it here.)

In the meantime, the upper low off southern Cal and Baja has fomented an extremely strong band of rain, now lying across SE Cal and the Colorado River Valley where dry locations like Blythe are getting more than an inch over the past 24 h.   Same for northern Baja where some places are approaching 2-3 inches, great for them.  You can see how the rain is piling up in those locations here.  In sum, this is a fabulous storm for northern Mexico and the SW US, whether WE get our 0.915 inches, as foretold here, or not! Rejoice in the joy of others.  Looking for an arcus cloud fronting the main rainband, too, that low hanging cloud in a line that tells you a windshift is coming.  Still expecting, hoping, for thunder today to add to the wind and rain drama.

Also, the present cloud cover, as the trough ejects toward us, will deepen up and rain will form upwind and around here as that happens, so it won’t JUST be the eastward movement of the existing band.  This means you might be surprised by rain if you’re outside hiking and think the band itself is hours away.  Expecting rain to be in the area by mid-morning, certainly not later than noon, with the main blast (fronted by something akin to an arcus cloud) later in the day.  OK, just checked the U of AZ mod run from 11 PM AST, and that is what it is saying as well!  Wow.

Finally, if you care, yesterday’s clouds:

6:45 AM.  Your sunrise color, thanks to a line of broken Cirrus spissatus. Jet stream Cirrus streak, as a matter of fact.
6:45 AM. Your sunrise color, thanks to a line of broken Cirrus spissatus. Jet stream Cirrus streak, as a matter of fact, moving along at about 110 mph.
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9:47 AM.  Ruffle of Sc topped Mt. Lemmon, while strange clouds formed just upwind of them. These kinds of shapes suggest an inversion where the air resists further upward movement and a smoothing occurs at the top similar to a lenticular cloud.  Photo taken at the Golder Ranch Dr. cattleguard. which really doesn’t work that well, as the neighbors below here will tell you.
The 5 AM, March 1st,  balloon sounding for TUS.
The 5 AM, March 1st, balloon sounding for TUS.
9:53 AM.  Looks like a crab with four hooks.  How funny.
9:53 AM. Looks like a crab with four pinchers. How funny.
12:23 PM.  Shredding tops of small Cumulus like this indicate that the air is very dry just above their tops, and the shreds racing off to the right, indicate how fast the wind increased as you went upward.
12:23 PM. Shredding tops of small Cumulus like this indicate that the air is very dry just above their tops, and the shreds racing off to the right, indicate how fast the wind increased as you went upward.
2:58 PM.  Something is changing here.  Notice how the tops are bulging and not immediately being torn into shreds.
2:58 PM. Something is changing here. Notice how the tops are bulging and not immediately being torn into shreds.  The air was likely moistening above cloud tops, and the inversion holding the tops back, weakening as our storm gets a little closer.
4:19 PM.  A line of heavy Cumulus had formed to the west, indicating more moistening and "de-stabilization" of the air.
4:19 PM. A line of still larger Cumulus had formed to the west, indicating more moistening and “de-stabilization” of the air.  However, the upper low was not advancing toward us any longer and no further development occurred as stagnated,  ratcheting up  its rainband over eastern Cal and western AZ.  The TUS balloon sounding suggested tops were getting close to the normal ice-forming level here, -10 C, the slight inversion on the morning sounding at 13,000 feet above sea level, and the one likely to have caused those smooth morning clouds,  was gone.
6:07 PM.  Just before sunset from near Oracle where we took mom for her BD.
6:07 PM. Just before sunset from near Oracle where we took mom for her BD.  The heavier Cumulus clouds faded with the sun.  They will arise today!

Below, just some pretty patterns observed later in the day.  Click to see larger versions.

3:28 PM.  Cirrocumulus began to appear.
3:28 PM. Cirrocumulus began to appear.
3:36 PM.  Twisted, tortured Cirrus (fibratus?).
3:36 PM. Twisted, tortured Cirrus (fibratus?).
3:50 PM.  Another view of Cirrocumulus. Though these clouds are still composed of liquid droplets, the 5 PM TUS sounding suggests they were at about -30 C in temperature.  It happens.
3:50 PM. Another view of Cirrocumulus. Though these clouds are still composed of liquid droplets, the 5 PM TUS sounding suggests they were at about -30 C in temperature. It happens.
4:00 PM.  An incredibly complex array of Cirrocumulus overhead.  Due to perspective, its about the only view that you can really see how complex the patterns are.
4:00 PM. An incredibly complex array of Cirrocumulus overhead. Due to perspective, its about the only view that you can really see how complex the patterns are.
4:20 PM.  Some iridescence for you.
4:20 PM. Some iridescence for you.
6:00 PM.  At Oracle, AZ.
6:00 PM. At Oracle, AZ.
6:22 PM.  Finally, from the "Not taken while driving since that would be crazy" collection, this oddity.  Looks like an high temperature contrail (aka, "APIP"). but the trail seems to shoot up into the cloud Altocumulus cloud layer (or down out of it).  Have never seen this before.
6:22 PM. Finally, from the “Not-taken-while-driving-since-that-would-be-crazy-though-it-looks-like-it-was” collection, this oddity.  Looks like an high temperature aircraft contrail (aka, “APIP”) in the lower center.  And the trail seems to shoot up into the cloud Altocumulus cloud layer (or down out of it). Have never seen that kind of aircraft track before since it looks so steep! “High temperature”  here means that it formed at temperatures above about -35 C.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Whew, the end.

——-

1Not!!!!!!  I thought this was a good read about this deplorable new stage of “climate thought enforcement” now in progress.  It was brought to my attention by climate folk hero, friend, and big troublemaker, Mark Albright.  Wow, maybe Mark will be investigated, too!  Maybe I should excise his name….

2I remember, too, how cute she was when she worked my lab/office at the University of Washington in the mid-1980s, and thought about asking her out, to detract from a serious commentary here.   She was a Penn State grad student, not a U of WA employee;  still, to ask her out would have been untoward.   A human commentary like this, one about feelings and things, help boost blog attendance.

100-150 mph winds overhead bring pretty patterns in Cirrocumulus clouds; also, an experiment in detecting the phase of clouds

If you thought those high clouds were moving faster than usual, you were right.  The winds were about 120 mph at that level, about 28,000 feet above sea level, and just over 150 mph a few thousand feet above that level.

You may have noticed two things, if you are good, that there were repeated formations of delicate Cirrocumulus clouds, likely starting as liquid drops, but quickly transitioned into Cirrus.   Sometimes, it was just flocculent Cirrus the whole way to us from the west.

The second thing that you may have noticed was that there was always an upwind clearing zone that remained stationary until late afternoon when it finally passed overhead.  Yesterday’s high clouds formed at that back edge.

How can you tell that the upwind edge of that sheet of clouds was initially composed of liquid droplets, but then froze naturally within a minute or three as it jetted downstream?

Perform an experiment to demonstrate the two phases.

In this case we will have an ice producing aircraft fly through both regions, the droplet region, and also the region where no droplets exist because they have frozen and are growing larger and larger as ice crystals.

What will be the predictable result of two ice-producing aircraft flying through these two different phases?

In the liquid cloud region, an ice canal will develop as the appearance of ice in a droplet cloud results in the evaporation of liquid droplets, the molecules of vapor from the evaporating droplets provide “food” for fattening ice crystals, where “deposition” takes place.  Under a microscope you would see the crystals getting larger, growing extensions; you would not be able to see the molecules producing that, of course.

The result of our experiment, something you likely will never see again in my lifetime:

DSC_3231

3:36 PM.  Letting the font size demonstrate the excitement I was feeling, that excitement filling the whole sky!  Maybe the temperature in this inadvertent experiment would be stupefyingly low, like -40 C (-40 F), in which case I might get a publication of my photos.  Another great aspect was that this canal was streaking toward me (us)!  It just could not have been a better situation.
3:36 PM. Letting the font size demonstrate the excitement I was feeling, that excitement filling the whole sky! Maybe the temperature in this inadvertent experiment would be stupefyingly low, like -40 C (-40 F), in which case I might get a publication of my photos. Another great aspect was that this canal was streaking toward me (us)! It just could not have been a better situation.  And I would add, in retirement mind you, to my CV and I don’t even have a grant!  It was going to be a great day!
3:40 PM.  See photo.
3:40 PM. See photo.
3:47 PM.  Normal contrail in ice cloud continues to evolve as ice canal gets closer.
3:47 PM. Normal contrail in ice cloud continues to evolve as ice canal gets closer.
3:49 PM.  The aircraft contrail that was emitted in all ice clouds.  Still are all ice, though you may say they look awfully tufted like they could have droplets. They're glaciated, all ice.  Go with me on this.  I'm the cloud maven.
3:49 PM. The aircraft contrail that was emitted in all ice clouds. Still are all ice, though you may say they look awfully tufted like they could have droplets. They’re glaciated, all ice. Go with me on this. I’m the cloud maven.
3:26 PM.  The scene before the experiment.  The upwind edge where the Cirrocu and CIrrus were forming is just above the horizon.
Helping hand points out ice canal. By this time the clouds around that ice canal had also transitioned to ice.
Also at 3:47 PM, a zoomed view of ice canal.  You can see the little ice fibers in that clearing, the ones than caused the evaporation of the droplets around the initial ice formation.  Likely at this point that the surrounding cloud, though rather "flocculent" looking was also now ice.
Also at 3:47 PM, a zoomed view of ice canal. You can see the little ice fibers in that clearing, the ones than caused the evaporation of the droplets around the initial ice formation. Likely at this point that the surrounding cloud, though rather “flocculent” looking was also now ice.
DSC_3282
3:52 PM. As usually happens with aircraft produced ice, the tiny, overabundant crystals are pristine, perfectly shaped hexagonal solid columns or hexagonal plates, and that perfect shape usually results in strong optical phenomena at the point where a sun dog or  22 degree halo is observed due to the refraction of sunlight in those crystals.  You only had seconds to see this, those clouds were moving SO FAST, and I missed the brightest point.

 

3:53 PM.  One final look at our receding ice canal, gradually being filled in by natural Cirrus.
3:53 PM. One final look at our receding ice canal, gradually being filled in by natural Cirrus.

Was holding breath, thinking about that CV enhancement, waiting for the TUS sounding, which was already in the air when these last few photos were taken, and, more importantly, it was going up near where the clouds were forming, so the moist level intercepted and its temperature would be pretty accurate for this shots.  Now, if its -40 C, oh man, we got a pub!  -36 C, maybe.  Temperature greater than about -35 C?  No pub, well, except here, which is something.  That’s because liquid drops at temperatures between -30 and -35 C have been reported by remote sensing and aircraft repeatedly.  Nature abhors forming an ice crystal in clouds without going through the liquid phase first.

Within a couple of hours the TUS sounding was in, and here it is:

The TUS balloon sounding launched about 3:30 PM, rise rate about 1,000 feet a minute.  Shows Cirrocu layer was "only" about -33 C (-27 F).  Boohoo.
The TUS balloon sounding launched about 3:30 PM, rise rate about 1,000 feet a minute. Shows Cirrocu layer was “only” about -33 C (-27 F). Boohoo.

I wasn’t going to get a journal pub.  I thought about that guy that thought he was going to win the Nobel Prize…..and I know now how he felt.science laughs_005

Now about those pretty patterns, by Simon and Garfunkel.  Enjoy.
1:08 PM.
1:08 PM.
1:08 PM.
1:08 PM.
1:13 PM.
1:13 PM.
1:35 PM.
1:35 PM.
3:01 PM.
3:01 PM.
3:04 PM.
3:04 PM.
3:07 PM.
3:07 PM.
1:34 PM.
1:34 PM.  Forgot this nice one…..

Today’s take

Jet core at 18,000 feet now passing overhead and DRIZZLE or very light rain from warm processes now (4:15 AM) evident on the Catalina Mountains.   The passage of that jet core at that level (500 millibars) seems to be an almost  black-white measurable rain or no rain discriminator in the Southwest US, so as that happens right now, chances of some measurable rain are good.  Still not expected to be more than 0.25 inches, but will now at least be 0.01!

The low clouds are pretty shallow now, and, if they rain, shallow clouds with tops warmer than -5 C (23 F) have to be pretty clean for that to happen.  Clean clouds is got bigger droplets, ones that reach the Hocking-Jonas threshold of between 30-40 microns in size and can collide and stick together forming still much larger drops that collect more and more tiny cloud droplets, kind of a chain reaction, as Nobel Laureate in chemistry Irving Langmuir described it back in 1948 after he got interested in clouds and rainmaking.

However, the “collision with coalescence process will be short-lived as cloud tops go up to well below freezing level this morning, and real rain falls (as is happening now (7:18 AM) down in TUS and to our NW.

Measurable rain should be just on the doorstep, and it will have to develop in upwind clouds as they approach us and the air begins to rise as it goes uphill from the lower deserts and encounters the Catalinas’  there isn’t much in the way of radar echoes upwind of us now.

The development of rain in clouds as they approach us in marginal rain situations like this one is not terribly unusual.  Sometimes, as a friend pointed out, new echoes in deepening clouds can appear over and over again near where I-10 runs to the SW and W of us in a purely orographic situation.

This is what CMP is hoping for, and the result of that might be a tenth of an inch or more.

Not to worry; plenty of model rain still ahead in models

1While several inches of model2 rain has occurred in Catalina and in the nearby mountains this month, most of which cloud-maven person has festooned his blog with model panels of, there really hasn’t been any ACTUAL rain.

But having said that, there is even MORE model rain ahead, some beginning tomorrow in these parts.  Tomorrow’s rain comes from a sub-tropical minor wave ejecting from the sub-tropics.  You know, as a CMJ, a wave from that zone means a ton of high and middle clouds,  i.e., likely DENSE Altostratus with virga, something that was seen yesterday off to the SW of us.  This time, though, some rain should fall from these thick clouds, though almost certainly will be in the trace to a tenth of an inch range between tomorrow and Monday morning.

Model rain from 11 PM AST global data then falls in Catalina on:

February 24th

March 1st

March 7-9th

with the model total rain in these periods likely surpassing an inch or more!  What a model rain winter season this has been! Astounding.  The model washes have been running full since late December, too!

BTW, that last model rain period is really a great one, a major rain for ALL of Arizona!

Some recent clouds I have known and a couple of wildflowers
7:36 AM, Thursday, Feb 19:  Iridescence in Cirrocumulus.
7:36 AM, Thursday, Feb 19: Iridescence in Cirrocumulus.
7:52 AM, Thursday, Feb. 19:  Iridescence in Cirrocumulus with a tad of Kelvin-Helholtz waves (center, right)
7:52 AM, Thursday, Feb. 19: Iridescence in Cirrocumulus with a tad of Kelvin-Helholtz waves (center, right), ones that look like breaking ocean waves.  Kind of cool looking.
9:52 AM, Thursday, Feb. 19:  Altocumulus perlucidus exihibing crossing pattern.  Makes you think about football.
9:29 AM, Thursday, Feb. 19: Altocumulus perlucidus exhibiting crossing patterns, rows perpendicular to each other. Makes you think about football and people running out for passes.
9:42 AM, Thursday Feb 19:  An extremely delicate crossing pattern in Cirrocumulus, center.
9:42 AM, Thursday Feb 19: An extremely delicate crossing pattern in Cirrocumulus, center.  You’ll have to drill in good to see it, but its worth it.
10:39 AM, Thrusday, Feb 19: Pretty (mostly) Cirrus spissatus, a thick version in which shading can be observed.
10:39 AM, Thrusday, Feb 19: Pretty (mostly) Cirrus spissatus, a thick version in which shading can be observed.
6:13 PM, Thursday, Feb 19:  No idea what that stick contrail is.  Looks like a flight pattern to induce weightlessness.  Climb rapidly, round off the top, and then go down.  You can be weightless for maybe 10-30 seconds.  Been there, done that in a C-130 Hercules, last FACE flight of 1973, Bill Woodley lead scientist.
6:13 PM, Thursday, Feb 19: No idea what that stick contrail is. Looks like a flight pattern to induce weightlessness. Climb rapidly, round off the top, and then go down. You can be weightless for maybe 10-30 seconds. Been there, done that in a C-130 Hercules, last FACE flight of 1973, Bill Woodley lead cloud seeding scientist.  But, you pay a price, get smashed on the floor as the aircraft comes out of the dive.  You cannot get up!
Let's zoom in and see if we can learn more about this cloud.... Nope.
Let’s zoom in and see if we can learn more about what happened here.  I think a jet pilot was having fun.
Nope.
6:54 AM, yesterday.  Altostratus virga provides a spectacular, if brief sunrise over the Catalinas.
6:54 AM, yesterday. Altostratus virga provides a spectacular, if brief sunrise over the Catalinas.
6:15 PM last evening.
6:15 PM last evening.
DSC_3011
From a dog walk this VERY morning, a desert primrose.
From this morning's dog walk.
And  a desert onion bloom.

The End. Hope you enjoy the copious model rains ahead!

———————

1Today’s title is cribbed from Spinal Tap song, which is really quite great,  “Tonight I’m going to rock you tonight.”

2WRF-GFS and Canadian Enviro Can GEM accumulated bogus outputs.

While waiting for R, maybe R+ at times, some thoughts on the Super Bowl

Actually, there are no thoughts about the Super Bowl here.  The title was  just another cheap attempt to attract a reader that might be both cloud-centric AND  a football fan, creating a moneyful increase in web traffic for this blog.

Yesterday’s gorgeous cloud patterns1

First you had your Cirrus, the highest of all clouds except for stratospheric nacreous clouds which kind of mess things up up there by eating ozone.  We will not display n-clouds.

Cirrus, as you know, ALMOST always precedes lower clouds since they’re moving so much faster than the lower ones.   So we get a sequence of clouds before it starts to rain that generally is the same, over and over again as in that movie about weather, Ground Hog Day.  But let us ramble on…

First, patchy Cirrus, then maybe a sheet of Cirrostratus, then the lower stuff as Cirrostratus thickens downward to become that gray sheet called Altostratus.  Throw in a few Altocumulus clouds that become a sheet underneath, and voila, your in Seattle, with rain on the doorstep.  Yep, that’s the Seattle, and well, the Middle Latitude Pre-Storm Cloud  Sequence (MLPSCS)2.

7:41 AM.  Birds on the wire, noticing the invading Cirrostratus fibratus.  Low smog plume moves NW out of TUS and into Marana.
7:41 AM. Birds on the wire, waiting for the storm, notice the invading Cirrostratus fibratus. Low smog plume moves NW out of TUS and into Marana again (at very bottom of image).

 

10:49 AM.  What a fine example of Cirrus spissatus (Cis spis) trailing larger ice crystals, certainly these would be "bullet rosettes", looking something like a cholla bud, except the spines that stick out all over look like hexagonal columns radiating out of a center crystal.
10:49 AM. What a fine example of Cirrus spissatus (Cis spis) trailing larger ice crystals, certainly these would be “bullet rosettes”, looking something like a cholla bud, except the spines that stick out all over in this type of ice crystal look like hexagonal columns radiating out of a tiny center crystal.  The ones NOT falling out are likely stubby solid columns, plates, prisms,  and “germs”, the latter not really germs, but tiny, amorphous  ice crystals not having grown a particular shape yet, all too small to have appreciable fallspeeds like the bullet rosettes.  A whole sheet of this cloud having so much ice falling out would constitute what we would call, “Altostratus”, gray and deep.

 

11:46 AM.  Another interesting scene.  Are these Cirrus clouds spreading out, or is it perspective?
11:46 AM. Another interesting scene. Are these Cirrus clouds spreading out, or is it perspective? Note bank of thick Cirrus on the horizon, too.  (I think they were actually spreading out some.)
12:49 PM.  Here comes the next lower layer, Altocumulus clouds.  However, note that ice formed in or just above this layer of Altocumulus, indicating that although it is one comprised of droplets (liquid) it is VERY cold.  What is your next thought?  HTCs (High Temperature Contrails) or "APIPs", as the writer named them back in 1983 though not a great name.
12:49 PM. Here comes the next lower layer, Altocumulus clouds. However, note that ice formed in or just above this layer of Altocumulus, indicating that although it is one comprised of droplets (liquid) it is VERY cold. What is your next thought? HTCs (High Temperature Contrails) or “APIPs”, where aircraft that fly through them seed them by producing huge numbers of ice crystals due to extra cooling provided by over the wing flow, jet exhaust water producing extreme supersaturations, or prop tip cooling.  Cause hasn’t been quite nailed down, but cooling is the leading suspect where the air is cooled to -40 C or so, and ice has to form in moist conditions.
2:26 PM.  With the Altocumulus and Cirrocumulus displays came periods of iridescence in the clouds, indicating tiny droplets less than 10 microns in diameter.
2:26 PM. With the Altocumulus and Cirrocumulus displays came periods of iridescence in the clouds, indicating tiny droplets less than 10 microns in diameter.  There were more grandiose displays, but they were so gaudy my photos looked fake.

 

4:04 PM.  Out ahead of the invading sheet of Altocumulus were these CIrrocumulus clouds with a cool herring bone pattern.  While called, "Cirrocumulus", these clouds were actually at the same level as the invading Altocumulus.  Its the fineness of the granulation that makes us refer to them as "Cc" clouds.
4:04 PM. Out ahead of the invading sheet of Altocumulus were these CIrrocumulus clouds with a cool herring bone pattern (“undulatus”). While called, “Cirrocumulus”, these clouds were actually at the same level as the invading Altocumulus clouds shown in the next photo. Its the fineness of the granulation that makes us refer to them as “Cc” clouds, even when they are in the middle levels, and not truly high clouds as the prefix “Cirro” would suggest.

 

4:09 PM.  The invading sheet of Altocumulus perlucidus translucidus (no shading, honey-comb pattern).  On the horizon, Seattle-like solid veil of Cirrostratus, something that's pretty rare here.
4:09 PM. The invading sheet of Altocumulus perlucidus translucidus (no shading, honey-comb, flocculent pattern). On the horizon, Seattle-like solid veil of Cirrostratus, something that’s pretty rare here. This was an exciting scene because of the advancing layers, the darkening on the horizon, in the context of the major rain ahead.
4:17 PM.  You have ice in your veins if this shot doesn't give you goose bumps.  So pretty, all that uniform flocculation up there.
4:17 PM. You have to have ice in your veins if this shot doesn’t give you goose bumps. So pretty, all that uniform flocculation3 up there in Altocumulus perlucidus translucidus.
4:24 PM.  I can feel that you want more flocculation...
4:24 PM. I can feel that you want more flocculation…

 

4:31 PM.  Maybe just one more...
4:31 PM. Maybe just one more…  Feeling pretty great now now that I’ve flocculated you so many times today.  Three or four is about my limit.
Ann DSC_2281
5:08 PM. APIP line, or HTC (“High Temperature Contrail”)–ones not supposed to occur at the temperature of this Altocumulus perlucidus translucidus, but they do anyway. Last evening’s TUS sounding pinned this layer at -24 C (-11 F!).   Note that no other ice can be seen falling from these very cold clouds.  The “castellanus” appearance of a contrail is extremely unusual, and may indicate a sharp decline in temperature at the level the aircraft flew. However, then it begs the question about why the Ac clouds aren’t turreted, at least, SOME.  You’ll probably have to take CM’s word that its an ice trail.  Note indication of a hole in the droplet cloud at far left of trail.  That’s a clue.
5:08 PM.  To the southwest and west, layers of Altocumulus, some having turrets, and with a beautiful veil of CIrrostratus above, advance on Catalina.  I love shots like this, though sans color, due to their rainy portent, even though our rain is not supposed to being for another 24 h, or this evening.
5:08 PM. To the southwest and west, layers of Altocumulus, some having turrets, and with a beautiful veil of CIrrostratus above, advance on Catalina. I love shots like this, though sans color, due to their rainy portent, even though our rain is not supposed to being for another 24 h, or this evening.

 

The weather just ahead

Of course, everyone, including media weathercasters, are all over the incoming stupendous storm event.  For a more technical discussion, here’s one by Mike L., U of AZ forecasting expert, who got excited enough about our storm to come to send out a global e-mail.  I think you should read it, though I left out all the graphics. I’ve already been too graphic today.

———–Special Statement by Mike L———————————-

“A very unusual heavy precipitation event is forecast for the next few days across Arizona and New Mexico as extremely moist air interacts with multiple short waves.  As seen in the below data from the NWS, the maximum monthly IPW for Jan is about 28-29mm.  If the various WRF forecasts verify, the upcoming storm will set new a new January IPW record.

The 12z WRFGFS indicates very high moisture levels being advected towards Arizona due to a low latitude low located west of the Baja spur.  While IPW has slowly decreased from the previous storm over much of the area, La Paz is seeing a upturn in observed IPW.  

As seen below, at 5pm today, some convection is forecast near to the low.  Lightning data has indicated there has been some strong convection during the day today.  Model initializations are normally suspect so far from any upper air stations, but it seems that both the NAM and GFS seem to have the intensity and location initialized well.  One item of note is that during the past few days, the models have had a trend of moving the heaviest precipitation back to the west.  Initially, the heaviest band was well in to NM whereas you’ll see later, it is now over much of eastern/central Arizona.  

By late tomorrow afternoon,  the low has only moved eastward slightly, but IPW continues to increase over NW Mexico and into Arizona.  Precipitation begins mainly over the higher terrain of eastern Arizona.

By Wednesday morning, the mid level low has intensified as a strong short wave dives down behind the mean trough along with CAA into the back side.

Significant synoptic scale lift is present over southern Arizona and into northern Mexico by this time.

Extreme IPW is forecast to be present during the morning hours on Friday and combined with the favorable dynamics, widespread moderate to heavy rain is predicted.  As the low becomes cut off, there will be an extended period for precipitation.

Precipitation rates are forecast to be above  .25″/hour in some locations during the morning hours.

Partial clearing is forecast by Friday afternoon which allows some heating.  Combined with cooler air aloft and high IPW, moderate amounts of CAPE are present during the afternoon.

By later in the afternoon, as Bob Maddox pointed out, convection forms and results in some locally heavy precipitation.

Tucson’s vertical profile is quite impressive with 700 J/Kg of CAPE and some vertical shear to support organized convection.  Hail is also a threat.

Convection continues into the evening over southern Arizona with a continued threat of hail and some lightning.  

The 3 day QPF is very impressive with widespread 1 inch amounts with some areas receiving over 3 inches.  Some of these areas are associated with the strong convection present on Friday afternoon/evening.  Confidence is low to medium due to the lack of upper air data and lack of run to run consistency as discussed previously.  Also, the output in this discussion was solely from the 12z WRFGFS.  The WRFNAM from last night had the heaviest precipitation somewhat to the east.  It will be informative to see the next suite of model runs overnight to see if this westward trend ceases.  There is a chance that it could continue and the heaviest precipitation is actually farther west than depicted below.

Very little of this precipitation falls as snow except at the very highest elevations, above 9k feet due to the sub tropical air-mass and lack of cold air.

Note that this discussion will only be available for organizations who are (or have) supported the Arizona Regional Modeling Program.  This change will take effect before next monsoon season.  Private individuals not associated with commercial/governmental agencies will continue to receive the discussions.  If your agency would like to support the Program, please email me for details. “

————–End of special statement by Mike L—————————

The End!

1Let us not forget Simon and Garfunkel’s telling descriptions of Patterns of life; they repeat in clouds, too.   (Pretty funny lead in commercial where Bryant Gumbel is asking, “What is the internet?”)

2Back in the old days when cloud forms were used to tell weather, Cirrostratus sheets, those high thin sheets, often with a halo,  foretold rain 70% of the time here in the US (see Compendium of Meteorology, 1951).    Deserts don’t much see this sequence.  Cirrus are mostly meaningless in them, just indicating some withering tail of a system with rain that’s far away most of the time.

3NOT a reference to an untoward sex act.

Rain continues to fall in Catalina on the 13th

Today is the 9th.

Great news!  Another decent rain assured now sa the models have converged on rain here on the 12th during a nice, and very sharp cold front passage, those in which the temperature can fall from a toasty 60s to 43 F over an hour along with a withshift to the NW from gusty SW winds.   So we have quite a dramatic weather event coming up.  Here’s what the Canadians have to say about it:

Valid at 5 PM AST, December 13th.  Areas where the model has calculated precipitation during the prior 12 h, are marked, from light to heavier amounts, green to blue to yellow.  There's a little yellow in Arizona north of Catalina.
Valid at 5 PM AST, Saturday, December 13th. Areas where the model has calculated precipitation during the prior 12 h, are marked, from light to heavier amounts, green to blue to yellow. There’s a little yellow area of heavy precip over Catalina (see arrow, lower right), and that’s why I am posting this panel!

But what does it all mean, all the models predicting rain for Catalina on the 13th?   Here’s what it means:

The chance of measurable rain here on Saturday,  the 13th is now more than 100 %; its in the bag.  Count on it.  This is weather forecasting at its best.  The rain may start in the early morning hours of the 13th.

The models have varied drastically on the amounts of rain, and so there’s quite a range that could occur.  From this keyboard:

Minimum amount is 0.15 inches (10% chance of less than that)

Maximum amount, 0.80 inches (10% chance of more than that)1

Since the average of those two theoretical “extremes” dreamed up for this situation by yours truly is 0.425 inches, that’s my personal prediction for my house.   It helps, too, that I am the same person who will also measure the rain as well.

Will look, too, for a little ice in the rain toward the end of it as the temperature plummets after the cold front goes by.

So, what’s yours?  (Everyone should have a personal prediction.)

Yesterday’s clouds

Not much going on, mostly Cirrus, then Altostratus in the afternoon, that gray icy sheet that dimmed the sun so well.  However, there were a few flakes of Cirrocumulus.

7:41 AM.  Kind of a mess.  Some ancient contrail streaks, natural Cirrus, and some Cirrocumulus flakes (dark thin lines).  Because the sun is low, Cc clouds can have shading, otherwise, no.
7:41 AM. Kind of a mess. Some ancient contrail streaks (streak in center), natural Cirrus, and some Cirrocumulus flakes (dark thin lines). Because the sun is low, Cc clouds can have shading, otherwise, no.
4:19 PM.  Classic Altostratus clouds, deep icy ones with tops at CIrrus levels, typically 25-35 kft or so above sea level.  Published meteorogists, looking at satellite imagery, often call this cloud "Cirrus."  How funny is that?  They do that because they see in the satellite imagery that the tops are cold, less than -40 C and don't realize that only a patchy type of Cirrus, spissatus, can have shading!  How funny is that, again?  But, here, my reader knows better than that!
4:19 PM. Classic Altostratus clouds, deep icy ones with tops at CIrrus levels, typically 25-35 kft or so above sea level. Published meteorogists, looking at satellite imagery, often call this cloud “Cirrus.” How funny is that? They do that because they see in the satellite imagery that the tops are cold, less than -40 C and don’t realize that only a patchy type of Cirrus, spissatus, can have shading! How funny is that, again? But, here, my reader knows better than that!

Enough fun for today….

The End

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1Reluctantly, I remind the reader that the maximum rain amount seen for the last storm, 0.40 inches (10% chance of a greater amount), was laughable;  1.16 inches fell in Catalina/Sutherland Heights.  However, in formulating an excuse, CM would point out that the models didn’t see it coming either.

Unusual patterns in afternoon Cirrus and Cirrocumulus clouds

Started out clear yesterday.  Below, an example of that completely clear sky in case you missed it.

10:06 AM.  Clear skies are evident.  HOWEVER, note shallow smog plume exiting Tucson and flowing northwestward across Continental Ranch where Mark Albright, lives.
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 overview of Cirrocumulus and Cirrus clouds with oddities.
3:14 PM Close up of previous cloud scene.  Note all the weird stuff going on.
3:14 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!
3:22 PM. More oddities. Going crazy trying to understand what the HECK is going on!
DSC_0052-1
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.
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.
4:02 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.
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 ballet dancers the way the clouds and the streamers were arranged.
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 cappillatus.  Look, it even has a tiny anvil spreading out!  How fun was that to see!
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.
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.