Cirrus clouds – Page 15

Rain today, clouds yesterday

Yep, that’s right, rain IS imminent! In case you forgot what they looked like, there’ll be a display of “hydrometeors” before 7 AM here in Catalina. Should last the whole morning at least. If you don’t believe me and think I just made this up, go here.

BTW, “hydrometeors”; what real meteorologists, well, maybe pretentious ones, call rain drops; remember, we’re METEORologists, we like to see things falling out of the sky.

Not raining now at 4:38 AM, but its on the radar here for the Catalina area from a great weather provider, Weather Underground. Amounts here likely to be around an inch in the next 48 hours. Still looking for a drop in temperature enough to bring our current (5: 1o AM) mid-fifties temperatures into the upper 30s in the rain as the cold front goes by, maybe tomorrow morning as well as a second little pulse of clouds and precip keeps things going for a second day. That temperature drop should lead to a little snow in the heavier periods of rain.

Second pulse?

Racing from the north central Pacific is a little blob of clouds down the “backside” of our humongus trough. Here, from the University of Washington Huskies, still playing basketball in the NIT tournament, is a 500 millibar map. The blob of clouds that will extend our rainy spell is located, on this map, a few hundred miles west of San Francisco. It is CRITICAL to us to get that second day of showers after the current front goes by with its strong rainband today.

The green lines on this map are contours along which the wind blows. Here you can see a HUGE fetch from the north central Pacific to Oracle Road, Catalina. To demonstrate this more clearly, click on the map below to get the full version, and place a finger on one of the green lines in the north central Pacific, say, just south of the Aleutians. You might want to pick the one labeled, “5580”. Then with your finger on that line, follow it southeastward (“down” toward the lower right), maintaining contact with the montior screen, until you exit the right hand side of the map. I hope you haven’t had a peanut butter and jelly sandwich before doing this.

If this map pattern was stationary, that’s where the wind would go, forever, “down” and then “up”. Where your finger reached the point farthest to the south on this map, and where the wind makes a sharp turn around San Diego, is what we call a “trough”. And, if you were to see a map at a LEVEL in the atmosphere, there would be a long extension of lower pressure from the Pacific Northwest to San Diego at the time of this map. But no, we meteorologists complicate things by using constant pressure surfaces which go up and down in height all over the map instead of constant level surfaces instead of an easy to understand constant level map with highs and lows on it. Oh, well.

This “second pulse” of clouds and precip is moving so fast, it will get to the “bottom” (south end where the wind curves to the north) of the trough before it has a chance to exit Arizona. That will add a whole second day of showers and rain with a very low freezing level tomorrow. Its a bit rare to see something like that catch up so fast to the main trough and, in a sense, delay its passage.

Yesterday’s clouds

Okay, you had yer flying saucer clouds here and there during the day, that is, in proper cloudspeak, Cirrocumulus (Cc) lenticularis (first photo), Altocumulus lenticularis (second photo, is lower, has shading, compared to Cc–that short flat cloud below the Altostratus layer), you had yer Altostratus band (3), followed by yer clear slot, beginning at 4 PM -hope you planned a picnic around it, or trip to the beach (4), then quickly followed by heavy, dense Altostratus layer, (see second shot with saucer cloud).

No sunset color due to the solid cloud banks to the west. Should be enough breaks in “post frontal” low clouds for sunset color today, however.

Boffo storm bops Burbank before belting Benson

…and the rest of Arizona tomorrow. Actually, at this hour, 5 AM, the storm coming here has not yet gotten to Burbank. Its only close. But, people get excited when you say things like that in the title, and that’s what we’re about here, weather excitement, not accuracy excitement.

Weather excitement?

Take a look at the NWS site here. They are beside themselves with excitement, issuing what appears to be hundreds of warnings for the entire State of Arizona, and not one drop of rain/snow has fallen yet! Imagine how excited they will be at the NWS when something actually happens! (hahaha, just kidding; you’re doing a great job down their guys and gals.) They just want to WARN us about this well-predicted, STRONG storm, one having the unusual characteristic of being well-predicted in the models more than a week in advance. Hardly ever happens.

So, with the NWS all worked up about winds and rain and snow and cold and stuff like that in our IMMEDIATE Catalina future (next few days), here at this keyboard we will try to fill in a cloud appearance niche, or try to.

Examining the AZ station and cloud plot here posted by our friends at the University of Arizona Wildcats Weather Department, this nice map.
You can see a sheath of clouds (whitish area) extending southward from southern NV and UT down past Yuma AZ. There is no radar echo with it now, or will there be. Your interpretation: must be Cirrus and Altostratus (thick ice clouds), maybe with some Altocumulus at the bottom toward the back (west side). You’ll notice, too, that it is COMPLETELY separate from the main frontal band that has not yet (5 AM AST) gotten to Burbank, CA.

Note cloud empty area or slot behind (to the west) this sheath of middle and high ice clouds over the Colorado River Valley. A very common sequence in the Southwest interior in late winter and spring is to have a completely separate slice of high clouds, even thickening up to look quite gray, maybe with some virga, give a false impression that the storm is imminent, much closer than it really is, followed by a spectacular clearing from western horizon. Often, this sequence, as is possible today, leads to astonishingly colorful sunsets here if the timing is right. You won’t read about possible colorful sunsets at the NWS today! This why I am here, to warn you about a nice sunset while they warn you about winds and stuff.

However, at the current rate of movement, this band of high clouds will pass overhead in the middle of the day. Drat.

What next?

After the high clouds go by, there is enough moisture around for middle clouds, though not decks of them. So in the hours after the ice shield goes by, that is this afternoon and evening, we should see some Altocumulus and patches of Cirrocumulus. As the winds increase over us, almond shaped clouds (flying saucers) are likely.

Update at 6:13 Am AST: “Lenticulated sunrise” in progress now! Check toward Mt. Sara L. Here it is, in case you missed it. Gorgeous.

Continuing…. Those kinds of clouds are good harbingers of storms. Some small Cumulus are likely to start showing up in the afternoon as well I think, but will be high based and too shallow to produce precip.

It will be, I think, one of our most photogenic days so get yer cameras ready for some interesting, and finely granulated Cc, or Ac lenses.

The main slug of low based clouds, rain/snow, cold air, windshift to the NW, graupel, lightning, etc., comes in after mid-night with the front. Temperatures are likely to drop 10-20 degrees as the front goes by tonight and the rain begins. Check it out here from the great weather calculator at the University of Arizona. And here for even more detail! Even the Great Beowulf Weather Calculator at the U of AZ is excited about this storm, predicting more than 3 inches of water-equivalent snow on the upper regions of the Catalina Mountains, which is clearly too much!

But how great it would be if it was correct!

Hang on. Breezes already at 6:37 AM, and you know what that means: one heckuva windy day this afternoon and evening, dusty, too.

I think I need to rest now, maybe lie down for awhile, let the weather excitement dissipate.

The End.

Cloud quiz

While waiting for the rain, here are some of yesterday’s clouds. What were they?

Answers printed upside down at the bottom except that WordPress wouldn’t let me do that. It would be great if you turned your monitor upside down before you looked at the answers. One is a trick “question” because I took a picture of a cloud behind what appears to be an inanimate plant, focusing on the dead plant and so the cloud shown in the background is a little fuzzy to make it more difficult.

1. Cirrus spissatus, the only type of Cirrus allowed to have gray shading in the daytime. Note mammatus like feature in the center.

2. Contrail, unusually turreted one (hmmm, perhaps a part of some government conspiracy–hey, I am kidding the “chem-trail” people). There’s also a patch of Altocumulus floccus (or Altocumulus perlucidus would be OK, too) lower part of photo.

3. Cirrus castellanus-turreted Cirrus, don’t see that species too often because it is rarely so unstable at that height. “Unstable”-the temperature dropped a LOT as you went higher up there, more than usual.

4. Altocumulus floccus, horizon, upper right, Cirrus fibratus (pretty much delicate, straight fibers) middle.

5. Ocotillo (hahaha, its not a cloud!) ((Another example of the juvenile humor that the writer seems to be afflicted with). OK, it looks like mostly Cirrus castellanus in the distance.

What do these kinds of clouds tell us?

The atmosphere is moist, but only patchy moist, a frequent occurrence in desert areas because “patchy moist” at middle and high levels in the atmosphere is most often all you get on the southern periphery of the major storms to the north of Catalina in the cool part of the year.

The atmosphere over us, too, is only in ascent at an overall rate of maybe an inch or two a minute; a bit more inside the clouds, less outside the clouds. One way to KNOW how slight the air is rising, even in the clouds, is to observe that snow is falling out of some of them, tiny ice crystals, typically in the low hundreds of microns in maximum dimension (width of a few typical human hairs, which are about 100 microns in width.) Such tiny ice crystals have fallspeeds less than 0.3 meters per second, and so they wouldn’t be able to fallout with higher overall “slab” lifting, the rate of that the whole upper air is lifting at these cloud levels. Q. E. D.

What caused the lifting? When you see clouds scattered over such a vast area, they have to be due to a disturbance in the wind field, a trough is likely nearby, normally upstream.

I have not looked at maps lately, but will NOW to see if there is a bend in the winds (indicating a trough) at these heights (mostly Cirrus level). I don’t see one on the 300 millibar map (30,000 foot map) and so I am not going to show it. But anyway, I am right, I am sure. Now, I will begin a serious investigation to prove I am right. The models will know if there is lifting going on.

Yes! I have been saved in my assertion by my former employer, the University of Washington‘s MM5 model, and this was the first thing I looked at! Look at the predicted high “clouds” (those above 20,000 feet) over Arizona for yesterday at 2 PM AST! They can’t be there in the model unless it thinks the air is going up some. OK, past the exultation stage now. Moving on. Actually, the model predictions of Cirrus-ee clouds aren’t really that great, so it was quite a surprise to see this.

The End.

Backspin ending; upper low moving off to east as big trough barges into West Coast

You can see all the action described above here and here: first the water vapor loop from the Huskies’ Weather Deparment that lets you see ALL the action, dry and moist air moving around, and then from this IPS Meteostar loop, you can drill down and see the clouds with the itty bitty radar echoes they produced over eastern AZ and NM as the clouds spin around that backspining low. Stopped moving this way, as you will see, early this morning as a big trough with its broad band of westerly winds moves into the West Coast pushing our low away.

Unfortunately, that “big trough” will only bring rain as far south as SFO in the days ahead while we warm up for a few days. I would look for a string of nice sunsets as Cirrus clouds on the periphery of the rainy systems to the north are drug this way , however, as the week begins. I guess that’s not so bad.

Here’s a nice weather map for you (more from the Huskies!), one for the 300 millibar level, 30,000 feet or so above sea level. You can see our spinner over the AZ-NM border, and the “big trough” which is about to brutalize the Pac NW and northern California:

Since a couple of those radar echoes last night are in our Catalina domain (a 100 mile radius, and rain was falling at Safford (3 AM AST), an old mining town NE of us), I now recommend that all readers of this blog check their dusty cars for sprinkles-its-not-drizzle on their dusty cars for a possible drop images in the dust, and a journal entry of a rain occurrence. And, yes, we had plenty of dust yesterday as the lower level winds came scooting from the east-southeast at 20-40 mph over much of SE AZ yesterday. The Catalina mountains protect the town and environs around Catalina from these events, so we only get to imbibe dust, not actually experience it being raised up around us as was the case in the city yesterday. You can notice this blocking effect nicely by driving south on Oracle on days like yesterday until you get to Pusch Ridge, Magee Road or so on Oracle, and then hang on to your hat. There’s a similar low level wind situation today, and so you could do that today, drive south on Oracle, and experience it for yourself, maybe log the event in your weather journal as well. I think readers in the years ahead would find it of interest that you did that. I did it yesterday, and it was pretty exciting to see that east wind roaring though the palms, etc., just as you passed Pusch Ridge!

Yesterday’s clouds

What would a cloud maven’s post be without clouds? First, take a look at yesterday’s time lapse from the U of A’s Weather Department. During this one day, you can see the Cirrus clouds first coming from the northeast (they take awhile to appear), and then by the end of the day, they are almost coming from the west as that upper level low center spun back toward Arizona from New Mexico. This is really cool, something you won’t see very often at high levels, this amount of turning of the wind in one day at that level. Also, you will see lots of Cirrus forming in dense tufts and then dispersing once ice has formed. That, too, is cool!

Here are some shots from yesterday: 1) Cirrus, 2) scruff of Cumulus humilis to the north, and 3), a dusty, Cirrus-ee sunset shot.

In the first shot, you may notice that these Cirrus clouds more resemble Altocumulus with its little flocculent masses. Since Altocumulus clouds are all, or mostly comprised of liquid drops, you have to be able to see that these little cloudlets are ice, not water, thus betraying the greater height of these clouds compared with the Altocumulus (Ac) clouds they resemble. There is a slight possibility, that for a second, these clouds had a liquid drop, such as upper center in the first photo. Those look suspiciously like little tufts that may have been liquid drops. However, while nearly all Ac REMAINS mostly liquid, even when trails of ice fall out, these clouds do not. One of the mysteries in our science is about the formation of ice. Some liquid drops in Cirrus clouds have been detected by researchers at the University of Utah¹ at -44 C! These are NOT the same researchers that were associated with “cold fusion” reports, BTW, ones that came out around the same time as this one.

The weather ahead

Latest model run, from 11 PM last night, has, after having several days ahead with rain, dwindled them to just two, the 19th and 20th of March. These are indicated to be, in totality, a good rain. Hope they “maintain” in the progs!

The End.

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¹Sassen (1986, Science)

Cirrus, maybe some lenticulars, and dust ahead

In case you missed it, the thin layers of Altocumulus clouds provided a bit of a sunset “bloom” around 6:30 PM AST yesterday. Here’s what yesterday looked like, and I am doing this because I have a strong feeling some of you like to live in the past, like I do when I think about my best sports days in high school and JC R’s bat, and maybe a coupla others after that, so that’s why I am reprising yesterday below):

Here’s what we are looking at, in order of their appearance: 1) encroaching Cirrus (its not a cloud name, its what it was doing), 2) later, the Cirrus thickening (usually downward) into a nice example of Altostratus, a cloud normally composed of only ice crystals and snowflakcs, 3) Altocumulus perlucidus translucidus (honey-comb pattern, quite thin), with traces of ice falling out if you look VERY carefully, and 4) and 5), the Altocumulus as it was briefly (you only had a few minutes) underlit by the distant setting sun (its 93, 000, 000 miles away).

Moving on to the future, such as the rest of today

Its great, weather people can really do that, look to the future and say things that will actually happen with a great degree of confidence, like for the rest of today. (HELL, an economist can’t even predict what will happen in the next few hours!)

What will happen in the hours ahead? Cirrus clouds, patchy ones here and there, and a good chance of some Altocumulus or Cirrocumulus lenticular clouds as the jet stream powers its way down here, shooting from the southwest over us by late in the day. Sometimes, and I have predicted this before without a lot of success, you get these tremendously fine grained clouds (Cirrocumulus) that suddenly pop out of the blue overhead. There’s an awfully good chance of seeing those today, too, with the strengthening winds aloft. Of course, I’ll be watching for you if you miss them, and will replay anything “exciting” tomorrow.

Also, as the low in southern Nevada strengthens tremendously during the day, the winds will pick up as you all likely know by now, and the blue sky will start to wash out in a brownish dust haze. Twin Peaks may not be visible from Catalina late in the afternoon due to dust. You can track the development of that low here, from the University of Washington. Right this moment, 5:50 AM, there is not much there, so a lot of the development excitement in southern Nevada is ahead. The NWS, Tucson is quite excited about all the things that might happen, as you will see here!

Enjoy and interesting day!

The End

Plethora of storms ahead; Catalina snow day still being foretold for Feb. 25th which is only nine days away now!

To help understand that odd word, “plethora” in the title in case you are befuddled by it, I have added a YouTube teaching module to help you out: “What is a ‘plethora’?”

Well, one of the great model runs of our time has come out once again last night after yesterday’s great model run of our time based on the that morning’s data. SEVERAL rain days foretold in the next couple of weeks! One of these is actually a snow day, Feb, 25th, first predicted by the models about a week ago. This would be the “real deal” here in Catalina, not some “diabatic” (a weather term opposite of “adiabatic”) fluke as was our inch or so of snow two days ago, one that happened due to extremely heavy precip in the clouds above us, thus drawing the freezing level downward.

The first rain day is today, likely beginning after 5 PM AST, and then continuing into tomorrow for a second day. Here are some rainy/snowy snapshots from our friends in Canada at the EnviroCan weather service where they use a modified version of the ECMWF (European) forecast model here. The first panel is valid for 5 PM today just before the rain is supposed to begin. (If you don’t click on the panels below, you’ll need binoculars to see what I am talking about.)

Does this pattern look familiar in that first panel?

Yep. “SOSO” as we have been seeing all winter when storms strike. In the lower left panel you will see all that moisture streaming (colored regions) into our today’s cut off vortex from the south from the Mexican Pacific and linking up with a moist plume from the Gulf. Interesting to see that. Also, as it gets cut off, and great for us, it begins to dawdle while edging eastward along the US-Mexican Border, allowing those moist plumes to “filler up”, just like at a gas station. So, the rainy areas with this low should be expanding/appearing as clouds are enhanced; deepen up and begin to precip. Very exciting.

What’s been great is seeing the amount of precip predicted in Catalina from this low increase gradually over time as the models were seeing that it was not going as far south as they thought earlier. Here is another panel for this storm, valid for tomorrow afternoon at 5 PM AST. While the low has gone by to the south during the day tomorrow, this model suggests that it likely will have rained on and off during the day. This is because so much moisture arrived in this low that it has developed a “wrap around” band of rain to its north and west, good for us, kind of like a sucker punch. You should be able to see that happening today and tonight in this great IPS sat and radar link, as well as clouds “appearing” over the deserts to the west and south of us, and then developing echoes as they deepen.

Our local U of AZ Wildcat Weather Department has this great depiction of this “wrap around” development from their own model run here. Nice!

Here are the additional days ahead with more rain, and also, low snow levels. Mt Lemmoner’s rejoice! Below, the next panel, Sunday afternoon into Monday morning, this next trough.

Brrrrr, another cold blustery day Sunday, but notice this one is NOT a cut off and so will move through rapidly. Then, 4th panel, a dollop on Tuesday, just a minor trough passes by, and then, after a break, the Arctic iceberg on the 25th. Check this trough out in the last panel. Awesomely cold!

With luck, and a little verification of these predictions, maybe the washes will run later this spring!

The Cloud Report part of blog

Had some complicated, but nicely detailed Cirrus clouds float over in the early afternoon, a part of our invading storm’s circulation. This was followed by a large clearing and then encroaching Altocumulus patches trailing virga (ice crystals) in gorgeous, fine strands that wiggled this way and that in the setting sun’s light as that falling snow responded to slight changes in the wind below those little flakes of Altocumulus cloud. Enjoy.

The End.

Snow day February 25th; “webby” Cirrus

Remember, whether it happens or not, you heard about it FIRST here! Tell your friends.

Was pretty excited to see this 500 millibar map (about 15,000 to 20,000 feet above sea level) for the morning of February 25th below from our friends at IPS Meteostar. Pretty cool, eh? This from the model run based on global data taken at 5 PM AST yesterday.

Note on that map, we are encircled by the jet stream, indicated by the brownish orange regions at the outskirts of this behemoth of a trough, a requirement for winter precip here. How “be-a- moth-ian” is it?

Check out how abnormal this pattern is in the panel below this one, marked by the dark blue bulls-eye here in Arizona! So, its really an unusual pattern that is being calculated by the computer.

An aside: Oddly, we use contours of the height above the ground of a pressure surface for our upper level maps¹, and the LOWER that height is (such as over AZ in the top panel), the COLDER the air must be overall below that height. Low sea level pressure also adds to this height “deficit”, but mainly its the density of the cold air that does it. The more dense the air is, the more rapidly you reach above you any particular pressure level. (It really would be so much better to have pressure maps with highs and lows at a constant level above us than having to divert attention for this explanation.)

So, in the panel below, its the LOW HEIGHT of at which the 500 millibar pressure was reached (i. e., 5340 meters) that tells you this is a cold, cold, cold, cold system. (They say that redundancy is the key to remembering things. Remember, “534” (decameters) is COLD).

What DOES that the huge anomaly from normal in the bottom panel tell us weatherfolk?

The forecast map for February 25th is a real outlier model forecast, and so we shouldn’t be proclaiming a snow day or anything like that here 15 days in advance because it is such an extreme prediction and likely to go wrong. So, that’s what I have not done here.

HOWEVER, this outlier prediction shown below, is a part of a jet stream pattern that is developing RIGHT NOW in which low pressure systems and cold fronts will come zooming down into the Southwest from the northwest, one that is likely to go on for a couple of weeks or more. I would guess there might well be a hard freeze at some point, though not in the immediate future. Be ready!

This developing pattern also means more chances for rain here in Catalina over the next few weeks, and with the cool air ahead, holding our late winter vegetation together better even if there is not much precip because it won’t get burned out. So, overall, good news unless you came to AZ for consistently warm days. Ain’t gonna happen so enjoy the warmth we have now!

Webby Cirrus clouds

Yesterday, moving rapidly out of the north, were some “webby” looking Cirrus clouds. These are always seen only right after they have formed, maybe 10-20 minutes or so after that. They start out as tiny flecks (which for a moment might be termed, Cirrocumulus clouds), and, possibly, for the briefest moment, may be comprised of liquid. They then convert to ice and as the individual crystals grow and fall out, or are dispersed by turbulence, the tiny flecks become larger and larger and some of the ice falls out in strands.

After about a half an hour to an hour, they are usually just masses of tangled looking Cirrus without much cellular structure. Here’s what they looked like yesterday in that younger formative stage. At most upwind end (lower part of photo), the newest flecks have formed, while the older Cirrus elements are broadening and becoming “webby” looking. The likely ice crystals in these older Cirrus, for some additional annoying trivia, “bullet rosettes”, spikey-looking crystals having columns jutting out from the original “germ” ice particle. Nice images of bullet rosettes here at the beginning of a long article…

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¹In the olden days, weatherfolk liked to look at “isentropic surfaces” which helped them figure out where the air was sliding upward and likely to form clouds and precipitation before there were computer models. These areas were well represented on constant pressure maps where the cold and warm air was being pushed around.

Pomp and circumstance, but only a hundredth

“Pomp”, in the form of some thunder and lightning, and a few hail stones between 10 and 10:30 PM AST; “circumstance” with a pretty strong trough going by. But they only delivered a hundredth of an inch of rain at the ground here in Catalina. I guess the bugs will be satisfied, but it was a tiny bit disappointing to me. Was hoping for TWO hundredths. The U of AZ computer model did a nice job foretelling a tenth or less of rain. The most rain reported around here is 0.12 inches way up in the Catalina Mountains at CDO and Coronado Camp.

In case you missed it, here’s when and where the lightning occurred from Strikestar-Astrogenic systems. The last panel, lower left, shows those surprise lightning strikes that occurred around 10:15 to 10:30 PM AST last night. BTW, these folks have the best presentation of lightning occurrences that I have been able to find, one that includes non-ground strikes.

Now its sit and wait in the sun for maybe two weeks or more for precip. The closest thing to a storm here in the next FIFTEEN days that the models (courtesy of IPS Meteostar) are showing is this very strong upper low and trough that, as shown below over the Four Corners area, passes by too far to the east of us on February 1st-2nd to be considered a threat.

This system been showing up on the models for days and days, sometimes as one that can bring rain here, but it hasn’t been shown that way lately in the models. The fact that it has been persistent as a feature that affects the Southwest is a good sign that something major will pass by us in early February, and at the least will bring quite a chill whether we get precip or not.

In the meantime, we will have to be content with a long, long stretch of a sunny weather malaise, where almost everyday is perfect for a winter day.

Clouds?

Here are some from yesterday, and again, a great, late-blooming sunset. Almost gave up on it happening. First, the nice strand of Cirrus yesterday morning that heralded the thicker layers behind it and shots of those multi-layered clouds consisting of Altocumulus, Altostratus (the smooth one), and then the sunset “bloom.”

The End.

“And I think its going to rain today”

Well, how can we forget that mournful Leonard Cohen song? And the sweet rendition of that tune by Judy Collins? It was played a lot in Seattle, of course, where I’m from. But, it also looks like it might be apt for late today right here in Catalina. Check out this “incoming” here from the U of AZ Weather Department’s model output here. This loop of rain areas will show you how the precip creeps toward us during the day, eventually overrunning almost the whole State of AZ. “Oh happy day”, to quote another song title. Just hope we get more than the tenth of an inch the model projects, all of which falls overnight tonight after midnight. (Hmmmm. Seems a little slow to me.)

Here’s a loop of satellite imagery and the surface pressure maps for the past 24 h from the University of Washington. The interesting thing about these maps, is how one hurricane-like center with lots of isobars off the Pacific NW coast crashes into British Columbia while a new low develops off the California coast and is now pummeling central and southern California while heading to the southeast and toward us. Reminds me of someone getting a “spare” in bowling by knocking two widely separated pins to the left and right to get it.

Why would storms divide in their paths like that? You have to look aloft at the steering by the jet stream. Low centers separating like that always means there is a split, a dividing point in the flow. Higher level pressure maps from the UW shows that. Below is a 300 millibar pressure map (about 9 km above sea level or around 30,000 feet), a level where the jet stream is just about the best developed. Notice how part of the flow whirls around the big vortex in the northern Gulf of Alaska and toward BC, while a more powerful branch dips toward California. Its that trough, that bend in the winds just now off California, that will come barreling through here tonight bringing that surface low center now near SFO with it–well, what’s left of it after it gets wrecked by mountains. The next chance for rain/snow is in early February.

Nice clouds again yesterday. Here are a few shots, including another nice sunset. The haze you saw was dust, leftover from the strong winds of the previous day in western AZ. The first, Cirrus over dust. The second, some Altocumulus with Cirrus, and finally, Altostratus with some under lit Altocumulus in the distance.

Pretty and eerie skies yesterday; let the rain begin today

Here are some examples from yesterday’s pretty, then toward evening, eerie skies with sprinkles, the latter due to backlit Altostratus opacus mammatus, to go the whole nine yards, an icy cloud with downward hanging protuberances that resemble something. I’ve reduced the size of that image accordingly. Below, in sequence, 1) Cirrus, 2) Altocumulus, 3) the incoming bank of Altocumulus with Altostratus clouds on the horizon late yesterday afternoon, ones with virga and mammatus; 4) the mix of Altostratus with virga and mammatus with Altocumulus after it got here, and finally, 5) that eerie scene last evening of what I would surmise was a sunset colored layer of Cirrus above the Altostratus clouds with mammatus that gave the Altostratus an orangish tint. I seem to be thinking a lot about mammatus formations today. Hmmmmm. Oh, well the CLOUDS were nice, and I guess you might say, our official cloud names a little suggestive. For the full fascinating day, go here to our great U of A time lapse movie for yesterday.

All of these clouds are emanating out of and around a low that a week ago, in the models, was supposed to have already gone by. Well, what’s left of it finally goes over us today, kicked out of place by a quite rudely interjecting jet around a cold trough in the NE Pacific and over the Pacific Northwest.

Here is a satellite loop from the University of Washington showing those clouds that went across yesterday and those similar versions that will be crossing our Catalina skies today, ones that are coming deep out of the tropics. You’ll want to crank up the speed button to really see what’s going, at the upper left of this loop. The mods have been seeing a bit more moisture with this upper level low (doesn’t show up on the surface maps at all) as time has passed and so maybe we can wring as much as a quarter inch out of it. Here’s what the U of A Beowulf Cluster has to say about the incoming rain amounts. These amounts, up to an inch in the mountains, would be fantastic and very satisfying considering the long dry spell. The best chance of rain is overnight, so we’ll have lots of pretty clouds, probably a lot like yesterday, during the day before the really thick stuff moves in.

The ominous aspect, though VERY exciting to us stormophiles, is, when you review that satellite loop from the Washington Huskies Weather Department, is the accumulation of clouds and storms in a long belt just north of the Hawaiian Islands. Take a look! In just a couple of days, those clouds and storms will begin streaming toward the West Coast like a dam breaking, impacting most heavily, northern California and Oregon with tremendous rains. You will certainly read about those rains! From experience, I can tell you that the most favorable mountain sites for rain will likely receive 20-30 inches of rain in just a few days as this pattern develops and matures with one strong low center after another racing across the lower latitudes of the Pacific under the soft underbelly of a blocking high in the Bering Sea.

Man, I want to be in the King Range/Shelter Cove area so bad! Let’s see, fly to SFO now, rent four wheel drive vehicle for forest back roads in the King Range, bring rain gauge, sleeping bag, tent for camping out and listening to 1 inch per hour rain intensity on tent roof. Hmmm….. Its doable. Maybe all of us should go there today, get set up, and then wait for those pounding rains with 50 mph plus winds. That would be great!

And the ocean waves will be something to see, too, along the Oregon and northern California coasts, thundering surf really. Been there, seen it. And believe or not, there are surfers who come to the West Coast for just these situations, the long tropical fetch that generates huge waves. And there is even a small cadre of folks who race to the coast just to see that thunderous surf. All very exciting. Well, kind of getting distracted here, and a little nostalgic. Those big rollers would look something like this.

Also, since I have doubtlessly piqued your curiosity about Shelter Cove and the King Range, below a shot of the King Range from Shelter Cove, a shot in the King Range, looking toward the highest peaks, and finally, an example of the people of Shelter Cove.

Now, where was I concerning Catalina? Oh, yeah, mods have more rain ahead, though we’re only sideswiped by the powerful storms affecting Shelter Cove. Best chance for the next rain is on the 21-22nd.

In sum, today’s focus, or more accurately, preoccupations? Mammatus and Shelter Cove, CA.

The End.