Art Rangno – Page 89

What’s up? Smoke, most likely

You may have noticed, if you’re from around here, that we did not exactly have an “Arizona Highways sky” yesterday. The sky was an awful whitish color tinged with blue (I’m fussy here). Below are examples of smog from the ground and from satellite. from yesterday afternoon. (Where there are clouds, BTW, the satellite can’t tell if there is smog under them.)

As you can see, the sky is not good over Catalinaland in this mid-afternoon shot from yesterday. And, it was not aloft in a layer as we have sometimes seen, but is partially obscuring the hills and mountains in the distance. It is also what we would call a well-mixed smog, which indicates its not generated locally. In that case of a very local source, there would be obvious thick and thin regions. Yesterday, it was homogenous, pretty much the same looking smog in every direction. (Tends to look worse toward the sun.)

In the aerosol satellite image, you can see we are in a blob of smog as indicated by the light turquoise area over Arizona and extending into northern Mexico. BTW2, dark blue in this graphic is a good sky, while a red one is awful. Our smog level here, as indicated by a parameter we call, “aerosol optical depth” (AOD), was around o.3 or so according to the satellite image below (probably on the high side). AOD measurement doesn’t know the height of the smog; its just how much is in the air between the top of the atmosphere and the ground.

For comparison, if the sun is NOT visible due to smog, the AOD would be about 4.0. Yikes! A really clean sky has an AOD of less than o.o5; its a really blue one and on such a day, from here you would be able to see Mt. Humphreys near Flagstaff if it went up to 40,000 feet or so, it is THAT clean. (You can actually see the tops of Cumulonimbus clouds near Flagstaff in the summertime from here in Catalina on these kinds of days with no intervening clouds.)

So where is it all coming from, I’d like to know?

To get an idea, we go to our trusty NOAA Air Resources Lab and their “HYSPLIT” model and run back trajectories for the air at the levels we estimate the smog is at. Of course, you can do this yourself; in fact, I have to say that it seems like I have to do everything for you.

Anyway, below are a couple of plots for various heights above the ground from ARL, 500 m (1500 feet), 2000 m (6600 feet), and 3000 m (10,ooo feet) for the past 4 days before the air arrived here.

You can forget about the one that starts at 3000 m (green line) above ground level in the Pacific. These plots also estimate the amount of lifting and descent the air went through, and you can see that the green parcel was caught up into a low center, got spun around in a circle, thrown upward to above 20,000 feet (7 km) and then descended on the back (west side) of the low. In going upward so much, clouds and precip forming in the upward moving air would have removed all untoward aerosols, so we can pretty much rule out something from Asia having crossed the Pacific, as happens from time to time.

Looking at those lower level trajectories (500 and 2000 m above ground level, blue and red lines in the plot) the likely culprit is found. Those ones represent back trajectories in much slower moving air that arrived over us, air that apparently spent a day or two in northern Mexico before getting here. That the of smog over us extended into northern Mexico and you start to think that the smoke probably was captured there and then eased northward across the border. This seems to be hinted at in the cloud wind field available through the University of Wisconsin and the US Navy’s Research Lab here. There are a couple of “wind barbs” (yellow colored ones) in northern Mexico that suggest southerly and southeasterly winds at levels where the smog was. Not an airtight case, but it probably drifted up from Mexico.

Enough about smog!

The case of the spaghetti plots; an update

In our last episode, it was foreseen that a confidently predicted, “Joe Trough” , was going to bash the West Coast on the last day of this month with a strong storm, little doubt about it. He had been tracked nicely by the computer. Looked the same, “buff”, potent, day after day 4-5, ten days away as he crossed the Pacific Ocean. But after entering the USA at the end of March, “Joe” lost control of himself, it was unpredictable about what he would do next. At that time, displayed here on this blog, one computer guess was that he was going to break up into pieces, one piece over Arizona for days, sitting around, dawdling really, producing scattered showers in the first week of April thoughout Arizona. It was an unusual pattern, but there it was on the model outputs.

Sadly, from the spaghetti factory at our NOAA Super Weather Computer weather center, and the wild fluctuations it showed, indicated “Joe T” might do a lot of different things after he entered the USA. We could see that this rainy Arizona forecast was just one of many possibilities for “JT”, he was “unreliable” after approaching the West Coast no matter how badly we wanted that forecast that came out to come true; we just couldn’t count on it.

Now “JT” is only a few days away from crashing into the West Coast, still well predicted. But how about after he enters the West Coast? What will happen now? Will Joe break up into pieces and dawdle over AZ? Will there be rain? Or will we have just a dust storm and a dry cold front?

Let’s look in on the spaghetti factory and see what happens to Joe on the way in now, only few days from possibly affecting our weather.

From last evening’s spaghetti plots (“ensembles” in weather higher ordered weatherspeak) this 96 h forecast showing “Joe Trough” as it is about to hit the West Coast. As you can PLAINLY see, the entire earth’s weather north of the equator is well predicted as far out as 96 h, valid the evening of March 30th, 5 PM AST. In case you’ve forgotten, when all of the lines run almost on top of each other, things are well predicted, little chance of a busted forecast. The southward bulge in the turquoise and red lines just off the West Coast is our incoming “Joe Trough.”

The next panel, for later, valid for 5 PM AST, March 31st, shows that “Joe” is now in the Great Basin doing his thing, and the southern part of “Joe” is over us! Yay! Or not.

Remember the Red Zone, not in fubball, but in these plots? The red lines represent pretty much the southern edge of the jet stream at this level, 500 millibars pressure, around 18,000 feet above sea level. The turquoise lines represent pretty much the northern side of the jet stream at this level.

So, what’s wrong with this pretty picture (2nd panel)? Joe’s Jet (sounds like a singer I’ve heard of), doesn’t pass south of us by all reasonable expectations. Those little “perturbations” they put into the model at the beginning of the run to see how they might change the prediction, and thus get a handle on its reliability in case of errors, missing data, chaos in general, have the Red Zone (where the red lines are grouped) north of us. Jet north of us, as these red lines indicate, means no precip no where ’round here.

Well, unless you count dust as precip, and it certainly will pile up some.

“Joe” is strong and cold, but passes too far to the north. But as he does, a huge, intense low forms in the Great Basin, drawing dusty southwest winds across southern Arizona before the dry cold front goes through with quite a chill.

Now, for a little humor to end this blurb, a real laugher spaghetti plot, that for 15 days from now. You’ll go into conniptions, burst out laughing, like I did I am quite sure with your knowledge of spaghetti plots when you see this one and what virtually “unforecastable” weather looks like in a spaghetti plot. They should put these in the newspaper as kind of weather cartoon.

Actually, after 15 days, they mostly look like this.

Ending on humor, The End.

The lenticular that came for breakfast and stayed for dinner

Some of you already know that there is a favored position for a lenticular cloud downwind from the Santa Catalina Mountains. Yesterday, a little fluff of Altocumulus lenticularis kept reappearing all day! It didn’t have the “classic” look of a lenticularis early on, but that’s what it was, hovering over the same spot, changing size some, disappearing then reforming over the same spot. That rough bottom early on suggests turbulence. You don’t want to fly there. Often, flying IN lenticular clouds is, as the smoothness suggests, completely lacking in turbulence. Its when you come out the downwind end of those clouds that you can experience some nauseating bumps.

Why was the lenticular cloud there all day?

Because there is a standing wave, or hump in the airflow downstream of the mountain that raises a moist layer to its saturation level where a cloud must appear, and not much changed in wind direction and moisture all day up there. The morning and evening sounding for Tucson were almost the same. Also, while that lenticular cloud was nearly always there, it was often “buried”; obscured inside that sometimes thick layer of Altostratus with its virga that moved in during the afternoon hours.

Some photos. (BTW, since I started adding captions, WYSIWYG has gone bonkers in the Word Press edit page. So excuse the strange organization and text in odd places–still learning here.)

SONY DSC — 1. Kind of a ragged Ac len, right side, 6:10 AM AST. Location, location, location tells you its a standing cloud, not one that will move off with the wind.

Below, photos of some of the other clouds of yesterday. I have to say if there was a disappointment, it was that there wasn’t as much Altocumulus as I thought, and virga trails were not as long as I expected, either. They were barely hanging down from that Altostratus layer, an indicating of smallish snowflakes in the Altostratus layer as well as very dry air below it.

DSCN1173 — "Altostratus over horse arena".

Lastly, a sunset shot, indicating the back edge of these high and middle cloud layers was over the horizon to the west.

Cloudy with snow above 15,000 feet

On deck, this cloud stream for today, as presented by the University of Washington Huskies Weather Department. As you will see, the whole stream rotating around that low off southern California has been thickening up overnight, a process that will continue, and so it looks like it will be a frequently gray day with Altocumulus, Altostratus, and Cirrus of various types piled on top of each at times. Don’t look for much direct sunlight today. Virga (snow), too, but no rain beyond the slight chance of a sprinkle. Most of the clouds you see will be composed of ice crystals and snowflakes. Also, with the wind picking up aloft today, lenticular clouds are likely again. Look to the NE of Mt. Lem.

Don’t miss a nice sunrise shot this morning.

Yesterday’s clouds

Below, after you have read all the captions, yesterday afternoon’s sounding from our friends in cowboy-on-a-bucking-horse-license-plate-land which, BTW, I think is a pretty cool looking license plate since I’ve been bucked off horses myself a few times and when I see that license plate can say, quite haughtily, “been there; done that”, and tip my hat to the driver. In fact, the horse I was bucked off most recently kicked about as big as the one rendered on that WY license plate, and while I ended up in the hospital with a big bill, HELL it was worth it when you can say things like this and show that you are truly embedded in western culture, which I love after leaving the Temperate Rain Forest-Starbuck’s culture of Seattle:

What do you see in this sounding?

The pinching together of the two heavy lines (temperature to the right, dewpoint to the left) tells you the height of the moist layer in which these clouds formed.

How high was that, you ask, or not?

The “300” line (refers to millibars of pressure) is about 30,000 feet above sea level (27,000 feet above Catalina) and the top of the moist layer, about at the “200” line, is 40,000 feet above sea level, 37,000 feet above Catalina.
So, they were damn high yesterday, running between 27,000 and 37,000 feet above the ground. The bottom temperatures were about -35 C (-31 F), and the top about -63 C. What’s interesting is that lenticular cloud was almost certainly comprised of liquid water drops on its upwind edge before glaciating (turning completely to ice a short distance downstream from that upwind edge.) One of the mysteries of ice formation in clouds is that Cirrus clouds don’t generally form until the conditions for a droplet cloud have been met. This means that when ice is present, it is in a highly supersaturated environment with respect to ice and in spite of the very low temperatures, the crystals can grow and fall out producing trails or fallstreaks as you could see in the Cirrus uncinus clouds.

Arriving in local skies today: clouds, high and middle ones

Now that your camera battery is fully charged, you will be ready for the panoply of high and some mid-level clouds that will be arriving overhead today. Should make for some great sunrise and sunset shots, but also daytime shots due to the interesting twists and turns in the Cirrus (ice) clouds that will float by. Maybe later today, Cirrocumulus and Altocumulus clouds will show up adding that extra dimension to sunset color. Typically, in these situations, the first clouds on the scene are Cirrus at the highest levels (30,000 to 500,000 thousand feet above ground level (hahaha-just checking to see if you are reading this)–OK, 30,000 to FORTY,000 feet above the ground here on a warm day in Catalina-Tucson like today.

Next, with the moisture layer thickening downward from those high CIrrus levels as the day goes by, there might well be some Cirrocumulus (Cc) cloud patches, ones between about 15,000 and 25,000 feet above ground level. Some times they evolve to Cirrus clouds within minutes after they form when they’re colder than -30 C (-22 F). Cirrocumulus are short-lived clouds usually in thin, isolated patches. They can have no shading by definition and they can display the most delicate granulations imaginable.

But those patterns change in seconds to a few minutes, and you have to have your camera by your side to get the best shots of that sort of thing, like other nature photographers who shoot birds and stuff like that. Did you realize that by shooting clouds that you were becoming a “nature photographer”? Often these patches can be higher level lenticular clouds (thin sliver clouds) that have smooth portions on the upwind side and then break into tiny elements downstream.

Finally, as the day comes to a close, some Altocumulus clouds might arrive on the scene; if not today, then by tomorrow at daybreak. They may also be in the form of sliver clouds, lenticulars that hover downwind of mountains–look to the northeast of Mt. Sara Lemmon today. But, given the high temperatures aloft, indicating that the Altocumulus clouds will have more water in them than on a cold day, look for some sprouts and little turrets. That extra warmth, say at 15,000 feet, results in an enhance updraft when clouds form at those levels because condensation releases a small amount heat to the atmosphere inside the clouds. That bit of extra heat is likely to lead to those itty bitty turrets (castellanus species of Ac)

Here is an example of the delicate Cirrocumulus (Cc) clouds we may see today and tomorrow.

No rain seen in models for two weeks now, but remember the wild chaos of the predictions beyond six days now, as indicated in “spaghetti plots.” That means rain for southern AZ may well show up again soon, along with that horrific early April cold spell.

The End.

Weekend slider, cloud excitement ahead, more about spaghetti

Check out these forecast maps from IPS Meteostar from last night’s 5 PM AST global data (less data from GOES-15, the satellite that covers the eastern Pacific and western US, which has gone belly up lately):

A ludicrous baseball metaphor for today; after all, its almost baseball season:

Let’s say your a very tall person with a bat a few hundred miles long standing in the batter’s box somewhere around Hermosillo, MX. A trough, like a baseball, has been thrown by the Pacific Ocean. Its coming down the “middle of the plate” (see panel 1) with the trough easing into southern California with a lot of rain). This one is gonna be jacked (will bring rain to all of Arizona!) It can’t miss. If it rains in southern California it can’t miss bringing rain to AZ!

You take a mighty swing (forecast rain), to go back to this silly metaphor. You didn’t noticed the “red dot”, something batters can see on the spinning ball when a pitcher throws a “slider”, a curving ball that, from a right handed pitcher to a right handed batter, veers away from the plate.

In this case the “red dot” to stretch this metaphor, is that the north winds on the backside of the southern California trough will be weakening as a new trough from the Gulf of Alaska roars down toward California and begins to catch up to it. The “ball” (trough) veers suddenly to the outside corner of the “plate”, Arizona, and spins into the dirt over Nevada and Utah. But you have swung anyway and struck out with the bases loaded (if you had thought rain from southern California was going to get here and water our wildflowers). The fans are booing now.

Well, enough baseball for today. The season is too long anyway.

Recall the AZ “jet rule”; no jet here and to the south of us as troughs go by; no rain no how in this cooler time of the year. Whilst the jet is south of our latitude on Sunday’s map (first panel), you can see that by Monday night at 11 Pm AST, the high velocity core has oozed over the NW corner of AZ (brownish regions in the second panel). The strongest winds are now on the east side of that trough, telling you its going to rocket off to the NE.

Cloud prognostication: get yer cameras ready!

The great thing about our “missed” storm is that the skies should be especially fabulous over the next three days (make sure all cameras are charged) because of having marginal moisture in the mid and upper levels of the troposphere as our “miss” goes by. That should mean interesting and photogenic clouds of all kinds up there: Cirrus, Cirrocumulus (fine grained clouds), Altocumulus (probably castellanus, lenticulars), and probably a spate or two of Altostratus clouds. Gee, you’ll have to get a cloud chart to know what I am talking about here! (Maybe you should get this one; it seems better than some of the other ones I’ve seen, and I don’t just say that because if you do get it, I will get some money.) ((Or go here, if you like to shop around)). Is this crass or WHAT?

The great thing, too, is that the Altocumulus clouds are likely to have nice virga trails, and it that kind of cloud (Altocumulus castellanus virgae) or Altostratus occur at sunrise or sunset, you can get the MOST fabulous photos. I like’em during the daytime, too, though. OK, so very excited about the cloud prospects ahead. Will be scanning skies.

The weather ahead

Another giant cold spell has erupted in the models. Check this big boy out over Az, valid for Sunday morning, 5 AM AST, nine days from now. Yep, you got yer low snow levels again, some showers, too. But the really interesting part is that it gets cut off out of the stream and sticks around for a few days. Look at the second panel, for FIVE days later! A remnant of it is still there, producing showers! In April? Seems unlikely, but could happen.

How do we check out how likely this cold spell and rain/snow is?

We think about spaghetti. Now remember, too, with GOES-15 out, there is also the fact that the models are working without as much information as they usually have. So, right off the bat, you have to downgrade anything “strange”, more than you normally would.OK, here’s some spaghetti for 168 h out, valid for a week from last night. This map was SHOCKING to me, because its telling you that the set up for our big boy is virtually guaranteed! I couldn’t believe it, its amazing!

So what am I ranting about?

This plot below says that a gigantic trough in the eastern Pacific between Hawaii and the mainland is virtually guaranteed. Look at how closely the contour lines are spaced in the eastern Pacific! This closeness says that the “signal” for this to happen is huge in the global data. Compare this spacing in the eastern Pacific, with the bowls of rubber bands, say, in the Atlantic and western Europe. The models are clueless about what is going to happen there. Conclusion: a few days before our forecast trough shows up, it is out there, and at least has the potential to be realized here in AZ two or three days later. Somebody on the West Coast is going to get whacked, little doubt about that.

But what happens on the days we are concerned about, April 1st and beyond? See next panel of spaghetti plots (2) for the afternoon of April 1st. The yellow lines are a couple of the contours in the forecast map for April first above.

The confidence factor has gone to HELL! Sorry for having to cuss. In the western Pacific, you can still be pretty confident of where the troughs will be, but look at the MESS now in the central Pacific to Moscow! Nothing is assured. All is hazy, fuzzy, out of focus, dimly lit, a drunken spider’s web, DAMMITALL, to cuss that bit more. While our trough has been foretold as of last night’s data, and it will maintain itself right up until reaching the West Coast (spaghetti 1), after that its anyone’s guess. Chances are good for a cool spell, but will it be historic with rain and snow, or a slight drop in temperature under sunny, breezy skies?

No one knows, but that first dish of spaghetti (1) has to make you at least hopeful that something strange will happen in early April here. Go here if you want to see the full animation.

The End.

Epilogue to historic storm; your broken records

Here, thanks to weather pal and researcher, Mark Albright, at the University of Washington, the low temperature and precip records set during our recent historic storm.

Cloudcast

Unfortunately, the next few weeks, it appears, will be characterized by only chances of clouds, not rain, and mostly high ones at that. Middle clouds like Altocumulus and Altostratus, MIGHT appear on the 24th. (Pitiful.)

Today it looks like a couple of Cirrus clouds are heading our way from the northwest. Of course, the temperature will be ratcheting upward now, too.

Sad to see that the poppies were mostly gone around this Catalina neighborhood yesterday.

Glumly, The End.

Whence graupel?

What a fantastically gorgeous, if uncomfortable day yesterday was! Such skies! Such odd temperatures for March 19th. And another day with ice falling from the sky, mostly “graupel”, but also some snowflakes (aggregates of dendritic crystals) at one point, too, when “stratiform clouds” came by (flat, layered ones) about mid-day. The total water equivalent, 0.08 inches, 0.75 inches for both days combined. With a high of only 50 F, it was also the fourteenth lowest high temperature ever at Tucson in March.

It was great, too, that “sample” day yesterday of the Last Glacial Maximum, imagining what it was like thousands and thousands and thousands of years ago when humans and dinosaurs co-existed on this cold planet. I could almost see the dinosaurs coming down out of the snowy Catalina Mountains, being chased by hunters, or vice versa. I have to say I haven’t researched this, but I have seen some movies about it.

What is graupel, you ask? A form of German wrestling? “Die zwei Männer graupeling sich auf der Strasse”?

Well, no my friend, it is what we weatherfolk call a tiny snowball that falls from a cloud. You can also call it “soft hail”, because we call it that, as well. You can easily mash it between your fingers because unlike hail, it has a LOT of air in it. We had a LOT of that “graupel”-soft hail off and on yesterday, once, around 7:38:36 AM AST with a roll of thunder.

Here’s what they looked like, up close, along with a raingauge measuring stick for size (its one inch between labels). You may have also noticed some, many at times, looked like little pieces of space debris, having a definite conical appearance. This is called “conical” graupel. Its quite common actually. The third shot shows, and this was somewhat miraculous, an element of conical graupel on the way down. I was stupefied that I had gotten such a shot by accident!

On the right side of this third photo you will actually SEE a conical graupel in flight, on its way down, and how it falls, wide end first because that is the heavy end. Also note the heavy shaft of snow/soft hail up against the Catalinas downwind. The graupel that fell in the photo came from the back side of that Cumulonimbus cloud. The second cloud shot shows the bottom of the cloud from which the graupel was falling. Many of you know that I specialize in these kinds of photographs, the bottoms of clouds, hoping to have a show someday.

But, what do you see in the cloud base photo? Not much. The best eyes will detect that slight, slight striated look due to falling graupel. Falls in strands reflecting the complex nature of the organization of liquid water and updrafts, wake capture in clouds. The first precipitation falls out through the heaviest concentrations of liquid water (at well below freezing temperatures), and that’s what graupel does. This the same as when the largest and heaviest raindrops in summer fall out from a cloud base with not much else going on. And, like our graupel, they are spread around, sparse compared with the heavy rain that likely will soon follow. So, graupel is the first thing that falls out of large Cumulus clouds, ones growing up to be Cumulonimbus ones.

Also you may have noticed that the graupel almost always was associated with a Cumulus clouds yesterday, localized clouds in lines with dark bases over you. Cumulus clouds are loaded with liquid water, at least in the rising portions. In those rising portions, a few ice crystals, or cloud drops might freeze. Thereafter, they begin collecting drops that freeze on them when they contact the ice.

Cumulus clouds at below freezing temperatures are avoided by aircraft because this is where cloud drops can hit the airframe, freeze instantly, and weigh down the plane, as happened with our little graupel. In Cumulus such as we had yesterday, a half an inch of icing can build up on the leading edges of airframes in just a few minutes while flying in their upper portions. Near cloud base, the drops are too small to build up much ice.

With some of the graupel up there in those clouds, at some point early on, the freezing of drops on it as it collided with them produced a side that was slightly heavier than the rest of it. That heavier side began falling downward, collecting more drops to make it more lopsided, conical. You can then assume that graupel that are not conical, collected drops pretty symmetrically, something that would happen only if they were spinning on the way down.

Associated with the formation of graupel, as on this day, is a sudden burst of ice formation in the entire cloud leading to “glaciation”. The liquid drops at below freezing temperatures are completely annihilated during this process in the turret initially spawning the graupel, and along with the remaining graupel, a dense shaft of precip drops out of the bottom. consisting of graupel and large snowflakes (aggregates of single ice crystals, sometimes hundreds of individual crystals in them). So, on the back of this Cumulonimbus cloud raking the Catalinas, graupel, on the forward side where glaciation has taken out the liquid water, aggregates, probably huge ones.

Gads, I want to go on, but this is getting to be a little LONG! However, here are a few more shots from that beautiful day. Some dessert after the heavy meal.

The End I think.

Re-living the Last Glacial Maximum–well for a day, anyway

After yesterday’s re-acquaintance with winter, a brief period of snow falling here in Catalina for a few minutes, and a whopping 0.67 inches of rain, we have another deep winter day ahead.

Here’s the National Weather Service’s forecast for Catalina, at least elevations of about 3200 feet.

“Today: Snow showers likely before 2pm, then rain and snow showers likely. Partly sunny, with a high near 46. West southwest wind between 8 and 16 mph. Chance of precipitation is 60%. Total daytime snow accumulation of 2 to 4 inches possible.”

A glimpse of a Catalina paleoclimate

A day like this, with snow expected and daytime temperatures reaching only the mid-forties let’s us experience what Arizona was like in the springtime 15,000 years ago or so during the Last Glacial Maximum (sometimes called the Wisconsin Maximum, referring to the area around the Great Lakes where ice was really piled up–no wonder we get visitors from Wisconsin; they remember.)

But, let us not overlook the other areas of the country during that Last Glacial Maximum. Ice was piled up more than a kilometer deep in Seattle! I am not kidding. Here is a shot of what the Space Needle might have looked like in those days of the Last Glacial Maximum when snow and ice were building up. Its pretty impressive since the Space Needle is a few hundred feet high. Hard to imagine, but there REALLY was ice deemed to have been 1 km deep in Seattle 15,000 years ago!

A huge amount of global warming took place, of course, after the Last Glacial Maximum, people started going back to Wisconsin and other northern climes. The warm era that followed the end of the Last Glacial Maximum, and the one we are now in is called the “Holocene”, BTW.

However, our current era also has a rather dark moniker, also being termed an “Interglacial” period, as were all those periods between ice ages in the Pleistocene when it was nice and comfy. “Interglacial” sounds kind of temporary, and they were back then, only about 10, 000 to 20,000 years long, and we are about 12,000 years into the “Holocene.” However the duration of interglacials is not pinned down real well and “orbital” forcing of ice ages (Milankovitch cycles, Wiki) puts the next one around 50,000 years from now.

Maybe it would be good to go look at some petroglyphs today and think about what the weather was like back then for those folks who made them.

Oops/Correction: Actually, in researching “petroglyphs” they seem to have appeared AFTER the Last Glacial Maximum, about 7,000-9,000 years ago. Hmmmph. That petroglyphs would appear then is understandable. People were happy it was warmer and took their happiness out on the rocks which were no longer so cold, thus explaining the world-wide burst of rock work. I work hard to provide you with information like this, information you can’t get elsewhere.

Today’s clouds

Its so cold up top today! Its -11 C at just around the top of Mt. Sara Lemmon. Since the tops of the clouds over us, even shallow ones, will be -15 c, and the deeper ones to -30 C today, lots of snow will form in them, and that means virga and rain/snow showers, graupel (soft hail likely). The upper level trigger for most of this will begin affecting us this morning, and with a LITTLE heating, cumuliform clouds should begin enhancing the Stratocumulus deck we now have.

Lower clouds with lots of ice in them look like yesterday afternoon’s clouds, shown in the photo below. That smooth texture on the left side of the photo is due to ice falling out, but the snowflakes and ice crystals are too small to reach the ground, except only the very largest. The shaft in the distance is due to a much deeper cloud in which the snowflakes and graupel (soft hail) were able to grow far larger than in the other cloud regions nearby. That’s because it had much higher cloud top, forced by stronger updrafts. The stronger the shafts, the the higher topabove it is a pretty good rule.

Gee, starting to “graupel” right now at 6:31 AM AST! Exciting.

So, look for a lot of smooth looking clouds today like those in this photo.

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.