Lots of interesting clouds yesterday; partial double rainbow, too

Light rain showers overnight, just before midnight, and again just after 1 AM AST,  raised our Sutherland Heights storm total to 0.33 inches, decent but disappointing in view of model and personal expectations (0.60 inches).

What was especially interesting is that those nighttime light showers didn’t show up on the TUS radar, suggesting very shallow tops, perhaps a “warm rain” event, one not having ice, or an “ice multiplication” event with tops warmer than -10° C, about where the tops were on the 5 PM AST TUS sounding.

By this morning, the tops were barely below freezing (about -3° C).  Don’t expect to see ice today, except at Cirrus levels!

5:53 PM.

5:53 PM.

5:52 PM. Drawing back a little.
5:52 PM. Drawing back a little.  Pretty dramatic scene I think with that sun break running along there underneath the Stratocumulus clouds.
7:06 AM. Had another round of amazingly shallow Stratocumulus clouds precipitating on the Catalina Mountains. Hardly any depth at all to this cloud, and yet there the precip on the mountain!
7:06 AM. Had another round of amazingly shallow Stratocumulus clouds precipitating on the Catalina Mountains. Hardly any depth at all to this cloud, and yet there the precip on the mountain!  Tops were hardly higher than Ms Mt Sara Lemmon!  Must have been drizzle.  Let’s check the sounding nearest this time, see what’s up:
The NWS at the U of AZ balloon sounding, launched around 3:30 AM. Seems to indicate cloud tops were colder than -10°C, plenty cold enough for ice formations, so not as exciting as if they were, say, at -5°C.
The NWS at the U of AZ balloon sounding, launched around 3:30 AM. Seems to indicate cloud tops were colder than -10°C, plenty cold enough for ice formations, so not as exciting as if they were, say, at -5°C.  So, I retract my excitement excitedly!
11:00 AM. Still overcast with Stratocumulus clouds, but occasionally ones showing precipitation, making them the whole scene, Stratocumulus stratiformis (covers a big portion of the sky) "praecipitatio" (is emitting precip, here maybe drizzle) or it may be very light snow. You can just make out the snowline, around 6,000 feet on the Cat Mountains.
11:00 AM. Still overcast with Stratocumulus clouds, but occasionally ones showing precipitation, making them the whole scene, Stratocumulus stratiformis (covers a big portion of the sky) “praecipitatio” (is emitting precip, here maybe drizzle) or it may be very light snow. You can just make out the snowline (center), around 6,000 feet on the Cat Mountains.
2:01 PM. Eventually the sky broke open to reveal that deep blue we see in the wintertime as Cumulus clouds began to take shape. Aren't these scenes tremendous, so clean looking, like you're out at sea, far away from land.
2:01 PM. Eventually the sky broke open to reveal that deep blue we see in the wintertime as Cumulus clouds began to take shape. Aren’t these scenes tremendous, so clean looking, like you’re out at sea, far away from land?
3:51 PM. Gradually the tops of the Cumulus clouds reached up to lower temperatures where ice could form and something resembling our summer rain shafts began to appear here and there.
3:51 PM. Gradually the tops of the Cumulus clouds reached up to lower temperatures where ice could form and something resembling our summer rain shafts began to appear here and there.
5:12 PM. The front side of somebody's nice rainbow.
5:12 PM. The front side of somebody’s nice rainbow over there toward Marana.
5:45 PM. And a little before the rainbows, some nice, dramatic lighting on our desert vegies under a dark overcast of Stratocumulus.
5:45 PM. And a little before the rainbows, some nice, dramatic lighting on our desert vegies under a dark overcast of Stratocumulus.

Last of the Cal rain blasters is making its way across the State today, with another 5-10 inches expected in favored Sierra and coastal ranges in the next 24-36 h. Numerous sites north of SFO have now logged over 100 inches since October 1st!  Imagine.  Great to see that Cal drought vanquished in a single year, so unexpected.  Let’s hope the Oroville Dam, N of Sacto, holds.

The End

PS: Using point and shoot cam now with “real” camera in the shop for awhile.

Rain clouds drop more rain on Catalina; 0.24 inches logged as of 7 AM

But what kind of rain clouds?

That’s why you come here, to answer important questions like that.  After all, those precipitating clouds could have been Nimbostratus, Stratocumulus opacus praecipitatio, Cumulonimbus capillatus incus flammagenitus,  or even just “plain” Cumulonimbus capillatus (no anvil),  and possibly, Stratus opacus nebulosos praecipitatio.

Of course, with no large fires around, we can at once rule out Cumulonimbus capillatus incus flammagenitus….(the new name for clouds on top of fires, formerly referred to by the more accessible terms,  “pyrocumulus” or “pyrocumulonimbus.”

For the curious, and since I broke my camera and don’t have the dozens upon dozens of photos to regale or bore you with, I will reach into the archives for a shot of “flammagenitus” and show you one from the pyromaniacs’ paradise,  Brazil!:

Brazil, 1995: Cumulonimbus calvus flammagenitus. Shot taken by Arthur In flight shot, Porto Velho to Maraba.
Brazil, 1995: Cumulonimbus capillatus flammagenitus. Shot taken by Arthur on flight from, Porto Velho to Maraba.  The black at the bottom is mostly smoke.  Where it starts to turn a little white is where cloud droplets are forming.  Smoky ice is just above the aircraft’s wing and a little behind it.  You probably didn’t expect to see a “flammagenitus” here today, but, here it is.

 

Now, on to more recently viewed clouds, like yesterday’s:

9:16 AM. Stratocumulus praecipitatio line the tops of the Catalina Mountains. What's
9:16 AM. Stratocumulus praecipitatio line the tops of the Catalina Mountains. What’s “wrong” with this scene?  Very shallow clouds are precipitating, ones likely exhibiting, yep, the rare phenomenon in Arizona of “ice multiplication” wherein ice forms in clouds with tops warmer than around -15° C or so in great concentrations (often 10s to 100s per liter.)  Here, probably not that high, maybe several per liter of unaccounted for ice.  Happens when the cloud droplets are larger than usual–so when you see shallow clouds precipitating, but ones with tops still below freezing, -5° C, say, you can report in your cloud diary that you saw some “ice multiplciation on that day.  You would definitely get some accolades for such a report if cloud maven club members were to read  it, perhaps, an “Observer of the Week” award.  Of course, you get a mountain of extra credit for stating that those crystals falling on side of our mountains (Sam Ridge here), “look like needles and hollow columns” those ice crystals that form at temperatures higher than -10° C (14° F).
DSC_2372
10:52 AM. The actual cloud that produced this mist-like precipitation has literally “rained itself out.” What’s interesting here for you is that there seems to be no demarcation of the melting level. Hmmmm. Was this all drizzle then that fell out of that cloud, starting at cloud tops noticeably below freezing? It happens, though usually that phase is short lived as ice takes over.
DSC_2371
10:52 AM. A wider view of this intriguing scene. You can see all the glinting rocks, too, due to a little water on them. So pretty, the highlighting and all.
DSC_2376
11:08 AM. This shot, not taken out the window whilst driving since that would be crazy, gives a nice profile to those shallow, precipitating clouds. Sure would have liked to fly through them, see what the precip actually was. However, we do know that it was snowing on Ms. Mt. Lemmon, so that implicates the ice phase. If you were up there, you may have seen those needles and hollow columns, of course, mostly in aggregates (snowflakes). And, to trigger the “ice multiplication” process, you may have seen some tiny snowballs falling, too, ones we call graupel or soft hail.
The U of AZ balloon sounding for 5 AM AST yesterday morning. May have been valid for those shallower preciping clouds.
The U of AZ balloon sounding for 5 AM AST yesterday morning. May have been valid for those shallower preciping clouds.

Later these scenes were overtaken by a slab of Nimbostratus and steady light rain for a few hours.

A note on the recent southern Cal rain blast

As you know, up ten inches fell in some mountain locations in southern California as a monster low pressure system smashed into the coast near San Francisco1.  You might recall, too,  that the shift of the jet stream (and thus storm track) into the southern portions of California was well predicted two weeks in advance in those crazy spaghetti plots.   You can’t always get much out of those plots except maybe the degree of uncertainty in  weather patterns a couple of weeks out, but that was a rare case in which the signal far upstream for something strong barging into southern Cal also strong.  And, of course, we are experiencing the residual of that storm, also as was indicated in those plots (“…the weather change around the 18th.”

Presently, a another sequence of extremely heavy rain is in the pipeline for central and northern California starting today, which will take a few days for it to come to an end.

Following a  break, what was intriguing in the model outputs, and a little scary was that it appeared that yet another scoop of tropical air was going to jet across the Pacific under another blocking high in the Arctic  and Gulf of Alaska  into California. Take a look at this prog:

Valid Sunday, March 4th, at 5 PM AST.
Valid Sunday, March 4th, at 5 PM AST.

Here’s where spaghetti can shed some real light:

From last night's global data, this output for March 4th at 5 PM with writing on it.
From last night’s global data, this output for March 4th at 5 PM with writing on it.

So while it is still possible that some model runs will indicate a blast from the sub-tropics affecting Cal, they can be pretty much waived off as outliers (not impossible “solutions” but rather unlikely ones.  Breath easier Califs!  At least after the current onslaught ends.

BTW, can you see what kind of weather is indicated in this plot for the SW and old Arizony?

Cold; temperatures below normal, precip likely at times.

The End.

——————————–
1The low pressure center that passed over San Francisco yesterday was not  as deep (988 millibars) as the notorious “Frankenstormmaggedon” of 2010 which barged into Frisco with a 979 millibar center.   You may recall, too, that spaghetti had strongly suggested a “Frankenstormaggedon”, as it was later called, also more than ten days in advance.  Recall, too, if you can recall, that 2009-10 was an El Niño winter with this kind of thing pretty much anticipated.

For history buffs, I reprise that January 2010 storm as seen on our national weather map.  You may recall that, if there’s anything left in that noggin up there, that Catalina experience no less than THREE inches of rain as this system went by, taking a couple of days:

11 AM AST, January 21st, 2010.
11 AM AST, January 21st, 2010.
Valid at 2 PM AST, February 17th.  Junior.
Valid at 2 PM AST, February 17th. Junior.

Astounding Cal winter continues

Water continues to flow in most of our washes and dry creeks, day after day, long after the rain has gone.

But look at these early February California totals (table at right in graphic) from the California Nevada River Forecast Center (with lots of rivers above flood stage right now)!

Cal first ten days of Feb 2017!

This winter will go down in history as one that was so majestically unanticipated and points to the difficulty of seasonal forecasts.

Still looking for major storms in AZ toward the end of next week, as suggested in those spaghetti plots of old.

The End

 

Dry, dry, hot, dry, all mixed up, then, blammo, the storms roll in again

Well, it will be pretty obvious, ludicrously so to spaghetti lovers, the sequence shown below.  It goes from “warm in the West (again);  cold in the East pattern to another undercutting flow from the Pacific, the kind we’re having right now under the “soft underbelly” of a big blocking high, except that the tropical flow from the Pac this time is a little too far to the north to give us anything.

But, it will be another floody situation for northern Cal in the coming days.   Some places, mainly north of “Frisco”,  have already picked up 4-6 inches in the first blast which hit yesterday.  Ten to 20 inches more is likely over the next week at favored locations.  Having quite the water year there, really a lot of water year.

You may recall that the current situation, alluded to in the “break on through to the other side” refrain used here about ten times,  was well predicted about two weeks in advance!  That’s what spaghetti can do for you!

OK, enough jabbering, let us move on to the current exciting examples that popped out from last night’s global data ( there are outputs after adding little errors at the start of the model run, to see how the flow is changed with them in it.  Sounds crazy, I suppose, but is considered a huge advance in forecasting, a stupendous tool, that is, to make errors in models at the beginning of the run).  Heck, they even do that in climate models that simulate 30-50 years from now, and you’d be amazed at how the tiniest fraction of a degree change the beginning makes (see Deser et al 2012).

Valid on
Valid Sunday evening, 5 PM AST, February 12th (TIme at the top is Zulu Time, as we used to say,  or CUT, Central Universal Time, which takes in a lot of territory IMO.  This is one you look at and say, “Its gonna happen.”  What?  A big blocking high pressure ridge along the West Coast in a little more than a week.  Done weather deal.  Period. The dip to the south in the blue lines over there by the Great Lakes says that cold air will be extruding into the eastern US.  So, we have a Nike swoosh in the jet stream across the whole Pacific and then it makes a sharp left turn up into Alaska, and NW Territories of Canada.  They must be jumping up and down now, seeing this.

Well, the first one’s not so exciting since we’re dry and hot for this time of the year, and its a common one that can get stuck for weeks at a time, so you REALLY hate to see models project a bulging ridge poking north along the West Coast.  It could mean a rainless February here, if it persisted.

Here’s the exciting follow up, though, pretty unexpected given the above, showing a sudden collapse of the West Coast ridge regime, and strongly suggesting that wet spell has begun in Arizona, including regions of Catalina and Saddlebrooke:

Valid
Valid at 5 PM AST, Friday, February 18th.  Given a day or so off, we would be looking at a rainy spell beginning somewhere about this time or a day or around it.   The thing that really jumps out is the clustering of the red lines (564 decameter) contour lines. ALL the way across the Pacific right into central Cal and the Great SW.  This means that the jet stream will once again break through a ridge at lower latitudes just as its doing now, but in this case, a little farther S, which should mean periods of rain for us, keeping those washes going, or restarting the flow in them if we’re lucky.

So, you’ll want to get outdoor work done before this.

Historical note of interest, added value content,  etc.

Some of you may remember that the 564 decameter contour (those red lines) at this level (500 millibars or around 18,000 feet above sea level on average) was used in the early years of forecasting before computer models (50s and early 60s) by southern California forecasters to demarcate where rain would fall in California–at and north of where that 564 decameter contour intersected the coast when upper troughs came in.    The Old Forecaster remembers, though not much else…

So those red lines barging into southern Cal after a LONG fetch from the subtropical Pacific in the plot above mean central and southern Califs better watch out for some major rains a little before we ourselves get a dousing around the 18th of Feb.

Isn’t it great what spaghetti can do, that is, constrain our future weather to fairly certain outcomes two weeks in advance!

There was a sunset yesterday, btw:

6:06 PM. Altostratus with tiny virga illuminated by a setting sun. haha Guess I didn't need to say the sun was setting
6:06 PM. Altostratus with tiny virga illuminated by a setting sun. haha Guess I didn’t need to say the sun was setting.

Upper level snow flurry passes south of Tucson!  Trying to generate some excitement here….

8:56 AM, Feb 1st.
8:56 AM, Feb 1st.

The End

Cal drought eases under avalanche of rain and avalanches (back country ones)

Since we have nothing better to do for quite a dry while here in AZ, and CMP is from southern Cal, where he kept a weather and a cloud diary1 and played baseball2, here’s the latest on the Cal drought we’ve heard so much about, below, from the Drought Monitor folks at the University of Lincoln Cornhuskies University as of January 24th.

Added to this map is a couple of rainfall totals in the drought affected regions from January 1st through the 23rd, 2017  (i.e., only partial monthly totals) from the CNRFC, a superb site, btw:

Ann 20170124_ca_noneDrought legendWell, as you can see, it takes India monsoon caliber rains3 to end drought completely in California.  Or, maybe the DM folks are just a little behind;   could be.  Avalanche hazards have been moderate to “extreme” during this period due to the tens of feet of snow that have fallen in the Sierras.   Yay for California water supplies THIS water year!

Here is a table of the top 20 rain totals through January 23rd from the CNRFC:

astounding Cal Jan totals considering CPC prediction

The End

————————————–
1Perhaps you don’t believe me that I kept a weather and cloud diary growing up.  Here a report from the San Fernando Valley:

April 1 1956 hail and snow in valley

2Perhaps you don’t believe me that I played baseball… Here’s one of my favorite pieces of evidence for having played baseball.  Sure, I cost us the game, but then,  I was mentioned in the article!

Pierce Cerritos game 2 1960

3Rainfall totals can be over 100 inches a month at the monsoon’s peak in India. The record is 366 inches in ONE MONTH at Cherrapunji in the NE corner of India in the Assam region.  Of course, CMP must go there; its on the “bucket list.”

Wintertime cold Cumulonimbus clouds erupt with sprinkles and snow flurries; no damage reported

One passed over at 9:19 AM with a hard multi-second, surprise rain shower.  One person reported a couple of graupel, or soft hail particles. Tipped the bucket, too; 0.01 added to our Sutherland Heights storm total.  Its now at 0.23 inches.  Of course, there was no damage, but putting that word in a title might draw “damage trollers”, increase blog hits….

The rest of the day was clouds withering, getting mashed down on tops as bases rose and tops settled back, then suddenly, about 3:30 PM, small areas of ice crystals began to show up in a couple of spots, and, boy, did things take off after that.  Tops were lifting to higher temperatures, likely due to an approaching trough, one that otherwise is too dry to do much else.

Honest to goodness cold, wintertime Cumulonimbus clouds formed, though not very deep ones.  Probably of the order of 2-3 km thick is all (eyeball estimate).

But with our cold air aloft, tops were well below -20° C (4° F), lots of ice formed in them and produced streamers of ice and virga across the sky, and in tiny areas, the precip got to the ground.

And with “partly cloudy” conditions, there were lots of gorgeous, highlighted scenes around the mountains.

Let us review yesterday’s clouds and weather and not think about the future too much, starting with an afternoon balloon sounding temperature and dew point profile from IPS MeteoStar:

The Tucson balloon sounding ("rawinsonde" in weatherspeak) launched about 3:30 PM yesterday. Takes about an hour to reach 60,000 feet, but goes higher. Cloud bases were just about at the top of Ms. Mt. Lemmon. Tops were only around 18,000 feet above sea level, but were extremely cold for such small clouds.
The Tucson balloon sounding (“rawinsonde” in weatherspeak) launched about 3:30 PM yesterday. Takes about an hour to reach 60,000 feet, but goes higher. Cloud bases were just about at the top of Ms. Mt. Lemmon. Tops were only around 18,000 feet above sea level, but were extremely cold for such small clouds.  Hence, they were only about 9,000 feet thick at their maximum.

So what do clouds look like when they have tops as cold as -28°Ç?

Well, I really didn’t get a good profile shot of those clouds, they were either too close, obscured by other clouds, or too faraway, so instead let us look at two dogs looking at something as a distraction:

4:11 PM. Dogs observing a plethora of glaciating Cumulus clouds, transitioning to Cumulonimbus.
4:11 PM. Dogs observing a plethora of glaciating Cumulus clouds, transitioning to Cumulonimbus.

Well, let’s start this when the ice first appeared in a cloud, much later in time than what was thought here yesterday morning.  If you logged this “first ice” you are worthy of a merit, a star on your baseball cap:

3:24 PM. FIrst ice of the day, finally, spotted on the SW horizon. The file size is huge so that you can see it for yourself. I had just about given up on ice in clouds, Notice, too, how small the clouds are at this time.
3:24 PM. FIrst ice of the day, finally, spotted on the SW  and WSW horizon in two little areas. The file size is huge so that you can see it for yourself. I had just about given up on ice in clouds, Notice, too, how small the clouds are at this time.

Well, while flawed from a cloud profile sense, here’s what they were looking at, it was the best I could do:

4:19 PM. Note sunlit shower reaching the ground.
4:19 PM. Note sunlit shower reaching the ground.  The hazy stuff is ice crystals, a lot of them all over the place.
4:22 PM. A close up in case you don't believe me that the rain was reaching the ground.
4:22 PM. A close up in case you don’t believe me that the rain was reaching the ground.  I sometimes find that credibility is lacking here.
4:39 PM. Eventually a cluster of precipitating clouds developed near the Catalina Mountains and here are dropping snow and graupel trails.
4:39 PM. Eventually a cluster of precipitating clouds developed near the Catalina Mountains and here are dropping snow and graupel trails.

Let us go zooming:

4:39 PM. Shaft up close. That dark, narrow line in the middle is without doubt a soft hail (graupel) strand. THere might be others, but this one is obvious. The verticality is due to faster falling particles, which graupel are because they are ultimately snowflakes that have captured cloud droplets on the way down, making them much heavier than just a snowflake.
4:39 PM. Shaft up close. That dark, narrow line in the middle is without doubt a soft hail (graupel) strand. THere might be others, but this one is obvious. The “verticality” is due to faster falling particles comprising that strand, which graupel are because they are ultimately snowflakes that have captured cloud droplets on the way down, making them much heavier than just a snowflake.
4:48 PM. Just snow falling out, no real "verticality", a sign of graupel falling out.
4:45 PM. Just light snow falling out here on the Catalinas, no real “verticality” in this shaft, which would be a sign of graupel falling out.
4:46 PM. An opening allowed this distance cross section of a cold, wintertime Cumulonimbus (capillatus) cloud streaming a shield of ice and virga downwind.
4:46 PM. An opening allowed this zoomed cross section of a cold, wintertime Cumulonimbus (capillatus) cloud streaming a shield of ice and virga downwind.  On the left sloping-upward part, the Cumulus turrets still contain liquid droplets (have that ruffled, hard look associated with the higher concentrations that go with droplet clouds compared to all ice clouds).  Sometimes, in spite of the low temperature, here, from the sounding the top is likely approaching the minimum temperature of -28°C, droplets can still survive for a short time before freezing, giving way to lower concentrations of ice crystals.   That appears to be the case here at the tippy top. of the cloud in the back  What is interesting here, an enigma, is that the foreground cloud in front of the cloud I was just discussing,  is clearly all ice from the smallest element to its top and mimics the cross section of the background cloud.  Could it be that its simply older and ice generated in the colder regions has permeated the whole cloud?

Below, diagrammed:

Same photo with writing on it since the written explanation didn't seem very satisfactory.
Same photo with writing on it since the written explanation didn’t seem very satisfactory.
5:07 PM. Graupel in the Gap (the Charouleau one). Well, maybe its a little beyond the gap.
5:07 PM. Graupel in the Gap (the Charouleau one). Well, maybe its a little beyond the Gap, but it sounded good to write that..  This started to fall out of a Cumulus congestus transitioning to a Cumulonimbus.  The first particles out the bottom are always the heaviest, hence, graupel or hail.

Looking elsewhere, there are snow showers everywhere!

5:08 PM. Nice shafting over there near Romero Canyon. Pretty straight up and down, so likely has a lot of small graupel in it.
5:08 PM. Nice shafting over there near Romero Canyon. Pretty straight up and down, so likely has a lot of small graupel in it.
5:08 PM. Looking down Tucson way, this is NOT a graupel shaft. Sure the particles are large, but look at how they're just kind of hanging, getting mixed around by a little turbulence. Guess aggregates of dendrites, ice crystals that grow like mad around -15° C, and because of being complex, often lock together when they collide. Its not unusual to have 20 or more single stellar. dendritic fern like crystals locked into a single snowflake and that would be a good guess about what this is. Where the bottom disappears, likely around 3000 feet above sea level, is where those big aggregates are melting into rain drops
5:08 PM. Looking down Tucson way, this is NOT a graupel shaft, but rather gently falling large snowflakes.. Sure the particles are large, but look at how they’re just kind of hanging there getting mixed around by a little turbulence, almost forming a mammatus look. There are likely aggregates of dendrites, fern-like ice crystals that grow like mad around -15° C, and because of being complex forms, often lock together when they collide. Its not unusual to have 20 or more single stellar. dendritic crystals locked into a single snowflake. Where the bottom disappears, likely around 3000 feet above sea level, is where those big aggregates are melting into rain drops.
5:10 PM. Interrupting the tedium with a nice neighborhood lighting scene as a sun poked between clouds.
5:10 PM. Interrupting the tedium with a nice neighborhood lighting scene as a sun poked between clouds.  We’re not completely cloud-centric here, but close.
5:26 PM. This strange scene of a very shallow snow cloud, completely composed of ice and snow, obscuring the tops of the Catalinas, but being very shallow, hardly above them may explain the cross section enigma. The snow cloud here is all that remains of a much deeper cloud that converted to all ice, then those crystals just settling out, the whole cloud dropping down as a snow flurry. It may well have been as deep as the cloud top on the left or higher before converting to ice and just falling to the ground en masse. Or is it, en toto?
5:26 PM. This strange scene of a very shallow snow cloud, completely composed of ice and snow, obscuring the tops of the Catalinas, but being very shallow, hardly above them may explain the cross section enigma. The snow cloud here is all that remains of a much deeper cloud that converted to all ice, then those crystals just settling out, the whole cloud dropping down as a snow flurry. It may well have been as deep as the cloud top on the left or higher before converting to ice and just falling to the ground “en masse.” Or is it, “en toto“?  What makes this odd is that there is usually some “cloud ice” (ice particles too small to have much fall velocity) at the level from which the precip fell from. You don’t see that here; just a belt of light snow.   Maybe this is why there was that shallow, glaciated cloud  in the Cumulonimbus cross section shot…..  That shalllow cloud was not a new portion, but rather a tail dragger like this stuff, once having been much higher and was actually ice settling out, not new rising, glaciated cloud.  From the back side, you can see that this ice cloud would appear to slope up  if viewed from the east instead of the west like our cross section iced out cloud.  Setting a record for hand waving today.  IS anybody still out there?  I don’t think so.  Maybe I need another dog picture….
5:34 PM. Here's the last of that unsual snow cloud as its last flakes settled to the ground.
5:34 PM. Here’s the last of that unsual snow cloud as its last flakes settled to the ground.

The day concluded with a very nice sunset:

5:53 PM. Sunset color with shafts of snow down Tucson way.
5:53 PM. Sunset color with shafts of snow turning to rain down Tucson way.

 

Now, the long dry spell…  Break through flow from the Pacific under the “blocking high”  eventually happens about a week away now, but more and more looks like that flow might stay too far to the north of us, rather blast northern Cal some more,  and not bring precip this far south.  The blocking high needs to be in the Gulf of AK, but now is being foretold to be much farther north…

The End, gasping for air here.  More like a treatise than a quick read!

Iridescence, jet streak Cirrus warn of overnight “middlin'” storm

I guess “billows” (“undulatus” in cloudspeak) two days ago in the late afternoon wasn’t enough of a sign that the weather was changing. Yesterday we had fast moving Cirrocumulus with rainbows in it, and as the sun was setting, “jet streak Cirrus”, a line of Cirrus clouds often seen in the very core of high altitude, powerful jet streams passed overhead.

How hard was the wind blowing up there in that Cirrus last evening? Oh, our Tuscon balloon sounding, lifting off around 3:30 PM, going up about a 1000 feet a minute to, indicates that the max wind up there at Cirrus level was 146 knots (just under 170 mph)! Yikes. Poor balloon.  Must be in France by now.

The storm has been a bit of a disappointment in rain production. We’ve only logged 0.22 inches1.  Not as much as foretold here, 0.33 inches, but that forecast was a better prediction than  by “Weather Underground Robotics” (0.58 inches).  Its great to beat a robot!

We had another sign yesterday in the fastest moving Cirrocumulus clouds I think you’ll ever see around here (about 100 mph), ones at just 18,000 feet above sea level, 15 kft above Catalina:   rainbows of color near the sun called iridescence (also called “irisation”).   Here, as is the norm here,  are a few too many shots of the same thing2.

DSC_1885

 

10:54 AM. The fist of weather is used as a prop to indicate that these colors are forming a ring around the sun.
10:54 AM. The fist of weather is used as a prop to indicate that these colors are forming a ring around the sun. Usually you try to find a light standard somewhere…maybe a “gopro cam on a stick” might do it. Just don’t look at the sun when you do this.
DSC_1894
10:57 AM.
DSC_1896
10:57 AM, pulling back some for perspective. As we often say here, “so pretty.” And look at how tiny the granulation is in this Cirrocumulus cloud is!

The colors themselves, of course,  don’t warn of something about to happen, but the fast movement from the southwest did; a powerful jet stream is over you.   That strong stream, the result of temperature gradients in the atmosphere, is dividing deep warm air from deep cold air, and steers the alternations of high and low pressure centers, and with those alternations of lows and highs along the jet stream, air is drawn from different latitude zones and the boundaries where those different masses of air meet at the surface, is called fronts.  Here, such as last night, its nearly always cold ones.

The rest of the day was pretty exciting, the wind arising suddenly yesterday morning, along with our usual great visibility, and darker blue wintertime skies, made the clouds stand out more.

7:56 AM. Looking to the west at a scattering of Stratocu patches.
7:56 AM. Looking to the west at a scattering of Stratocu patches.
7:57 AM. Highlight on the hills above Saddlebrook. Stratocumulus overhead.
7:57 AM. Highlight on the hills above Saddlebrook. Stratocumulus overhead.
8:42 AM. This patch of Stratocumulus was the result of a lift zone that often produces clouds headed our way in southwesterly flow. The difference here is how limited in size this patch was allowing you to see where that lift zone was. Downstream, though, descending motions creamed this cloud, one that sat there most of the early part of the day. Usually a whole layer is over us, with a clearing visible toward the SW horizon.
8:42 AM. This patch of Stratocumulus was the result of a lift zone that often produces clouds headed our way in southwesterly flow. The difference here is how limited in size this patch was allowing you to see where that lift zone was. Downstream, though, descending motions creamed this cloud, one that sat there most of the early part of the day. Usually a whole layer is over us, with a clearing visible toward the SW horizon.
11:02 AM. Still out there, still limited in size. Wind here now 20-30 mph with stronger puffs.
11:02 AM. Still out there pretty much near the same spot, still limited in size. Wind here now 20-30 mph with stronger puffs.

 

DSC_1904
11:40 AM. By this time it had shifted closer to us, still forming on the southwest end, dissipating at the downwind end where the cloud is so ragged due to mixing with dry, descending air.
12:42 PM. Creeping closer, but still a standing wave, dissipating as it came toward us.
12:42 PM. Creeping closer, but still a standing wave, dissipating as it came toward us.  It was about this time that it disappeared, the sky becoming more complex with no simple standing waves.

The sky at last, considering the power of the trough approaching, FINALLY began to fill in.  Started looking around for the first sign of ice having formed in these clouds as the air aloft became cooler. Along with this filling in by Cumulus and Stratocumulus clouds, some sun highlights began to appear on our mountains, contrasted by the darkening skies above.

1:55 PM. Stratocumulus banks up against the Catalinas, Samaniego Ridge.
1:55 PM. Stratocumulus clouds  bank up against the Catalinas, Samaniego Ridge.
2:03 PM. While Stratocumulus banked up against the mountains, huge temporary clearings occurred elsewhere. Notice how shredded the tops of these clouds are and how the tops lean to the right. They're revealing the great increase in the wind with height, and yet, how dry it was above this layer (that, by the ragged cloud tops mixing with the very dry air just above them.)
2:03 PM. While Stratocumulus banked up against the mountains, huge temporary clearings occurred elsewhere. Notice how shredded the tops of these clouds are and how the tops lean to the right. They’re revealing the great increase in the wind with height, and yet, how dry it was above this layer (that, by the ragged cloud tops mixing with the very dry air just above them.)
3:38 PM. Here comes the Jet Streak Cirrus! Also about this time, the frontal windshift line, marked by low scud clouds in the cold air, began to appear on the NW horizon. It was an exciting moment. Here we go! FROPA within a coupla hours maybe. Well, took longer than that....
3:38 PM. Here comes the Jet Streak Cirrus! Also about this time, the frontal windshift line, marked by low scud clouds in the cold air, began to appear on the NW horizon. It was an exciting moment. Here we go! FROPA within a coupla hours maybe. Well, took longer than that….
3:52 PM. A little ruffle of Cirrocumulus leads the advance of the jet streak Cirrus.
3:52 PM. A little ruffle of Cirrocumulus leads the advance of the jet streak Cirrus.
4:11 PM. Cloud line forming above the frontal windshift line. Was progressing this way at this time, but was to stall, maybe back off.
4:11 PM. Cloud line forming above the frontal windshift line. Was progressing this way at this time, but was to stall, maybe back off.
4:11 PM. Zooming, floating over Saddlebrooke, this close up of our FROPA and windshift line. Ended up backing off, dissipating, maybe reforming later after dark.
4:11 PM. Zooming, floating over Saddlebrooke, this close up of our FROPA and windshift line. Ended up backing off, dissipating, maybe reforming later after dark.  These lowest clouds form in the colder air associated with the windshift line at the nose of the front as the moist air ahead of the front  mixes with it and is lifted.  We see this with most of our incoming cold fronts, and in our summer thunderstorms.  The best cases  form “arcus clouds”, a solid line just above and behind the windshift at the ground.  These kinds of ragged clouds, in cloudspeak, are called “pannus.”  Was pretty excited here, as no doubt you were, that FROPA (frontal passage) was imminent, might happen within the hour.  Nope.
4:40 PM. In the meantime, our jet streak CIrrus moved overhead, the clearing behind this thin band leading to some memorable fading sun highlights on the Catalinas.
4:40 PM. In the meantime, our jet streak CIrrus, above the Stratocumulus clouds,  moved overhead, the clearing behind this thin band leading to some memorable fading sun highlights on the Catalinas.
5:40 PM. No words needed.
5:40 PM. No words needed.
5:43 PM. "Fading sun and rain gauge." Another one of those exceptional scenes you won't find anywhere except on this blog. Tell your friends. A small mammal, termed a "packrat" is decimating my prickly pear wind protection for this gauge! A lot of rain loss occurs due to wind. drops missing the collector! It very upsetting to see this happen.
5:43 PM. “Fading sun and rain gauge.” Another one of those exceptional scenes you won’t find anywhere except on this blog. Tell your friends. A small mammal, termed a “packrat” is decimating my prickly pear wind protection for this gauge! A lot of rain loss occurs due to wind. drops missing the collector! It very upsetting to see this happen.
5:43 PM. Even the often despised teddy bear cholla can be so beautiful in this fading sun, the spines capturing it so well.
5:43 PM. Even the often despised teddy bear cholla can be so beautiful in this fading sun, the spines capturing it so well.

Eventually our jet streak Cirrus provided the background for another great sunset scene:

5:56 PM.
5:56 PM.

 

 

A 300 millibar (about 30,000 feet above sea level) with an IR satellite image for yesterday at 5 PM AST. Arrows denoted the jet streak Cirrus cloud, enhanced in the downwind region of the Baja mountains.
A 300 millibar (about 30,000 feet above sea level) with an IR satellite image for yesterday at 5 PM AST.   The Cirrus layer extended from about this height to around 35, 000 feet above sea level.   according to our TUS balloon sounding.  Arrows denoted the jet streak Cirrus cloud thatpassed over us,  enhanced in the downwind region of the Baja mountains.  Note that the wind at San Diego max wind was even slightly stronger than our wind max was at this level at152 knots.  This map is the courtesy of the University of Washington Huskies Weather Department.

Today’s clouds and weather

From that map above, you’ll see that there’s a “tail-dragger” trough still to the west of us and about over Sandy Ego (haha). That’s going to keep the air over us extremely cold, and with some sun, the Cumulus clouds that arrive are expected to have tops colder than -15 to -20° C, plenty cold enough for the formation of ice.
Ice means precip, snow up there, rain down here in spots. So, we could still pick up a few more hundredths if a shower happens to drop by. The chance of isolated very light showers in the area is 100%, but no one can tell you if one will actually land on us. You’ll have to be watching, mostly after 12 noon. Look to the west toward the Tortolita Mountains, terrain that ought to spawn one or two of those.

Looks like a longer dry spell ahead; several days to a week, maybe more.

The End

—————————-

1CoCoRahs gauge, btw. NWS-style gauge had only 0.20 inches, likely due to enhanced wind loss associated with my collapsing prickly pear protector.
2 I was driving and had to park and jump out of car to get these.  You only have seconds or maybe a minute or three to capture stuff like this.

Billows before the storm

Its not something a weather-centric sailor would say, but its what happened yesterday before today’s certain storm.   Maybe sailors should consider it…but with no cussing,  though.

The Weatherunderground weather site forecast for Catalina has 0.58 inches predicted for our storm. Such forecasts, I have to say, are “objective” and are based are model outputs that yo-yo forecasts every time a new model output  comes in.

To educate you on how bad this is, why just yesterday, based on the SAME model but a different set of global data, the model said we would have, 0.59 inches.   So, its already changing our forecast, diminishing it!  How bad is that?

The problem with those forecasts is that they are heavy with “objectivity”; there is no human intervention.  Its the work of a robot of sorts.   And we know what robots are doing to the economy and jobs.

Here, straight from a human heart,  we had a forecast of 0.33 inches total from this storm,  one laden with emotion and often based on wishful thinking when large amounts are forecast.  They’re often, based, too,  on pattern recognition (“looks like that storm that brought us that much last time, or look where the core of the jet stream is!”)1

That forecast of 0.33 inches in the gauges right here in Sutherland Heights is not going to change just because some new data came in!

So, which one do you want?  A forecast that yo-yos every few hours as demonstrated by the Weather Underground one?  Or one that stands tall against new data?

I think the answer is obvious.

OK, enough about “robots” and weather; on to yesterday’s afternoon billows:

DSC_1840
12:49 PM. Layer of Altocumulus opacus moved in during the mid-day hours. Looked a lot like “Altostratus” to some, I am sure. But if you looked carefully as I always do, you’d have seen the sun’s disk in the brief thin spots. You can’t see the sun’s disk in Altostratus because its full of cloud and precipitation-sized ice crystals, which cause enough interference with the incoming sunlight to prevent the outline from being seen due to diffraction.   So if labeled it even momentariy as “Altostratus” you will get a demerit at the next meeting of Cloud Maven Junior club when your cloud diary is inspected by the other members.
DSC_1849
1:59 PM. Showed signs of devolving into a Altocumulus opacus perlucidus layer as small cloudlets began to show up. No billows here, but let’s look over there next, but an hour an a half later.
DSC_1850
4:06 PM. A very billowy sight! Or, as we cloud technicians would say, Altocumulus or Stratocumulus undulatus. The individual elements are a bit large for true Altocu, yet the layer is still quite high off the ground, about 7,000 feet above Catalina, or about 1,000 feet above the top of Lemmon. (This from the TUS sounding.)
DSC_1851
3:07 PM. Billows galore!
DSC_1852
3:07 PM, but a little more over there.
DSC_1854
3:10. Billows to the north!
DSC_1857
3:35 PM. Just going on and on!
3:38 PM. The billows (undulatus) structure was fading quickly, here almost two perpendicular waves are interacting with this cloud cutting it up into square elements resembling waffles.
3:38 PM. The billows (undulatus) structure was fading quickly, here almost two perpendicular waves are interacting with this cloud cutting it up into square elements resembling waffles.
DSC_1860
3:38 PM. The billows were pretty much gone, and the sky cleared spectacularly after this.

Well, there you have it, another tediuous contribution from the CMP.

The End here,  but the beginning of the next storm!

———————————–
1Analogs to previous weather patterns are also part of the forecasting arsenal used by computers and other forecasters these days.

The CDO roars after our 1.42 inches of rain

A few more hundredths fell after 7 AM yesterday, boosting our storm total to a remarkable 1.42 inches, January now about twice our long-term average.

Here’s what all that precip did to our beloved Cañada del Oro Wash:

3:53 PM. The CDO in full flow.
3:53 PM. The CDO in full flow at East Wilds Road, road closed.

Yesterday’s clouds

8:04 AM. A Stratocumulus overcast with areas of virga and light rain showers began the day.
8:04 AM. A Stratocumulus overcast with areas of virga and light rain showers began the day.

After a few more hundredths of rain, the skies broke open, and as we know well, some of our most spectacular scenes occur under deep blue skies punctuated by puffy Cumulus clouds, shadows and highlights on our now snow-capped Catalina Mountains.

10:36 AM. Cumulus clouds race toward Catalina borne on brisk southwest winds.
10:36 AM. Cumulus clouds race toward Catalina borne on brisk west winds.  In looking at this scene you can feel them coming at you.
10:36 AM. Deeper clouds capable of producing ice and precip still lay to the SSW of us.
10:36 AM. Deeper clouds capable of producing ice and precip still lay to the SSW of us.
11:19 AM. Heavy Cumulus line the Catalinas, spewing ice farther downwind.
11:19 AM. Heavy Cumulus line the Catalinas, spewing ice farther downwind.  Glinting rocks highlight the scene.
1:38 PM. Coming at you. The south end of the Tortolita Mountains is a common formation point in westerly and northwesterly flows for cloud street development, a line of clouds that stays in the same place, but elements are replaced.
1:38 PM. Coming at you. The south end of the Tortolita Mountains is a common formation point in westerly and northwesterly flows for cloud street development, a line of clouds that stays in the same place, but elements are replaced.
1:38 PM. The end of this cloud street shows that its tops got high enough to form a little ice, seen by that veil like cloud coming out the downwind end.
1:38 PM. The end of this cloud street shows that its tops got high enough to form a little ice, seen by that veil like cloud coming out the downwind end.
2:57 PM. Samaniego Ridge and its new coating.
2:57 PM. Samaniego Ridge and its new coating.
3:06 PM. Cloud streets continuing to stream off the Tortolita Mountains, but are now half the depth they were 2 h ago. No ice will form now.
3:06 PM. Cloud streets continuing to stream off the Tortolita Mountains, but are now half the depth they were 2 h ago. No ice will form now.
3:48 PM. "Devil's Post Pile" to the left of Samaniego Peak catches a sun break.
3:48 PM. “Devil’s Post Pile” to the left of Samaniego Peak catches a sun break.
4:01 PM. Last of the Tort cloud streets, shallower yet (estimated depth, 1000 feet) is about to fade into oblivion, wherever that is.
4:01 PM. Last of the Tort cloud streets, shallower yet (estimated depth, 1000-1500 feet) is about to fade into oblivion, wherever that is.

In the meantime, more highlights on Sam Ridge:

4:50 PM.
4:50 PM.  So pretty!
4:50.  Drawing back a bit for perspective on the scene.
4:50. Drawing back a bit for perspective on the scene.

Finally, that incredible sunset afterglow on our mountains:

5:46 PM.  I hope we never take such sights as yesterday's for granted.
5:46 PM. I hope we never take such sights as yesterday’s for granted.

 

The End.

Oops, oh yeah, storm tomorrow, supposed to begin in mid-day to afternoon hours.  Looks like a third of an incher.  Also looks to be a bit colder than the last storm, may see a flake or two by Tuesday morning.

Thunderblasts after midnight awaken sleeping Catalinans with 50 mph winds, graupel, and R++; latest storm total now 1.38 inches!

In case you don’t believe me that over an inch fell, this digital record from Sutherland Heights with writing on it:

20170120-21 rain day
Your last 24 h of rain in the Sutherland Heights, Catalina, Arizona, USA. Total resets at midnight.

Probably a little more to come, too.  Got some blow damage, I’m sure.  Will be looking for roof shingles around the yard today.

12:45 AM. Your radar and IR satellite imagery for our blast last night from IPS MeteoStar
12:45 AM. Your radar and IR satellite imagery for our blast last night from IPS MeteoStar .  That tiny red region near Catalina represents hail and/or extremely heavy rain.

And, as everyone knows from their favorite TEEVEE weatherperson, “New Storm to Pound SE Arizonans!”  Begins Monday night, Tuesday AM.  May have snow in it as it ends.

Your know, its no fun telling people what they already know, so lets look ahead beyond the normal forecast period of great accuracy, beyond not seven days, not eight, but beyond TEN days!

First, we set the stage with a ten day look ahead (from last evening) in a NOAA spaghetti factory plot:

Valid for 5 PM, Monday, January 30th. If you've not seen this, you'll be screaming "warm in the West, and damn Cold in the East." Its a common pattern often associated with some of the driest years in the West when it recurs over and over again during a winter.
Valid for 5 PM, Monday, January 30th. If you’ve not seen this, you’ll be screaming “warm in the West, and damn Cold in the East.” Its a common pattern often associated with some of the driest years in the West when it recurs over and over again during a winter.

This plot indicates that the pattern of a towering, storm-blocking ridge is certain along the West Coast by ten days–will be developing for a day or three before this,  That ridge represents an extrusion of warm air aloft over the entire West Coast extending all the way into Alaska.  The couple of red lines in and south of AZ are due to the change of a minor, likely dry, cutoff low in our area about this time (plus or minus a day).

In other words, this plot suggests a warmer, dry period develops over AZ, and storms are shunted from the Pacific Ocean, located west of the West Coast, all the way to Anchorage and vicinity,  They will  be welcoming a warm up in weather up thataway at some point in this pattern.

Is that it, then, for the AZ winter precip?  It could happen.  Just one more storm after the current one fades away today?

Hint:  Sometimes anticyclone ridges like the one in the plot above get too big for their britches, and fall away, or, break off like a balloon from a tether, and a warm blob of air aloft sits at higher latitudes, often floating off to the northwest.

The exciting ramification of this latter scenario is that in the “soft underbelly” of the “blocking anticyclone” (as in American football), the jet stream throws something of a screen pass, goes underneath the belly of the blocking high,  and races in toward the West Coast at lower latitudes.  Having done so, such a break through pattern (“Break on through to the Other Side”) results in heavy rains in Cal and the Southwest.

Izzat what’s going to happen?

Let us look farther ahead, unprofessionally, really,  and see if there is evidence in spaghetti for such a development and you already know that there must be because it would explain why I am writing so much here.  Below, the EXCITING spaghetti plot strongly indicating break through flow breaking on through to the other side, i.e., the West Coast,  from the lower latitudes of the Pacific:

Valid on Thursday, February 2, at 5 PM AST. Flow from the lower latitudes of the Pac will, in fact, break on through to the other side, as told in song by the Doors1.
Valid on Thursday, February 2, at 5 PM AST. Flow from the lower latitudes of the Pac will, in fact, break on through to the other side, as told in song by the Doors1.  Who knows what they were talking about but here we’re talking about a jet stream….

Well, we’ll see in a coupla weeks if CMP knows what he is talking about..  I think this is going to happen, resembles what’s happening now, and weather patterns like to repeat, more so within the same winter.  However, how much precip comes with this pattern will be determined by how much flow breaks on through to the other side….

Yesterday’s clouds

Let us begin our look at yesterday’s clouds by looking back three days ago before the Big Storm.  We had a nice sunrise.   Here it is in case you missed it:

DSC_1680
7:21 AM. Altostratus sunrise. Virga is highlighted showing the precipitating nature of Altostratus. Amount of virga can vary.
DSC_1686
7:31 AM. Same kind of view, different colors.
DSC_1689
7:40 AM. Highlight on the Tortolitas. This is why you carry your camera at all times.
9:04 AM. Pretty much solid gray after that nice sunrise for the rest of the day with cloud bases lowering and raising. Early on, cloud bases were well above 10,000 feet; i. e;, above Mt. Lemmo, and would be called, "Altostratus opacus." The virga is very muted, and there are embedded droplet clouds as well as a droplet cloud layer (Altocumulus) encroaching on the right. Estimated ceiling here: 12,000 overcast." (Pronounced, "one-two thousand overcast" if you want to make your friends think that maybe you were a pilot at some time in your life.)
9:04 AM. Pretty much solid gray after that nice sunrise for the rest of the day with cloud bases lowering and raising. Early on, cloud bases were well above 10,000 feet; i. e;, above Mt. Lemmo, and would be called, “Altostratus opacus.” The virga is very muted, and there are embedded droplet clouds as well as a droplet cloud layer (Altocumulus) encroaching on the right. Estimated ceiling here: 12,000 overcast.” (Pronounced, “one-two thousand overcast” if you want to make your friends think that maybe you were a pilot at some time in your life.)
12:58 PM.
12:58 PM. Clouds began to appear on Samaniego Ridge as the moist air above us lowered steadily.  However, due to lowering cloud tops, the ice in the higher overcast layer was gone. Here there are two layers above the scruff of Stratus fractus (I would call it) on the ridge.  The lower one looks like its a Stratocumulus, and the higher one a solid layer of “Altocumulus opacus.”  Its already rained some, and we were in between storm bands.
2:48 PM. Looked like the Altocumulus opacus (stratiformis, if you want to be exactly correct) was breaking up just enough for a sun break. But no, kept filling in as it headed this way from the southwest.
2:48 PM. Looked like the Altocumulus opacus (stratiformis, if you want to be exactly correct) was breaking up just enough for a sun break. But no; it kept filling in as it headed this way from the southwest.  No ice, or virga evident, so tops are pretty warm, probably warmer than -10° C (23° F) would be a good guess. Hah!  Just now looked at the TUS sounding and tops were indicated to be at -11° C, still very marginal for ice (absent drizzle drops in clouds, which causes ice to form at much higher temperatures, but you already knew that.)
4:24 PM. Small openings allowed a few highlights to show up on the Catalinas underneath that Altocumulus opacus layer.
4:24 PM. Small openings allowed a few highlights to show up on the Catalinas underneath that Altocumulus opacus layer.  And  clouds were still topping Ms. Mt. Lemmon, indicating a good flow of low level moisture was still in progress.

Moving forward to only two days ago, the day preceding the nighttime blast:  a cold, windy day with low overcast skies all day, shallow, drizzle-producing clouds, something we don’t see a lot of here in Arizona.

8:08 AM, January 20th, 2017, btw. "Gray skies, nothin' but gray skies, from now on", by Irving B.
8:08 AM, January 20th, 2017, btw. “Gray skies, nothin’ but gray skies, from now on”, by Irving B.  Stratus fractus underlies an overcast of Stratocumulus.  Some light rain is falling toward Romero Pass on the right.
8:10 AM. A really special shot. Stratus with drizzle is a very difficult photographic capture. I can feel how enthralled you are with this view toward Oro Valley. You know, I do this for YOU.
8:10 AM. A really special shot. Stratus with drizzle, shown here,  is a very difficult photographic capture. I can feel how enthralled you are with this scene toward Oro Valley. You know, I do this for YOU.  Look how uniform the gray is!  It just takes your breath away!
9:44 AM. Before long, drier air down low moved in, eradicating our beautiful Stratus layer, leaving only holdouts (Stratus fractus) along the Catalina foothills below the heavy layer of Stratocumulus.
9:44 AM. Before long, drier air down low moved in, eradicating our beautiful Stratus layer, leaving only holdouts (Stratus fractus) along the Catalina foothills below the heavy layer of Stratocumulus.
10:20 AM. The wind had now shown up, and these ragged, shredded shallow Stratocumulus shedding drizzle or very light rain showers stormed across the Catalina Mountains. This was quite remarkable sight, since such shallow clouds as these are more often seen in clean maritime locations like Hawaii. Scenes like this suggest that the cloud droplet concentrations were very low, and that there were larger than normal cloud condensation nuclei on which the drops could form, getting a head start in the sizes needed to produce collisions with coalescene (larger than 30 microns in diameter (about one third to one half a human hair in diameter, for perspective.)
10:20 AM. The wind had now shown up, and these ragged, shredded shallow Stratocumulus shedding drizzle or very light rain showers stormed across the Catalina Mountains. This was quite remarkable sight, since such shallow clouds as these are more often seen in clean maritime locations like Hawaii. Scenes like this suggest that the cloud droplet concentrations were very low, and that there were larger than normal cloud condensation nuclei on which the drops could form, getting a head start in the sizes needed to produce collisions with coalescene (larger than 30 microns in diameter (about one third to one half a human hair in diameter, for perspective.)

 

3:12 PM. Lower, drier air moved in, eradicating the Stratocumulus and revealing the rarely seen Nimbostratus precip-producing layer. This layer, considered a mid-level cloud, is usually obscured by, you guessed it, Stratocumulus clouds.
3:12 PM. Lower, drier air moved in, eradicating the Stratocumulus and revealing the rarely seen Nimbostratus precip-producing layer. This layer, considered a mid-level cloud, is usually obscured by, you guessed it, Stratocumulus clouds.

By the end of the day, the clouds had lowered again, and we were about to have a very interesting night!

5:01 PM.
5:01 PM.

The End

———————-
1Remember how great we hippie relics thought that first Doors album was? Later, the Doors, and that era were to be made fun of by 80s punk and humor group,  The Dead Milkman in “Bitchin’ Comaro.” (Its worth a listen.)