Category Archives: Pyrocumulus

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).
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.
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.
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.

Cooking with solar; dusty cool snap still ahead (25th or so)

It was 99 F here in Catalina yesterday.

Spinning entity in AZ today.  See it here in the water vapor imagery from the Huskies, the Washington ones.  Not much moisture with it, but we did see a couple of….. of…..yes, “Cumulus fractus” yesterday, maybe one big enough to be a humilis, if “big” and “humilis” can be used in the same sentence.  In case you missed them:

No ice.

The zoomed shot is because Mr. Cloud-maven person could detect a “pyrocumulus” on top of the Crown King fire on the horizon.  Can you?

Here’s the sat image, also from the Huskies, and you can see the tiniest little white spec on the top of the smoke on the left side.

Likely more Cumulus today.  Yay.

At least some hot air relief is on the doorstep as a couple of weak troughs buzz the State in the next couple of days, but then its back to The Oven for a couple more.

However, after that, a much bigger cool down is still ahead…

Dusty Coolsnap coming to town

I wish there was a western singer by that name because I would probably buy his/her records.

Anyway, he’s coming to town around the 24-25th-26th, and its going to be real windy, REALLY windy with a lot of dust around, but then we won’t be cooking with solar so much then.

This is due to “big trough” implanting itself in the Southwest then.  Will cause a lot of weather mayhem in the West for late May.  Here are some scenes from the upcoming “show”, courtesy of IPS Meteostar:  Opening the show will be The Ovens, with their hot rendition of 102 degrees (or more) here in Catalina on the 21st.

It will be so great to see “Dusty” after that! Hahahaha.  Oh, well, I’m trying really hard here.

OK….now look at all the isobars in the maps below, valid for the afternoon of the 24th and then the 25th! Bunched in the State of AZ those days around that huge low center, first in southern Nevada and then,  the next day,  over Needles, CA!  Wow.  It just sits there!  This is going to be fun, something besides hot air to think about.

Note, too, all that precip that creeps down into southern Nevada on the 25th.  Sadly, that’s about as close as it gets to us here in Catalina.  Oh, well, maybe things will “improve” for us as the event gets closer in the models.   The real cool down is after the low goes by,  after the 25th.

The End.




Story time: They said they couldn’t exist, but we found some anyway (extra giant raindrops)

While waiting for the chance of rain mid-week next week, I thought I would tell another science story…

How me and Doc Hobbs got into the Guinness Book of World Records

Rain drops bigger than about 5 mm in diameter (only about 0.2 inches) are thought, mainly through lab experiments, to break up into smaller drops before they reach sizes larger than that.   Also, they had not been reported to reach sizes larger than that until the mid-1980s when researchers sampling modest Cumulus congestus clouds topping out at only around 14,000 feet around the Hawiaan Islands reported intercepting drops that were 4-8 mm in diameter.  This was pretty big news.

Later, while flying with the University of Washington’s research aircraft we intercepted (imaged with aircraft laser probes) drops that were 8.6 mm across and more likely as large as a centimeter, and not on one, but two different occasions separated by a few years.  These were larger than the ones reported by the Hawaiian researchers.  (Yes!!!! Spiking football now!!!)  

First, the award-certificate  for those who might be skeptical, and whose display is best part of today’s blog!  I mean, really, I could have put 257 worms in my mouth or that sort of tawdry thing, but this was much better, more digestible.  Oddly, neither Peter V. Hobbs, my co-author, and I know how we got this Guinness Certificate;  it just came in the mail sometime after our article,  Super-Large Raindrops appeared in the journal,  Geophysical Research Letters in 2004.  You know, it wasn’t that great of a “certificate” either.  I thought it would be on onion paper, or some other exclusive bond.  Instead, it was on something like a cheap, thin cardboard paper.  Still…….

The two instances of where these giant drops were encountered were in completely different, contrasting aerosol environments:  one in a clean, smog-free, oceanic environment near the equator in the Marshall Islands, and the other under a smoke-filled Cumulus congestus cloud in Rondonia, Brazil,  an area where there were many fires where the tropical forest was being burned away.  (We were in Brazil 1995 along with other research aircraft to study the nature and extent of the smoke being produced by those awful fires.)  Since any rain is thought to be hard to produce in smoky clouds that do not get to the Cumulonimbus stage, giant drops from them was news, too.  Of course,  many of you out there enjoy photographing images of raindrop splatters on various surfaces as kind of a hobby, particularly as  rain begins to fall.  Below, is an example from a friend of that sort who prefers to photograph those splatters as they occur on cement as an artform.  I think her work is in a local gallery…

So, knowing how much general interest there is out there  in rain for desert dwellers, which still might occur on Wednesday or Thursday, is the reason for today’s blog on huge raindrops.

Below is an example of what rain drops look like when they imaged by laser probes on the University of Washington’s research aircraft as we flew through those two instances of giant raindrops.  The images of the drops are the shadows of them.   As they pass under the wing of the aircraft, some go through a laser beam without being disturbed.   The laser shines on photosensitive diodes that get turned off and recorded when they are shadowed.  They stay off until the laser beam hits them again, thus recording the dimensions of whatever it was has passed by.    You then look at the diodes that were turned off for the tiny fraction of a second that something went through (for our aircraft, around 100 to 120 mph) and get an image of it that tells you whether it was a drop, ice crystal, snowflake, graupel, whatever.  Pretty amazing when you think about it.  You’ll have to click on it to really see anything.

The large red drops on the left side in the bottom rows are the partial images of the record setting drops.  The probe elements were not wide enough to see the whole drop.   On the right side is an ellipse fitting routine applied to the raindrop images we recorded that better displays the true size of partially viewed drops.  In this case, that algorithm suggested the very largest were about 1 cm (you can use that as a scale for the other ones), but because it is an estimate, does not count in the record books.   Only the actual measurized size was considered in the Guinness record.  The top two panels are from the Brazil encounter, and the bottom two panels are from the one near Kwajalein Atoll, Marshall Islands.

Here are some photos of the two areas we flew in so that you can see how different they were in character.  First, Kwajalein Atoll (note the gigantic runway, constructed in WWII, had its own cloud on calm days  !).  Second,  an example of a moderate-sized Cumulonimbus cloud, one similar in size or even a bit larger than the one Mr. Cloud-maven person himself was directing the University of Washington’s Convair-580 research aircraft into, targeting the heavier strands of rain that first falls from convective clouds.  It was so GORGEOUS there in Kwajalein!  I loved it there.  The skies, the sunsets!  Oh, my.

Kwajalein Atoll, BTW, is the terminus of the Vandenberg missle launches.  As yet another aside, on the TEEVEE there in Kwajalein, there were announcements in big red letters, like the ones for severe weather,  that told you when a missle had been launched at Kwakalein from Vandenberg, and when it was coming into the middle of the Atoll (you hoped!)  Folks would then gather on one of the Atoll beaches to watch the show.  It was so exciting!

As an aside, I have to tell you that one of the charms of that place, run by Raytheon, a name you are familiar with around here, was that you could not own a car, or house, or just about anything else, paid no taxes if you were a permanent employee, etc.  You had to have a bicycle for transportation for the most part.  It was like the atmosphere of a small (“communist”, hahaha) town (3500 lived and worked there).  Everyone went outside and walked or rode down the streets in the evenings.  Another charm was that the manager of the Kwajalein Missile Range site had hair down to his waist!  It was AMAZING!  Both he and his wife seemed to be in their late 30s with two little kids, and told me how much they loved it there!  Many others did, too.

Now on to the smoky environment in the State of Rodonia, Brazil, 1995, in the  “dry season”,  where the other giant drops were encountered.   Rodonia, at that time of year and in those days, was a pyromaniacs paradise.

First, the University of Washington’s research aircraft sitting on the runway in Porto Velho, Rodonia, Brazil.  By clicking on this image, and looking under the wing on the left, you can see the “Y” shaped probe that imaged the giant drops as they flew by.  Other images show the “Green Ocean” in smoke, and some ground shots that show how widespread fire was there.  In fact, after a couple of months there, we kind of got “into the culture” and wanted to burn some things up ourselves.  Check the fire along the highways!  No “Fire Danger is High” signs there!   I think its time to reprise Deep Purple’s “Smoke on the Water” (which is just about everywhere else in Brazil, anyway)  to get you in the mood for the shots to follow.  I will be jumping around now…  (Too bad Beethoven couldn’t write songs as good as this, but then he wasn’t that great with words….)  The last shot is a sunny day in Cuiaba, a large interior city of Brazil, during the burn season.

As an epilogue it should be pointed out that Brazil is making good progress in controlling the amount of burning compared to that which was going on in 1995.











Below is the region of “pyrocumulus congestus clouds (those due to fires below them) where the giant drops were encountered, near the city of Maraba, Brazil.  It was a little different than Kwaj!


The End (at last)


“Pyrocumulus”, an awful sight yesterday evening

There may have been some sharp eyed folks that saw a great looking Cumulus congestus in the distance off to the NNE of Catalina yesterday.   The shots below were just before 7 PM LST.  Perhaps there was a shower or thunderstorm on the Mogollon Rim.

Sadly, even I was fooled for a few microseconds until you notice that there is NOTHING even slightly resembling the size of that cloud anywhere in the sky.  Then,  it dawns on you that it must be a “pyrocumulus”, the kinds of artificial Cumulus clouds that form atop the highest, and hottest portions of fires when there is a bit of humidity in the air. Once the fire dies down some, then all you see is smoke, the last evidence of the trees and the plant life consumed below.  Likely was a new fire, too, dammitall.    It was probably 50-75 miles away;  also just visible in the satellite imagery.   The second shot is an attempt at a close up, marred a bit by some kind of large insect that happened to fly by as I was shooting.  Just above the horizon of that second photo, you can JUST make out the telltale smoke below the bottom of the pyrocu.  The last photo, from Hornepayne, Ontario, Canada, is an example of a pyrocu up close, just as it was forming.  This was due to a prescribed burn by the Canadian government.  The cloud droplets are white while the smoke is black.   The cloud droplets are about 100 to 1000 times larger than the smoke particles, and reflect (have a higher albedo) more of the sun’s light than do the smoke particles.


Rain update:  Still looks like a great onset of the rainy season after a little “hip fake” today and tomorrow, that is,  a slight insertion of tropical air ahead of an unusually strong, winter-like storm in northern California.  That weak insertion of tropical air should lead to a few weak, high-based showers and thunderstorms on the high terrain.  And with high bases, there will be the chance of exceptional winds near showers due to the virga and rain falling into otherwise pretty dry air.   After this little episode,  the normal summertime anticyclone aloft rears up from the Tropics and after a couple of dry days and plants itself to the north of us.  This allows more humid tropical air to arrive pretty much on time, around the 3rd and 4th of July.  So, get ready!  It will be so great to see all the dust washed off the cacti, the stupendous sunsets, the lightning, the rainshafts, the whole works.  I’ve waited a year for this season to roll around again!  There won’t be a living thing that is not “happy” by the middle of July I would think, unless there has been too much flooding, always a possibility here.