Category Archives: Circumzenithal arc

“Peru’s Niño”

I thought you’d like to read this (Peru’s Niño), forwarded to me by Niño expert, Nate M.   Pretty incredible to read about what is happening down there in the wake of the Big Niño of 2015-16,  which really turned out to be more of a couch potato in terms of weather production in the Great SW.

But, all this winter,  along the Equator near the coast of South America, there has been something we used to call an “El Niño”,  but is downplayed or ignored these days because of a new definition that seemed to explain more weather when it occurred, “Region 3.4” a large zone along the Equator WAY out in the Pacific rather than something near the South American coast (that zone now called, “Regions 1 and 2”),  as nicely illustrated by NOAA here.

But what has been the effect of what we might call the “Classic Niño”, a warm strip of water along the South American coast, one that doesn’t extend too far into the Pacific?  “Read all about it”, as they used to say.   Its pretty remarkable.

And here’s what the SST field looks like.  Its boiling down there off South America!  (Speaking figuratively, of course):

Sea surface temperature anomalies as of yesterday from the Navy!
Sea surface temperature anomalies as of yesterday from the Navy!  Wow.  That hot water is fueling giang Cumulonimbus clouds, ones that spew out huge anvils that can affect the weather in the mid-latitudes, disrupt the normal winter patterns of where highs and lows like to go.  Could such a warm anomaly, limited to the near coastal region of South America, have created this astounding winter in the West?

Peru’s Niño can be thought of as a “classic Niño”, the ones written about in the decades before about 1990 or so when the definition of what constituted a  NIño (or Niña) was expanded and delineated more sharply among several definitions that were floating around. We ended up focusing on a region WAY out in the Pacific Ocean called, “Region 3.4” that SEEMED to explain more over the prior years.

What’s so interesting about this is that the “Classic Niño” has been underway pretty much all this winter, and we’ve had, especially in California, a classic Niño response; that is,  abnormally heavy precip farther down the West Coast that no one anticipated.


Well, the correlations with Cal precip and “classic Niño” occurrences will take a huge jump upward after THIS winter!

End of Statement (hand-waving)  on Niñoes.


Local weather statement:  for immediate release

Cooler, fluctuating weather foretold here for that latter part of March, I don’t know how many weeks ago, is on the doorstep after the long, anomalously hot dry spell.  Poor wildflowers have been suffering, too, fading, looking a little stunted after a great beginning, one rivaling the great displays of 2010.

All of the local weatherfolk are on top of this now, and so no point recasting that stuff.  HECK, you can go to Weather Underground1
and get as “good as can be” forecast for Catalina (Sutherland Heights) out to ten days!  And, there’s nothing worse for a weather forecaster with forecasting in his blood, than to be excited about an “incoming” and when you mention it to a neighbor he replies, “Yeah, I heard about that already.  Supposed to get a quarter of an inch.”  There is no air whatsoever in the “balloon” after that.  So, if you have a weather-centric friend who says something about the upcoming weather, pretend that you haven’t heard about it yet, “DON’T say something as hurtful, as “Yeah, I heard about that already.”

So, here, we go the long route because most weatherfolk are afraid to go too far into the future because its often WRONG.  Our models tend to lie a lot after about even a week, so only the brave go out even ten days!

However, here, we go out as much as two weeks and more because its not a truly professional site but rather want to get something out there earlier than other people, sometimes called a “scoop” in the news and weather business.  That’s why our motto here is, “Right or wrong, you heard it here first!”  Furthermore, if a longer range forecast posted here is WRONG, you won’t hear about it anymore!

Cloud maven person will say this about the first incoming of several fronts:  comes in early Thursday morning, its strong!    Rainfall potential:  10% chance of less than 0.12 inches, 10% chance of more than 0.75 inches.  Best of those is the average, or about 0.4350 inches in this one.  It has great POTENTIAL to be a soaker, but mods have been all over the place; hence, the large range of potential amounts.  At least some measurable rain seems to be in the bag, a paper one please, because plastic is insidious.  Note, CMP’s forecast is more generous than that found in WU’s latest forecast for Catalinaland.

The weather WAY ahead, unprofessionally so

Let us look beyond the professional forecasting limits to April:

We know we got several storms/fronts zipping across AZ as March goes out like a lion, but what about April?

Looks like that pattern will continue into April with temperatures below normal for the first part.  The end of the unprofessional forecasting portion of this blog, though we do have our NOAA spaghetti to hang our umbrella on….  Check it out for about two weeks ahead.

Some clouds recent clouds, including a couple from yesterday

2:33 PM.  Yesterday afternoon saw a few globs of lenticular forming on top of mini_Cumulus clouds, ones that made you think the summer rain season could be at hand, given the 90+ heat of yesterday around these parts.
12:52 PM.
12:52 PM.  A high  (above 30 kft above the ground) and cold (less than -40°C patch of Cirrocumulus cloud that is going to transition to CIrrus over the next 10-20 minutes.
1:12 PM:  Later that same patch as those cloudlets spread out and merge into just an ordinary Cirrus after being that delicate-looking patch of Cirrocumulus. Most Cirrocumulus clouds are not this cold, but rather evaporate or fatten into larger elements of “Altocumulus” clouds, rather than transition to Cirrus.
Had a nice sunset a couple days ago (15th), some liquid Altocumulus cloud slivers with higher Cirrus.

The End

1Although “Weather Underground” might sound like an org has a radical origin, maybe something left over from the late 1960s, this particular one was NOT formed by 60s “weatherman” terrorists like Bill Ayers and Bernadine Dohrn (the link is for those of you who may have set trash cans on fire, as happened at San Jose State to protest the Vietnam War, to look back at those days in horror or nostalgia; take your pick) , but rather by genuine weather geeks (haha, I count myself among them, those that can’t get enough of weather, there can never be too much, like the guys mentioned in this “Cloud City” article.)

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

What a day, Mr. and Mrs. Catalina!

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

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

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

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

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

Some photos documenting the excitement of yesterday

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


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


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

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

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


The End


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

Another fireball over Tucson! Backwards halo seen, too! Rain on tap

Check these out in yesterday’s “Olympics of optics” where all kinds of goofy optical things were seen:

3:19 PM.  Fireball crosses Tucson skies.
3:19 PM. Fireball crosses Tucson skies leaving long plume of “smoke.”  Photo not touched up in any way shape or form because that would be wrong.  Note: always carry your camera with you since you only have seconds to capture something like this.
3:19 PM Fireball crosses Tucson skies 2.
3:19 PM Fireball crosses Tucson skies 2.


3:57 PM. Then there was this “wrong way1” partial halo a few minutes later.  Could it be another  sign of climate change, as almost everything that happens is? The sun is below the bottom of the photo; haloes are supposed to go around the sun not around nothing.  When a partial halo around nothing occurs like this, its called a “circumzenithal arc”  caused by tiny, pristine ice crystals like hexagonal plates.   If you want to read about optics of all kinds, go  to the University of Washington Huskies weather department where they have optics chapter online.



















4:10 PM.  Contrail passes through or above Cirrus uncinus.  Yesterday was one of the top (worst) days for contrails above and in view of Catalina IMO.
4:10 PM. Contrail passes through or above Cirrus uncinus. Yesterday was one of the top (worst) days for contrails above and in view of Catalina IMO.  Note lines of contrails above and behind weather station. We hope it was due to an unusual confluence of conditions such aircraft flying a heights different from normal due to a peculiar wind profile, Cirrus moisture at the level of the airways, that kind of thing since we rarely see as many as yesterday.


 Today’s clouds

Thickening and lowering, ho hum, the usual as a trough aloft (bend in the jet stream winds up there) off southern Cal and Baja approaches today.  Ahead of the bend in the winds, seen in the map below, the vast layers of air rise ever so gradually, something like cm per second.   But, its enough to produce sheets of clouds.

What kind of clouds?

Heavy, dense and gray ice clouds we call Altostratus (As), with thicker and thinner spots should dominate the day.  Then as the moist layer lowers,  that is, as the As  “bases”,  really just comprised of falling snow that only looks like a solid bottom, get lower, patches of virga will start to reach the ground later today.  Altocumulus ought to be around, too, water droplet clouds not cold enough to be completely iced up.  Expecting those layer clouds, or undercutting layers to be low and lumpy enough to be termed Stratocumulus late in the day.


The strongest winds at 500 mb (around 18,000 feet above sea level) will be to our south beginning today, a necessary condition for virtually ALL wintertime rain here.  CM is expecting some rain to fall in Catalina later today, or tonight as this bend in the winds aloft goes by.  Expected amounts in this first wave,  trace, minimum to 0.25 inches max by mid-day tomorrow.

Its really dicey situation since its not clear how deep the moisture is off Baja now, but looks potent enough for as much as a quarter inch from this keyboard, though less is more likely.  Sorry the range is necessarily so great.

BTW, the WRF-GOOFUS model didn’t have ANY rain predicted for this time frame period in both of the 5 AM  AST and 5 PM  runs of yesterday.   So, we’re out on a bit of a limb.

After tommorow….

After 5 PM AST tomorrow,  all peoples and models see more rain for Catalina as two waves/troughs barrel in right behind the first one that goes over tonight.  The 2nd and 3rd ones produce a couple of rains through Thursday with big breaks likely in between.

The total amounts for Catalina between now and Friday morning still look like they will be contained within the range of  0.25 inches (things don’t go so well;  disappointing really) and an inch (things go really well).  Best guess is average of those, for a few day total of 0.625 inches.

The End


1Remember “Wrong Way Corrigan”? Picked up that fumble and scored a TD for the other team?  Maybe it was an early sign of the effects of concussions in fubball.