Category: Altocumulus clouds

“And I think its going to rain today”

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

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

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

 

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

 

 

 

 

 

Near miss on rain; pretty clouds and a nice sunset

Here are a couple of scenes from pretty yesterday, a day that the phony numerical models had rain predicted for us one to two weeks in advance, and then dried that system out as far as we here in Catalina are concerned as the days got closer.  This happens all the time in the models, so you would think I would develop a tough skin to these repeated disappointments, but I haven’t.  Oh, photos.  Here they are-the middle panel having a nice pancake-like stack of Altocumulus lenticularis clouds northeast of Charouleau Gap:

 

 

 

 

 

 

 

So what was the missing ingredient? Well, the core of the jet stream at around 18,000 feet above sea level, what we call the 500 millibar pressure level as well, stayed just to the north of us. If you have read this blog, you know that the core at 500 mb has to be over or to the south of us and that didn’t happen. Its a necessary condition in the cool season here, but not always sufficient. Shown below is last evening’s 500 mb map, courtesy of the University of Washington with station plots and infrared satellite imagery. Those two flags and a wind barb for our Flagstaff balloon site (“rawinsonde” site) shows that the core of the jet stream was just about right over Flagstaff at that time, and the wind was over 120 mph (105 knots)! Note that the wind at the same pressure height on this map is “only” 65 knots over Tucson.  By this morning, that core had settled a little more southward to between Albuquerquequeque and El Paso, and along with that the precip shifted a bit south as well.  Darn, had this happened 12 h earlier we likely would have gotten a small amount of rain.

If you look at a loop of the radar echoes during the late afternoon and overnight from IPS Meteostar, you will see that the precip is confined to near that jet stream location and northward.

Shown on the Washington Huskies loop is another powerful storm about to strike the West Coast.  THIS one WILL bring the jet stream core south of us as it passes over on Monday night-Tuesday morning, the 23rd-24th, and circumscribed inside that jet stream core will be moisture and clouds low enough to produce at least scattered showers, and may a nice rain band of a few hours duration.  So, maybe the rest of January won’t end up as rainless after all.

The best thing about this next trough is that it gets stuck as a cut off over west Texas and causes quite a bit of rain there in that drought stricken region for a couple of days.  Might have to drive over there and see how happy the people of west and central Texas are when the rains begin.

Don’t want to end this session without a long distance model teaser, “big storm” from IPS METEOSTAR as shown here valid on February 3rd at 5 PM AST.  Note how it resembles once again our early winter pattern of the isolated cut off upper low.  Hmmmm.   Maybe there will be something to this one because of this winter’s theme song of cut offs.

 

The End.

Twice as nice; 0.53 inches in Catalina (0.58 inches as of 6:39 AM AST)

What a superb rain that was last night.   It just kept coming until finally we piled up an astounding-to-me 0.53 inches by 4 AM this morning.  The regional rain reports from around Tucson can be found here.  As you will see, the upper regions of the Catalina Mountains got around an inch (1.22 inches at CDO wash at Coronado Camp now).  Mt. Lemmon probably got a little more, but the record says “0.00” due to snow at that elevation.  This is a substantial boost for our emerging spring desert vegetation after our four week drought.  This is so much better than that near rainless January of last year!  Looking at some of the statewide precip reports, it looks like the Catalina area and the Cat Mountains got more than anywhere else.  Lucky us.

If you would like to relive yesterday, at least in clouds, go here to the U of AZ time lapse.  One of the things you will see later in the day are Altocumulus lenticularis clouds over the Catalinas.  You will see their upwind edges spurt upwind (seem to go the “wrong way”, against the wind) as the lifted air got more moist, one of the tricks that these clouds can pull.  You will see quite a panoply of clouds in this movie, from Stratocumulus, Altocumulus, Altostratus (dead gray and smooth higher layer), Nimbostratus (when the rains come) along with some mammatus formations.  Hmmmph.   There’s that “m-word” again, the one I used so many times yesterday.  Wonder what’s going on?

“But wait, there’s more!”  

If you call now (well, actually if you continue reading) you’ll find that a few more hundredths of rain are possible this morning before about 8 AM AST, AND, (We interrupt this blog for an important message: “hey”, just started raining again now at 5:03 AM!  Yay!)

all of the model runs are indicating rain again on the 22-23rd timeframe; even the “pernicious” 00 Z run from the 5 PM AST global data.   (I have questioned that output of late, rationally or irrationally,  because it kept drying the State of Arizona out whilst the model runs before and after that time, foresaw precip in spades in the State.

Here is a sample of the IPS Meteostar renderings of what happens in our rain window of the 22-23rd according to our latest model run, one from 11 PM AST data.  Note green areas of precip in the 6 h ending at 5 AM AST, Jan 23rd.  This is pretty satisfying since another good rain will keep us on track for a great spring bloom.

On other fronts…

While I could go on to talk about all sorts of things due to the ambiguity of the subtitle phrasing above, I will actually only talk about weather fronts, not this or that. 

The coming floods in northern Cal-Oregon still on track.  Storms break through from the Pacific “under” the Bering Sea “blocking” high, one that diverts the potent Asian jet stream that comes into the Pacific into two branches, one of which is forced southeastward in the central Pacific where water temperatures are warm.  (Just heard some rain on the roof again.  What a nice sound that is!)  The other branch goes deep into the Arctic and merges with the southern branch in the eastern Pacific after it turns southward over AK.

Those warmer storms, heavy with semi-tropical rain clouds, race to the West Coast once the southern jet breaks through the weakening southern part of the blocking high.  And once that jet stream has broken through, its days before things change, so the duration of rain adds to the colossal totals certain to occur now. In a ten day span, beginning tomorrow, the peak totals in this event will likely exceed 30 inches of rain.

Here is the current weather map (5 AM AST today) from the University of Washington that illustrates the odd flow pattern developing now from the central Pacific to the western US.  The block  is developing from a ridge in the eastern Pacific now (evidenced by the lack of green contours in it) that extends from the tropics all the way to the Bering Sea!  It will fracture in its southern portion tomorrow.  It has overextended its “reach”,  in a manner of speaking, at this point, and will fail just like a dam break and all those clouds to the west of it will flood eastward.  Its a pretty exciting thing for us precipophiles.

 

 

Canadian behemoth

One particularly bruising storm, one the size of Asia practically, with “tentacles” from the Aleutian Islands to Minnesota, was shown to develop in this series of storms battering the West Coast in the European model run by Environment Canada based on last night’s data.

I show this output below because you RARELY see a low whose circulation is this big, at least one of the biggest I have ever seen, portrayed on a weather map (upper right panel).  The map below showing this colossal low is valid for the evening of Jan. 21st.  The entire West Coast would be battered by this bruiser.

The End.

 

 

Pretty and eerie skies yesterday; let the rain begin today

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

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

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

 

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

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

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

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

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

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

The End.








 




Models warming up to rain; some cloud shots from yesterday


Been kind of sitting around waiting for the billions/trillions of numerical model calculations to get it “right”, that is, to come back with some decent rain SOMEWHERE in Arizona after some pretty sad  dry model results over the past couple of days.

Today,  the great USA WRF-GFS model (rendered by IPS Meteostar) finally got it “right” by showing rain over Arizona on at least three days during the next 15 when it examined global data from this morning balloon, satellite, surface, aircraft, personal weather stations, rumors, TEEVEE weather presenters’ data, etc.   Here are the days on which rain is shown in our great state, a state that ranks 21st in objective measures of subjective happiness by US State.  The first rain is just this Sunday afternoon and evening, the 15th.  Be ready.   This is from the cutoff that got lost off the coast of Baja, one that was a week ago the models foretold that it was supposed to be over Catalina today!  Unbelievable.  It was only off by a 1000 miles.

The second AZ rain day is Saturday night into Sunday, the 21st-22nd.  This rain is only supposed to stay north of about Phoenix.  That’s OK.  That’s followed by a much heavier burst of precip on the night of the 23-24th, again mostly north of us (3rd panel).  That’s OK#2.  We benefit when the rain and snow falls in the north, too.

Lots to look forward to!

BTW, when that Pac jet slams the West Coast from the central Pacific, starting next Tuesday afternoon, it will cause a lot of excitement for weatherfolk and plain folk as floods develop over the following few days in northern California and Oregon.  In some places in northern California it has been as dry as the Great Drought of 1976-77, which was dang dry along the whole Pac coast.  They’ll soon be “exulting-complaining” about all the rain filling up the reservoirs and washing things away, respectively.  Watch your local newspapers.

 Yesterday’s clouds (see below)

Loading Images


What a great, if a cool day it was, to watch Altocumulus and Altostratus pass by. There were a number of places where it looked like an aircraft may have created some virga in supercooled Altocumulus clouds, but lots of natural mammatus type virga, too. You can see the whole day go by from the U of A campus time lapse camera, pointed at the Catalina Mountains, here.  That small hole in  the middle shot was likely caused by an aircraft, the ice from that passage, long gone.  And, of course, there was the superb sunset!  How nice it is to be here.

While waiting for a “better” numerical model output….

As we say, “if you don’t like the model run now, wait 6 h and get a new one with different results.”

Last night’s model run based on global data taken at 5 PM Arizona time, was truly mediocre in rain in Arizona in the week to two weeks ahead.  Sure, great storms bash northern California, where they need rain desperately this year, and Washington and Oregon as well, ones that are likely to make the news, the jet stream was again retracted to the north in that run.  Take a look at this, courtesy of IPS Meteostar for Sunday, January 22nd and notice where the reddish area is compared to the output I showed yesterday (below).  The impacting jet stream is now centered over Portland, Oregon, fer Pete’s Sake!  Its outrageous.  No rain is imminent here with a map like that!  We’re on the wrong side of the jet stream as anyone can see.  Just yesterday, we had the kind of output from global observations that showed the Pacific jet stream (JS), this on model calculations from only six hours earlier than the output shown in the first panel.  As you can see, in that slightly earlier run, the JS is shown bursting into California at almost the exact same time on January 22nd instead of into Oregon.  That second panel was loaded with rainy portent for Arizona (see last panel)!   So, its worth checking into IPS Meteostar, a weather provider I favor for their nice imageries, later today to see what the 5 AM AZ Time global obs say.

Why do these fluctuations occur that prevent confidence in weather predictions more than a few days out?  Well, we have a reason:  “bad balloon.”  (Or “missing balloon.”)

While small changes in initial conditions in themselves can cause vast changes in model outputs many days ahead, sometimes these problems are caused by errors in measurements and probably more often, missing measurements in the global network.   The models then have to guess what is happening in the missing data regions, usually with the help of satellite measurements, and/or use the prior model run’s prediction of what was supposed to be in the missing region.

I am getting the impression that the quality of the 00 Z runs are not as high in reliability 1-2 weeks in advance as those at 12 Z.

In the meantime, while waiting for a new more better model run, a word about today’s clouds…

Right now (8:44 AM AST) we have an overcast layer of Altocumulus (Ac) with patches of Altostratus (As) clouds. The former are mostly composed of droplets while the latter are ice clouds. The TUS sounding indicates that the Ac layer is based at -20 C (-4 F). Those Ac clouds are ultraripe for aircraft produced ice, and right this minute, I would say that much of the virga around is due to aircraft on those “supercooled” clouds. This is particularly evident if you see straight lines of virga, or a hole with ice in it. Here’s a line of virga (those downward hanging protuberances called “mammatus”, to the SW of Catalina right now that looks suspiciously like it may have been produced by the passage of an aircraft through some Ac.  That passage would cause tremendous numbers of ice crystals to form, and then fall out as fine snow we call virga.

“(the reviewers)… are still unconvinced by these controversial claims.” A science story.

Alternate titles, choose one or all:

 1) The story of APIPs (Aircraft-Produced Ice Particles)

 2) They said it couldn’t be done, but they did it anyway

 3) ‘An embarrassment for the airborne research community’–Dr. John Hallett, 2008

OK, “baby I’m bored” with the lack of clouds and precip,  and so I thought I would share my boredom with this long tome on aircraft effects on clouds.  Why not bore other people if you’re bored?  I’ve thrown in some alternate titles above to peak and pique your interest.  Speaking of “thrown”,  Mr. Cloud-maven person was also thrown off his big (I mean huge1),  young horse lately; “JohnT”, as he is named, doesn’t like people to sit on top of him sometimes.  Not easy to sit at a computer these days, hence the lack of “acitvity.”

OK, on to the story of APIPs.  The title quote was written in 1982 by the Chief Editor of the American Meteorological Society’s, J. of Climate and Applied Meteorology (JCAM) summing up the opinions of the three reviewers at the bottom of a second rejection notice of a manuscript, one that had been fluffed up with more evidence of APIPs.   However, the Editor allowed us (me and Peter Hobbs, director of the Cloud and Aerosol Research Group at the University of Washington) another crack at it, and by the THIRD submission (requiring a bit of chutzpah),  a colleague and me had found photographic evidence of aircraft having produced icy canals in supercooled clouds, and that visual evidence really pushed our third manuscript, now as big as JohnT, over the top in getting accepted and  published.

The phenomenon came up again last summer in a Wall Street Journal article, one in which Mr. Cloud-maven person was asked his opinion.  This phenomenon (APIPs) is attracting more attention these days, so I thought I would pass this background story along.  I hope will encourage authors with rejected manuscripts, which I myself have quite a few.   You might have something really good.

Yes, that’s right, lucky Mr. Cloud-maven person was involved in this interesting chapter of science that happened way back in the early 1980s when he was part of the flight crew in the University of Washington’s Cloud and Aerosol Research Group (CARG).  Occasionally, and mostly in studies of ice development in Cumulus clouds, I got to direct the University of Washington’s first research aircraft, a 1939 manufactured, Douglas B-23, into Cumulus and small Cumulonimbus clouds.  It was heaven for me, a storm chaser type person, having done that here in AZ way back in the mid-1960s chasing summer thunderstorms all over the State with my camera and rain gauge.

We had a viewing dome on the top of the fuselage of that B-23 and I sat in a swivel chair, head protruding into the “bubble.”   I was kiddingly referred to as the “bubblehead.”  I think they were kidding, anyway…  Those who know me will understand that title.   Sitting there with head in the bubble, allowed me to see EXACTLY where we exited a cloud and could direct the pilot to EXACTLY that same cloud blob we had just exited.  The pilot was fond of turning the plane sidewise for this return so that one wing was pointed straight down in the turns and we often got back in within 90 s to two minutes.  It was an exciting as well as sickening experience.

We did that because we wanted to see how that element of the cloud had changed with time.  Did ice form?  Did the drops get bigger or smaller?

This viewing dome gave us a huge advantage over other research aircraft doing this kind of research.  Below, that B-23 aircraft sitting on the tarmac at Boeing Field, Seattle2.  The second photo is a view from the “bubble” located toward the rear of the fuselage.  Nice!  I was so lucky!

One day, while looking over our Brush strip charts from the flights, I noticed some odd spikes in the ice crystal detector we had. Also, since we were one of the first groups to get a probe that produced shadows of the particles in the clouds as we flew in them, I was able to see that the particles producing those spikes were oddly similar sized, as though they had formed simultaneously, something not seen so much in natural clouds. Pretty soon it became apparent that these spikes and odd particles ONLY appeared after we had gone through the same cloud for the second or third time.

I remember walking into Professor Peter Hobbs grand office with a strip chart with those ice spikes and saying, “I think our aircraft did this.”

He was unfazed; did not have a particular reaction.  Peter Hobbs was always open to new thoughts, and that helped allow me to go forward with a further investigation even if it meant some of our past data and publications might conceivably be compromised, ones however, I was not involved with as a fairly new (5-years in) employee at the U of WA.  No vested interests here!

After awhile, after aircraft plots showed that the spikes were within tens to a couple of hundred yards (meters) of where we had been before in a Cumulus cloud, a very short paper was written up on it and submitted to JCAM in late 1981.  It was quickly rejected.

Ours was a highly controversial finding due to both the high concentrations of ice that we found (hundreds  to over a 1,000 per liter) but most of all due to the temperatures at which we were reporting this effect, -8 to -12 C.   Our plane was,  in essence,  seeding these clouds with ice crystals, changing their structure.  Since the volume affected was initially quite small, it was likely that only having the viewing dome allowed us to find them on the second and third penetrations of the clouds.

This inadvertent aircraft effect had even been looked for by our aircraft group leader, Dr. Prof. Lawrence F. Radke before I had arrived and after the University of Washington acquired the B-23.  He didn’t find’em though.  Larry was also aware that an aircraft COULD do this in those early days with the B-23.

So, when I found them and a paper began taking shape, the skeptical Larry Radke called them,  “Art-PIPs.”  It was so funny.

Later, with the skeptical Larry at the helm, we got some money from the NSF to try to produce them in various clouds, and sure enough, we did.  It was amazing finding those crystals in those test flights since even I couldn’t be absolutely positive sure that this was real.  Why hadn’t this phenomenon been reported decades ago?   That, too, was part of our problem:  why you, why now?  And why hadn’t I seen the holes and canals of ice produced by aircraft as a cloud photographer for decades even by then?

Some ground observers had seen trails and holes in “supercooled” clouds like Altocumulus.   Those holes and canals were occasionally reported over the decades (!), but not in the technical journals.  A couple of really lucky observers had even seen the type of aircraft that had caused them.  But the airborone research community, ignored or did not know about these reports, ones that appeared in non-technical weather magazines like Weatherwise, Weather, and Meteorological Magazine (the latter two in England).

Furthermore temperature data were nearly always absent in these visual reports.  So, it could be reasoned they had occurred at very low temperatures, below -25 C or -30 C.  Clouds that cold, but still consisting of only or mostly of liquid droplets do occur, the ones in which an aircraft could leave an “ice canal” or a “hole” with ice in the center, falling slowly out.

If we had been reporting our finding at cloud temperatures of -25 to -30 C, maybe we’d have got into the journal on the first try and reviewers would have yawned.  But at -8 to -10 C cloud temperatures?  No way!

Why?

Research aircraft had been going back and sampling the same cloud, usually a Cumulus one,  for a couple of decades by the time of our report.   Furthermore, those aircraft re-penetrations were almost always in the same temperature domain that we were reporting this effect, to about -5 t0 about -15C.  And one of the main findings in those early days of aircraft sampling was that nature was producing far more ice in clouds than could be accounted for in measurements of ice nuclei, particles on which ice can form.  Concentrations of ice nuclei were largely determined from small cloud chamber measurements made on the ground.

These early cases of high ice concentrations in clouds with tops that were not very far below freezing (greater than -15 C) were called cases of “ice multiplication” or “ice enhancement.”   No one understood how such ice developed and many theories were put forward initially in the 1960s.  The issue was largely explained by the “Hallett-Mossop riming and splintering mechanism”, a mechanism discovered in the mid-1970s and today is still believed to be the primary reason for high concentrations of ice crystals in clouds with tops warmer than about -15 C.  Oh, yeah, ice multiplication is real and NOT due to aircraft penetrations!

But our paper on APIPs, if true and published,  would cause researchers to have to go back and look at their research data (even us!) and investigate whether their own aircraft had contaminated their published studies with artifact ice crystals.  An entire body of airborne literature would come under question.  This was not a pleasant thought for anyone who had  conducted such studies.

Why would you go back and sample the same cloud?

To see how it changed with time.   How many ice crystals formed as time went by?  Where, and when?  These were techniques used in trying to get to the bottom of the “ice multiplication” phenomenon.  In fact, the Chief Editor of JCAM himself was involved with numerous aircraft that sampled clouds in a huge summer Cumulus cloud study program in Montana in those days (called “CCOPE”-Cooperative Convective Precipitation Experiment)  That study, like so many other airborne studies, was to determine how ice onsets in clouds, how high the concentrations of natural crystals were in clouds with various cloud top temperatures, and the potential of cloud seeding to increase rain.

While academic scientists did not particularly welcome these reports and were dubious and largely ignored them (did not change their aircraft sampling strategies), or when they looked could hardly find any APIPs, it was soon evident that purveyors of cloud seeding services were elated!   Our finding suggested to THEM that all that natural ice formation reported in re-penetrated clouds  in research articles over the years might be wrong, and rather due to ice produce by the aircraft!  Maybe those clouds that had been reported with a lot of natural ice, which made them unsuitable for seeding, was because the researcher’s aircraft had produced it, not nature.  Purveyors of seeding would like clouds that are below freezing, about -5 C and colder, with no ice in them.  If the concentrations of natural ice crystals forming in clouds ice get to 10s to 100s per liter,  those clouds are deemed unsuitable for seeding to add more ice.  The crystals might be too small if you add more in those cases, and not fall out.  If surveys of clouds in a region find that they have lots of ice in them, its “no paycheck” for commercial cloud seeding interests. (Usually, cloud surveys aren’t done before commercial programs begin.)

Thus, those who had interests in cloud seeding actually saw our result as a way to discredit findings of high natural ice concentrations in clouds, findings that made them appear unsuitable for seeding.  It was a bogus argument since numerous FIRST penetrations of clouds had encountered high ice particle concentrations, still, they had SOMETHING to hang a hat on.

This was indeed an ironic twist, being supported by the cloud seeding community!

Me, usually with Peter Hobbs as a co-author, had been discrediting various published cloud seeding results in the literature via reanalyses and journal commentaries for several years (e.g., here) when our APIPs finding finally hit the “streets” in 1983.

Given these a a priori possible biases between academia and in the commercial cloud seeding world in detecting APIPs you can imagine where the major “confirmatory” studies of this phenomenon came from. Yep, those associated with cloud seeding programs!  It took 8 years (1991) for our finding to be independently confirmed (the best way) using several types of aircraft in marginally supercooled clouds.   Then pretty much the same workers amplified their findings with another paper in 2003 WOODLEY et al. 2003.  For those of you who don’t know the cloud seeding literature, Woodley and Rosenfeld and Peter and I have had a major clash in the cloud seeding literature (i. e. and big i. e., and bigger still)

We loved it!  They loved it!  Even the great John Hallett got involved and found in lab experiments that the mechanism was the extraoardinary cooling at the prop tips, momentarily down to -40 C, a temperature at which ice forms spontaneously in high concentrations (here).  It had also been suggested that prop aircraft could do this by the late Bernard Vonnegut back in the late 1940s in a less widely distributed report from a General Electric research lab and in the J. Applied Physics.

Today this phenomenon is taken pretty much for granted, and has been more widely detected from time to time in satellite imagery in thin clouds as here.  In thicker clouds, the effects of aircraft go largely undetected.  Recently, in a widely distributed news release that accompanied their formal publication, Heymsfield et al reported a case in Colorado in which aircraft-produced ice effected a snow shower on the ground instead of just being a hole or canal in some thin clouds as we normally see.  They opined that aircraft could actually help delay flights from the airports that they were taking off from or landing at in special conditions.  (That’s what the Wall Street Journal article was about.)

Why was it an “embarrassment” to the airborne research community, as John Hallett (of Hallett-Mossop) asserted?  Because they should have found out about APIPs right from the get go, especially in view of the occasional lay publications that had photographs of ice canals in supercooled clouds even in the 1940s, ones  that could only have been produced by aircraft.  It turned out to be a major oversight.

Below, a cartoon I did before the paper was accepted making fun of how a researcher, thinking that natural ice multiplication processes were taking place (i.e., the Hallett-Mossop riming splintering mechanism) might overlook all those ice crystals streaming off, in this case, the Husky 1 aircraft.

Below, some photographic evidence of what aircraft can do to supercooled clouds, the last one taken about two weeks ago over the Cat Mountains.

Finally!  The End.

 

 

 

 

 

 

 

 

—————————

1The 6-year old horse in question is about 15 hands, 1200 lbs, not really a Clydesdale.  I have overemphasized our horse’s size for personal reasons.   You don’t want to be injured getting bucked off a Shetland pony, but rather something HUGE!  It just sounds better.

2That B-23 aircraft, wherever it went, brought a crowd out to see this antique “tail-dragger.”

Low spin cycle continuing off Baja; water being added

That enfante terrible now dawdles over the coastal waters of California and northern Baja today, adding some water to its central system as seen here from IPS Meteostar.  Note, too, a scruff of Stratocumulus clouds racing northwestward in the Gulf of Baja abouit the latitude of the border between north and south Baja.  This is good.  Still, this is a marginal storm as it trucks through on Sunday evening and I will be happy if we get a quarter of an inch.  Mods don’t think rain will get here until the upper center is upon us later Sunday.   Here is the whole map forecast sequence showing temperatures and winds aloft at 500 mb from the U of Washington unranked Huskies who play #12 Baylor in the Alamo Bowl –what a horrible bowl game that is for Baylor–on Dec 29th.  Still, as a spin off myself here into the SW like all of our lows this year, but from the U of WA, I will be rooting, of course,  for the “company team” along with my friends and former grad students with whom I worked.  BTW, these are pretty maps with lots of color as you will see.

You will also notice in this 4 day series of forecast maps for 500 mb that yet ANOTHER low drops into the Yuma area replacing the current one that begins to move toward us later today.  That new low develops via the back door from Colorado and nests over Yuma as a cut off at the end of the forecast cycle above.  That ‘s an unusual trajectory for a low! However, mods think its too dry to produce any rain as you might imagine.   But with another low center aloft ending up in the SW, it demonstrates again our characteristic pattern for this early half of the winter, having become something of a low magnet.  It certainly has been strange to see so many cut off lows.

BTW, the longer term picture after our little rain is a dry one for the next two weeks;  it may well mark the end of our cut off low fantasia.  Hope not.

Today’s clouds…

The marginal amount of moisture circulating around the periphery of this Baja low, I think will spin out some spectacular middle and high cloud streaks and patches over us such as Cirrus, Cirrocumulus with its tiny granulations, and Altocumulus lenticularis here and there, ones that often break up into small and interesting cloudlets downstream.  Get yer cameras ready!  Some of this began to happen yesterday afternoon.  Sometimes you see the most amazing tiny delicate patterns, very photogenic.

Here are a few shots from yesterday, beginning with that sunrise patch of Altocumulus and ending with a sunset shot.

Grandson of “Frankenstorm” knocking on Heaven’s door (Catalina, Arizona)

Well, I think Catalina, AZ,  being next to the Catalinas, is “Heaven’s door”.   I think, too, to have a second consecutive thought,  that we’ll get more than an inch out of this Big Boy which is rare here in Catalina for a storm in the wintertime.  Not close in areal extent to the original “Frankenstorm” that struck the West Coast in January 2010 with record setting low pressure, but a potent one anyway.   In the January 2010 storm we received 1.41 inches the first day and 1.18 inches the second to “ice” a fabulous wildflower bloom that year.  We sure seem headed to a fabulous bloom season this year, too.

BTW, there has been a lot of rain in droughty Texas.   We are brothers/sisters in drought relief it seems these days.  How nice; adds to the holiday cheer.  Maybe the price of hay will go down..  It seemed interesting to throw something about Texas in there.  Here is a map showing that great TX rain of yesterday from WSI Intellicast1.  These radar-derived amounts precipitation are pretty much spot on–I’ve checked ground gages a number of times.  We should be seeing “green”,  1-2 inches) over much of AZ in the next couple of days, too.  So, the map below is like a preview for AZ.

Speaking of green, look at the “green-for-rain” in AZ in the lower right hand panel of this forecast for this afternoon ending at 5 PM MST.  During the prior 12 h, beginning at 5 AM MST, the entire State of AZ is virtually covered.   I am just beside myself when I see a map like this!  And look how far to the south of Baja California the circulation of the storm extends.  Its gorgeous to see this.   I guess there could be some flooding here and there, and some “snow birds” might complain about the “crummy AZ weather”, but….you can find people who will complain about anything.  See the whole wonderful model sequence of rain and mayhem in AZ here, and in much more detail from the U of A weather department, here.

Look, too, at how excited the National Weather Service, Tucson is!  They must have 50 bulletins out–be sure to keep reading them.  They are really having a lot of “fun” down there, too.

Late breaking storm bulletin:  We have sprinkles in the area (0425 LST).  Check this radar-cloud map out from IPS Meteostar.  What a great day this is going to be!  Enjoy.   Good chance we’ll see water in the CDO and Sutherland Washes, and maybe some snow mixed in with the rain as the storm closes out Tuesday evening now.

But is this storm the end of our “fun” weather?  Oh, no, my friend.  Another cut off low develops in our area after speeding down as a trough out of the NW in five days.   Another round of significant rain is likely, though not as much as this one.

Some cloud notes from yesterday, including some chat about the unusual streaks.

In that warm afternoon yesterday, it was so great seeing sheets of Cirrus and Altostratus (ice clouds, Altostratus with heavy shading) massing on the horizon, knowing that this time it was NOT just going to be a sky decoration for a nice sunset, but were clouds filled with stormy portent. You probably noticed the lack of sunset color due to the extensive coverage of those clouds upwind. No break allowed the sun to under light them, a sign of extensive clouds upwind to the southwest.

Also, unless you were blind you saw some unusual events in the thin Altocumulus (translucidus) layer yesterday: ice canals and splotches of ice produced by aircraft that flew in them. When so many happen as did yesterday mid-day, its a good bet those Altocumulus clouds, though comprised of liquid droplets, are terribly cold. While the TUS morning sounding did not pick up this mid-day layer, one can be confident that it was likely colder than -20 C or -4 F.

What you also saw was examples of how the presence of ice within a droplet cloud, causes the droplets to evaporate, and the ice crystals to grow and fallout, something that happens on our rain days. However, because there were so many ice cyrstals produced by these aircraft (almost certainly all jets) they compete for the tiny amount of water available at -20 C and form small crystals with little fall velocity.

So the trails of precipitation are very fine and don’t go very far. Here are some examples of that rare phenomenon, rare because for us to see it, takes a thin, cold water droplet cloud, and it has to be high enough so that aircraft are frequently penetrating it. One wonders why, in some of these cases, the trails yesterday were so long with an aircraft probably could have climbed or descended a couple of hundred feet to avoid flying in a light icing producing cloud (the Altocumulus layer composed of supercooled droplets)?  Note “ice optics” in ice canal in the first photo, a weak sun dog so I didn’t just make it up that the canal was ice.  I you wanna know more about this phenomenon, go here and/or here.

Great weather map day

Check this map out below from the University of Washington Huskies Weather Department.  The whole 24 h series of sea level pressure maps is here and watch how things change in the SW and western Arizona just in that time.  You rarely see lows of this magnitude in our area as we have right now, and this much change in just 24 h in a sea level pressure map.  As you can see from the low center  centered over Ajo, AZ, (below) the air is going in counterclockwise circles in our State.  Well, of course, friction caused by cactus and mountains turns the air toward that low center, trying to get rid of it.  But, the forces producing it so far are stronger so far and so it has a very low pressure (less than 1004 millibars) for this time of year over AZ.

Note, too, that all the clouds and precip (shown here) and by those white areas on the map below, are to the west and north of the center.  But that will change as the upper air low center (second map) spins back to the southwest a bit and the air over us changes in direction from the southwest, as it is now on this upper level map, to a more southerly direction in the hours ahead.

In the meantime, Pacific air should be gaining a presence over the interior of Baja and begin circulating from there up toward us.   Clouds should literally start appearing out of the clear skies to the southwest of us in satellite imagery today (such as here) and then those clouds will work their way up this way, likely increasing in depth and coverage as they do.

Another exciting prospect is that this same process, clouds appearing out of the blue, will likely start happening over us as the day progresses, and maybe, in view of the strong winds aloft, some nice “flying saucer” clouds, namely, Altocumulus lenticularis, flat, lens shaped clouds that hover over mountains will show up over the Catalinas.

These are great days ahead for weather folk, and I hope in spite of any inconveniences caused by quite wonderful inclement weather, you will enjoy this dynamo of a weather day.  Of course, you wanna go here, to the NWS, for all the great details.

Rain?  Supposed to begin in these parts between around 4 PM and 6 PM today (you can see this here from the U of WA model).   Interestingly, this model has a rather thin band of precip sitting over us for more than 12 h.   Good grief!  Too good to be true I suppose, since we might get well over half an inch, and would certainly, if it happens, push our wildflower prospects for this spring up in view of our 1.83 inches here in Catalina in November.

Also this;  a nice satellite view of the US where you can see the night lights of the cities, if you’re up early enough and haven’t seen it before.

The End for now.