Author: Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.

The Tucson storm passes by Catalina like so many other September storms

With continuous thunder and threatening skies for Catalina, the mammoth Tucson storm that dropped a record 2.83 inches for the wettest day ever in September at the International Airport passed by Catalina early yesterday afternoon.  Here’s what a fraction of it looked like (using a bad ISO setting, darn it).  Also at the TUS AP it has become the wettest September of record halfway through the month with over FIVE and a half inches!

Of course, we here in Catalina land have been missed by most of those heavy September rains and have had only a crummy 1.17 inches.  Still, better than nothin’.   And there have been some fabulous sights during these past days.  Below are a couple of shots from yesterday.  That easily visible roiling motion in that last shot, if you saw that Cumulus congestus-going-to-Cumulonimbus, was a real indicator of how unstable the air was, that is, how easily it could go upward yesterday.  This situation us due to the cooler air aloft we have right now, along with mid-80 temperatures at the ground.   This is the kind of roiling, churning action you see in those big boys in the Plains States, East, and South when severe weather lurks.

Mods think we have a chance for rain today, too.  Maybe it will be our time, we will win the rain lottery today.

Below, thanks to the U of AZ, we have a time lapse movie of part of the storm, anyway, to the right side of the image.

Dreamy weather ahead:

Of particular excitement in the longer range NCEP (“government”) models, although almost certainly wrong as they usually are that far in advance, is that a tropical storm advances toward Arizony in early October.  Mark your calendars.  Might as well.


 

 

 

 

 

 

 


Another summer thunderstorm day!

We’re on the cusp, of course, for the end of the summer rain season, and so every day like yesterday is a particular treasure.  Take a gander here at the bulging morning Cumulus congestus and Cumulonimbus (albeit, marginal ones) clouds early on over the Cat Mountains.  Note detached top of small Cb to left with virga.   Some science:  note, too, that it appears to be a droplet cloud with snow virga underneath.   The presence of a droplet cloud tells you that the cloud top did not get excessively cold, probably no lower than about -20 C.   Those big boys of the afternoon and their all ice, spreading anvils would have tops colder than at least -30 C.

Did you notice, too, how much lower the cloud bases were yesterday than the prior day?  (Com’on!  You’re supposed to notice things like that as a nascent cloud assessor!)  So, all in all, I was very happy yesterday.  Note in the second photo, this tiny start up Cumulus cloud seems to be making an unseemly gesture to the clear sky above, as though it will alone fill in that overly blue sky.  Well, it was joined by its big brothers later in the day to produce some nice showers, 0nly 0.05 inches here in Catalina “Heights”, but 0.16 inches just a mile N in the Sutherland “Heights” district.  Here’s what it looked like later on yesterday afternoon from Sutherland Heights:

Lastly, another one of our glorious sunsets to top off another exciting weather day.

Scattered rain in AZ forecast next ten days!

Last night’s model runs continue to indicate a showery spell of no less than 10 days duration in the State of AZ.  IPS Meteostar, a private weather provider,  has repackaged the National Center for Environmental Prediction numerical model predictions here.  No one cannot be excited by this prospect in view of our droughty August.  What’s REALLY interesting, though likely in some error, is that a tropical storm moves up the Baja Coast , dies, but its remnant moves into AZ in 10 days (see model forecast below valid for September 14th).   As a forecaster type of person, as well as a cloud-maven kind of person, this would be like Christmas in September to have something like this happen where maybe an inch or two of rain spreads over parts of the State.  This is because we are supposed to be getting drier and drier as the summer rain season withers in September, and so this would be an anomaly.  I’ve always liked weather anomalies, and this might be a real good one.  However, as mentioned in prior writeups, these kinds of things come and go in the models, and so its best to think of it as like in a dream right now, but a pleasant one.

Some cloud shots below from yesterday.  It was SO NICE to see that first little Cumulus cloud pop up over the Catalina Mountains in the early afternoon!  While the depth of the Cumulonimbus clouds locally was limited by dry air and an inversion (temperature reversal aloft) and they could not produce strong rainshafts as a result, still in was nice to see ANYTHING dropping out of those clouds!  Here we were lucky enough to register 0.o2 inches, enough to cut the dust some on our gravelly neighborhood roads.

 

 

Toad’s night out; 0.93 inches

What a superb rain that was here in Cat land!  The early signs, which I pointed out to a friend well before it happened, fully developed, “behemothic” Cumulonimbus capillatus incus clouds before noon.    Take a look at some of the early “warning” developments.  I included a baby Cumulonimbus capillatus cloud just for the heck of it; it was so CUTE!  First, tall thin Cumulus reaching the ice-forming level before noon (fibrous portions technically making them Cbs), the baby Cb, and then a behemoth of a complex to the N of us.  This was SUCH a great opening for the day!   How anyone could not be excited by these sights unless you were indoors all day without windows, I don’t know.  Also, I get quite sad thinking about Catalina-ites that feel they must move to higher ground when the temperature rises in summer here.  Look what they missed!  Of course, they also missed the screeching toads last night, too, not a pleasant sound, but nice to think it was because they, too, were excited about all that rain that fell.   What helped our rain total, and the desert re-greening now in process, was the giant areas of more stratiform rain areas, debris clouds from the original thunderheads that normally here do not produce much or any rain.  In the Midwest, a cold front comes through with leading thunderstorms and a windhift, and then it rains for three hours afterwards from the trailing  “stratiform”, well, really Nimbostratus-like clouds (ones commonly seen in Seattle, for example, when steady rain is falling).  And we had a lot of that late yesterday afternoon that enhanced the rain totals from the downspout portions of the thunderstorms.   That steadier, moderate rain that went on for several hours added about as much here as did the initial dump.

 

 

 

 

 

 

 

Of course, Mr. Cloud Maven person got quite excited when solid bases began to appear overhead, requiring documentation as in this photo, his signature shot.

What was exceptional was the frequency here of cloud to ground lightning strikes, many close ones,  yesterday afternoon.   I had not seen so many strikes and the time between them could be measured, seconds I think. Even going out to the “trace detector” (an old car parked outside) seemed dangerous though it is only 50 feet away.  Cut down on photo ops, too, dammitall.

Its thought that a higher frequency of strikes might be due to greater updraft speeds than usual in the clouds overhead.  Typically, guessing here, they might be 10-20 kts in our thunderstorms, yesterday may have reached 30-40 kts.  Not much literature re this sort of thing in AZ thunderstorms.   BTW, the greatest measured updraft was about 80 kts, or close to 100 mph!  Yikes!  The plane that measured that, an “armored” T-28, was taken upward 5,000 feet before you could say skiddadle.

Rain dump truck; 0.73 inches

As per my photographic niche, I began to capture some promising bottoms of clouds yesterday afternoon around 2 PM.  The first shot shows a promising cloud (so-so sized Cumulus congestus) drifting westward over Mt. Sara Lemmon.  The next shots show the progression in the appearance of the bottom (my specialty) before the dump truck was emptied.  Nice!  Its always satisfying to document the bottoms of clouds BEFORE the dump truck is unloaded.  Before it was over, visibility was momentarily less than 50 yards in swirling winds and blinding rain.  Unbelievable moment.  According to our tipping bucket gage, rain rates got up 8.4 inches per hour at that peak moment.  (The record, Btw, is over 12 inches actually recorded in less than an hour in Missouri!).  A few minutes after the last photo is when the rain started.

Well, it was a great rain, and the desert veggies seemed to respond to this one event by propping themselves up overnight and looking noticeably greener.

Thunder-rooskie

With a thunderstorm at 7 AM LST yesterday mainly toward Saddlebrooke, you may have thought, “What a thundery day this will be!  It will be like Cherrapunji during the Indian-Bangladesh monsoon season when it rains and thunders all day and inches of rain pile up!”

And of course, it wasn’t going to be like that at all, rather it was the famous deceptive weather “play” called, “thunder-rooskie”, whose first derivative was executed in a Nebraska in a fubball game in which the ball was not hiked by the Big Red offensive team, but was left on the turf for some lineman to pick up while all of the other players were too busy pushing each other around to notice the “egg” just lying there.   (Actually, the name of that trick play was “fumble-rooskie”, as students of the game will know.)  At least here in Catalina, we did get measurable rain in the morning, pretty refreshing, too, of 0.04 inches.  Lots more toward SB.

So wha-happened?  First, that mostly stratiform overcast helped keep temperatures down; only 91 F in Catalina yesterday.  100 F have sent volcanic explosions of Cumulonimbus clouds into the sky, but, except in a few isolated areas and on the White Mountains, that didn’t really happen.  Too damn cool.

Also, when you have a disturbance strong enough to produce rain and the rare morning thunderstorm, more often than not it is replaced during the daytime by dryer air asscoiated with an attendant couplet of descending air motion, and a little of that happened yesterday, too.  So, rain and thunder at dawn are often associated with disappointing afternoons here in Cat Land.  Naturally, I hoped for more, seeing those low cloud bases topping Samaniego Ridge, even during the afternoon.  But other than an occasional, and very brief tower, they did not even make it to the height where ice forms and rain falls out.

Here’s the rest of our muggy, but dry day:

 

Drops away!

As a photographer, you like to develop a niche.  My niche, of course, if you follow this site, is gray matter overhead, an amorphous, gray balls.  Now yesterday was a great day for adding something to my collection since a Cumulus base, one that was clearly headed for better things than just being a Cumlus cloud, developed almost straight overhead, giving me a great chance for another “signature shot.”  See below.  I don’t know of any other photographer that specializes in this kind of shot; kind of sad, really.

Once again, you’ll have to click on the image to get a proper size, and hold your monitor over your head.  People seem to enjoy doing this.  Make sure your plugs and connections to the monitor are long enough to do this maneuver.  Sometimes I forget to tell people this, and then they get mad when an external hard drive falls on the floor when performing this maneuver and it won’t work anymore.  Sorry.

Of course, I monitored this base and kept shooting ( you never know which one will be the best) it, and then, there came the strands of the first drops out the bottom, that fabulous moment so few photographers catch because it is VERY subtle.  Next photo, if you can detect it!

OK, this is probably too hard for you to see much in the second shot, though I can see something.

How about a bit later, when its obvious?

Pretty cool, huh?

I was really hoping for those giant drops, but the initial shaft was just a hair to the east, and so while it rained HARD, the main load was dumped toward Sutherland Wash to the east.  But, we did get 0.16 inches here. See next photos

What were seeing in this emergence of a fall streak is the overhead transition from a Cumulus congestus to a Cumulonimbus calvus to Cb capillatus.  Eventually only the “hair”, that is, the fibrous ice cloud is left up there.  The whole bottom two thirds of the cloud has rained out.  Since there were so many Cumulus clouds that went through this transition yesterday, we were left with a huge amount of what would be called, probably should stretch your tongue before trying to say this so you don’t injure it, “Altostratus cumulonimbogenitus.”  Here’s the great sunset shot showing mostly that mass of ice cloud up there (underlit by the ray of sun).  Enjoy once again!

 

 

 

 


 

Everywhere but here

What a great cloud day yesterday was with thunder on the Catalina Mountains by 10 AM. It seemed so promising for a major rain here in Catalina. But no, shafts to the left, shafts to the right. In fact, we were “surrounded” on three sides by shafts at times, but only residuals of those shafts got here to produce a measly 0.04 inches!  Still, it was nice to see those cloudbursts out there drenching something.

Here are a few photos of yesterday’s clouds, beginning with a 9:44 AM morning shot, once SO FILLED WITH PORTENT.  I remember how happy I was!  Look, the bases of the Cumulus clouds are touching the top of Table Mountain!  Think how warm they must be, maybe 12 F (50 F)!  And we remember that the WARMER the cloud base, the more easily they rain!  Also note ice falling out of the right side of the top of this cloud in the first photo.  Imagine, at 9:44 AM, those towers were already able to ascend to the level where its cold enough for ice to form, and you know what that means, RAIN falls out! Yay!

Below, is an example of that assertion about rain and ice.  First, a cloud (cumulus congestus) whose top has already reached that level where ice forms–look how different it appears in that highest sprout in the middle of the photo, how smooth it looks compared to the crenellated, cauliflowery look in the turrets below.  But there is NO rain falling out yet.  That conversion to ice has just happened.  The much higher concentrations of cloud droplets are being replaced by much lower concentrations of ice particles, and that’s why you can visually detect this change in appearance.  The lower concentrations of ice make the cloud look a bit less detailed in top structure.

While that highest portion is already converting to ice, you still see no shaft. This is a great moment to impress your friends with some razzle dazzle conversational meteorology:  “Hey, guys, that cloud is gonna have a helluva shaft of rain in just a coupla minutes!”  It would be a magical moment for you.

How long will it be before you see a rain shaft?  Only about two minutes! And here, in that first shaft shown in the next photo two minutes later,  are where the largest rain drops and sometimes hail will be found. You don’t want to go over the speed limit, but under this type of cloud BEFORE the shaft is out the bottom is where you should be to see some real rain excitement, that is, rain bouncing about 6 inches off the pavement, but you’ll have to pull over, maybe some close lightning strikes, too.

Finally, a typical afternoon shot of the rain shafts around Catalina, in this instance, looking toward Twin Peaks.

Man, that was a fun day yesterday for cloud viewing!

The End.