“Sprinkle rain”, thought to be only capable of a trace, piles up 0.06 inches in Catalina

Yesterday’s news, of course, and a surprising development “locally” where measurable rain during the day seemed remote, at least at 6 AM yesterday.  But, a blob of rain moved in around noon and gave out 0.06 inches.  We’ll take it.

And as you all know, much more rain from our tropical system off Baja is just ahead, U of AZ mod says beginning late tonight and continuing into most of tomorrow morning as you can see here.  If you want to see the forecast rain/snow in all of Arizona pile up over time, go here (from the U of AZ).  The model is thinking between 0.25 and 0.50 inches here, an inch or so on top of Ms Mt Lemmon.  Gut feeling is that we’ll see more than half an inch here from this, with a good chance that it will go beyond noon tomorrow when the mod thinks its all over.  Hoping, anyway.

Below, amounts forecast by the U of AZ model ending at noon tomorrow.  The model was run on data from last night at 11 PM AST.

Ann 0001Dk










Also yesterday, we had a very brief but fabulous sunrise “bloom” illuminating the bottoms of the thick Altocumulus clouds overhead. It looked something like this1:  Hoping for same today.

7:23 AM.  Year different from 2013 because Mr. Cloud-maven person did not have a memory card in his camera....
7:23 AM. Year different from 2013.









In case you missed it, here’s what gray skies and light rain look like, falling of course, from that great steady rainmaker, Nimbostratus.

12:31 PM.  "Riders were approaching (under Nimbostratus), the wind began to howl...."  That Dylan line would been that bit better with "Nimbostratus" in it.(From "All along the Watchtower")
12:31 PM. “Two riders were approaching (under Nimbostratus), and the wind began to howl…”2  Well, OK, one rider. Note rain haze against Pusch Ridge and smoothness of sky due to precipitation fallout that obscures cloud detail.  When you saw that smooth sky approaching from the SW, that was the time to turn your horse around and head for the barn, as here.











The rest of yesterday? Blasé. Steady diet of overcast Stratocumulus/Altocumulus clouds sometimes with splotches of virga, and a sprinkle here and there. Here’s pretty much what the rest of the day looked like:

2:01 PM. Two layers of Altocumulus are visible, the lower one on the S horizon beyond Pusch Ridge. Cloud detail (rumples and such) shows that there was no precipitation falling from these clouds. If someone asked you why, you’d say that the layer was not cold enough to produce ice crystals-snowflakes, things that would grow and drop out the bottom. The cloud droplets in these clouds are too small to fall, and even if they did float down and out, they’d be gone in a few seconds because they are so small.


4:46 PM.  Creamy-looking Stratocumulus.  Sometimes cloud bottoms look this way because of a moist layer overrunning dry and stable air, air that raggifies the cloud bottoms.
4:46 PM. Creamy-looking Stratocumulus. Sometimes cloud bottoms look this way because of a moist layer overrunning dry and stable air, air that “raggifies”  cloud bottoms and wind shear at cloud bottom can produce concave (inverted bowl-looking bases).  TUS sounding at 5 PM shows air speed sped up a little at cloud base over wind just below them and  wind direction turned about 10 deg from that just below cloud base.  Was it enough?  I guess so,  but not really sure except by sky.





















Rain still foretold for Sunday night into Monday morning, followed by a cold blast, but amounts have been on the decline.  Could be just a few hundredths to a quarter inch is about all this one can produce.

Clouds today

More interesting scenes today of “multiple layers” as we would call them, and not as widespread as yesterday overall;  Altocumulus (and with the wind picking up aloft, a lenticular here and there–look to the NE of Ms. Mt. Lemmon)  Altostratus, Cirrus.  And, with luck, a great sunset.

Way ahead…….

In the usual model vagaries, absent rain in them after this Monday for awhile, rain has shown up, beginning on the 4th of February.  This is a new development in the models for that period.  The NOAA spaghetti plots give this system pretty good support–that is, something is likely to approach the central and southern California coast a day or two before our possible “storm” on the 5th.  but thereafter, not much confidence for a storm here.  So, likely to be on the doorstep for us on Feb 3rd or so as it.  Interestingly, it rains for two days off and on here, Feb. 4th and 5th, and the rain follows a trajectory from the Pacific much like we have today, which is always a good sign since the atmosphere likes to repeat itself.  You can see the full sequence here.



1A replica of yesterday’s sunrise since Mr. Cloud-maven person’s camera failed to ingest a memory card prior to a dozen or so snappages.  Camera acted like there was nothing wrong!

2That Dylan line would been that bit better, more dramatic, with “Nimbostratus” in it.
(From Dylan’s, “All along the Watchtower”, the best version, it goes without saying, performed by Seattle’s own Jimi Hendrix.)

By 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.