In case you missed it, this eye-candy from last evening as a crepuscular ray highlight some lower Altocumulus below the main layer:
6:40 PM. Lower patch of Altocumulus is under lit by a ray of sunlight. Higher layer would be termed Altocumulus opacus. This was quite a dramatic scene and had to sprint up a hill from a neighbor’s place to get this and the next shot.6:42 PM. Was gasping after sprinting up hill in an obsessive-compulsive pulse to get this shot. But it was worth it.
11:19 AM. Small Cumulus were erupting nicely over Mt. Lemmon and the Catalinas, but oddly, due to the southeasterly winds aloft, they were larger in an extended cloud “street” downwind. See next shot taken at the same time.11:19 AM. That cloud street went for miles!
Now, for the rest of the day. The Cumulus clouds with tops flattening into Stratocumulus were a bit disappointing, their tops, in a few places, did reach the level where ice would form in them and virga and a few light rainshowers fell out. Remember, gotta have ice to have precip is Arizona, mostly.
1:21 PM. Larger patch of Cumulus, spreading out due to a “stable layer” has reached upward to begin forming some ice. That fallout of ice is causing the base to look a little too smooth. If you can detect this, you have reached the pinnacle of cloud maven-ness. Its just beginning to come out, very hard to detect at this point, more obvious in minutes. Even I wasn’t sure at this point, but hedged an opinion about it to myself.
1:42 PM. Same patch trailing ice, though barely. Still a difficult proposition to see it. Its just SLIGHTLY frizzy/fuzzy at the bottom, a look due to low concentrations of single crystals and a few snowflakes.2:08 PM. Now the presence of ice is obvious. You have a wonderful itty-bitty rain shaft reaching the ground, and an ice veil around the edges (upper left) of this cloud. Even a little baby could see that there was ice now. But as little and as long as it took to form and fallout, you would guess that the top was marginally cold for ice formation, a superb scenario for research aircraft. From last evening’s TUS sounding, looks like they were barely ascending past the -10 C (14 F) level, maybe to -12 C to -13 C here in those tops that overshot a little inversion at -8 C. Those flat-topped Altocumulus clouds that rolled in during the evening as the sun set had tops around -8 C, just a little too warm for ice to form in them.3:27 PM. But that TUS sounding was not indicative of the air just a 100 or so miles south of us where large and deep Cumulonimbus arose. Can you see a Cb calvus top in this photo? It was pretty exciting to think that air capable of producing large storms was so close after it looked for awhile like a longish dry spell. The moisture was returning faster than models foretold a few days ago.3:27 PM Zoomed view of distant Cumulonimbus calvus top, far easier to see without the smog of the day before!
Today, the inversion is gone, and dewpoints are increasing all over southern Arizona as we start into a real tropical push. So chances of rain here in Catalina are zooming upward. Should be some nice “Cbs” around.
Tropical storm Lorena is headed toward the tip of Baja and its remnants will come into southern California and Arizona over the next few days. Hang on for some potential mighty rains, something to bring our summer rain season totals to more respectable levels here in Catalina. Very excited, as are all local weather folk!
Also, no end to summer rain season yet appearing in mod run extending out for two weeks (from last evening’s global data crunch). Still seems to hang on, for the most part, through the 20th of September. Excellent.
Pattern clouds: Cirrocumulus undulatus in odd, parallel lines. I had not seen parallel lines like this before. Fragments of Altocumulus are also present.
7:55 AM. Hope you saw this–I ran out of the house since these delicate patterns are usually gone in a couple of minutes.12:21 PM. Ms. Mt. Lemmon starts to do her thing, send moist plumes of warmer air upward, with cloud remains trailing off to the NW. A southeast flow is present just above mountain top level, giving hope that later, a thunderstorm will drift off the Catalinas toward Catalina.2:47 PM. Not a great base, but still, it holds promise of representing the bottom of a cloud that can produce measurable rain.3:09 PM. During halftime I am able to go outside and notice that the Cumulus clouds are still trying to do something, but only light, barely visible showers have fallen toward Samaniego Ridge.4:06 PM. After the game was over (which game? Dunno, they’re all great) I am able to go outside again and see that a giant cell has formed dropping an inch or more out there to the NW of Catalina. There are frequent cloud to ground strikes. But, there are no more Cumulus above the Catalinas! What happened? End of rain possibility story.
Though only a few drops hit the ground here in Catalina, the day ended with a pretty sunset. This marked the third day in a row where large Cumuluonimbus clouds cells at least an inch of rain in southern Arizona, but we got missed, something that also happened several times in early August.
Some of the moisture doing this is from old, former tropical storm, Elena, particularly the moist plume that resulted in yesterday’s pretty pattern clouds shown in the first photo. Check the moist plume (whitish stream) from her here.
Looking ahead…..
While Elena was a bit of a disappointment as far as producing rain here in Catalina, her lower level moist plume too far to the west, a sibling storm is arising off Mexico, one that the models (hah!) as they did before, have calculated will cause a renewal of our summer rain season; showers are foretold for several days beginning around the 3rd as that storm trudges up the west coast of Mexico toward Baja. You can see the storm and the showers here in this rendering of the WRF-GFS model by IPS MeteoStar. Remember those green areas on these maps are those in which rain is foretold to have fallen in the previous 6 h (later in the run, in the prior 12 h). There is a LOT of green over SE Arizona after the showers begin to occur by the afternoon of the 3rd.
As is commonly heard these days from people concerned about drought, “think green”!
6:40 PM. A little hole in the clouds allows the late evening sunlight to penetrate into the aerosols we have over us, thereby producing an orange ray of sun.
5:54 AM. What are these rays called?2:14 PM. Where am I? The heaviest rain in all of Arizona fell here yesterday.5:29 PM. Why wasn’t it raining on the Catalinas from these dark clouds?6:16 PM. Where is virga and snow falling out? “If you miss one more, you’ll be out.”7:19 PM. “Who was buried in Grant’s Tomb?” A nice sunset, as almost always here, with a little snow virga hanging down from dense Altocumulus clouds
The weather ahead.
Rain in the area, the models say, every day for the next few days. Check here and with Bob (our local expert), who seems to be mad a lot, even titling his blog, “madweather.” I guess he’s not afraid, like some men, of showing his emotions. I get mad myself, but usually its when it doesn’t rain on me that day.
About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno
