Cbs off early and often yesterday

Day went pretty much as planned for us by the models, with Cumulonimbus (“Cbs”, in texting form) clouds arising early and often, moving in from the SW, more of a fall pattern (which is approaching too fast for this Cb-manic person).  If anything, those clouds arose earlier than expected with dramatic morning results;

But those storms that got here divided as they approached The Heights yesterday;  cell cores went right and left with places like Black Horse Ranch down by Golder Drive getting 0.53 inches, and a place in Saddlebrooke, 0.94 inches yesterday, while we only received 0.23 inches.

Seeing this happen in real life was tough.  Still, there was a last rain burst after only 0.14 had fallen that was really great as the sky began to break open and the sun was almost out when it happened.   That last parting shower dropped a final 0.09 inches in just a few minutes.  So, maybe we were a little lucky.

BTW, you can get area rainfall from the Pima County ALERT gauges here for the past 24 h.  And, also, from the U of AZ rainlog network here.  USGS.  Coco.  NWS climate reports.  (Editorial aside:  (earlier cuss word, “dammitall”, has been removed)—WHY don’t they gather all the rain reports into one comprehensive site???!!!)

 

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7:04 AM. Soft top Cumulonimbus protrudes high above other clouds producing a long shadow on a lower Altocumulus perlucidus layer.
7:04 AM. Soft-serve Cumulonimbus calvus top emerges above lower Cu and Altocumulus clouds.
7:04 AM. “Soft-serve” Cumulonimbus calvus top emerges above lower Cu and Altocumulus clouds.  This kind of top goes with weaker updrafts, likely less than 10 mph.

 

10:04 AM. Showers and heavy Cumulus (Cumulus congestus) continued to range along the Catalina Mountains toward Oracle.
10:04 AM. Showers and heavy Cumulus (Cumulus congestus) continued to range along the Catalina Mountains toward Oracle. These were nice clouds.
10:14 AM. Looking in the upwind direction from Catalina, not much going on though storms are raging in the Catalina Mountains. That farthest line of bases, though, drew your attention yesterday, I am sure, given the explosive conditions we had for storms.
10:14 AM. Looking in the upwind direction from Catalina, not much going on though storms are raging in the Catalina Mountains. That farthest line of bases, with that fat one out there toward I-10, though, drew your attention yesterday, I am sure, given the explosive conditions we had for storms.
10:36 AM. OK, this is looking potent. Finally, tops have reached the ice-forming level and precip is ejecting out.
10:36 AM. OK, this is looking potent. Finally, tops have reached the ice-forming level and precip is beginning to eject out the bottom of the one on the right.  So big, high, top visible, which was of concern, thinking it might only be a light rainshower.  Generally, the higher the tops, the more that falls out the bottom1.
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10:57 AM. A two part panorama of the incoming, broken line of storms. Part A above, looking SSW with Pusch Ridge on the far left.

 

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10:57 AM. Part B of panorama, looking at this exciting line of showers and thunderstorms toward Twin Peaks, Marana, and Oro Vall

 

 

 

 

 

 

 

 

11:07 AM.

11:07 AM. A strong shaft has developed, indicating much higher tops than in the earlier scene above at 10:57 AM.
11:07 AM.

11:07 AM.  Close up for instructional purposes.  Let’s say you’re hang gliding and want to go up into the clouds.  That lower extension next to the rain shaft is where the strongest updrafts would be, and, on top of it, the fastest rising top.  Have a nice ride!

 

 

 

 

 

 

 

 

11:14 AM. Hole in rain aiming for house! Will cloud roll, buoyed my outflowing winds ahead of rainy areas develop new rain shafts?
11:14 AM. Hole in rain aiming for house!  This could be bad!  Will cloud roll ahead of rain areas, buoyed my outflowing winds ahead of them develop new rain shafts?

 

12:23 PM. By this time it was all over, the 0.23 inches had fallen, leaving some evidence of flooding. In a change of pace, I wanted to get that evidence in combined with a sky photo so that you could see that there were still clouds around.
12:23 PM. By this time it was all over, the 0.23 inches had fallen, leaving some evidence of flooding. In a change of pace, I wanted to get that evidence in combined with a sky photo so that you could see that there were still clouds around.  Cloud has some ice in it, too.

 

3:53 PM. A final threat of rain appeared as the winds turned briskly from the north and new turrets formed above it and, for a time, headed toward Catalina. It was a dramatic scene, to be sure, but one that disappointed. The clouds forming about the outrushing wind from heavy rain to the north, diminished in size as they approached, no longer reaching high enough to form precip. Partly this is because of our lower temperatures yesterday afternoon, and because when the air goes southbound from areas to the north, its always moving a little downhill and that works against new clouds, too.
3:53 PM. A final threat of rain appeared as the winds turned briskly from the north and new turrets formed above it and, for a time, headed toward Catalina. It was a dramatic scene, to be sure, but one that disappointed. The clouds forming about the outrushing wind from heavy rain to the north, diminished in size as they approached, no longer reaching high enough to form precip. Partly this is because of our lower temperatures yesterday afternoon, and because when the air goes southbound from areas to the north, its always moving a little downhill and that works against new clouds, too.

 

3:59 PM. While the dissipation of those clouds was disappointing and not unexpected, to be honest, still it was good to be out and see how green the desert has gotten since the end of July.
3:59 PM. While the dissipation of those clouds to the north was disappointing and not unexpected, to be honest, still it was good to be out and see how green the desert has gotten since the end of July.

 

The End

Oops today is supposed to be drier witih isolated Cbs, more tomorrow as moisture from TS Lowell leaks into AZ.

The extremely strong hurricane that forms after TS Lowell is sometimes, in the mods, seen to go into southern or central Cal (!) as a weak remnant circulation or stay well offshore, as in the latest 11 PM AST run from last night.So, lots of uncertainty there.  Check out the spaghetti below for the bad news:

Valid in ten days, Aug
Valid in ten days, Aug. 19th, 5 PM AST.  Those blue circles WSW of San Diego represent a clustering of the most likely position of that hurricane then.  And, that cluster is too far to the west to us, or maybe even southern Cal any “good.”

—————————–Historic footnote——————————
1“TIme to be distracted from the task at hand…. “Generally”, of course, is a fudge word. For example, in the tropics, it was learned back in the 1960s that rain fell as hard as it could about the time the tops reached the freezing level, and before ice had formed. Didn’t rain any harder even if the tops went to 30 or 40 thousand feet!   These results were confirmed in aircraft measurements in the Marshall Islands, oh, back in ’99 (Rangno and Hobbs 2005, Quart. J. Roy. Meteor. Soc.).

Some of the biggest rain drops ever measured (5-10 mm in diameter!) were in clouds in the Hawaiian Islands whose tops that had not reached the freezing level–see Bob Rauber’s 1992 paper in J. Atmos. Sci.,  with Ken Beard, the latter who tried to get rid of intercollegiate athletics at UCLA when he was there in the turbulent late ’60s, as did the present writer at San Jose State (a story for another day).  But then,  BOTH me and Ken went on to become science weathermen, not the radical kind of Weatherman, i. e., those under Bernadine and Bill, because we left our radical roots and reggae back behind in the ‘1960s, 70s, and/or 80s (well, maybe not reggae…)

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.