A morning surprise; 0.22 inches here doubles the July total

At least it wasn’t predicted the day before, but how nice to see a “mesoscale convective complex1” (a bunch Cumulonimbus clouds clustered together) come roaring over the Cat Mountains yesterday morning.  Here it is, in case you missed it and want to see it again, from the beginning when what was going to happen was in doubt:

11:00 AM. Major rainshaft, and accompanying dark base where updraft is forming new precip approaches Catalina area.
11:00 AM. Major rainshaft, and accompanying dark base where updraft is forming new precip approaches Catalina area.
11:47 AM. THe dramatic backside of this cluster, resembling those seen in the Plains States, good mammatus, too.
11:47 AM. The dramatic backside of this cluster, resembling those seen in the Plains States;  good mammatus, too.

 

 

 

 

 

 

 

It was great, too, to see some evidence of water on the ground, and several natural livestock ponds form due to the storm.  Its been too long since puddles formed.  I like puddles, BTW2.

11:18. Evidence of significant rain; a puddle has formed.
11:18. Evidence of significant rain; a puddle has formed.
4:38 PM. Calves inspect new livestock pond on Equestrian Trail Road.
4:38 PM. Calves inspect newly formed livestock pond on Equestrian Trail Road.  Mom not impressed.

 

 

 

 

 

 

 

 

Go here to see some regional rainfall totals from the Pima County network and here for the U of AZ network.

What was best was the clarity of the air after the rains washed all that smog, and we had our brilliantly white clouds against that deep blue sky back:

4:10 PM Cumulus mediocris over the Catalinas.
4:10 PM Cumulus mediocris over the Catalinas.

Today:

First, right now (6 AM) we have some of the best Altocumulus castellanus around I have ever seen.  So pretty!

U of AZ 11 PM mod run expecting afternoon showers/TSTMS over Cat Mountains today, trailing off to the NW and near Catalina proper.  Showers and lightning now to the S-SW, expected to die out before reaching us. So, happens, look for bases launched in the late morning and early afternoon to drift overhead–often a street of clouds forms over the southern portions of the Cat mountains about where that dark base in the first photo is, and if we’re lucky, will dump in this area.  Look toward Table Mountain and a stream of clouds from around there headed this way.

 

 

 

 

 

 

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1It would be great if you used this term with your neighbors when talking about yesterday’s rain:  “That was a great MCS that came through yesterday morning! Hope we get another one today, though rain in the morning here is rare, but anyway…..”  Neighbor  “A what went through?”  You:  “Oh, sorry, I meant a nice cluster of thunderstorms. ”  You continue:  “As a cloud-maven junior, I’m learning a lot incomprehensible jargon that I can use to impress neighbors.  Hey, have you heard of the ‘diffusion domain’?  That’s when you’re flying in clouds and you can’t see either the ground or the sun!  The next time you fly and that happens, tell the passenger next to you…..”Hey, I think we’re in the diffusion domain.”

2Photographed a lot of puddles on a trip to Death Valley in 2005 (wettest rain season there in 75 years).  It was a lot of fun for me.

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.