Dusty humbug produces 0.01 inch of rain in Catalina

When the massive dust cloud rolled in from Tucson-Oro Valley, I heard a neighbor screaming at the kids outside, “Go inside, the rain is coming!”  A “humbug” is an imposter, meant to deceive, and for a time, I’ll bet many folks, like my neighbor,  thought a good rain was coming along with the darkening sky (composed mainly of….”Altostratus cumulonimbogenitus”–kind of a silly name, some with areas of virga).  There were also dark-looking Altocumulus opacus clouds, and Cumulus humilis at the bottom of the As here and there (e.g., see second photo).  So, it was a threatening sky to be sure!

Go here to see dust storm roar through Tucson, courtesy of your University of Arizona Wildcats Weather Department.  Very exciting!  Plus you will see all the cloud movement that was going on before the dust hit.

Below are a few shots from yesterday’s dramatic dust cloud as it rolled and roiled northwestward out of the Tucson metro area and up the Oro Valley.  First, a cloud shot that showed truly remarkable Cumulus-Cumulonimbus development east of the Catalinas just after 7 AM AST yesterday.   You knew at this point, it was going to be an interesting day with so much so early.

Then, "whilst" in a local gym, this came round the corner of Pusch Ridge (2:59 PM AST)
3:04 PM AST: Within 5 minutes it attained the classic "haboob" shape roaring into Oro Valley.
By 3:10 PM AST, it had filled the valley.
Finally, 4:33 PM AST, descending on Catalina from the NNE, a weak thunderstorm and a bit of rain to turn the deposited dust into mud. Cleaning all windows this morning.
All this was caused by the huge splash of rain to the east and southeast of Tucson yesterday earlier in the day.  With high bases, and lots of dry air below, as you all know by now, the scene was set for a massive drop of cold air as the rain evaporated below the bottoms of those clouds.
Next: June preview in May
The total of maximum temperatures added together over the next 7 days will be HUNDREDS of degrees!  This makes no sense at all, but it does sound dramatic.  It will be hot for awhile.
But then what?
Pretty strong signal from the NOAA Spaghetti Factory that another cut off low or trough will barge into the State by the 25th of May.  With that would be a strong cooling, and maybe some rain.
The End.

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.