“The Magnificent Seven” (minute storm); 0.13 inches!

A reference to yesterday’s seven minutes of mayhem here in Catalina/Sutherland Heights; alludes to but an old 1980s song by the English punk band, The Clash about really bad weathermen:

“one says sun, one says sleet1.”

Back to weather and yesterday’s microburst with three minutes of sheets of unbelievably heavy rain with rice-sized hail, 50-60 mph gusts, blazed across Sutherland Heights between 4:06 PM and 4:13 PM. It was a memorably violent storm, comparable in those worst 2 minutes or so to anything we see in the summer, and it was completely un-predicted for Catalina the day before  (0% chance of rain here) though showers WERE predicted for the higher terrain of eastern AZ yesterday).  For the full story, see Bob M’s excellent discussion.  For just clouds and stuff, here is OK.

Looks like the Sutherland Heights got the most of anyone anywhere near here.  No reporting station in the Pima County ALERT system in Catalina or in the Catalina Mountains got measurable rain, that’s how local our storm was.  Rarely if ever do you see that happen.

Stuff blew everywhere and I felt lucky not to lose some branches of trees in the yard. Here’s yesterday’s cloud diary.  First the background about what was happening, the TUS balloon sounding of the atmosphere:

The TUS sounding at 5 PM AST (launched around 3:30 PM). Classic inverted sounding associated with downbursts.
The TUS sounding at 5 PM AST (launched around 3:30 PM). Classic inverted sounding associated with downbursts.  Cloud bases are at 0 °C (32 °F) at 14 kft above sea level, or about 11,000 feet above us in Catalinaland.  Lots of turning of the wind, too, helpful for stronger storms.  So, rain and hail had a long ways to fall, cool the air, drag it down and blast the surface.
9:43 AM. Castellanus of the morning. Patch Cirrus on top. Recall that in my cloud chart it says when you see this cloud, it might rain within 6 to 196 h. Pretty accurate yesterday since it rained about 7 h later here.
2:11 PM. Cumulus were reaching mediocris stage around here while off to the horizon, Cumulonimbus tops could be seen over the higher terrain of the Mogollon Rim.
2:11 PM. However, a single Cumulus congestus just past the Tortolita Mountains was transitioning into a little Cumulonimbus. Precip is fall out of that lofted flat side of the cloud to the left of the main base. What a surprise to see that! But it was clearly too small to do anything.


3:00 PM. However, those cloud over there kept shooting up turrets, becoming larger and larger until we had us a full blowed Cumulonimbus and something in the way of a rain shaft (Code 2, transparent, except for that one strand–almost certainly a hail or graupel shaft).
3:54 PM. While CMP had to be inside for an hour, this surprise happened just to our SW, with rain falling on this side of Pusch Ridge! Wow, WHAT an interesting day this is turning out to be! Not only was there rain, but thunder!  Didn’t think it would get here, well, maybe a sprinkle is all.
4:02 PM. The rain shaft had gotten denser, and there are tendrils of heavier precip. Thunder is a remarkable every minute. Didn’t look vigorous enough for that kind of electrication rate. What’s really promising now is that darker round blob in the upper right hand corner of the photo indicating new cloud growth. That raining part of the cloud would hardly make it here even if it came right at us, given the light winds up there; needs to be replaced by new cloud growth. Was thinking now, “Gee, it might measure!” No thought of wind yet since that shaft looked kind of weak..
4:04 PM.
4:04 PM. Looked down on Catalina to see this remarkable site, a surface dust plume racing through town, rain just behind it! At this point you could see that it was going to blast the Sutherland Heights, so was a pretty exciting moment, and the rain was certainly going to be measurable if the gauge didn’t blow over!
4:04 PM. Another view of this shaft just before the wind came roaring over the hill in the foreground. From the incredible but very short-lived torrential rain, Sutherland Heights must have gotten one of those narrow strands, but again it would not be one of those you see there, but something dropping out almost on top of us.
4:06 PM. Here it comes, just over the hill. You can see the surface dust plume advancing north into Catalina where no rain fell!
4:06 PM. Here’s something you rarely see, dust blowing off the little hills above the Sutherland Wash, Baby Jesus Trail area. Rain was just starting here.
4:09 PM. Just about the peak of the rain shaft. Horsey retiree Jake shows that the wind si blowing away from the corral. The visibility is relatively high in this extremely heavy rain because the shaft was so tiny.
4:09 PM. Just seconds later the shaft had moved a few blocks away and down the hill (whitish area running from left to right). Note expanse of blue sky in the background, too.
4:13 PM. Storm is virtually over and here you can see the amount of water that came of the roof, and some wind damage (cushion out of place). Some cushions went down the hill.
4:43 PM. The day ended peacefully enough with more Cumulus and distant Cumulonimbus clouds around. Great sunset scene of clouds over the Catalinas, but was enjoying live classic rock music at a friend’s house with some 50 others; no camera.

Too dry today for rain.  Next chance for rain around the 17-19th as that bigger (but maybe drier) cold trough settles in.  Temps will be nice, though.  Lots of intermittent trough action indicated in 06 Z mod run through the rest of May, so May should continue to be pretty interesting and likely devoid of never-ending heat month as sometimes happens here.  This scenario pretty well supported in those crazy NOAA spaghetti (or Lorenz) plots.

The End


Photos not loading in WordPress now, so quiting here, dammitall!  Must go on to other chores now.  Not happy!


OK, photos finally went in. Happy now, though too many photos as usual.


1I doubt that happened….  Really, this was a song about people who don’t like to go to work, kind of anti-capitalist which is ironic because it was that system that allowed the boys to make their millions (billions if they had invested wisely into Microsoft in the early 1980s) and gone on to help the world with their billions like Bill and Melinda.

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.


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