About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno
Big shots
First, yesterday’s sunrise rainbow, in case you missed it.
5:56 AM. Virga/RW– (very light rain shower) from Altocumulus opacus (‘thick”) leads to an early morning treat. The rainbow faintly extends all the way up to cloud base, indicating that the freezing level was at or above cloud base. The TUS morning sounding indicated that this layer was based at 14,000 feet and about 0 C. Some sprinkles did reach the ground, but shadows from terrain or other clouds prevented the bow from reaching the ground.
“Dumps of the Day”:
12:57 PM. North of Saddlebrooke, this cloudburst. With bases as low as they were, LTG, indicative of stronger updrafts in the storms yesterday, likely an inch or more fell in this one. If anyone drove under this with a gauge, I’d like to hear from you, get some ground truth. Also note how obscured this tremendous Cumulonimbus is by the layer of Altocumulus, showing that on really moist days, it doesn’t have to get real hot and sunny to generate big storms.
A little later, this masterpiece of a cloudburst, without doubt one of the most dramatic I have seen in five summers here, or anywhere really. Here’s the sequence:
1:57 PM. Nice looking shower, but kind of so-so at this point. Drifted away from the “action” for about 15 min, and came out, jaw dropped when I saw what had happened over there! You just cannot take you “eye off the ball” here in the summer for even that long without some “volcano” going off. Check out the next shot.2:13 PM, just 16 min later, we have a serious cloudburst over there somewhere near Railway Ranch mining operations next to the Tortolitas. Easily 1-2 inches in 15 minutes kind of rainrate1. Was losing control here and took a lot of shots, just in awe of how nicely shaped it was, the lighting, the lightning, lots of it, feeling lucky to be alive and living here in Catalina and seeing something like this, and on and on. But I had to remember that sights like this are only seconds in duration. So much water is falling out at this second, and smashing into the ground, that the air has to get out of the way, and this columns like these flare out on the sides, and, it can rain out in minutes if the updraft isn’t continued somewhere else. In this case it was on the right side, and new dumps kept falling out as it propagated north. Took some video to prove it, too.2:14 PM. One minute later. Look how the blast at the ground is spreading out already! Unbelievable sight! So pretty, too.2:35 PM. New splash-downs occurred as those dark bases in the earlier photos, representing the updraft portions feeding the storm, gave out, first with fine fibers, if you looked closely, then the whole dump. With each new smash down (does that expression come from wrestling vaudeville?) new updrafts are launched adjacent to the dump and the cycle is (usually) repeated. About this time gusty NW winds from this storm hit Saddlebrooke and Sutherland Heights, but, alas, no new Cumulus formed above it. Must have not been enough of an upward shove, and/or our air too cool.3:05 PM. Eventually, all of those dark Cumulus bases got rained out and no new ones formed, leaving this “debris” cloud to continue raining itself out. At this stage, little if any new precip is forming up there. If you flew in it, what you would find for precip is giant snow flakes, amid lots of other tiny ice crystals, and some residual small cloud droplets, all of which are disappearing. Those large snowflakes melt into normal-sized raindrops (not ones splashing 3 inches off the pavement as would be in the “dump”). The rain here is more and more beginning to resemble the rain that falls in our winter storms. Seeing an absence of new Cumulus near us made me kind of sad at this point after the euphoria and hope just two hours earlier when I thought maybe the outflow winds that roared through would launch new Cumulus over ME. But no, it was all over at this point, with no chance of appreciable rain in “The Heights” (of Sutherland). We did get a sprinkle from a similar dying gasp of a storm that crept over the Catalinas from the east a little later.
Looks like today, absent the latest mod runs and using older material, always a little risky, looks very similar to yesterday, except as yesterday compared to the tropical day before that, our cloud bases are heading upward overall as the level of moisture declines.
Also, like yesterday, there’s very little steering wind for our storms, and so they tend to sit and die, unless the outflow winds can launch new buildups that blow up into Cumulonimbus clouds. Those outflow winds are chaotic, and where that happens, well, you’ll have to be watching. Though Ms. Lemmon, our nearby friend, did not produce much of anything yesterday, you figure that’s going to change today.
The good news ahead is that there is no clear cut end to our summer rain season yet, though there will be greater and lesser days of activity, as usual . Eventually the westerlies aloft will sweep down into Arizona and clear it out once and for all, but that’s not in the cards yet over the next 15 days.
Being Saturday today, NCAA college football day in America, I hope you will be able to separate yourself at least once from the TEEVEE at least once during the day, preferably after 11 AM, to view our too soon-to-end summer clouds. Remember, you can watch football until February 2014, but you only have maybe two weeks more of big Cumulus and Cumulonimbus clouds and lightning spectacles. Think about it.
The End.
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11-2 inches has been measured in hourly recording gauges in 15 minutes here in AZ. When that happens, you don’t have beads of water running off the roof, you have pretty much a solid waterfall.
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.
