About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno
Another day, another rainbow, another trace of rain; ho-hum
Kind of getting tired of gorgeous rainbows every day, ones without a lot of rain here in The Heights. But, here they are again:
5:44 PM5:54 PM.
Upwind Cumulonimbus clouds faded as the trudged toward Catalinaland yesterday, bottoms evaporating, raining out, leaving only a big patch Altostratus cumulonimbogenitus way up (at least ten kft above the ground) there with rain drops just big enough to survive evaporation and reach the ground just before 3 PM.
2:18 PM. Heading for Catalina, right side will maintain–note nice flat base, left side of heaviest shaft is a gonner. So, hope is on the right (not a political statement, but rather referring to the part of the cloud you want to be heading for you, which is not the shaft itself due to the short lifetime of shafts, but the new parts where new shafts will emanate. No renewing base/updraft over there on the left. You hope that segment isn’t exactly heading for you. We shall see in just a few minutes of yesterday time.2:24 PM. OK, we’re done as far as rain goes in Catalina from this. The updraft and solid base are propagating to the right, meaning that nice appearing rainshaft will be what targetis us. But the lives of shafts are so short without renewal, and that renewal is going to slip to the west of us. Notice how in six minutes the shaft on the left is almost completely gone.2:48 PM. Hard to believe that this is all that’s left of that pleasant Cumulonimbus cloud, an Altostratus translucidus cumulonimbogenitus , maybe with praecipitatio as well with it since you can see a veil of preicpitation is reaching the ground. Note the sun is shining through larger ice particles like snowflakes, its disk cannot be made out, though its position can. If this cloud was a thin droplet cloud, the sun’s disk could be seen as a sharply outlined disk.
In the meantime, all the excitement, possibly spurred by the gusty outflow winds that accompanied the above seen, was happening almost overhead to the NW-NE, as a great line of Cumulus bases blackened. They were already passed us, but if they unloaded and sent a pulse of wind out and toward us, then we might end up in a wind clash zone, with huge clouds forming overhead. OK, was dreaming again, but here’s what was going on, which ultimately led to another major dump on the CDO watershed.
2:20 PM. Dark Cumulus bases mass over Saddlebrooke and north. No precip trails yet, but they were virtually assured. Started videoing this scene about now.2:28 PM. In just eight minutes this has become really menacing, possibly a major dump on Saddlebrooke with more golf balls flooding down into the CDO wash as happened the previous day. Now looking for the first strands of the largest hydrometeors (likely hail or graupel) to drop through the updraft, which is looking very substantial at this time due to that well-formed base.2:30 PM. Here’s a close up of that base over Saddlebrooke, now placed in the “Cloud Base Collection” series that we offer to readers from time to time. We’re hoping ot get into a gallery soon.2:37 PM. “Thar she goes!” This is really hard to see, but at top center the rain/hail/whatever is just starting to show out the bottom. Some of these, likely gigantic drops, are already reaching the ground. Notice the slight dimming of the Cumulus clouds in the background. That would be the developing rainshaft is going to be.2:39 PM. Now even little teeny babies can see the shaft dropping out.2:42 PM. For all to see now….just three minutes later.2:44 PM. Just another two minutes later. Its pretty remarkable how fast these things collapse. The whitish strands are likely hail/graupel shafts, often located on the upshear/upwind side of thunderstorms.2:49 PM. Soon the plop of all that rain push enough air out of the way that the shaft extruded outward toward the west. Note that rain would be falling on people from a raining cloud some mile or three away. The heaviest rain seen in the ALERT gauges from this event was only 0.79 inches at Pig Spring, near the Charouleau Gap. The peak rain was probably in the 1-2 inch range.
Hiked over to see if the Sutherland Wash, east of the similarly named housing development, Sutherland Heights, had a good flow from our “Mighty Kong” of prior day. It had:
3:45 PM. The Sutherland Wash scene showing that it flowed bank-to-bank as did the CDO here in Catalina.
The weather ahead
Seems Remnant Roslyn will spit out another snippet of moisture ahead of our fall-like cold front passage late Sunday or early Monday bringing clouds, and with clouds, a slight chance of measurable rain. Don’t hold your breath for measurable rain IMO. Hope I’m as wrong as the prediction I made to a friend that the Stanford Cardinal would trounce the wildly overrated Washington Huskies fubball team last night.
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.
May not be relevant to Catalina, but re your prior work at UW in cloud-seeding. There were experiments much earlier than you noted, in the PNW. E of the E-slope of the Cascades in NCentralOR, may have been in the late ’50s. Poor results, partly because any upslope is minor. Firm doing the study then tried to switch gears and sell hail prediction services…
Yep, I think you’re right about this.
I even had that report at one time (maybe Bob Beaumont was in charge?), but now that report has been shipped off to the U of WA library and scanned by them. They have a fairly large collection of “gray literature”, non-peer reviewed Final Reports from quite a few cloud seeding companies. I think one of those sets is that from Project Cirrus by Vonnegut and Schaefer in the late 1940.
I collected them during my career at the U of WA.
Gee, just now looked it up and here it is, AND Bob Beaumont was the lead author!
May not be relevant to Catalina, but re your prior work at UW in cloud-seeding. There were experiments much earlier than you noted, in the PNW. E of the E-slope of the Cascades in NCentralOR, may have been in the late ’50s. Poor results, partly because any upslope is minor. Firm doing the study then tried to switch gears and sell hail prediction services…
Yep, I think you’re right about this.
I even had that report at one time (maybe Bob Beaumont was in charge?), but now that report has been shipped off to the U of WA library and scanned by them. They have a fairly large collection of “gray literature”, non-peer reviewed Final Reports from quite a few cloud seeding companies. I think one of those sets is that from Project Cirrus by Vonnegut and Schaefer in the late 1940.
I collected them during my career at the U of WA.
Gee, just now looked it up and here it is, AND Bob Beaumont was the lead author!
http://westernwaters.org/record/view/142011
art