Ice cream “Sunday” with a pileus topping

Yesterday’s cloud of the day:


6:20 PM. Cumulonimbus calvus pileus. Hope you had your camera. This would have been a good example to add to your collection.  “Calvus” or “bald” is a short-lived period when a Cumulus congestus top is converting to a fibrous (“capillatus”) appearance.  That left bulge is clearly loaded with ice.  The pileus forms in moist air being pushed up by the rising turret below it.  I wanted to be inside that cloud so bad!  There’s real magic going on when the droplets are being converted to ice, along with the appearance of hail and/or its soft, squashable version, graupel.


 Fantasy storm of the day

….popped out of the WRF-GFS run from 12 Z yesterday, rendered,  as we say, by IPS MeteoStar.  Tropical storm “Q” is shown in the Gulf of Cal/Sea of Cortez racing north into Arizona.  Pretty cool, huh?

A map configuration like this hasn’t been back yet, and wasn’t there in any run before this one, so we can throw it in the trash pile of bogus model predictions so far, though the models DO have a strong hurricane “Q” in the works. Mods now show it going NW and out to sea off Baja.  Still its fun to see how much fantasy rain can fall in Arizona.  Kinda reminds one of the track of infamous Tropical Storm Octave, October 1983, almost passing over Tucson on the same day 31 years ago.  You remember “Octave” I am sure.  You can read about it and a very similar eastern Pacific hurricane season to this one here.

Valid October 1st at 5 PM AST.  Flooding rains from tropical storm "Q" move into Arizona.
Valid Wednesday, October 1st at 5 PM AST.  Flooding rains from tropical storm “Q” move into Arizona.

The Cumulus ahead

Whilst CMP was glumly anticipating the end of Cumulus clouds, tropical ones on a daily basis anyway, due to the onset of westerly winds aloft, it has been pointed out by more astute forecasters, like forecasting legend, Mike L, at the U of AZ, TEEVEE ones, NWS, etc., (i e., namely, everyone else who knows anything at all about weather) that tropical air will still be feeding in enough from the east below the westerlies to keep some Cumulus going here and there, some even becoming Cumulonimbi with rain! Your errorful CMP was actually glad to be “informed”, glumness disappearing.

Also, we got that cold front coming on the 27th or so, with another chance of rain as humid air is drawn northward ahead of it. So, another coupla chances to make this a decent water year, one that ends on September 30th. We’re just surpassing 15 inches now; the normal, computed from 37 years at Our Garden here in Catalina, is a little less than 17 inches.

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.