Desiccated cold trough waves goodbye; is replaced by days of regular May heat for awhile, but not too long

Oh, me. So much wind, so much bluster, so gigantic aloft, but so little rain. Well, actually none here. Review of troughy’s last day on Sunday, Mom’s Day, where it tried to rain here:

5:35 AM. With light showers around to the NW-NE, was clinging to hope that a sprinkle might fall from one of this clouds if it could grow that bit deeper, colder on top. But, no.

6:25 AM. Gone, all hope of even a sprinkle.

6:24 AM. Light shower from a weak Cumulonimbus cloud passes just to the north of Saddlebrooke. So close…. Note rain shaft is transparent, something we would refer to as a Code 2 rain shaft.

6:35 AM. Another longing look at that shower, drifting off to the east. Note the icy plume on the downwind side on the right. Since this Cumulonimbus cloud’s not very deep, and cloud top temperature likely -10 °C (14 °Ï) or even a little warmer, you should guess that those crystals up there are columnar in shape, hollow sheaths (seems redundant) and needles. Its a little unusual to see those kinds of ice crystals in Arizona, especially from a few miles away, since they are only millimeters and fractions of millimeters in size.

Normally it take lower temperatures to have ice in our clouds. The cloud drops have to be larger than usual at that aforementioned temperature for those high temperature crystals to form. Only on especially clean aerosol days could that happen, or if there are large dust particles. Since there was no sign of dust, and the visibility was at least 100 miles, one guesses that it was the unusually clean conditions with weak updrafts at cloud base (i.e., ones result in only the best and biggest cloud condensation nuclei to activate) that led to larger than normal drops at temperatures warmer than -10 °C. Well, killed that audience. But sometimes you just get carried away with how much you THINK you know… Remember, my demand to stop blogging for a million dollars is still on the table if you want to strangle yourself at this point due to content overload.

9:20 AM. Nice Cirrus of many varieties and species, fibratus (fairly straight tendrils) is one, maybe some uncinus (hook or tuft at the top) in there, too.

6:55 PM. One of those visual treasures that occurs on our mountains when we have some clouds around.

7:08 PM. The two eyes of a fearsome sun blaze at Catalina as it split into two parts going over the horizon, the foreboding angry face of the hot days just ahead before another big cool down. In that regard, that is about a big cool down coming, it is well to remember that it was also foretold here that the big cool down we just had would also be accompanied by some rain, a quarter to half an inch, a forecast that was in error by a quarter to half inch.

The End

Author: 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. View all posts by Art Rangno