Black is beautiful

Here in this part of Catalina another 0.11 inches dropped from the sky in two weak, but great thundershowers yesterday afternoon, one that will help keep the greening of the desert coming on strong. As many of you know, my photographic niche is cloud bottoms, particular dark ones, and to me, beautiful, dramatic ones when rain or hail filaments begin shredding the air below them, followed by the dump.

Below are a couple of those bottom shots from yesterday. This cloud trucked off from over Catalina toward the SW and over Oro Valley/Marana where it began to rain.

3:55 PM. The bottom of a small Cumulus congestus (it was at least 6,000 feet thick, 2 km) at the time this photo was taken, trust me.
3:57 PM. A closer look at this nice dark bottom; was hoping for signs of rain strands as you probably were, too.  However, they came out later, several miles away.

Later, two weak, but welcome thunderstorms rolled off the Cat Mountains from the NE, giving us 0.05 and then 0.06 inches in the second. Below, here they come!

4:13 PM. Thunderstorm one.
6:37 PM.  Thunderstorm two. Close strike caused a power outage here.

Yesterday’s rain totals can be found here (rainlog.com) and with the Pima County Flood Control Network. Some areas in and near Tucson recorded over an inch again. How fine.

Today?

The dewpoints are higher, cloud bases are a bit lower, and so monster dumps in the area are VIRTUALLY guaranteed (never can tell exactly where they will be).  However, conditions aloft are also conducive to larger shower areas than yesterday’s were, that is, large clusters of Cumulonimbus clouds are more likely today, meaning larger areas covered by rain, and longer durations of rain.  Cool.  You can get the “skinny” from the U of A model here.

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.