A thunderstorm is in progress when you can hear thunder. Yesterday, beginning at 1:20 PM, we were having a thunderstorm in Catalina due to those modest Cumulonimbus clouds on top of the Catalinas. Here are those clouds, ones that streamed northwestward and died. This first photo of an isolated, flat cloud is the remains of what was a bulging Cumulus congestus turret that sprouted over Mt. Lemmon. It was of interest because at this time the tallest sprouts were just reaching the point where ice would form at noon to 1 PM yesterday. Its really unusual to see a marginal ice-producing turret like this dead one in the first shot. Such a cloud is of great interest to researchers studying the characteristics of ice formation since normally turrets ascend quickly through this initial ice-forming level to much lower temperatures, and the onset of ice temperature has to be estimated.
The rainshafts from these Catalina clouds were transparent (“Code 1”) the whole time they were producing, indicative of not much rain having fallen from them.
You can go here to the Pima County Alert site to see the rain totals hereabouts and in Tucson overall. CDO Wash at Rancho Solano (just NE of Saddlebrooke) got the most, 0.43 inches, due to a cell that developed later and is shown below.
This same Cumulonimbus can be seen at the very left edge of the view on the great U of AZ time lapse movie for yesterday here.
As the day starts, you can also see the waves in the atmosphere rippling through those Altocumulus/Ciirrocumulus clouds we had in the morning. Fascinating.
The next event was caused by the rush of winds from a strong cell near Marana that sent rain-cooled air pushing north into Oro Valley. That push of air gave a lift and a life to a developing Cumulus over Saddlebrooke just north of us, and before long, out dropped the load of rain, with occasional thunder with it, too. Here’s the “trigger cell” SW of Catalina with its rainshaft at the max which sent that rush of wind that in turn, pushed up the Cumulus over Saddlebrooke.
The full sequence of that Saddlebrooke cell is shown below.
Not a bad day yesterday–two thunderstorms in one day is always good–but less productive than hoped for here, always the case if there is less than an inch.
As you can probably feel, the humidity is still high. Dewpoints here are again in the upper 50s, quite juicy for AZ and that means another day of these sorts of clouds. Yay! I love photographing the bottoms of clouds, ones that are going to deposit a load, but before there is any sign of it coming out. And we will all have a chance to do that again today.