of raingauges wanted. It was another spectacular sunset yesterday evening after another dry day here in Catalina. You hate to see a completely dry day go by during our peak of the summer rain season, July 5th through August 20th.
Below, the best we could do over Mt. Sara Lemmon in the way of Cumulus clouds, a “medicocris” one is what I would call it, followed by a couple of shots of that great sunset. That Cumulus was pretty pathetic I thought, though it was trying as hard as it could. You really don’t want to be a Cumulus mediocris in life, but there it is, and that’s as “important” as that cloud got, to the “mediocris” stage. Really hoped for more yesterday, too, since the morning Altocumulus cloud bases were a bit lower than the prior dry day. Some remnants of the morning Altocumulus are there above that Cu med.
If you caught the remnant of the moon yesterday morning through those Altocumulus clouds, you saw something a bit unusual. You couldn’t detect any cloud movement. In fact, the relative movement of the moon toward moonset almost seemed faster than the cloud movement! That’s not good for storms either, since its better if there is a bit of wind shear, turning and speed increases with height, not virtually calm all the way up. If you want to read a little more deeply about this sort of thing from one of the world’s best experts on convection, Bob Maddox, who lives right here in Tucson, go here to Maddweather. Has a great web page on our weather, and storm structures.
Learned something, too, yesterday. I did not think you could have Altocumulus lenticular (sliver) clouds with virtually 2 kts of wind. But, there they were in these sunset photos. An old weather saw, obviously a bit flawed, is that lenticular clouds require appreciable wind.
The models are wetting it up here over the next few days, and we’re not that far from conditions that produce large storms. In this last photo. taken at 7:02 PM, you can make out a Cumulonimbus cloud on the SW horizon, and the huge gray shield to the S was the remnant of a large cluster of storms near the border. So, get ready, and dust your gauges off!
Last, after The End, is the NWS sounding (courtesy of the U of AZ Dept Atmos. Sci.) for yesterday around 5 PM LST. Where the green line pinches in toward the white line is where the two cloud layers shown in the sunset photo were located. On the far right are the wind “barbs” showing how light the wind was, less than 7 kts.