Afternoon clouds smaller than expected

Yesterday at this time it appeared that we had a good chance of a few high-based Cumulonimbus clouds with some virga and the chance of a sprinkle making it down to the ground.  Well, the precipitating clouds were even higher than expected, but with some nomenclature razzle-dazzle, I think we can say that the forecast of Cumulonimbus clouds in our domain did, in fact,  verify.  Below, the first use of the cloud descriptor, “Nanocumulonimbus.”

6:57 PM. Zoomed view of Nanocumulonimbus capillatus producing snow flurry as it drifted toward Catalina.
6:57 PM. Zoomed view of “Nanocumulonimbus capillatus” or maybe “calvus” (center; too small to tell which species for sure) producing a snow flurry aloft (virga)  as it drifted toward Catalina.

The early morning clouds were spectacular full of promise for yesterday, promise that went mostly, well, entirely really, unfulfilled. Here are those sweet morning clouds, more like Altocumulus castellanus, though some reached sizes that they would have to be termed, Cumulus congestus and Cumulonimbus, the latter with some virga and light rainshowers to the ground.

5:51 AM. Distant Cumulus congestus or Cb calvus NNW of Catalina. Held a lot of promise for the remainder of the day. But was just too dry in the end.
5:51 AM. Distant Cumulus congestus or Cb calvus NNW of Catalina. Held a lot of promise for the remainder of the day. But was just too dry in the end.
SONY DSC
5:51 AM Tall, sunlit Altocumulus castellanus line SSW of Catalina.

 

6:04 AM. I thought this was a great scene because that little wedge of brilliant white tells you that one turret from this grouping has shot many thousands of feet higher into the thinner air where the sun's light has not been diminished by the passage through the lower denser atmosphere. Very pretty I thought.
6:04 AM. I thought this was a great scene because that little wedge of brilliant white, center, tells you that one turret from this grouping has shot many thousands of feet higher into the thinner air where the sun’s light has not been diminished by the passage through the lower denser atmosphere that results in the brownish colors of the surrounding clouds. Very pretty I thought.

Today’s clouds

U of AZ WRF-GFS mod thinks there’s a better chance of showers and thunderstorms here in Catalina today, but this is dependent on a easterly surge of moist air this morning. Don’t get your hopes up too much, since we’re kind of on the westerly edge of this surge, and then it goes away. SO, everything really has to come together, and right now, our dewpoints are really down (37 F here) and the moist air is still east of TUS. But, as you know, some of the fun of weather forecasting is weather watching and seeing what Nature is actually going to do.

The weather way ahead

Mod outputs, including spaghetti plots, not looking that great for a full resumption of our summer rain season.
But, with a trough tending to recur along the West Coast in these plots, there’s the chance of a tropical storm being steered this way late in the month. Hey, remember August 1951? Maybe that will happen again in AZ to make August a more respectable rain month after sputtering most of the month…. Dreaming, of course, of the unlikely.

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.