Not expected by this brain yesterday, but several of those many more Cumulus clouds than expected also fattened up to heights where ice began to form, also not expected. As you know, that means precip fell out, at least up there. As a weatherman-cloud person, there are always surprises every day (!) to delight and disappoint you. Its quite and exciting life we lead.
How cold were those tops?
Well, you know, colder than -10 C on a day with very high and COLD cloud bases1. How high and cold were the cloud bottoms yesterday. Oh, about 0 C (32 F, of course) at 14,000 feet above the ground, 5,000 fee above Ms. Mt. Lemmon, the taller tops extruding upward to between -15 C and -20 C (5 F to -4 F), about right for the amount of ice that developed, “eyeballed” concentrations of a few to 10s per liter of air in those clouds (for size, think of a liter size plastic bottle of Bud Light with some ice crystals in it). (Remember, a LONG time ago in another area of the Universe2,3, Mr. Cloud-Maven Person flew into such clouds with instruments aboard his Cloud and Aerosol Research aircraft and can say things like this with what appears to be some authority.)
Here are those clouds from yesterday, which I am sure you logged with excitement in your weather diaries:
Today the cloud bottoms are 1,000 feet lower than yesterday afternoon. But is it a diurnal effect where bases are always lower in the cool mornig (“morning”; intentionally spelled wrong to see if you’re paying attention) than in the afternoon? BTW, if you like soundings, go to the “Happy State of Wyoming, the nation’s happiest4, to see all the soundings you want at the University of Wyoming
But, we have a windshift in the middle levels traipsing over us late this afternoon (U of AZ TUS sounding forecast here), and that will be, we hope, something like a fork lift; help to push cloud tops up just it goes by. (However, I can find no evidence of such a windshift in larger scale models, so MAYBE I have mistaken a diurnal shift induced by our mountains as a “trough”. A trough would be a lot better, a diurnal turning of the wind, not so great a weathermaker. Another one of those “surprises”; they can come from all quadrants.
SO, high based Cumulus, some growing into Cumulonimbus clouds here and there, with some sprinkles because the bases are too high for a really good rain. But, hey, if you want a really good forecast, not a crummy one like this, see Bob and the NWS.
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1Remember cloud bases can be cold, but NOT temperatures, which are high and low. The AIR is warm and cold.)
2Remember the solar system is speeding along (45,000 mph or so) in the Universe around the Milky Way Galaxy to god knows where (the constellation Hercules, according to the Stanford Solar Center).
3Quite fond of footnotes; they add a scholarly aura to trashy writing like this.
4OBJECTIVE HAPPINESS BY STATE We’re not THAT happy in AZ, BTW, but people are really happy in Wyoming, Montana, South Dakota. Huh.
