Rain to fall in Arizona today and yesterday

“Rains, some heavy, fell around the State yesterday, according to late reports received here this morning.  ‘The Heights’ in Catalina joined yesterday’s rainy frays around the State when a sprinkle of small drops accompanied by a faint rainbow moved in just after 4:30 PM.  No injuries were reported.”

“Forecasters told CM News this morning, that more rain, in area and intensity in southeast Arizona, can be expected today and tomorrow as an air mass having a bigger cape than the one worn by the air masses earlier in the week moves in.  More news on this breaking story at 11.  In the meantime, watch for a big cape in the sky today.”

Humorist and former newspaper reporter, Dave Barry, speaking at the National Press Club in Washington some years ago, and in a serious moment, asked his audience of reporters rhetorically, “Why can’t we get it right?”

That query inspired the above pseudo-newscast above about how a reporter might miss understand a jargon-speaking meteorologist like me, talkin’ CAPE, as I understand it.  CAPE, or “MCAPE”, is a measure of the amount of potential energy that can be released after clouds form.  When its high, over a thousand units, say, large thunderstorms can easily form.  When its low or zero, “you ain’t going nowhere“, as Bob Dylan wrote.   And on those low CAPE days, clouds don’t1.  At least upward.  They’re going to be flat, “stratiform” clouds.

Here is a prediction of MCAPE over the State from our own U of AZ Weather Department.  You can see more CAPE moving in for today, so, in theory, if we get a little sun, we should have a more active thunderstorm day around these here parts than yesterday.

Skies and clouds were fabulous yesterday due to the great visibility, and yes, due to the slightly darker blue of the sky as the sun revolves around the earth2 at lower angles these days with the approach of winter.  Not so much forward scattering by aerosols, which brighten the sky to a lighter blue or whitish color when the sun is higher and nearly overhead as in June and July.  I think I’d better insert another boredom interruption here. Maybe a nice picture of a turtle…or is it, “tortoise”? SONY DSC

 

That should do it.   Continuing…..

Here are a couple of cloud scenes from yesterday, the first an oddity for summer, an Altocumulus lenticularis right over Catalina–usually they’re on the other side of the Cat Mountains due to westerly flow, but yesterday the flow was from the east and pretty strong up there.

6:29 AM. Ac len overhead, no ice.
6:29 AM. Ac len overhead, no ice.
9:41 AM. Before long, Cumulus clouds were streaming off Ms. Lemmon, forming a cloud street across Catalina and Oro Valley. The early start a good sign for early showers.
9:41 AM. Before long, Cumulus clouds were streaming off Ms. Lemmon, forming a cloud street across Catalina and Oro Valley.
The early start a good sign for early showers.  The Ac len remains in place to the right above the Cu, devolving into separate elements farther downwind.
11:20 AM. While the early start was good, one could sense a problem; the flatttening of the top indicates that this Cumulus congestus cloud had to puncture temperature barrier, this the first indication that while there would be showers and some thunder here and there, it might not be an explosive day.
11:20 AM. While the early start was good, one could sense a problem; the flatttening of the top indicates that this Cumulus congestus cloud had to puncture temperature barrier, this the first indication that while there would be showers and some thunder here and there, it might not be an explosive day.
12:47 PM. While those clouds streaming off the Catalinas did produce some rain (reached high enough to form ice) that temperature barrier kept them from developing dense, hard shafts. This little streamer was spectacular, though. Had to pull off and jump out of the car, since something like this lasts only seconds before it changes into something less interesting.
12:47 PM. While those clouds streaming off the Catalinas did produce some rain (reached high enough to form ice) that temperature barrier kept them from developing dense, hard shafts. This little streamer was spectacular, though. Had to pull off and jump out of the car, since something like this lasts only seconds before it changes into something less interesting. Note dry space withing this little streamer.  Incredible.
SONY DSC
4:33 PM. In spite of the temperature barrier, some clouds were able to cluster into major storms, this shot toward Tucson and Marana.

 

1:19 PM. Some did make it, though.
1:19 PM. Another example of the pretty sky day and an isolated shower.

Have to quit here, its after 5 AM, gasping for bits and bytes from exede.com, an org that’s starting to choke me now, since I’ve looked at too much weather stuff in my first 30 days with them.  Be warned…..

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1Bob, of course, wrote a lot about clouds and storms, e. g., “Rainy Day Women”, etc.  Here he writes, again turning to the sky in his very first line;  “clouds so swift, rain won’t lift, rails is frozen, you ain’t going nowhere.”  Song was posted up there as a boredom interruption in case you’re bored already.

2Thus claim has not been evaluated by the FDA.

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.