“Back in the (cloud) saddle again”

Who can forget those profound words of Aerosmith and Steve Tyler, “I’m BACK in the saddle again”?  Just the way he says, “I’m BACK…”  is really something.  Well, if you can’t remember anything anymore, here’s a reminder.  Wasn’t that great “rockumentary” movie by Rob Reiner, “Spinal Tap” about these guys?  BTW, pilots on VFR flew through cloud saddles between turrets all the time…  So, there really are “cloud saddles.”

First of all to start today,  you budding cloud-mavens out there should, as always, be reviewing yesterday’s skies here to make sure you got all the clouds down in your cloud log, a service provided for you by your University of Arizona Weather Department.  Since this link is overwritten each day, you probably should go there now.

In the meantime, while you’re scrutinizing that time lapse film, a cool front will go by this morning.  Nice, except no rain outside of isolated sprinkles from mid-level clouds like….Altocumulus opacus virgae, you know, those dense loooking clouds with little snowstorms under them meaning their tops were colder than -10 C (14 F).

Later, after a brief gap in those mid-level clouds, some honest to goodness LOW clouds are supposed develop just after the front goes by later this morning.  How do I know that?  I cheated by going to the Wildcat Weather Department model results produced by the MASSIVE Beowulf Cluster and saw that clouds are supposed to get low enought to top Samaniego Ridge by mid-morning.   Check the sounding predictions here if you don’t believe me.  You’ll see the temperature and dewpoint lines pinch together at sharply lower altitudes beginning around 9-10 AM AST, with cloud bases predicted to be down to about 7,000 feet!

Haven’t seen cloud bases (bottoms of Cumulus and Stratocumulus) as low as that since the last rain which I missed because I was driving mom all the friggin’ way to Asheville, NC, and back to see my brother in his “new life” there.  There’s a lurid story behind that new life, one that you would naturally be quite interested in, but it shall remain hidden from view.

But why don’t those lower clouds that move in and top our Catalina Mountains rain/snow?  Tops too warm, predicted to be warmer than -10 C, so, no ice can form, a necessary ingredient for stuff to fall out the bottom.  You probably knew that already, and I am beginning to feel a little useless.  Oh, well.

Here’s a nice plot of today’s weather around the SW and the satellite cloud scene at 5 AM AST from the U of A (again):  Wow!  Rain drops hitting roof now, 5:37 AM!  Overhead cloud tops still colder than -10 C!

Remember, if you are an intelligent person you will NOT CALL THESE FEW SCATTERED DROPS “DRIZZLE”!!!!!!!  Its a rain shower, a very very light one, that you might “code” as RW— (three minuses).   Drizzle drops float in the air, and are close together; these are not.  There are IMPORTANT cloud reasons for denoting this difference.  Some day I will tell you the “science story” about a well-known scientist, really considered the best in his field, who told me to leave his office and never come back after I informed him it had been drizzling outside.  So, I Mr. Cloud-maven person has some “drizzle baggage”…..he is carrying around.

Note the gap in clouds over us now and that little scruff to the west.  Those are the lower clouds that will move in later.  Below this, our Tucson sounding for 5 AM AST, where you can see that the tops of these Altocumulus clouds are around -20 C (-4 F).  Bases are indicated to be around 15,000 feet above sea level, or 12,000 feet above Catalina.  Poor drops have to fall such a long way in such dry air.  No wonder only the biggest ones, likely HUGE snowflake aggregates, or maybe even “graupel” up there, made it down.

Will quit here……

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.