Yesterday’s Catalina-centered blast dump: 0.83 inches; 0.53 in 16 minutes

Nice weather we’re having lately.   Nice desert greening we’re having now, too.

What a day yesterday was!  Look at the sunrise view of Altocumulus at the start of the day.  And, too, how about some neat patterns before all the mayhem.  What a day, to repeat.

Yesterday’s blast and dump that struck just after 2:30 PM yesterday can be seen in a side view here, courtesy of the University of Arizona Wildcats Department of Atmospheric Meteorology.

Watch those dark cloud bases move over the southern portions of the Cat Mountains at 2:30 PM in this time lapse film!   Pretty dramatic, and also see how fast a cloud can drop a load of precip its been carrying in some of those around Tucson yesterday.

Below is what those same clouds looked like rolling over the Cat mountains toward us from our Catalina vantage point.  This was pretty darn exciting to see!  Why?

First, that dark line of bases was streaming toward Catalina from Table Top peak.   Next,  the bases are pretty large, meaning a there is pretty large area of updraft, and 3) MOST importantly, the bottoms looks solid, no bright spots interspersed among the dark base telling you that the updraft has holes in it.  A solid, contiguous base like this suggests a good AND contiguous updraft, and a LOT of water is being condensed above those bases.

Can things change and holes develop even at this point?

Yes, have been horribly disappointed a time or two when that has happened, and when it does,  its kind of like the beginning of a love affair you thought was going to be a good one but goes  “south” all of a sudden because you made some assumptions based on too little “data” and other misinterpretations due to wishful thinking and delusions and then you find out that those assumptions and perceptions were incorrect and you REALLY were delusional cum laude.    How painful is that?  But then you have to “man-up”,  as we say today, and pretend that nothing happened…or you’ll lose face.  Yes, I have had to do that with some cloud bases that have let me down.

Or taking another tact here for sports fans, a cloud base that falls apart is like a seeing a running back breaking into the open, with a clear field ahead.  Everything LOOKS good until he trips and falls at the 10 yard line.   You’re so upset, you go down to the Golden Goose thrift shop and buy a pair of ladies’ used tennis shoes and send them to the miscreant running back as a way of pointing out your displeasure.  You don’t want to admit you were wrong in your “a priori” assessment that a touchdown would surely be scored.

Well, you get the idea.  It can all go bad just from looking at the cloud base and making an “exterior”  assessment because you really don’t know what’s happening “above” (as in people).  So, you have to “hold back” your emotions just that bit to keep from being hurt by a nice “cloud base.”  Was I talking about weather somewhere in here?  OK, back on task.

But that cloud base yesterday did not fall apart; it did not disappoint!  Rather it remained solid until that magical point that all that water/hail/graupel up there above the bottom of the cloud begins to shoot down, often in strands or filaments.  The strands or filaments are almost always due to hail or graupel shafts.  Hereabouts they are likely to have melted into large drops on their way down.  (When flying through these kinds of clouds, as the writer did for many years with the U of WA Cloud and Aerosol Group, flying through those miniature shafts of hail/graupel (soft hail) was like someone throwing a handful of rice at the pilots window.  They were only tenths of a second in duration, maybe 10-30 yards (meters) wide.   Its still not clear what cloud “microstructure” and circulation leads to such tiny strands within large clouds.  Uh Oh, getting deep here.

Check out the next couple of photos, especially number 2 and 3.  For maximum precip excitement, I would have, and I am sure you, too, wanted to have been about 1 mile farther toward that base as the bottom drops out.  That’s where the largest raindrops, hail or graupel are going to be.  Of course, all that water is going to shove a lot of air out of the way, and that’s why we saw those momentary blasts of wind to 50-60 mph, at least right here.

Here’s a map of the local area rainfall, thanks to the U of A rainlog organization.  It will show you how well we did relative to the rest of Tucson.


The End.