Another dramatic Catalina weather day-the book

OK, this one’s a little long, lots of twists and turns in the weather plot before its over….but as the Arthur, I felt they were needed (that is so funny! ūüôĀ
We’ll start with the “end” of the book; cut to the chase: the mods have another possible big day this afternoon, ¬†Check it out here.
The result of heavy rain in the Catalina Mountains late yesterday afternoon is shown below. ¬†These shots were about 2 h after the main dumps up there had occurred. ¬†Some neighbors and me was just standing around chatting, had come down to see if there was ANY flow in the CDO. ¬†Nope. ¬†But, since we were having a good time, kept on chatting. ¬†Then, the roar! ¬† (BTW, you could hear the Sutherland Wash roaring from about a mile away. ¬†Must’ve been something over there.)
7:16 PM. Sittin’ around chattin’ up neighbors and vice versa. Nothing seems to be happening in the dry CDO wash at E Wilds Road.
7:28.00 PM.  Oops.
7:28 PM plus 3 tenths of a second

Amounts around here in and near Catalina were generally between 0.4 and 2 inches, with the lower amounts here and up at Sutherland Heights, darn.¬†You can see the Pima County rain table (here)¬†and the¬†U of AZ rain network totals here¬†(they’re usually not complete until later in the morning). ¬† These are totals for the 24 h ending at 7 AM. ¬†You can also review yesterday’s cloud action in the¬†U of AZ time lapse movie¬†for yesterday, rated R for violence. ¬†Max totals in NW Tucson were over THREE inches!



Below is a review of yesterday, beginning with an attempt at some true art, one I’ve entitled for a possible museum showing, “Ants and Castellanus.” ¬†Remember, Altocumulus castellanus/floccus are a good indicator of an “unstable” atmosphere at the level they formed at. ¬†The ants, flying ones, tell you that there was good soil moisture, which is actually important in keeping the boundary layer air moist by replenishing it during a warm day. It was good seeing those ants in swarms like that, they seem to be having a lot of fun, exuberated by moisture, perhaps thinking of more soil moisture ahead.

So, in this ONE photo I took for you, you have TWO indicators that are suggestive of the day ahead; ¬†it might rain again1. ¬†You could tell your friends things like this and sound quite wise concerning nature. ¬†Really something like this should be in the Farmer’s Almanac.

Frankly, while the best models we have available had quite the rain over us yesterday afternoon by 4 PM, it didn’t shape that way. ¬†It was still dry and not much going on. ¬†I am guessing that the colossal amount of rain-cooled air from the previous rain day kept the trigger point (the high temperature) for huge clouds a bit delayed, but it was only by about 1-2 hours! ¬†The rain arrived here between 5:30 and 6 PM. ¬†Pretty remarkable accuracy, never mind the bugs, when you think about it.

Often on days like this, where the atmosphere is primed for huge clouds, they go through cycles where it seems like all of sudden they putting themselves together, bases clustering for an upward explosion, but then a few minutes later, the whole sky looks in disarray, the bases having broken into small segments, tops of the clouds ragged.  That happened a couple of times yesterday afternoon and so I wondered if the explosions would ever happen. Sometimes, in time lapse films you can get a sense of this as waves, gravity waves like ocean ones, in the atmosphere pass by with the clouds in films seeming to all fatten up at once, and then subside as the wave passes.

But then, it happened, all of a sudden, first an cloud on the west end of Tucson, south of us, which had been struggling, began massing, “shafting” (putting out multiple rainshafts), and putting out lighting. ¬†That was it, with the model background of massive clouds, you knew that this was it, the sky was going to go bonkers all over. With but a brief interruption, it did. ¬†I was beside myself snapping photos every few seconds, being out of control again with these stupendous scenes of transition and drama!

Here are too many:

2:49 PM. Its supposed to be raining all around, but nothing is happening. Clouds are ragged and “ill-formed.”
3:09 PM. OK, lookin’ good, base massing over Cat Mountains.
3:09 PM. Phooey, falling apart, stagnating.
4:09 PM. Ok, at last; this is looking good, VERY good.
4:23 PM. ¬†Bigger and better, now “shafting” (producing rainshafts).
4:30 PM. Phooey, fizzling out.
4:34 PM. When did this happen? This looks tremendous. Must be that SW wind pushing out of the dying showers to S-SW and lifting the air over the Catalinas.
4:39 PM. Here come the strands, the ones that lead the dump! I might get something, its gonna be close.
4:42 PM. “Thar she blows!” But I will be missed.



















5:17 PM. When did this happen#2? This is an incredible sight; an outflow from some GIGANTIC complex roaring past and over Pusch Ridge toward Marana.
5:21 PM. Only four minutes later but look how far its pushed out from Tucson!
5:30 PM. Outflow winds and arcus clouds push into Oro Valley.
5:35 PM. In the meantime, the dump on the west side of the Catalinas, shown here, is beginning to push air back toward Oro Valley leading to clashing winds to invigorate clouds not yet raining upwind of Catalina.
5:39 PM. Outflow winds from the Catalinas produce this diabolical sky. About this time, and for another half hour, lightning in the clouds overhead and toward Charoleau Gap occurred every 1-2 seconds! Yeow.


1I would consult some computer models before taking that thought too much farther. ¬†For example, if the computer models are showing rain later in the day, and you’ve seen some castellanus and flying ants, I would definitely mention this proverb to friends, say, during a morning walk. ¬†Otherwise, keep it in your back pocket.