Not a bad storm, but not a good one, either

0.28 inches here in this part of Catalina, 0.31 inches at the bridge and Golder Ranch Dr., half mile away, 0.29 inches at Sutherland Heights.  Coulda been more.   Pima County ALERT gage reports here FYI.  Most there, 0.47 inches, Catalina foothills, compatible with the southerly flow; clouds bank up more on that side of the Cat Mountains when the flow is mostly southerly.  U of AZ rain network, here.

OK, I shouldn’t be the storm grinch…  It was great to get something when the models were often oscillating between zeroes and rain out a week or so from yesterday.

December is a benchmark for us: now with 2.11 inches of rain,  its the first month of this calendar year with above normal rain outside of July and August.  All of this has fallen since we fell into the “trough bowl” in mid-December.

Point, models!

The onset of rain here, that is the first drops, did not fall until about 6 PM, EXACTLY as the U of AZ Beowulf Cluster model run said!  It doesn’t get better than that.   The amount, too, was exactly that predicted, in the range of 0.10 to 0.50.  Think I’ll quit.  Yesterday at this time, me, myself and I were anticipating around half an inch, with a 0.20 inches as lower limit, one we just climbed over; 0.80 inches upper limit .  Also, thought the first drops to fall, in our little attempt to “Beat the Model” would occur before 5 PM AST.

The transitioning sky yesterday afternoon

Not much seemed to be happened yesterday as the Altostratus clouds thickened and thinned with the sun occasionally popping out strongly enough to produce shadows.

But, as a cloud-centric person, the only variety of human reading this blog, you may have noticed, even been awestruck by the drastic change that occurred between about 2:30 PM and 3:30 PM.  Started getting hopeful about some drops getting down in Catalina before 5 PM.   Here’s what happened, all due to a surge of moist air that started to come in below the height of the Altostratus in mid-afternoon, and that surge being associated with the approaching upper level trough.  First, two “before” pictures of a “stagnant” sky:

8:18 AM. Cirrus and Altostratus translucidus (in the distance)  also a mainly ice cloud) in a nice, radiating configuration, most likely due to perspective.
1:59 PM. Yawn. Sun bright, no sign of the drastic change hoped for. Clouds are Altostratus translucidus; too much shading overall to be called Cirrus, though a higher, separate layer of Cirrus was sometimes seen.

 

 

 

 

 

 

 

 

 

 

 

 

2:32 PM. Sky changing rapidly. Distant lower layer on horizon. Small Cu popping up around the Catalinas! Here we go!
3:03 PM. Sky changing fast! Looks a little threatening already. Stratocumulus forming under Altostratus opacus and translucidus. Altocumulus also present.
Photo title: Horse under a lowering sky.
4:20 PM. The further lowering of these cloud decks, with a new one with virga on the distant horizon to the southwest was too far away to get here by 5 PM, just as Beowulf said.

 

 

 

 

 

 

 

 

 

The weather ahead

Grim, in a word now.  “Trough Bowl” exiting right (east) for an extended period of time, so we’re more or less away from the storm track for awhile.  Gradual warming trend, of course, along with that.

HOWEVER, a fantasy storm has shown up, if you’re a fantasy weather forecasting league person, this one will get you a LOT of points.  Check this forecast out from the WRF-GFS 00 Z (5 PM AST) global data (rendered by IPS MeteoStar).  Summary?  Juicy.

Valid 5 PM AST, January 12th. Colored areas denote where the model believes precipitation has fallen over the prior 12 h. Blue regions denote especially heavy precip.

 Valid for the same time as the map above showing where the 500 mb trough is with all that rain (over LAX).

But, of course, we know when to laugh at progs like this.  Go to the ensembles of spaghetti and see if there is ANY veracity to a big trough in the upper levels, one that would HAVE to accompany a rain map like this.  “These are their stories”, to quote a TEEVEE line:

Valid for the same time as the 500 millibar (mb) map above. Not REAL hopeful, though there is some chance of verification as indicated by several of the red lines running across Baja. Look for this storm to come and go in the model runs in the days ahead.  Overall though, the big northward bulge in the red and blue lines suggest a storm-blocking ridge along the West Coast is the most likely outcome of this mess, with a trough over northern Mexico and the Rockies, the latter too far east to do us much good but keep the temperatures down.

 

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Categorized as Definitions

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.