Encore of disappointment

Yesterday afternoon and evening were remarkably similar to the day before;  great, spectacular banks of brilliant white turrets with black bases approached from the northeast filled with rainy portent, but, as with that previous day, disappointed.   Once again, those clouds tended to fade some as they much beyond the Catalina Mountains, southwestward across Catalina, Saddlebrooke, and Oro Valley.  Even the rainfall here in Sutherland Heights, 0.08 inches, was almost identical to the day before!

While there were many similarities, one had to be hopeful looking at those clouds as they spread across the valley.  They many more Cumulus turrets above them compared with the prior day, had not faded completely to flat stratiform clouds riding an outflow wind.  In fact, if you noticed, as they encountered the warmer air to the west of us, ramped up into major storms around I-10 and farther west.  They are still going strong, now, a little before 4 AM, approaching Puerto Peñasco/Rocky Point!   (This is a peak time of day for rain in the Colorado River Valley, oddly,  spanning Yuma to Needles since many of our evening storms here continue on to that area during the night.)

Models still have lots of rain in our future as tropical storms whiz by in the Pacific west of Baja over the next 5-10 days (models have, not surprisingly, backed off direct Arizona hits for now1).  Still there’s plenty of time and water in the air to catch up on our normal summer rainfall.  At 4.58 inches, we’re not terribly behind the six inches expected in July and August in Catalina, and with recent rains, the desert has rebounded in a satisfying green over the past couple of weeks.

From the afternoon of August 16th.
From the afternoon of August 16th.  Anyone for “cactus golf”?

Of course, it you were up early yesterday, you may have seen the lightning (LTG) to the south through southwest.  We missed a nice complex of heavy rain that brought 1-2 inches in a couple of spots as it passed across Tucson and into the Avra Valley.

Your cloud day

6:32 AM. Miniature arcus cloud leads the way ahead of those heavy Tucson rains.
6:32 AM. Miniature arcus cloud leads the way ahead of those heavy Tucson rains.  At the leading edges, many of those clouds would be called, Altcoumulus castellanus, mid-level clouds with spires.  But sometimes they cluster, as yesterday into clouds too large to be “Altocumulus” clouds, but rather Cumulonimbus ones with mid-level bases.
7:03 AM. Rain continues to move westward into Avra Valley and Marana.
7:03 AM. Rain continues to move westward into Avra Valley and Marana.  Note crepsucular rays shining down on Rancho Vistoso or someplace like that.  There are quite a few “Vistosos” around it seems.
7:36 AM. I loved this little guy, all by itself of up there, trying to do the best it can to be something. Such a pretty scene if you can avoid the snail implication.
7:36 AM. I loved this little guy, all by itself of up there, trying to do the best it can to be something. Such a pretty scene if you can avoid the snail implication.
2:05 PM. Of course, the Cloud People like me always want to document "First Ice" of the day, and here it is in this sprout off the Catalinas. Can YOU see that critical aspect of our clouds in this shot, one not taken while driving, of course?
2:05 PM. Of course, the “Cloud People” like me always want to document “First Ice” of the day in his/her cloud diaries, maybe mention it to neighbors later, and here is that moment for yesterday afternoon in this sprout off the Catalinas. Can YOU find that critical aspect of our clouds in this shot, one not taken while driving, of course?  Remember, almost always in Arizona, clouds need ice to rain.
4:44 PM. As predicted in the U of AZ model, great banks of Cumulus and Cumulonimbus clouds roar down from the Mogollon Rim and other high terrain to the northeast of Catalina with the promise of a substantial rain. Looking N across Sutherland Heights and Saddlebrooke
4:44 PM. As predicted in the U of AZ model, great banks of Cumulus and Cumulonimbus clouds roar down from the Mogollon Rim and other high terrain to the northeast of Catalina with the promise of a substantial rain. Looking N across Sutherland Heights and Saddlebrooke
5:36 PM. Incoming Cbs (Cumulonimbus clouds) getting really close, but cloud maven person forgets to look up and in a couple of minutes, giant drops are falling by the millions. Kinda reminded me of that time at the Mitchell, SD, airport in '72 when I was radar meteorologist on a project having four aircraft that were to be sent up to try to prevent hail by "overseeding" them with silver iodide. Well, it was midnight or so, and the radar can't look up, but rather out, at storms to send the planes toward, and the 1-inch hail stones started pummeling the airport from a cell that developed overhead, like that one yesterday afternoon did over Sutherland Heights!
5:36 PM. Incoming Cbs (Cumulonimbus clouds) getting really close, but cloud maven person forgets to look up and in a couple of minutes, giant drops are falling by the millions. Kinda reminded me of that time at the Mitchell, SD, airport in ’72 when I was radar meteorologist on a project having four aircraft that were to be sent up to try to prevent hail by “overseeding” them with silver iodide2. Well, it was midnight or so, the radar can’t look up, of course, but rather out, at storms to send the planes toward. Well, the 1-inch diameter hail stones started pummeling the airport from a cell that developed overhead, like that one yesterday afternoon did over Sutherland Heights!

 

5:41 PM. Surprise! Extra big drops, too, for a brief time, and 0.06 inches. It was so fantastic!
5:41 PM. Surprise! Extra big drops, too, for a brief time, and 0.06 inches. It was so fantastic, as unexpected rain always is!

 

6:02 PM. Its looking "oretty good" here, a couple of expansive, solid dark bases. But, there are also those "weak" updraft updraft areas denoted by broken light and dark areas.
6:02 PM. Its looking “OK”, better than the day before here,  with a couple of larger, solid dark bases. But, there are also those “weak” updraft updraft areas denoted by broken light and dark areas. Nice lightning on the left;  lighting on the right.

 

6:37 PM. While one of those bases unloaded with a few cloud-to- ground LTG strikes over there by the Palmer in Sutherland Valley, the base to the north of us just could not work its way S, and unloaded
6:37 PM. While one of those bases unloaded with a few cloud-to- ground LTG strikes over there by the old Golder Ranch  in Sutherland Valle. The bases to the north of us just could not work thier way S, and pretty much remained in place, unloading on Charouleau Gap

 

6:49 PM. Hopes for a substantial rain fading fast as the cloud base this side of the Charouleau Gap rain area began to look chaotic. The rain that's falling there needs to be replenished by new turrets that convert to ice, and if that's not happening, then the rain just falls out and the storm ends. Here, that rainy area was just not replenished by building turrets, and so got lighter and lighter until it faded away.
6:49 PM. Hopes for a substantial rain fading fast as the cloud base this side of the Charouleau Gap rain area and estedning overhead of Sutherland Heights began to look chaotic, not firm and smooth. The rain that’s falling on the Gap needs to be replenished by new turrets that convert to ice, and if that’s not happening, then the rain just falls out and the storm ends. Here, that rainy area was just not being replenished by building turrets adjacent to it, and so it got lighter and lighter until it faded away. Also, the rain shafts never had that black, straight sided look that goes with strong convection.

 

7:03 PM. Rosy glow at sunset...yet another great name for a western singer! But, getting back on task, notice the rain shafts and how wispy they are, with sloping rain. That indicates the tops aren't too high, the updrafts weak, and the clouds probably just barely made it to the ice-forming level.
7:03 PM. “Rosy glow” at sunset…yet another great name for a western singer! Where do these come from?  But, getting back on task, notice the rain shafts and how wispy they are, with sloping rain. That indicates the tops aren’t too high, the updrafts weak, and the clouds probably just barely made it to the ice-forming level.

 

U of AZ mod run from last evening’s 11 PM AST data indicates a day today like the past two:  coupla small Cumulonimbus clouds on the Cat Mountains by mid-afternoon, then a line of big storms again sweep down from the higher mountains to the NE in the evening.  Maybe today we’ll get that big rain finally.  If nothing else, the skies will be spectacular and dramatic again.

The End.

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1A peak just now at the 11 PM WRF-GFS run shows that the unusually strong tropical storm not so far offshore from San Diego has been resuscitated.  Go here to see this exciting storm and all the rain we’re supposed be getting over the next two weeks.  Getting pretty worked up about it again.
2Does seeding to reduce hail work? The evidence is mixed, and is not convincing to national panels or the American Meteorological Society. Still, that type of cloud seeding is carried out in many locations in the Canadian and US grain belts.

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.