The first of many cloud blobs in the days ahead, some rain-filled, passes over during the night

Here it is.  You may need an optical enhancement tool to see the radar echo speck nearest Catalina, and its not the one nearest the arrowhead below, but continue in that direction:

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Satellite and radar imagery for midnight last night. Notice cloud blob and radar echoes over and near Catalina, Arizona. I really thought there’d be some drops here as this went over!

You can also check on all the rain  that  fell overnight in the region  here, courtesy of Pima County ALERT rain gauges.  BTW, they aren’t capable of reporting traces, so if you see  bunches of zeroes, it doesn’t mean some drops didn’t fall somewhere in the network.

Non-verification of this rain can also be found via our fine TUS NWS “storm total” view, 10:30 PM to 4:30 AM this morning:

Regional radar-derived storm total from "rainy cloud blob."
Regional radar-derived storm total from “rainy cloud blob.”  Arrow almost reaches Catalina; didn’t want to cover up a pixel of rain, if there.  THAT radar did not pick up the rain I feel must have fallen, so we have quite a conundrum.  If you would like to see for yourself how much rain fell last night, go here.  Will be looking for drop images in the dust as soon as it gets light, too!

In the meantime, all those rainy cloud blobs to our NW right now (first image) look like they will be able to just make it to Catalinaland after all.

In our last chapter, it looked like the strong cold front would move through tomorrow as just a dry cold one, but now the chances of having a little rain (a wet cold one) have been zooming up.  The models have readjusted their thinking and now that critical ingredient, the core of the jet stream (at 500 mb) passing over us ahead of the trough core itself is being predicted.

And with that configuration as the front goes by Catalina, and believe me you’ll know by the 10-15 degree temperature drop, a tiny amount of rain might fall.  Also, look for a pronounced lowering of cloud bases to the W-N of Catalina as it gets close, something in the way of an “arcus cloud”, marking the leading edge of the windshift to the N.  Could be nice and dramatic looking tomorrow.  Those cloud base lowerings are pretty common with fronts here.

How much rain?

Oh,  possibilities range between 0 (a complete bust is still possible) to only about 0.25 inches, tops in the “best” of circumstances.  But, this keyboard would like to see ANYTHING measurable; that would bring happiness.

There are some more rain blobs showing up in regular intervals in the days ahead for you to think about, as rendered by IPS MeteoStar.  Arrows have been added to show you where you are, if you are in SE Arizona:

Valid tomorrow morning at 11 AM AST. Colored areas denote regions where the model has calculated precipitation during the preceding 6 h.
Valid tomorrow morning at 11 AM AST. Colored areas denote regions where the model has calculated precipitation during the preceding 6 h.

In the storm below, which is pretty much going to happen now, the range of amounts as seen from here, at least 0.15 inches, top, 0.50 inches, best guess, therefore, 0.33 inches (from averaging the two.)

Val at 11 PM, March 1st. Colored areas are those in which the model has calculated that precip has fallen during the prior 6 h.
Val at 11 PM, March 1st. Colored areas are those in which the model has calculated that precip has fallen during the prior 6 h.

There’s great uncertainly in whether this last storm will actually occur, so range of amounts are zero to 1 inch.  :}   See reasons for uncertainty below, besides being too far in advance or our models to be reliable anyway.

Ann 2015022300_CON_GFS_SFC_SLP_THK_PRECIP_WINDS_264
Valid Friday, March 5th, at 5 PM AST. Colored regions NOW denote areas of precipitation that have fallen during the prior TWELVE hours. (Mod resolution degrades after about 192 h, and so a coarser view of precip areas is used.)

While a significant storm on the 1st is virtually assured according to spaghetti, this last major event in the panel above is doubtful.  See below,  in another lesson on consuming weather spaghetti:

Ensemble spaghetti valid for the same time as the panel above, 5 PM AST Friday, March 5th. Not much support for a storm, low confidence is indicated by the LACK of bunching red and blue lines, unlike those off the East Coast, and over there east of Asia.
Ensemble spaghetti valid for the same time as the panel above, 5 PM AST Friday, March 5th. Not much support for a storm, low confidence is indicated by the LACK of bunching red and blue lines, unlike those off the East Coast, and over there east of Asia.  So, while a great storm is predicted in last evening’s model run, prepare for sadness and disappointment as a hedge.

 Yesterday’s fine clouds

7:10 AM. A couple of shafts of big virga. Likely a drop or two reached the ground.
7:10 AM. A couple of shafts of big virga. Likely a drop or two reached the ground.  Could have been caused by aircraft penetrations, or, taller Altocumulus castellanus-like turrets that reached lower temperatures, produced more ice.  They look suspiciously like an aircraft artifact due to their very small size.
7:41 AM. Nice stack of lenticular pancakes in the lee of the Catalinas.
7:41 AM. Nice stack of lenticular pancakes in the lee of the Catalinas.  You can see some great lenticular occurrences in the U of AZ Time Laps movie for yesterday.  There are also a lot other fascinating things that go on in yesterday’s clouds, too.
8:05 AM. Natural virga approaches Catalina. Looked for a drop as it went over, but saw none.
8:05 AM. Clearly natural virga approaches Catalina. Looked for a drop as it went over, but saw none.
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8:22 AM. Pancakes downstream from Ms. Mt. Lemmon.
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8:44 AM. Fairy dusters in bloom!
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9:07 AM. Doggies, Emma, and little Banjo, sample and inspect water STILL running in the Sutherland Wash!
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1:46 PM. After a brief sunny period, banks of Altocumulus invade the sky.
2:46 PM. Altocumulus opacus clouds continue to fill in, darken.
2:46 PM. Altocumulus opacus clouds continue to fill in, darken.
5:40 PM. Muliple layers of clouds stream ahead of sprinkle producing cloud blob just upwind at this time.
5:40 PM. Muliple layers of clouds stream ahead of sprinkle-producing cloud blob just upwind at this time. Note how the Altocumulus opacus clouds disappeared, leaving lenticular like formations, with a thin ice cloud (Cirrostratus) above.

The End, though I COULD go on and on and on, and then on some more.  Its who I am….

Author: 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.