Catalina embraces a second day of rain

Drops, that is.   There were about 140 or so the night before last, noticeable only  if you left your dusty car outside, and TWO drops yesterday between 4:08:22  and 4:08:51 PM, as the last remnant of a shower cloud moved overhead from The Gap (the Charouleau one).

You HAD to be outside running around to encounter them, I do mean “running”, to increase the sample volume and your chances of detecting a drop in marginal rain situations. You have to  “want it”,  to be the best you can be about traces, that is.  And I wanted to report another trace real bad.  I love to report traces of rain, the most underrepresented rain event of all, the poor relative of measurable rain.

And, of course, more shower chances ahead, March 17th through the 20th, as remnant of the upper level trough that produced our last two days of clouds and sprinkles returns to us like a boomerang after producing generous rains in Mexico.  It also meshes with a weak trough from the Pac at this time, so its pretty troughy for a few of days.   Nice.

Today’s cloud pic archive will begin with the sunset the evening before last, since domestic responsibilities1 prohibited posting the usual tedious cloud array yesterday.

6:32 PM, March 12th.  Rosy glow, a nice name for a female western  singer, bloomed late in the day (was less than expected that day).  Lots of virga spewing out of iced up Stratocumulus clouds.
6:32 PM, March 12th. Rosy glow, a nice name for a female western singer, as well as a sunset, that bloomed late in the day (was less spectacular than expected that day, but still something). Lots of virga spewing out of iced up, high and cold-based,  Stratocumulus clouds.  Since you wanna know more, the TUS sounding indicated bases at -10 C, and tops at -20 C (4 F), that latter temperature explaining all the ice that formed that day.

Yesterday’s clouds

The temperature structure aloft was pretty much the same as the previous day, except that cloud bases were slightly lower and warmer, “only” -7 C or so, with tops again around -20 C (4 F), plenty cold enough for plenty of ice and virga from the modest Cumulus and Stratocumulus clouds that developed later in the morning.

Rainshafts were that tiny bit heavier it appeared, seeming to reach the ground with more gusto than the similar day before.

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11:44 AM. Groups of small Cumulus began forming over the mountains.
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1:23 PM. Cumulus and Stratocumulus fill in the sky. Slight virga is apparent if you look really hard.
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2:29 PM. A light rainshower douses Marana and vicinity. Note the rumpled top of this cloud suggesting dominance of the water phase with just ice underneath. The dark bottom of the cloud is often called a “cloud base” by pilots, but is really the transition zone where the snow is melting into the more transparent rain and is not really a Cumulus cloud base, one composed of droplets forming in an updraft,  as in the prior photo.

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Rain shaft on The Gap.  Can you detect it? Its coming right at us!  Here's where the responsible observer realizes that he must be outside, or provide another means of detecting isolated drops.
3:58 PM.   Rain shaft on The Gap. Can you detect it? Its coming right at us! Here’s where the responsible observer realizes that he must be outside, or provide another means of detecting isolated drops as the cloud head begins to pass.

And, below, why we love our mountains and desert, especially on these kinds of days.  About this time, the “light show” begins, ending with a dramatic sunset.

6:14 PM.  Even the horrible becomes beautiful in the evening light.
6:14 PM. Even the horrible becomes beautiful in the evening light.

DSC_4662 DSC_4654 DSC_4648 The End

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1I had to take my mom, whose she’s really old and fragile,  to the doctor ,  and then to the supermarket.  This personal information posted for the purpose of inducing empathy in case I have a really bad forecast.  People will remember that I take my mom places.

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.