Harder rain falling now at 4:04 AM; you’re probably not up

I’m not missing any of this.  Its too good.  Supposed to rain off and off until the frontal blast about 10 AM -Noon, then clear up for awhile, then scattered showers develop from what will be icy looking Cumulus and small Cumulonimbus clouds, kind of the usual storm chronology we have here.  This sequence shown in the U of AZ model run from last night is here, and its been well-predicted by the media weather folk as well.  Don’t watch TEEVEE much, but I did catch some bits and pieces by George.  It was pretty comprehensive, quite good really, and then I started to feel sad.  Why am I doing this, blogging about weather myself when its already out there????????????????????????  Oh, well.

It will be interesting to see if there is more than a few flakes of snow as the front goes by, the rain becomes moderate to briefly heavy, and that’s when the precip will start to have ice in it, maybe turn to snow for awhile due to a diabatic effect where the snow level comes down due to big melting snowflakes dragging it down.  An early morning frontal passage would have been better for the best snow accumulation, but, oh, well.

Still looks to be an appreciable amount here, both eyeballing the situation and in the U of AZ mod run from last evening.  From this keyboard yesterday, the best estimate for this storm that just kind of popped out was 0.450 inches (the median between a lower limit of 0.20 and upper one of 0.70 inches).  Since “we” last wrote, the U of AZ model has increased its precip for us, as though it was affected by something I said.  The green “half inch” region has crept that bit closer to Catalina in this latest run below over where it was yesterday.

Accumulated precip for the 24 h ending at midnight tonight.
Accumulated precip for the 24 h ending at midnight tonight.

And we’ll need as much rain as we can squeeze out of this one as the follow up series of storms foretold so long ago in the mods have disappeared–shown during a time when our “truth viewer”, those NOAA spaghetti plots were down for a few days, or they might have tipped us off to be more “circumspect” about a run of storms by showing that they were not reliable predictions.  No further rain is forecast for the two weeks after this now!  Dang!

The intermittent rain that has been falling is WAY ahead of the front, over there by Yuma as I write at 4:41 AM.

IPS satellite-radar loop for the Southwest here.

Its developing in the moist flood of air that rushed in overnight at lower levels along with a huge icy shield overhead, no doubt a thick Altostratus with virga on top of Stratocu, maybe dumping some drops into the lower cloud deck.  Need more of that.

——————Learning module———————–

The effect of rain drops falling into a lower layer of Stratocu?

If you dropped a cup of water on the top of the layer yourself, the amount coming out the bottom would be more than a cup.  Those fast falling drops, about 5-10 meters per second, say for regular raindrops, collide with the itty bitty cloud droplets blowing sideways in the wind.  The larger cloud droplets, say bigger than 20 microns in diameter, collide and stick to the fast-falling raindrop, adding to its size.  We call this accretion.  That bottom kilometer of storms where otherwise “harmless”, non-precipitating Stratocu is likely to be,  is critical for appreciable snow and rainfall due to this process in mountainous regions.  Almost always, the impression is that its the Stratocu that’s precipitating, but usually its not.  So, when you see a raindrop fall, thank a Stratocu deck for making it that bit bigger, thought in some cases to increase precip by 50% due to the effect of accretion in the bottom  kilometer (3300 feet).

Might look like this if you could step back to the south of the Catalinas today and draw a crummy cartoon of what was happening, but it was the best you could do at the time

From a 101 class I taught at the U of WA, with modifications to show I am in Catalina, AZ.  Background: couldn’t get the real guy to teach that class that summer, and so I was enlisted to do the job at the last minute, thus lowering the accreditation rating of the University of Washington. You see, I have NO ADVANCED degree of any kind, and to have a lecturer without the big Ph. D. means you go DOWN!  On the other hand, unlike most faculty at ANY university, I have been asked my opinion on something and was quoted about it in the Wall Street Journal in 2011!  Oh, yeah, baby!  Wanna spike a football right now!  Credentialism; a bunch of hooey (sometimes).


————end of learning module and statement on credentialism aloong with a display of immaturity—————

Back to the storm….  After a couple of light and brief showers, we have amassed 0.01 inches!  Only 0.44 inches to go to make a perfect prediction!

Yesterday’s clouds

Kind of a bust, really, and admitting that will make up for some exultations above.  Sure, there were some Altocumulus with virga hanging down, but those virga trails needed to be about 20,000 feet longer to be anywhere near where I thought they would be.  And then it cleared off almost completely during the afternoon!  Oh, well.  Pretty day, with lots of wind and mild temperatures.   Here are a few shots:

6:55 AM.  Altocumulus floccus virgae--has virga.  These were up around 20,000 feet above sea level, or about 17,000 feet above ground level here in Catland.  Top temperatures with all that ice falling out?  About -26 C (-15 F).
6:55 AM. Altocumulus floccus virgae–has virga. These were up around 20,000 feet above sea level, or about 17,000 feet above ground level here in Catland. Top temperatures with all that ice falling out? About -26 C (-15 F).
7:12 AM.  Ditto.
7:12 AM. Ditto.
9:46 AM.  More of the same but less.
9:46 AM. More of the same but less.


6:25 PM.  A vast shield of Altostratus/Cirrus advances on Catalina.
6:25 PM. After a clear afternoon, a vast shield of Altostratus/Cirrus advances on Catalina.


The End for now, anyway.

















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.