Backspin ending; upper low moving off to east as big trough barges into West Coast

You can see all the action described above here and here:  first the water vapor loop from the Huskies’ Weather Deparment that lets you see ALL the action, dry and moist air moving around, and then from this IPS Meteostar loop, you can drill down and see the clouds with the itty bitty radar echoes they produced over eastern AZ and NM as the clouds spin around that backspining low.   Stopped moving this way, as you will see, early this morning as a big trough with its broad band of westerly winds moves into the West Coast pushing our low away.

Unfortunately, that “big trough” will only bring rain as far south as SFO in the days ahead while we warm up for a few days.  I would look for a string of nice sunsets as Cirrus clouds on the periphery of the rainy systems to the north are drug this way , however, as the week begins.  I guess that’s not so bad.

Here’s a nice weather map for you (more from the Huskies!), one for the 300 millibar level, 30,000 feet or so above sea level.  You can see our spinner over the AZ-NM border, and the “big trough” which is about to brutalize the Pac NW and northern California:


Since a couple of those radar echoes last night are in our Catalina domain (a 100 mile radius, and rain was falling at Safford (3 AM AST), an old mining town NE of us), I now recommend that all readers of this blog check their dusty cars for sprinkles-its-not-drizzle on their dusty cars for a possible drop images in the dust, and a journal entry of a rain occurrence.   And, yes, we had plenty of dust yesterday as the lower level winds came scooting from the east-southeast  at 20-40 mph over much of SE AZ yesterday.  The Catalina mountains protect the town and environs around Catalina from these events, so we only get to imbibe dust, not actually experience it being raised up around us as was the case in the city yesterday.  You can notice this blocking effect nicely by driving south on Oracle on days like yesterday until you get to Pusch Ridge, Magee Road or so on Oracle, and then hang on to your hat.  There’s a similar low level wind situation today, and so you could do that today, drive south on Oracle, and experience it for yourself, maybe log the event in your weather journal as well.  I think readers in the years ahead would find it of interest that you did that.  I did it yesterday, and it was pretty exciting to see that east wind roaring though the palms, etc., just as you passed Pusch Ridge!

Yesterday’s clouds

What would a cloud maven’s post be without clouds?  First, take a look at yesterday’s time lapse from the U of A’s Weather Department.  During this one day, you can see the Cirrus clouds first coming from the northeast (they take awhile to appear), and then by the end of the day, they are almost coming from the west as that upper level low center spun back toward Arizona from New Mexico.  This is really cool, something you won’t see very often at high levels, this amount of turning of the wind in one day at that level.  Also, you will see lots of Cirrus forming in dense tufts and then dispersing once ice has formed.  That, too, is cool!

Here are some shots from yesterday:  1) Cirrus, 2) scruff of Cumulus humilis to the north, and 3), a dusty, Cirrus-ee sunset shot.

In the first shot, you may notice that these Cirrus clouds more resemble Altocumulus with its little flocculent masses.  Since Altocumulus clouds are all, or mostly comprised of liquid drops, you have to be able to see that these little cloudlets are ice, not water, thus betraying the greater height of these clouds compared with the Altocumulus (Ac) clouds they resemble.  There is a slight possibility, that for a second, these clouds had a liquid drop, such as upper center in the first photo.  Those look suspiciously like little tufts that may have been liquid drops.  However, while nearly all Ac REMAINS mostly liquid, even when trails of ice fall out, these clouds do not.  One of the mysteries in our science is about the formation of ice.  Some liquid drops in Cirrus clouds have been detected by researchers at the University of Utah1 at -44 C!  These are NOT the same researchers that were associated with “cold fusion” reports, BTW, ones that came out around the same time as this one.








The weather ahead

Latest model run, from 11 PM last night, has, after having several days ahead with rain, dwindled them to just two, the 19th and 20th of March.   These are indicated to be, in totality, a good rain.  Hope they “maintain” in the progs!

The End.

1Sassen (1986, Science)

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.