High and middle clouds lining up for Catalina in early December

(Formerly titled:  “Storms lining up for Catalina in early December”)

Things change.

Confidence was never real great in the spaghetti plots we rely on for hints about the reliability of our longest range “wishcasts,” as a friend puts it.   Now it seems we’ll only see high (Cirrus) and middle (Alftocumulus and Altostratus) clouds on the edges of the rain areas that move across California, maybe the NW corner of Arizona, too, during the first week in December.  Oh, I suppose there could be some virga with a sprinkle here from the thickest of those middle clouds, but that’s about it now.

But, on the happy side, we’ll see our usual array of stunning sunrises and sunsets under warm conditions when those high and middle clouds begin arriving about Saturday, the envy of many northern “climers”, or “northlats” this time of year.  (Starting to see those Illinois, Minnesota, Ohio, license plates now, aren’t we?)

Our next chance at rain after that is not good but revovles, and the air does, around a cutoff low that gets stuck out of the mainstream here in the SW in mid-December.  Those, unless you’re in the exact right position, or are gigantic like that one back in ’67, often have limited amounts of moisture.  If you’ve never seen a cut off low, here’s what they look like in the middle troposphere, a forecast valid for this Monday afternoon:

Example of a cut off low at 500 millybars, or around 18,000 feet above sea level.  They kind of meander around not doing much, then eventually dissipate as this one does as it begins to move eastward.
From the University of Washington Huskies Weather Department, this example of a cut off low at 500 millybars, or around 18,000 feet above sea level. They kind of meander around not doing much, then eventually dissipates/”opens up” into just a bend in the winds up there,  as this one does as it begins to move eastward and then northeastward (the killer for us) as it comes into the Cal coast.  Most of the jet stream, as indicated by numbers of contours, is far to the north, something that allows lows like this to pretty much have a mind of their own for awhile. The bulging northward contours over us mean that it will be toasty and dry here, maybe some Cirrus clouds around..


So, it would kind of lucky for us to get something out of it.  And, when you’re in a droughty period,  as we have been in for the past EIGHT weeks, things like that don’t usually work out in your favor.  Its like being a football team that loses the close ones but also gets blown out in other games.   Since we’re talking about sports now, a pause for a sports exultation: Washington1 volleyball somehow beat No. 1 Stanford on Wednesday!

Special Scientist,  Bob Maddox,  who is an actual expert and does a superb weather blog for this area,  has passed me a long range forecast from the CPC (Climate Prediction Center) recently that I will share with my reader:

A wet mid-winter  in the Tucson area been forecast!

How wet?  2 inches in December, 4 inches in January, and a colossal 6 inches in February.  Wow.  There would certainly be flooding at some point later in this period.

These results derive from a longer range forecast model the CPC runs.   Although the fantasy factor is high here, still, something to hope about.   With a bit of an El Niño in progress, and this forecast resembling the tendency for El Niños to act up in aiding wetness in the Great Southwest in the mid-winter to spring, there is some SLIGHT credibility here.

Too, such forecast amounts resemble the great El Niño winter of 1992-93 that helped ruin the Biosphere 2 experiment, then in progress because there were too many clouds and not enough sunshine to make it “work.”  Imagine.

OK, already getting too worked up about this.  Will quit here.

The End


1The writer was employed in studies of clouds by the University of Washington’s Cloud and Aerosol Group, and quickly adopted the company teams as his own, one of the signs of a great employee, one who wore Washington this or that sports Tees in the off hours, no doubt helping to enhance Washington revenue streams.

One thought on “High and middle clouds lining up for Catalina in early December”

  1. Hello Dr Rangno,

    I am a professional meteorologist, now retired from the Canadian weather service. I have been following your ‘cloud-maven’ site for quite some time and then suddenly it disappeared in late October or early November. I was delighted when I noticed it had reappeared again via the Bob Maddox web site.

    I have taken thousands of photographs of clouds over my many years of appreciating the sky scapes. I admire your ability to frame so many perfect pictures showing cloud structures of interest over Arizona. Here in Ontario, the winter cloud patterns are not nearly as photogenic nor as interesting as those in the warmer seasons. For one reason, ice crystal fallout tends to obscure much of the cloud morphology in the cold season.

    Glad to see your site is back again. I look forward to your photographs of both landscapes and the Arizona sky and your enlightening explanations of some of the interesting cloud features you observe. Thank you for taking the time to update your site on a daily basis. It makes for a must read for me every day.


    Dave Brown

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