“Trough, there it is”,

Again, paraphrasing a skit from that old, innovative TEEVEE show. In Living Color, featuring Jim Carey, the Wayan Bros. etc., to describe the results of this run of the NCEP “ensemble of spaghetti” plot.  This is a great output!  Mmmmmmm, makes me want to throw a meatball on it right now!  As in yesterday’s presentation from this keyboard, this plot is valid for football day, Saturday, Nov. 10th, at 5 AM AST. (Cloud pics at bottom.)

What’s to make of it?

Plan on being cold, very cold, my friend (s)—plural if there is more than one reader.  There’s no way of avoiding being cold now on the 10th and for a couple of days after that.  There’s probably going to be be some minimum temperatures in the 30s, maybe lower in the washes.

What this plot shows is that the signal for a huge temperature change pm the 9th-10th is very strong; its not gonna go away.  And that is shown by the blueish lines that are packed together and dip toward Arizona with a lack of lines to the north of us over Nevada-Utah, Idaho-Montana into Canada.

Where the lines bunch together indicates where there is high confidence that the predicted pattern (yellow lines) will happen.   You can see that the red lines are also VERY bunched south of AZ, another strong confidence indicator.   Also, at this time of year, those blue lines indicate where the jet stream will be, along the 5580 meter height above sea level line, the height where a pressure of 500 millibars (mb) will be found, to add some complications to this discussion.

Below is what the model actually predicted at 500 mb from last night’s global data taken at 5 PM AST, from IPS Meteostar with the map valid for 5 AM AST, November 10th.   At this point, the cold air has already arrived here in Catalina, likely the evening before.  However, if the winds aloft are what is predicted, we’ll likely be dry.  Dang!

In model run after model run we are going to see predicted, almost the same thing; a big cold trough barging into the West with the jet stream dipping way down into AZ.  Along with this exciting development,  a strong, strong low center will form inland at the ground, probably over Tonopah, NV, where they like to nest.  That low center will bring our first really windy day as it moves toward Utah, probably beginning on the 9th when the temperature is still comfy.

Then after those strong SW winds, an extremely sharp cold front will go by in which the temperature plunges maybe 10 degrees in an hour or so as the wind shifts to the NW, probably on the tenth.  Maybe you should think about getting a new, better thermometer/temperature sensor to document this.  Just a thought.

So, our cold event, like the movement of the Sandy the Hurricane, is well predicted though the exact timing is still, of course, fuzzy.   But count on something like this happening here in SE AZ.

Cultural impacts of sudden cold air:

Let’s see if the AZ Cats have a home game on the 10th…..  Oh, my gosh, its Homecoming for the AZCats!  Maybe they should practice in a large refrigerator after all these warm days.  Fortunately, they play Colorado, a really crummy team, so maybe they won’t have to practice that much. :}

Rain with that cold air?

It looks marginal since the passage of the jet stream aloft is nearly overhead so far, not much if any of it to the south, the wintertime requirement for rain here.  So, if there is rain, it will be a very slight event.  But, will have nice clouds banking up against the Catalina Mountains for a day or so in that cold air.

Farther out:   the models are suggesting this will be the “new pattern” for a few days, that is, it will recur, and another trough heads this way after this one, so we’ll have another chance for rain a few days after this upcoming cold spell.

One great aspect of this “new pattern” is that droughty areas of the Plains States will get hammered with substantial rains and snow, good for the winter wheat crop, and thus, all of us!

Pretty cirrus makes for pretty sunsets; these from yesterday:

5:42 PM.

The End.



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.