Uh-oh

“Call the uh oh squad1.”  I wasn’t going to blog today, was going to take a few hours off, enjoy the TG week by cleaning up the place all day before guests arrive tomorrow afternoon, not really enjoying anything at all, really, but rather,  having gone into a new mental frame of mind, a higher one, in which you notice things that you didn’t notice before that are now “wrong”:  the clutter, the dirt, the shabby windows, the dog hair.   You now see them all!

But then when I saw the newest spaghetti plot, heart started pounding, not just because I love spaghetti, real spaghetti and these plots, but also because of what I saw in the new plot: The “old outlaw”, that old prog, the “old outlier” of yore, the one I showed yesterday with its severe storms for AZ and Catalina, and then went on and on about it likely being an “outlier” model run, and really, exerting a LOT of mental energy to try to explain why those severe storms were UNLIKELY to happen here in southern Arizona.

But that forecast of strong storms is, in fact, becoming the mode in the model!  Outlier a la mode; a weather dessert of sorts for us in precip-challenged old Arizony.

Compare these plots below carefully for the SAME verification time, the first, the very one I showed yesterday, and the second, hot off the NOAA spaghetti site from last night:

Valid at 5 PM AST, December 7th.
Valid at 5 PM AST, December 7th.
Valid for the same time as the plot above, but generated 24 hours later. I think you see what I mean by "uh-oh."
Valid for the SAME time as the first plot above, but generated 24 hours later.
I think you’ll see what I mean by, “uh-oh.”

What’s so different?

That trough in the mid-Pacific is now foretold to be much deeper (extends farther to the south; compare), a key for our own much deeper, more southward-penetrating trough downstream here in the West.   Those blue lines (that cold 552 height contour at 500 mb) are now bunched farther south in the new spaghetti plot for both locations, in mid-Pac, and in the West, with many fewer of them to the north (open, blackish regions).

Not much jet stream amplitude (north and south meanderings) upstream?

Probably not much downstream, either.    Look, too, at how the yellow lines have amplified here between the two plots!  So a firming up of high amplitude upstream translates to a better chance of troughs extruding southward into old AZ downstream.

But why did things change?

After all, NOAA puts in tiny errors at the outset of model runs to help show us what the most likely outcomes are, so we don’t expect to see “outliers” start to dominate progs as they have started to do since two days ago.  But they have.  Dunno for sure why things changed, but one would guess some real errors out there must have been large,  larger than the ones NOAA starts with to see how the model runs change (disperse) from the one they put online for us to see.

Valid at 5 PM AST, December 5th. That contour at 500 millybars represents the cold interior border of the jet stream with really cold air there, aloft and at the ground. The jet core at this level is far south of us at this time. Is it raining here? If you have followed this blog your answer, without even needing to look at the precip forecast, is, "oh, yeah, baby", probably lots of it, too.
Valid at 5 PM AST, December 5th. That contour at 500 millybars (about 18,000 feet above sea level) represents the border of the cold interior of the jet stream with really cold air there, aloft and at the ground. The jet core at this level (brown area) is far south of us at this time. Is it raining here? If you have followed this blog your answer, without even needing to look at the precip forecast, is, “Oh, yeah, baby”;  probably lots of it, too.  I got so excited I misspelled, “Ensanada”! (Let’s see if anyone notices…..)  Maybe its a test to see if ANYONE is reading…since I misspelled it twice!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

In case you don’t believe me, that is, what I wrote in the caption above about it raining a lot here just judging by the 500 mb configuration, I now present the precip forecast for this period, one I had not seen before writing this sentence, and show it to you.

Rain areas for the 12 h ending in the early morning of December 6th (5AM AST)
Rain areas for the 12 h ending in the early morning of December 6th (5AM AST)

Actually, rain begins (in this mod series from IPS Meteo) during the day of December 3rd, as the storm that threatened rain at the close of November, first of December, FINALLY dribbles in from the Pac.

So, this could be quite the weather period for Arizona coming up. Certainly enough cold air and severe storminess is making its way down the coast from AK and points north, that we should be hearing about severe weather, snows in unusual places, blizzards, that kind of thing, before this system gets here. Looks like we’ll have plenty of warning, too, to prepare for an “interesting” spell of weather, hard freezes following the storms, windy periods, maybe another inch of rain over a few days, that kind of thing.

Great pattern for the flowers of spring!

Of course, that far out, its not in the bag for significant rain, but cold air, a hard freeze late in the first week and beyond?  That seems to be the MOST confident outcome.

Today?  You got yer Altostratus, nice sunrise, just now, and those clouds, thinning to Cirrus, likely augmented by Altocumulus,  will likely be here all day–check sat loop here from the Huskies.  Enough holes in this cloud sheet, though for a great sunset I think.

The End.

 

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1 But who out there would remember that single, and Robert Ellis Orall?? But I have it!

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.