Forgetting about our mud for a moment; thinking of the danger to others as seen in future weather maps

Have had 1.75 inches here in the Heights last few days.  Horsies are tromping around in significant mud.

But, to resume a theme about others from the prior entry, those in California, they’d better be paying close attention to the weather a week and more out.  In this weather watcher’s opinion, which should count for something, California may be in for an unforgettable January.


Recall how those “ensemble-spaghetti-Lorenz” plots had an unusually constrained (contours of flow, red and blue lines that were unusually bunched together all the way from Hong Kong to ‘Frisco even 10-15 days out?  That indicated a high confidence forecast of where the jet stream would be.

USUALLY, the contours are pretty wild, scattered all over the eastern Pac after about 10 days or so,  and Cloud Maven Person got overly excited about this esoteric part of weather forecasting, and decided to write a partially decipherable tome on it.

Well, that constrained jet, blasting into Cal  from the subtropical latitudes with a terrible ferocity, has continued in model run after model run now, and CMP’s excitement has been further elevated, maybe to penthouse level now, hard to elevate it more.

Way below are a few examples from just last night’s model run based on global obs at 5 PM AST, showing a few sample of the jet stream predicted pattern at 500 millibars, or around 18, 000 feet (from IPS MeteoStar, as usual).

THESE are extraordinary maps, and extraordinary maps mean extraordinary storms, AND they are appearing with extraordinary consistency.

They are also compatible with what we saw in those ensemble-spaghetti plots of a few days ago.  So, like the “Frankenstorm” of 2010 that hit California, this series of strong storms hitting Cal in just over a week, will be considered to have been “well-predicted” by those crazy plots.

Is FEMA ready?

I think they will be involved at some point.

But, too,  this is a forecast series where we (those in Cal) have lots of time to get ready for big, destructive events.

Like what?

For Cal, the usual.

1) Huge waves smash the coast, some home roll into the ocean. With a jet having a gigantic fetch from the Pac, huge waves are a certainty, surf will definitely be up, if that’s what you do because the surface winds will ALSO have a huge fetch to build those giant rollers.

2) Winds.  At some point, hurricane force winds blow stuff around in one of more of the low centers generated by such a powerful jet stream.   Looking at the pattern, I think one within this storm series may produce 100 mph winds or more somewhere in Cal.

3) Flooding.  Can the nearly empty Cal reservoirs we’ve heard so much about be filled up in a series like this, something that might go on for one to two weeks?  I think so,  some anyway.  But this is a truly wild thought, and as you can see, CMP is kind of out of control here.

It is certain that the rains with one or more of the low centers that slam the West Coast during this series will produce rains of 10 or more inches in a day  in the hill and mountain regions of Cal.

Also, the series begins with a strong, but maybe not exceptional storm about 8 days from now, this after a pretty good rain has already occurred, so the ground is going to be pretty wet when the Big Series hits.

The jet stream pattern strengthens and shifts farther south with each day after this first major storm, and that’s when the real onslaught will hit.

I don’t want to get people overly excited like I am, but I am terming these, and the whole recent series of unbelievable jet streams bashing into Cal, and even Baja!, “the California calamity maps.”

Valid Monday, January 18, 5 AM AST.
Valid, Monday, January 18, 5 PM AST.


Skipping ahead:

Valid Thursday, January 21st, at 5 PM AST. EGAD! WHAT a monster!
Valid 5 PM, January 22nd. One blast is finishing up, but look at the jet entering on the left/west side. Once again, “egad!”


Skipping ahead some more….

Valid at 5 PM AST, January 24. Upper cut to jaw of Cal from the Pacific. This one would be quite bad in rain, wind, floods.


Now the timing of these things WILL VARY as the mod runs keep churning out results, but in CMP’s view, the pattern that will cause CA havoc is locked in now, promulgated ALMOST without doubt by our Big Niño.

Here is another amazing map from a prior run, that just makes your jaw drop due to what the models are sensing is “out there” for Cal and the West Coast:

This is looks like it was for another planet, the jet SO POWERFUL and heading into Baja!
This is looks like it was for another planet, the jet SO POWERFUL and heading into Baja!
Crespuscular rays due to light rain from precipitating Stratocumulus (i.e., “praecipitatio.”, if you want to impress your friends.)
Pretty good sunset color. The clouds?  Stratocumulus.
Weather station and mountain sunset color.  You don't see that too often....
Weather station and mountain sunset color. You don’t see those together too often.  Mountains topped by non-precipitating Stratocumulus clouds.


How will SE AZ do?

Seems like passing rains will hit during this CA bludgeoning period, but floody weather not expected.

Since we’re pretty much at our average total for the month of January right NOW, CMP is going out on a limb and predicting an above normal total for the WHOLE month.


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.


  1. Fun read, thanks. I FINALLY understand the spaghetti now – but because of this post combined with your email. I understood that the lines were small errors introduced into the model, but I didn’t understand still what the lines represented – rain or what. Now you wrote that it is the predicted pattern of the jet stream. I didn’t get that before. But I’m a little at a loss what the jet stream means except for rain now, since it is represents warm, wet air picked up over the ocean?

    My house in San Diego had a LOT of rain out of this previous storm – the tree in the back broke in half and landed on the porch, taking out a gutter. Hopefully not more of the same is coming.

    Thanks Art.

    1. Hi, Matt,

      The jet stream is driven by the temperature gradients through the deeper atmosphere from the poles to the Equator, and where that DEEP temperature contrast is strongest, is where the jet is strongest. Might be -40° C on the cold side, and “only” -15° C on the warm side. Lesser gradients, lesser jet as a rule. Its strongest between 30 and 40 kft, as I think I may have written earlier.

      For some reason (“isentropic analyses” were in favor in those days hahaha–that kind of analysis helped decipher where the air was moving up or down, actually, and we don’t measure “height” with our balloons, but rather pressure, temperature, humidity and wind, from which the height could be calculated). So, in the last century, they decided to have constant pressure maps instead of constant height maps (the latter would make upper level weather maps so much more comprehensible to students!) . Now that sentence is mostly incomprehensible.

      I taught 101 met one summer at the U of WA, should get my notes out. Since I only have a bachelor’s degree, the U of WA likely took quite an accreditation hit that year (1987).

      To get to a particular pressure above you in a hurry, the surface pressure and the density of the atmosphere play a role. A LOW HEIGHT, can be associated with low pressure and/or a DENSE atmosphere in which the pressure changes rapidly with height, that way getting to any pressure above you faster, resulting in a shorter distance. So, if it took 5,340 meters to get to 500 millibars, and the pressure is about average at the ground, the air would be very dense above you, i. e., cold. The opposite would be true if the height to 500 millibars, was, say 5,640 meters. It would be much warmer above you, took a greater distance to get to 500 millibars. But BETWEEN those two heights would be a LOT of difference in temperatures and density of the atmosphere. Presently the spaghetti plots are showing those TWO contours only, blue and red, respectively. 5640, or 564 “decameters, has some historical meaning since in the early days of forecasting for southern California, that contour marked pretty well where the boundary of rain was in troughs. So, a grouping of red 564 lines in Cal is likely where the southern boundary of the rain will be.

      In the ensembles/spaghetti plots in deep winter, those TWO height contours (534 and 564 decameters) are the only ones displayed because of their characteristic deep cold/deep warm signatures. At this time of year, 5340 height is close to the cold side of the jet where the gradients are usually less in just all cold air, and the the 5640 on the warm side of the jet, all of this at 500 millibars.

      So, the jet at 500 millibars is mostly squeezed between those two height contours on the ensemble plots.

      Those plots would be indecipherable, kind of like my writing here, if ALL of the predicted height contours were on them. The characteristics of the 534 and 564 contour in squeezing where the jet will be makes them the best choices for display on the plots right now. Those selected contours will change as the year goes on and it begins to get warmer, the jet defined by slightly different height contours.

      I don’t feel like I am doing so great here, and am reluctant to post it… hahah, sort of.

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