Some distant Catalina rain still showing up in SOME model runs

OK, there are a lot of graphics and discussion today, much of it unnecessary as usual, but there it is.  We’ll begin with yesterday….not today.

Yesterday morning’s WRF-GOOFUS run once again had rain in Arizona/Catalina area.  Was heartened since the prior 24 h’s predicted rain had disappeared in the three runs after that.  Here’s what came out YESTERDAY morning for Wednesday the 12th.  Cool, eh?  Below this map is the corresponding upper level map.

Valid for Wednesday December 12th at 5 AM. Green areas denote where precipitation fell in the prior 12 h.
Also valid for Wednesday, December 12th. Note how the jet stream at this level pours down from the Pacific NW into California and then across northern Mexico.

Then the same thing happened as the day before,  that Catland rain disappeared again in the model runs up to last night’s.  Not good.

But, I am happy to report that the rain is BACK, and why I am at this keyboard this morning.   The very latest run, one that was conducted using the data from last evening at 11 PM AST is shown below with AZ rain again, this one valid for 11 PM AST on the 11th.

Now you might wonder why I would go through all these machinations to show you likely model illusions of rain here in the distant future, providing you only those ones that have rain here in them.

That’s because this is not about being objective, but rather SUBJECTIVE, really caring about rain here.

There is no way I am going to show you model outputs for our region that have no rain in them!   I only show those ones that have what I want to have happen here, rain, and that’s why I show them.  Its a very biased sample that you get.   But its quite altruistic of me since any rain ahead MIGHT yet help the spring blooms that we ALL enjoy.  So, by being subjective, I bring hope where maybe there wouldn’t be any.  You can see I am really thinking of others in being so biased.

“What does the spaghetti say?”, you ask, as a person having a tremendous amount of weather perspicuity.  “These outputs any good?”, you continue in a burst of meteorological eloquence.

Grudgingly, I am providing the NOAA “ensembles of spaghetti” map for the same time, December 12th.  I’ve added an arrow in case you don’t know where you are.

Ensemble members valid for December 12th, affectiionately known as a spaghetti plot. Remember this crazy lines are due to deliberately putting little errors in the initial analysis to see how much difference they make from the real forecast that came out using the actual data. The wilder the lines, the less reliable the longer term forecast.

Now, the blue lines indicate more or less where the heart of the jet stream will be, the red lines, the periphery, or it when they are separate from the blue lines, a separate branch of the jet stream bordering the sub-tropics.

As you see here, the bulge toward the equator in the RED lines over our area strongly indicates that a trough WILL be here in the southern branch of the jet stream on December 12th.  Often however, those troughs in that southern branch often only bring high or middle clouds; no rain.  Need a bunch of blue lines down thisaway to get rain, and as you can see, MOST of the blue lines (“members”) are well north of us.

What to conclude from this?

That distant rain on the 12th shown repeatedly by a biased Mr. Cloud Maven person, would still have to be considered an outlier model run.  But having said that, these spaghetti plots have been getting more supportive of a rain.  Instead of a 5% chance, now maybe its up to 20%, based on the map above because some of the blue lines are beginning to be extruded toward Arizona.


Weather coming up elsewhere in the US

BTW, in these model runs, one of the things that is a real eye-opener from the lastes run from last night is  a gigantic mass of cold air that comes down into the Rockies after December 12th and affects most of the US.  Awful for Christmas travel.  Here’s a predicted surface weather map for December 15th, annotated to help you figure it out.

That mass of cold air is shown to move very rapidly into the US from the Arctic, and so the air will not be modified much by its  southward movement–the configuration below is probably good for -40 F or even lower in Montana and some other high valleys in the northern Rockies.  Hope you’re not traveling then…

Looks, too, like that icy air will be traveling over ice and snow until it reaches the US border according to this snow-ice coverage map from NOAA below.  No wonder Canadians mass on the US border!  Its apparent from this map! That will also keep that air relatively unmodified (keeping it as cold as possible) until it hits mostly bare ground in the good ole USA.

The End.