Map discussion

The weather ahead

Since we have no weather/clouds to blab about now, it seemed like a good idea to look ahead at our fantasy weather, produced by models, and see what they have for us.  And in these future weather charts, something once again for us here in Arizona to dream about.  These maps below were produced from global data taken at 5 PM AST last evening. Check these rainy maps out, high points annotated like cartoons FYI:

Valid for Tuesday, October 9th at 5 PM AST.
Valid for Wednesday, October 10th at 5 PM AST, 24 h after the first map above. Rain intensifies in Arizona.

And what do we look at to see if this has ANY chance of verifying?

A bunch of spaghetti!

First, the upper level map at 500 millibars that goes with all the rain on that map above, that one valid for the 10th.  This is to see what the upper level configuration is like that is producing this wide area of rain in the SW US.

Aha!   A low center is over the interior of central California at 500 millibars, and moist air (shown in green, of course) has been drawn up into it on its eastern flank, moist air that had been over us (take my word for it).  OK, this looks good.

Valid for the afternoon of Wednesday, October 10th at 5 PM AST.

Below is one of “ensemble” plots created by putting deliberate errors in to the global data to see what happens to the predicted patterns using the real data after small errors are introduced in the initial data–very clever technique.

Will the “perturbed” maps look anything like the ones I that were produced from the real global data taken last night?

Let’s look and make some kind of interpretation that will say “yes” to rain in Arizona, beginning in 9 days (Tuesday the 9th) and continuing off and on for several days!

Valid for Wednesday, October 10th at 5 PM AST

Well, since you’ve been trained in the analysis of these “spaghetti” plots, you will quickly see that it looks pretty damn promising.  It is virtually GUARANTEED that an upper low center will be in the SW US, cut off from the main flow pattern which has angled northward from the Pacific into northern Canada (blue and yellow lines up there).    That yellow circle over central Cal is the actual prediction, and the clustering of blue lines in that same area shows that the “errorful” predictions also see that happening.  So, in that clustering of blue lines, it can be seen that our “low” in the SW is a quite reliable prediction.

Does it guarantee rain here though?  Nope, just that the chances are going to be good in that October 9-12th window.

Also very, very, very, evident in this plot is that the people in the eastern third of the country are going to be very unhappy with all the cold air that they are going to experience before the middle of October.  That weather is, from this plot,  “in the bag.”  Notice how the blue lines cluster in that area and are extruded to the south, indicating that deep cold air will be extruded from polar regions into the eastern US then.  I like the word, “extruded”, BTW.  Sounds great, kind of like an onomatopoeia, like “thunder.”  You can feel it.

Its likely that many low temperature records will be set beginning in about a week in the Plains States and eastern US.  (Remember “air” is “cold”; “temperatures” are low).

An aside:  It will be interesting to see how the media handles this upcoming cold spell.  It has seemed, from this keyboard, that high temperature records get more attention than low ones. We shall see.

The End.