Our deep blue sky, loaded with interesting Cirrus clouds yesterday, and generally low in contrail impact, makes southeast Arizona a haven for Cirrus cloud watchers. Though no one site is completely immune from them, a sky like this, so free of contrails, is impossible on most of the Atlantic Seaboard due to air traffic. It was just so pretty here yesterday with so few contrails! Here are a few shots:
The weather ahead: cold front’s a coming
Its been well predicted for 1-2 weeks that a cold front would pass through our area on Dec 9th-10th. At times the models had substantial rain here, but it’ll be a dry blast from the north Sunday night. What makes us here in Catalina a little different in experiencing this frontal passage is that the high pressure behind the front pushes air along the Catalina mountains from the north here, and we often get quite a windy episode, 15-30 mph likely Sunday night. But, because we have no official weather reporting stations, and the Catalina Mountains block that north wind from Tucson so that they don’t get it, so us here in Catalina are about the only folks that know its quite windy, with a chill in the air.
This cold front is part of a large scale pattern change in the jet stream that is taking place, one that will vastly increase our chances of rain in the weeks ahead as storms barge into the Pacfic Coast farther south than they have and head this way. No longer will we be in a stagnant condition where day after day the weather is almost exactly the same; not much wind, temperatures above normal. Instead there will be occasional windy episodes as storms get close, temperatures closer to normal, and we hope, one that gets far enough south for a good rain.
Some rain is showing up now overnight on the 13th-14th. In our rain frequency chart, the peak rain days in December were the 11th-13th, deemed a statistical fluke from this keyboard in the 35 year record.
But, here’s a rain threat materializing in the very window. Hmmmm. Further, if you look at the spaghetti plot for this time period, a trough is guaranteed in this region on the 13th-14th, though getting circumscribed by the jet stream that is, its south of us as the trough goes by is what’s marginal with this trough situation, a requirement for almost all winter rain here.
This is the best I could do, in examining the several model outputs over the past 24 h. Below is the very wettest forecast panel that popped out for southern Arizona during the past 24 h. The panel below is from yesterday’s 18 Z (11 AM AST) global data and is for the evening of December 15th, about two weeks. Nothing like what is shown in this panel showed up in model outputs afterward, dang. Doesn’t mean it couldn’t happen, but its not a good sign. Still, I thought you should see it.
The 18 Z (11 AM AST) model run doesn’t ingest as much global data as ones at 12 Z and 00 Z, 5 AM AST and 5 PM AST, respectively. That means that the 18 Z run is not as reliable as those other two, is more susceptible to having goofy outputs (outliers) than the other ones. “Less data, more filling”, of rain gauges anyway.
We ARE on the brink of a major change in the flow pattern, that is, where the troughs/jet stream will be positioned. We have been well to the south of the jet stream and all the storms carried with it. That will change in about a week. We will have recurring troughs here in the Southwest after that, meaning less warm days, along with occasional chances of rain. The signal for this to happen is pretty strong in the spaghetti plots.
The question is now how strong will those the persistent troughs be as they sporadically drop by in the weeks ahead. The strong ones for now, like the one shown below that causes rain here, are outliers for the time being. Stay tuned. Gut feeling here is that we’re headed for a wet regime, finally. Its due.
The model outputs from last evening do have a little rain here on the 10th, and NOTHING on the 15th as shown above, so I am not going to show those disappointing outputs. You’ll have to go to IPS MeteoStar to see those renderings.
Cirrus moving in today, the remnants of one of those monster rainy fronts that bashed northern and central Cal for the past week or so. Should be a great sunrise display; get camera ready.
From the U of A Wildcats Weather Department, this loop of those approaching Cirrus clouds.
How much rain in the past seven days in northern Cal?
They needed it. The arrow shows where the author would like to have been during those seven days, filing daily reports of stupefying amounts of rain.
I mention these rains because this episode of heavy rains was pretty well indicated in the NOAA spaghetti factory plots back in mid-November. This flooding event is a great example of those occasional situations where a forecast two weeks out can be inferred to be pretty reliable by examining those spaghetti plots. Those likely heavy norcal rains were expeculated on here based on spaghetti in a November 14th blog. I really think that you could’ve done this, too, by now!
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.
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.
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.
Some 8 days ago a spaghetti plot indicated with confidence that a “warm in the West”, “cool in the East” pattern would develop. Well it has materialized. Thanks to Hamweather, this chart shows the records set with that pattern so far. They’re not so numerous, but the forecast of a strong trough off the West Coast pulling warmer air north into the West and a trough in the East dragging down cold air from Canada has verified. The point of this is that those strange looking “spaghetti” plots can have some power if you’re not overwhelmed by all the lines.
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BTW, after learning about this spaghetti verification, you might want to consider adding to your collection of cloud maven junior tee shirts this new attractive—well, stunning really — “I love spaghetti” black Tee offering with a truly gorgeous multi-colored example of the NOAA-NCEP “ensembles of spaghetti.”
Here’s last night’s example from NOAA-NCEP to get you excited about getting that tee:
I think you’d look great in it, and, of course, most sophisticated when it comes to being a cloud maven junior and advertising that you know about something like this. Most people have never heard of these plots, which puts you ahead of masses.
Remember the “You are here” Milky Way Galaxy tee showing where the earth was? Well this one would be as good for you to be seen in as that one! And this new cloud maven junior tee is only $29.95 plus shipping and handling, which brings the total to $75.42. (I’ve been studying how the online vendors do it….)
Think of all the people you might meet that would ask you about your tee by saying, “Huh?”
Then you would go on a long spiel, making new friends, by pointing out areas on your tee where the signal is strong and the forecast reliable, and where the forecast model is clueless. In the above example tee, that trough north of the Hawaiian Islands 15 days from now looks pretty solid while things are pretty clueless in central Europe, roughly diagonal from the trough north of Hawaii. You know where Hawaii is, don’t you?
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The weather ahead, way ahead…grasping for a switch to be turned on
A great pattern popped out yesterday. Hasn’t been seen since, but it was so exciting that I thought I would share it with you. We’ve been in a stagnant pattern for a LONG time now; storms racing across the Pacific into the northern half of the West Coast. As a weatherman, we’re always looking for the switch; patterns like that just don’t last ALL winter, but a tipping point happens, and boom, everything is suddenly different.
In this model run from yesterday, a tipping point happened and the storms began moving southward along the Alaskan coastline to off California in about 10 days. One of those is shown here near San Francisco. At this time in the run, December 15th, 5 AM AST, extensive rains are shown in Arizona!
While it might verify, there has not been support for this pattern since, and the ensembles of spaghetti, shown above, are not very encouraging, actually not at all, only suggesting a trough in the northern Plains States. A trough is suggested in the southern Rockies, and not a strong one at that since that trough is mainly confined to the red lines, those demarcating the periphery of the jet stream, or may even be a weak southern branch separate from the northern one. Usually doesn’t rain here with those.
But, this quasi bogus output looked so great, I had to post it anyway. I was so excited yesterday when it came out, because we know there WILL be a pattern change. There always is, even if its short-lived and isn’t a total drought buster. I guess this indicates a degree of desperation when you’re posting model outputs with little chance to verify.
November will finish out dry. And, with the extremely dry October we had followed by a rainless November (Correction here on November 25th! Egad. We had a nice rain here on November 9-10th in which we received 0.48 inches, about half of November’s average! Brain fading…. End of correction.)
….you can’t help but start to fret over March, and those great blooms that erupt so quickly in our deserts. From what I have experienced and have learned, fall and early winter rains are critical for bountiful spring blooms; January and February rains, not so much.
Rain is beginning to show up in the first week of December, but, that far in advance, its showing up beyond the model’s credibility horizon of about 6-7 days. Also, the panels below are from the 06 Z (11 PM AST) model run, one that is not plumped up with as much global data at the runs at 12 Z (5 AM AST) and 00 Z (5 PM AST), so even more likely to be faulty.
Still, its the best I can do for finding future rain in Arizona/Catalina. I am posting these maps at full size to make them look more important, have more visual impact, maybe put some pressure on the next model run to come up with something similar.
Will report back when these two rains show up again…or if some interesting clouds float by.
May insert some filler material blogs in the meantime…
These are sad times when you can’t find a model run with at least some AZ rain in it. The last two USA model runs, compiled from global data taken at 00 Z (5 PM AST) and 06 Z (11 PM AST) don’t have ANY rain in Arizona. Prior two runs did, ones that came out during the day yesterday.
The rains in yesterday’s model outputs were late in the month and into early December. I exulted all day yesterday because the “ensembles of spaghetti” were strongly suggesting those rains were associated with “outlier” model runs, more extreme ones that couldn’t be counted on.
But, those rains kept reappearing. I unilaterally decided, i.e., had a “hunch”, that the “ensembles” themselves were, in a sense, “outliers”, lying about no rain in AZ. They were missing something.
Looks like I’ll get burned on that “hunch”, as would be expected by an objective scientist. Now I will talk about something else…
Maybe the costly and more accurate Euro model, which could save thousands of lives by being free and warning poor people of big storms and winter cold way in advance, has rain here in it here, but I am too poor to afford to look at it. The Canadian Environment Canada model1, built on the Euro one, only goes out to 144 hours, not the 5000 hours ahead that we seem to need to see a rain predicted in Arizona someday.
BTW, as an example of that Euro model’s non-availability, if you go to the University of Washington’s model outputs web page, you will see the daunting words for the Euro-UK MET model, “restricted.” The letters are in RED to make sure you know you can’t get it. Don’t hit the latest run link to the right, you will be asked to enter your ID and password, and because you don’t have one, you are punished by not being able to go back to where you started. Rather, you end up in an endless loop asking for your password and ID to make sure you don’t come back again and mess around thinking you might “get in.” You will have to close your browser. If you have a password and ID, then post that model somewhere, oh, man, you are in for fines and, who knows, maybe some jail time.
Its a sad forecasting world out there.
Here are the sad (lotta “sad” today) conflicting rain/no rain model outputs for the SAME time and day, the first panel from yesterday morning when I was happy, and the second panel below, from the very latest run:
On to happier things, should have some gorgeous clouds and skies today as a tropical system skirts SE AZ. Virga likely. Keep cameras ready for a great sunset.
Why would they name their organisation, “Environment Canada” when you already have to go to a Canadian site to look at it?
Here’s is the latest model run from our USA WRF-GFS (aka, “goofus”, as the Europeans might call it, looking down their noses at our inferior weather predicting model compared with their “ECMWF” model as described (here) in the November 9th issue of Science.
It was an upsetting read, BTW. Seems the Euros use bigger, faster computers than we do, ones that they were able to afford by charging a lot of money to see the results. Very bad.
In case you want the meat of that Science article: “From the BEGINNING (this writer’s emphasis) ECMWF has been the world champ in medium range forecasting. Today ECMWF forecasts remain useful into the next week, out to 8.5 days. That leaves the rest of the forecasting world, inculding the U. S. National Weather Service with its less powerful computer, in the dust by a day or more.”
What have our guys (includes women) been doing all these years? (Just kidding, maybe.)
OK, onward with what we have to work with…..
This WRF-GFS run is just from last nights 11 PM global data crunch, the VERY latest as of this writing. I picked it out from earlier runs to show because this run latest has a lot of rain in Arizona. Namely, it was a subjective call to display a few snapshots from it. Displaying the results of this run has nothing to do with scientific objectivity. Enjoy; it might not be real rain that falls to the ground, only real in the model’s calculations. Still, its great to see and think about.
Instead of showing the full size of these model outputs as I normally would do, I thought I would size them in proportion to their credibility based on the Science article. We can’t see the better ECMWF-British model results unless we pay a lot of money, so this will have to do. Unless you click on these below, you’ll have to use a microscope…
So, once again, our late November-early December storm has returned to the model fold. Its been coming and going. For example, the 5 PM AST global model run had NO RAIN in AZ, so I didn’t want to show those results.
But just ahead….this
In the nearer future….. Seems the Environment Canada computer model, built around the SUPERIOR ECMWF model, has rain here in about 48 h from now resulting from a tiny, weak low that ejects from the deep tropics right over us. Cool, though the air itself would be warmer and more moist than we usually see at this time of year in a rain situation (higher dewpoints). Must regard this as a serious rain threat now. Here’s a snapshot of that rain day from Enviro Can (see lower right panel for 12 h rain totals and areas covered–would fallen overnight tomorrow night into Wednesday morning. The whole better than the US model runs is here.
Another fabulous early winter day in Arizona. Out of state license plates picking up in number. Can’t blame ’em. Here’s a sample of yesterday’s skies and another great sunset:
Once again we were treated to a spectacular sunset, another one in a long series of occasional sunset spectacles, ones that probably go back before the 1900s. We didin’t have color film in the 1800s, so we can’t be for sure if there were spectacular sunsets here except via artist’s renderings, of necessity, of course, analog ones comprised of subjective estimates of sunset colors being seen, not the real ones. I you would like to read about clouds in paintings over the centuries, go here and here. In this second link, you will find that Leonardo da Vinci was quite interested in Cumulonimbus downbursts gave painting them a shot. Its not that great, to be honest.
We meteorologists often sadly ruminate on the career of Leonardo, thinking that had he only turned his attention away from art, sculpting and the like, and instead turned to the problem of weather forecasting, how much farther ahead we would be today. A real shame. Maybe we wouldn’t be relying on spaghetti plots so much.
Also got a trace of rain here in Catalina–you could sure get that smell of rain as soon as you went outside this morning.
We also had some real interesting mottled-looking skies yesterday due to Altocumulus underneath a layer of Altostratus translucidus. Those underlying Altocumulus clouds were in a layer with a lot of instability (temperature dropped rapidly with height in it) and so there were many little spires (castellanus and floccus varieties). This happens because a little bit of warmth is added to the air when moisture condenses in it, and that bit of warmth was able to drift upward. As that happens the air around those little cells of updrafts settles downward gently to take the place of the rising air creating voids. So, you get clear air spaces between the little cloudlets. I think that’s what happened here.
Let see, what else is going on…. Most of that plume of moisture from the tropics is gone, and so only expect a few Cumulus today. Oh, yeah, big storm about to slam northern Cal and Oregon. Take a look at this map series from the Washington Huskies to get an idea of how its growing in size before hitting the coast.
No rain predicted here in past two model runs (last evening and last night, 06 Z) for the next 15 days, but we are quite sure that’s wrong. Will be looking for that end November early December rain to reappear because I have a subjective hunch it will. If it doesn’t reappear, I will likely pretend I never said anything about it, in keeping with long tradition in public weather forecasting.
BTW, and belaboring the point a bit, here’s an example of how errors in public forecasting SHOULD be handled; “right up front”, in this case, an anonymous Seattle forecaster addresses the terrible temperature forecast he made the previous day following day:
Just after I was asserting from this typewriter that the big storm, the Great Wet Hope in late November, was surely bogus, out popped another wet forecast for AZ n the model run crunching global data from 11 AM AST yesterday. Here it is below, first panel. You MAY remember that the nice early rains that we had in November last year were associated with a similar pattern of an upper low center near San Diego.
What to think of this “outlier” forecast, one NOT supported in the ensemble of spaghetti plots (model runs where small errors are deliberately input to see how those runs change from the ones based on the actual data). There very little support for panel 1 in those “perturbed” runs, but there it was again, a big AZ rain!
Well, its still unlikely, but the chance of it actually happening are now much improved. Something out there is causing the model to come up with a good rain in AZ at the end of the month. I did not think I would see any rain again in AZ in any more model runs.
And, sure enough, the model run based on data just 6 h later than the one shown in the first panel, took it away again! See the second map below and look at the astonishing differences over Arizona and the Southwest overall!
I won’t show it, but the “perturbed with errors” model runs that we look for to discern credibility in the longer term forecasts like these, STILL does not support much of a chance for a rain to be realized on the 29th.
But, that second appearance of an “outlier” in another model run….hmmmmmmm. Will be watching for a return; you start to get a feeling that it might well be seen again.
As I finish this blog blurb, the 11 PM global data should have been crunched by now, and will look to see if there is yet another huge change (well, there are always large changes, but here, I’m talkin’ for us!) Will let you know in about 2 minutes…. Stand by, generating new web window now…..
Oh, my gosh! Its changed again (3rd panel) to a huge West Coast troughy situation, completely different than the run at 5 PM AST last evening with the big ridge over us (bulge to the north). I have to post this latest map, again for late on November 29th. The situation you see in the third panel leads to another big rain forecast in AZ, though a couple of days later, early December! This is so great! Compare the second and third maps.
Now, you can really start to put some credibility in the supposed “outlier” forecast and, as a discerning meteorologist, say to the spaghetti plots with their little deliberate errors, “Go to HELL! You’re missing something big out there with those puny errors you start with.”
Calming down now, well, you can’t cast the thought of warm dry weather (seond panel) for late November out yet, but something IS being missed out there, which makes this an exciting period–just to see what happens. Though an admitted precipofile, at least here in AZ, not so much in SEA, I am putting my mental marbles on the trough in the West depictions now. Just a hunch.
Let’s check, could be goofy, but its all we’ve got right now for a rain, the map below valid for Thursday, November 29th, 5PM AST. The whole series is here.
Of course, the weather sophisticate would want to see what’s “up top” at the same time; see where the jet stream is (brown areas on the map below). Seeing that the J-Stream is right over us, and also being an Arizona precipophile, he might opine, “I find this quite credible.” It also shows massive cold in the West, Rockies, and northern Plains States.
“Who you gonna call”, to establish credibility? Storm Busters! (Or not) Yeah.
Here is the NCEP “ensemble of spaghetti” for this same time, from the SAME model runs, showing the huge system in the West:
Summary of spaghetti: There is no indication of a major cold trough/storm in the West, as would be indicated by a bunch of blue lines dipping down to AZ. Ain’t there.
In fact, its kind of shocking to me that there isn’t the slightest indication of a major trough in this region. So, the actual model run shown in the first two maps turns out to be an extraordinary outllier; some goofy measurements somewhere out there on our globe, got into the model and produced a spurious huge trough, cold and storm.
Amazing isn’t it, that there can be little tipping points due to slight errors in measurements somewhere that can wreck the whole thing, make giant changes from what really is going to happen? And to detect them, that’s why we do the “ensembles of spaghetti.”
What will happen in the next model runs? That trough on November 29th will almost certainly go away. So, the rain in AZ is “real” in the model run, but not real in life. And as we say here, “dang!”
After viewing this spaghetti plot, our AZ precipofile would now look back at those awesome maps for November 29th, and dejectedly, or even with model rage, and say, “Those maps from last night are full of….oops…. have no credibility whatsoever. What is the matter with this model it could even begin to calculate such a ludicrous pattern. Who’s the goofus out there that reported some bad data?” He would not mention a chance of rain late in the month to his neighbors.
This was meant as a “learn you and me up on spaghetti plots” module.
Mostly very thick Altostratus clouds with lots of embedded droplet clouds, ones like layers of Altocumulus clouds inside them. Made for a very dull afternoon. Here are a couple of shots: