Well, it will be pretty obvious, ludicrously so to spaghetti lovers, the sequence shown below. It goes from “warm in the West (again); cold in the East pattern to another undercutting flow from the Pacific, the kind we’re having right now under the “soft underbelly” of a big blocking high, except that the tropical flow from the Pac this time is a little too far to the north to give us anything.
But, it will be another floody situation for northern Cal in the coming days. Some places, mainly north of “Frisco”, have already picked up 4-6 inches in the first blast which hit yesterday. Ten to 20 inches more is likely over the next week at favored locations. Having quite the water year there, really a lot of water year.
You may recall that the current situation, alluded to in the “break on through to the other side” refrain used here about ten times, was well predicted about two weeks in advance! That’s what spaghetti can do for you!
OK, enough jabbering, let us move on to the current exciting examples that popped out from last night’s global data ( there are outputs after adding little errors at the start of the model run, to see how the flow is changed with them in it. Sounds crazy, I suppose, but is considered a huge advance in forecasting, a stupendous tool, that is, to make errors in models at the beginning of the run). Heck, they even do that in climate models that simulate 30-50 years from now, and you’d be amazed at how the tiniest fraction of a degree change the beginning makes (see Deser et al 2012).
Well, the first one’s not so exciting since we’re dry and hot for this time of the year, and its a common one that can get stuck for weeks at a time, so you REALLY hate to see models project a bulging ridge poking north along the West Coast. It could mean a rainless February here, if it persisted.
Here’s the exciting follow up, though, pretty unexpected given the above, showing a sudden collapse of the West Coast ridge regime, and strongly suggesting that wet spell has begun in Arizona, including regions of Catalina and Saddlebrooke:
So, you’ll want to get outdoor work done before this.
Historical note of interest, added value content, etc.
Some of you may remember that the 564 decameter contour (those red lines) at this level (500 millibars or around 18,000 feet above sea level on average) was used in the early years of forecasting before computer models (50s and early 60s) by southern California forecasters to demarcate where rain would fall in California–at and north of where that 564 decameter contour intersected the coast when upper troughs came in. The Old Forecaster remembers, though not much else…
So those red lines barging into southern Cal after a LONG fetch from the subtropical Pacific in the plot above mean central and southern Califs better watch out for some major rains a little before we ourselves get a dousing around the 18th of Feb.
Isn’t it great what spaghetti can do, that is, constrain our future weather to fairly certain outcomes two weeks in advance!
There was a sunset yesterday, btw:
Upper level snow flurry passes south of Tucson! Trying to generate some excitement here….
In case you don’t believe me that over an inch fell, this digital record from Sutherland Heights with writing on it:
Probably a little more to come, too. Got some blow damage, I’m sure. Will be looking for roof shingles around the yard today.
And, as everyone knows from their favorite TEEVEE weatherperson, “New Storm to Pound SE Arizonans!” Begins Monday night, Tuesday AM. May have snow in it as it ends.
Your know, its no fun telling people what they already know, so lets look ahead beyond the normal forecast period of great accuracy, beyond not seven days, not eight, but beyond TEN days!
First, we set the stage with a ten day look ahead (from last evening) in a NOAA spaghetti factory plot:
This plot indicates that the pattern of a towering, storm-blocking ridge is certain along the West Coast by ten days–will be developing for a day or three before this, That ridge represents an extrusion of warm air aloft over the entire West Coast extending all the way into Alaska. The couple of red lines in and south of AZ are due to the change of a minor, likely dry, cutoff low in our area about this time (plus or minus a day).
In other words, this plot suggests a warmer, dry period develops over AZ, and storms are shunted from the Pacific Ocean, located west of the West Coast, all the way to Anchorage and vicinity, They will be welcoming a warm up in weather up thataway at some point in this pattern.
Is that it, then, for the AZ winter precip? It could happen. Just one more storm after the current one fades away today?
Hint: Sometimes anticyclone ridges like the one in the plot above get too big for their britches, and fall away, or, break off like a balloon from a tether, and a warm blob of air aloft sits at higher latitudes, often floating off to the northwest.
The exciting ramification of this latter scenario is that in the “soft underbelly” of the “blocking anticyclone” (as in American football), the jet stream throws something of a screen pass, goes underneath the belly of the blocking high, and races in toward the West Coast at lower latitudes. Having done so, such a break through pattern (“Break on through to the Other Side”) results in heavy rains in Cal and the Southwest.
Izzat what’s going to happen?
Let us look farther ahead, unprofessionally, really, and see if there is evidence in spaghetti for such a development and you already know that there must be because it would explain why I am writing so much here. Below, the EXCITING spaghetti plot strongly indicating break through flow breaking on through to the other side, i.e., the West Coast, from the lower latitudes of the Pacific:
Well, we’ll see in a coupla weeks if CMP knows what he is talking about.. I think this is going to happen, resembles what’s happening now, and weather patterns like to repeat, more so within the same winter. However, how much precip comes with this pattern will be determined by how much flow breaks on through to the other side….
Let us begin our look at yesterday’s clouds by looking back three days ago before the Big Storm. We had a nice sunrise. Here it is in case you missed it:
Moving forward to only two days ago, the day preceding the nighttime blast: a cold, windy day with low overcast skies all day, shallow, drizzle-producing clouds, something we don’t see a lot of here in Arizona.
By the end of the day, the clouds had lowered again, and we were about to have a very interesting night!
———————- 1Remember how great we hippie relics thought that first Doors album was? Later, the Doors, and that era were to be made fun of by 80s punk and humor group, The Dead Milkman in “Bitchin’ Comaro.” (Its worth a listen.)
For fans of NOAA spaghetti, this plot generated from last evening’s global data. Really, the uncertainty is overwhelming:
Every so often one of these goofy ones comes out, a real knee-slapper. The real situation is that we have a series of storms on the doorstep, the stronger ones barging in on the 20th or so, as the bonafide spaghetti outputs were indicating. These will be cold ones; yes, cold ones on tap, with a good chance of snow in “Catalina-by-the-Mountains”, which might also be a good new name for our little CDP.
Wasn’t going to blather about clouds and weather for a few days since there wasn’t any, just sit around and wait for those end of November storms to get here, then regale you with cloudy pictures.
But when I went to the NOAA spaghetti factory just now, I was blown away, beside myself, when I saw those outputs. Being one of the meteorological sophisticates, I suspect you’ve already trampled these maps. But, at the risk of being redundant again and again, here are a couple of jaw droppers from last night’s global data with errors input into the computer model at the beginning of the run to see how much the upper level forecasts change. There are always errors in measurements, they’re not perfect, and so by deliberately putting errors in models, we can see that range of differences in the outcomes. At first, there are virtually no differences because the errors are tiny. But over time their effect grows.
In these plots below, when the two colors of crazy lines cluster (red, representing the warmer side of the jet stream, and blue, the colder side) , it means the errors had little effect, and the forecast of a general pattern on the jet stream is one you can have great confidence in.
Below, a forecast via the “errorful ensembles” to be alliterative there for a second, in which the confidence can be quite high showing that a gigantic cold trough will sit atop most of the western US in the coming 9-12 days. Really, these are incredible:
So, how will it play out?
Well, we already have rather quickly passing cold troughs with their cold fronts ahead in late November, one that passes late on the 27th likely to boost our Sutherland Heights precip totals to our average value or above.
Then, the cold pattern gets amplified by this gargantuan trough that sets up a few days after those first couple of cold shots, setting the stage for cold and colder blasts. So the beginning of our cold weather and snowbirds muttering that they came to Arizona too soon, is just a few days ahead (followed by a “sucker hole” of brief temperature recovery and a few sunny days. (Well, I might be complaining, too, since cloud maven person, the writer, moved to Arizona from Seattle to be warm all day, every day. haha, sort of.)
On the other hand, there’ll be some great cloud shots in spite of the cold, and you and I, the rest of the cloud people, will both manage, warmed by the euphoria of being alive with such gorgeous scenes and exciting, changeable weather.
BTW, will close this shot-from-the-hip blog with a forecast of snow in Catalinaland in early December. That’s right, CMP is expecting measurable snow right here in Catalina.
Remember our slogan, “Right or wrong, you heard it here first!”
Note that within this swath, Catalina is predicted to get over an inch of rain! Note that the swath is not very wide. A wide swath of heavy rain would be one as wide as the State. So, we have to figure that this is a lucky hit at this time, and count on something less as a virtual certainty since the swath above will move around as new model runs look at it. Typically, they shift a little east over time in those future model runs. Hope not.
Have cameras ready for a pretty sunrise. Lots of high ice clouds up there.
The weather WAY ahead
Spaghetti suggests more rain chances after a several day dry spell following the Monday rains. Check out the “pretty strong” indications that we are in the trough bowl as the month comes to an end, meaning troughs should be populating Arizona during the last days of November. In turn, good November rains, and one seems to be in the high confidence pipeline for SE Arizona as a whole, means the spring wildflowers will be given a boost. I will go on record here as now forecasting, if that’s what this is, a wetter than normal November rain total1. Our November average since 1977 is 0.96 inches.
1This sentence will be deleted in the event of a drier than average November and will, therefore, not be on record.
Well, I think so, anyway, and those rain chances seem to carry right into the first week of November. I think you can see that in these graphics from NOAA based on last night’s global data. As in “Where’s Waldo”, can you find the State of Arizona? The US?
You got yer ridgy flow on the top (“top” meaning, “Canada”, around where that yellow line humps toward the north) and yer broadly cyclonic flow on the bottom (“bottom” meaning, “Baja Cal and Mexico”) that is, across the whole western part of North America. This indicates that we will have a configuration that suggests a “split flow” where part of the jet stream and a trough is forced into the Southwest. Models are showing a big trough and cutoff that brings substantial rains to Arizona!
Of course, model forecasts are pretty dicey at this range, more than 10 days, and so that’s why I am reporting it fully here with great excitement! That’s what we do here, go over the edge, not just up to it.
And, for that slight amount of additional credibility, the “WRF-GFS” has been spitting out big storms for Arizona over the past several runs during this late October period. See Arizona rain below from this rendering from IPS MeteoStar:
Since I ran out of anything more to say, I will post a second version of this same map as a public service for international readers who are clueless about states in the USA:
Below, the upper level configuration that goes with the pattern above:
So, there are some questions about the magnitude of this event, will it be a spring wildflower energizer with a major rain, or a just a breezy spell with a dry cold front going by? I’m on the side that a good soaking rain will fall sometime in those last few days of October.
This September 8-10 model-projected Arizona deluge caused by a dying tropical storm? Then followed by four more days of rain around here?
But you wait a lifetime to see model outputs like this, and so I’m going to save it here, even if it is “fantastic”, “phantasmagorical”, surely imaginary in a sense, is model craziness, etc.
Nevertheless, treasurable moments in model output have been given to us desert dwellers overnight, the kind of rain-in-the-desert projected events that Hallmark cards were made for.
Here are the panels from IPS MeteoStar, a division of Sutron, where you can buy meteorological sensors, real good ones. I am posting so many of these panels, which is a little crazy in itself, because in 24 h this series (linked to above) will be overwritten by the next model run from 5 PM AST global data today, and we will likely never see such a wet series again foretold in a model. in our lifetimes. Who knows, it COULD happen, but prepare for a broken heart:
Now that most have left this blog to go elsewhere, let us have some spaghetti to see if there is any hope that a tropical storm-sucking trough will be along the West Coast, and in a position to draw a hurricane northward along the Mexican coast by its southerly steering winds aloft.
As you can see, a trough (emphasized by the blue lines above) is destined to lie along the West Coast, in a position to steer any tropical storms toward Arizona that might be moving up the Mexican coast. So, it looks like the chance of a tropical storm entering the state is certainly a fair amount greater than zero around the 9-10th of September.
Partly its because I can’t think of anything else, brain pretty empty, but check this out:
Measurable rain to fall in the Sutherland Heights, Catalina, in May 2016!
OK, got that “scoop” out…. Here’s the link to NOAA from whence the above map came.
BTW, here’s what a split flow storm looks like as it comes into southern Cal. Man, if it was January or Feb, this would be a real gully washer, a “get the sandbags out” kind of storm. I love this map so much!
Now a little more on these kinds of crazy ensemble maps (“Lorenz”, as named here, or more known more generally as “spaghetti” plots)
This kind of map was telling us we had rain threats at this time in April and at the end of the month some 10-15 days in advance, so far in advance that media weather folk would likely consider it unprofessional to make such a prediction so far in advance. Since we’re not worried about being unprofessional here, we have leapt into the void! Just go ahead and say things! Get the story out now!
Today a strong upper level trough with precip in the mountains of central and northern AZ will indeed be occurring today and tomorrow as was indicated by those crazy maps so long ago. The hoped for rain here will not occur.
However, the storm near the end of the month, also indicated way back then, looks even stronger than the present one, and it will reach farther south than today’s, and so will not only bring some rain and very cool air to the central and northern AZ mountains, but likely around us, too!
I think you are going to like May!
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