0.48 inches fell after 7 AM yesterday, a nice addition to the 1.83 inches already “in the (raingauge) can”, with a 0.01 inches dollop overnight here in Catalina/Sutherland Heights, slightly more and less here and there, with several inches in the local mountains. That addition brought our storm total to 2.31 inches, about 2.5 times normal for the month of November which averages only 0.96 inches.
Recall that at the beginning of the month, it was deemed by the Climate Prediction Center of NOAA that we in SE AZ would experience below normal precip. But this just shows how HARD it is to predict monthly precip anomalies in semi-arid and arid regions where ONE good storm of just a day or two, can blow the forecast (thank goodness!)
Much harder to blow a monthly forecast in places like Seattle where monthly totals are based on many rain days, and if you only had 25 days with rain in a month instead of 30 due to some storm deflecting pattern, then it might turn out to be a droughty one (hahahahaha, kidding my Seattle reader). Those CPC forecasts have a greater chance of verifying in wetter areas where one rogue storm won’t blow those forecasts up.
Also recall that this season we have no La Nina nor an El Nino to hang our climate forecasting hat on. Makes it tough as well.
If Carl Sagan was a meteorologist today, he would be describing our 2-day November drought bustin’ storm as one worth “billions and billions and billions” where nearly every corner of our drought-impacted State got substantial rains. Should help, too, with wildflower eco-tourism in the spring; at least some wildflower blooms now guaranteed.
Should be a gorgeous day today with deep blue skies punctuated by fluffy Cumulus clouds, some tall enough to form ice and produce virga and light showers here and there; not likely to measure here, though. Lots of Stratocumulus1 around early before breaking up into Cu.
Next rain chance? As November closes out into the first coupla days of December.
Yours and mine; the weather and clouds of yesterday
7:31 AM. Doggie Zuma notes R- OCNLY R (light rain occasionally moderate rain) forming puddles, decides to return to house. Dog photo likely to increase web traffic…..
10:48 AM. Light to moderate rain continued for another few hours while the back edge of the band was just over the horizon to the west!12:12 PM. Clouds (Nimbostratus) beginning to lift above ground, Catalinas plainly visible. SOmetimes this scene is described in aviation parlance as, “Ceiling ragged”, cloud bottoms becoming visible because not much precip is coming out anymore. So this is a horrible report to read, “CIG RGD”, often due to cloud tops descending in height, and/or much drier air moving in, both suggesting, as it did yesterday, that the worst of storm is over.2:40 PM. One of the great sights after a storm are the sun glints due to water on the Catalina Rockies. Hope you caught some of this yesterday.2:41 PM. “Standard issue” crevice cloud. You’ll see this over and over again on “Sam” (Samaniego) Ridge. And, as suggested, a great place to hike to, then go in and out of cloud, one that can remain there for hours. Remember how you used to play hide and seek in the fog when you were little? BTW, fogs are real dense when they’re full of pollution, more fog droplets to cut visibility down. So that’s the kind of fog you want to play in and see if you can run away in and disappear in it from your brother.3:56 PM. And as the storm clears, we get these wonderful highlights on the Catalinas.4:42 PM. As the sun set, our second band of showers approached, consisting of heavy Cumulus (i.e., congestus) and small Cumulonimbus clouds with shafts of rain.
———————————— 1 Stratocumulus: “flat Cumulus”, a cloud name oxymoron
And we might even end up with TWO inches total for this storm! Amazing! I couldn’t imagine it, even as a precipophile with a known bias, that more than 1.5 inches would fall from this situation (10% chance of more than that I wrote), with a best guess of only about an inch.
Even the mods grossly underestimated the amount of rain that would fall during the day yesterday, and THAT was the huge surprise in this situation, with several inches falling in the Cat Mountains in the first 18 hours. It appeared in the models that the major rains would occur overnight and this morning, rather than during the day yesterday.
Three to five inches of rain have fallen in the Catalina Mountains since the storm began about 36 hours ago. Is the CDO flowing? Sutherland Wash? Streamflow reports for the CDO don’t show anything at this hour, surprisingly.
We’re now in the main cloud and rain band wrapping around the upper low near San Diego and more showers, maybe a roll of thunder, will continue through this evening. This band was supposed to be the major rain producer, in the mods, but likely won’t now, though won’t be as great a rain producer as yesterday. Probably a tenth to half an inch likely during the day as the band continues over us for another few hours. And here is your U of AZ mod rain forecast, hour by hour.
While not forecast in this U of AZ mod run, sometimes secondary bands develop separate from, and behind the main one we’re now in, and I think there is a pretty good chance of that happening today. Often, there’s a nice sunbreak as the main band departs and before the second separate one comes through, so watch out for that possible surprise in case you think the storm is over.
Pity the poor Oregon Donald DuckTM football team, playing in “Eugene weather” against the Cats today in Tucson, Arizona. Imagine what they expected the weather to be here even a week or two ago! And those poor Tour de Tucson bicyclers, too, peddling around flooded streets!
Upper low passes overhead later in the day tomorrow, which means a day with the coldest air will be over us then, and with that, we’ll have some great looking Cumulus and small Cumulonimbus clouds, scattered showers, maybe enough depth for some graupel and lightning before the weather dries out again for a few days.
Sometimes in these situations like we have today, dramatic line of showers/thundershowers with a fronting arcus cloud can develop to the west and southwest and roll across Marana and Oro Valley in the afternoon. Will be looking for something exciting like that today.
Coming up, another forecasting conundrum….
While the US model has a trough passing over Cal as November closes, while the GEM Canada has the SAME trough offshore of Baja at the same time, a huge dispersion in model results we don’t see very often when they start with the SAME global data and its only five or six days away!
Recall the USA model was in error for the current storm early on, showing it to come inland and be rather dry when the Canadians came up first with a monster using that same global data. So, leaning toward the Canadian model this time around; that the incoming low at the end of the month has a good potential to produce more rain here by having a more offshore and southerly trajectory before arriving.
Below, the Canadian solution, and below that, the USA one, FYI as an example about what weather forecasters have to deal with sometimes:
Valid at 5 PM AST, November 28th. Low of interest (LOI) off Baja Cal. In USA GFS mod, its over Fresno, Cal at this same time! Can’t be two places at the same time. Believe this depiction will be closer to the truth.Valid for the same time as the map above. Quite a difference, huh?
Yesterday’s clouds
11:43 AM. Characteristic cloud shot for November 22nd, 2013.And with the massive amounts of rain and puddling, the desert quickly responded in unexpected venues. Here on Equestrian Trail Road, prickly pear cacti emerge from a road puddle.
Yesterday, too, after the light to moderate rain in the morning, was a rare episode of Arizona drizzle. I am sure the best of the CMJs noted this. And what does it tell you? The clouds overhead are exceptionally “clean”, droplet concentrations are LOW, likely less than 150 per cubic centimeter, or 150,000 per liter, which we consider low, though it probably sounds high to normal people.
The aerosols on which cloud droplets form on, called “cloud condensation nuclei”, or CCN, got pretty much wiped out by rain, as you would guess yesterday, and so air involved in cloud formation hasn’t got a lot of CCN available. Normally in inland areas, clouds with 300, 000 to a million droplets per liter are common.
When droplets are few, the water that condenses in the cloud is dispersed on fewer drops, and so each drop tends to be larger than in polluted clouds. When they are larger, and reach diameters of 30-40 microns (about half or so of a human hair) they can collide and stick together, form a much larger droplet that falls faster and collides with more and more droplets until it falls out of the cloud. In this case, because its a thin Stratus cloud, the droplet only can grow to drizzle size, one by definition that is smaller than 500 microns in diameter (about five human hair widths. They don’t or BARELY make a disturbance in a puddle. So, when you saw those drizzle drops falling out, you KNEW that the largest droplets in that shallow Stratus cloud overhead had attained 30-40 microns in diameter.
Do you need to know this? No.
12:33 PM. Very exciting scene. The rarely seen Stratus deck, AND a drizzle occurrence in progress!
I’m trying to keep you busy today. Maybe you’re retired and you don’t know what to do with yourself. Well, today you can look at building precipitation totals in Arizona all day! It will give you something to talk about.
In fact, occupying retirees with searches for precip data is why we have so many different sites that record precipitation. We have a lot of retirees in AZ, low temperature refugees, and we need to keep them occupied and out of trouble.
Imagine how awful it would be if we had ALL of these rainfall amounts in ONE place and you could look at them all immediately, or have a map plot of all these sites and amounts? Imagine just CoCoRahs and Rainlog.org being friends and cooperating together and just having one site for their rainfall collections? It would be like the Berlin Wall coming down, precipitationally speaking. Oh, well, that’s not gonna happen.
Oh, yeah, the Heights of Sutherland here in wonderful Catalina, AZ?
Got 0.17 inches overnight. “Main bang” still ahead, quite a long ways ahead, considering the passing showers we have now. Doesn’t look like the major band will get here until after midnight, then pound on us most of the day tomorrow. This prediction from the Huskies of Washington’s Weather Department model seen here.
So being on the toasty side of the cold front, should be a pleasant, mostly day with dry spells in between showers, and maybe, if the low clouds break a little, with fabulous middle and high cloud patterns associated with the powerful jet stream overhead (winds at Cirrus levels today and tomorrow should be over 100 mph!) Have camera ready.
Range of amounts from this front, a little in the withering stage as it goes by tomorrow, here in The Heights of Catalina, 0.4 to 1.5 inches, median guess 0.95 inches. Just too cellular in nature to be sure you get hit with all that’s possible, so you fudge on the downside some.
HOWEVER, just viewed the accumulated precip from our great U of AZ mod and it shows about 1.5 to 2.5 inches here, with the model run ending at 1 PM tomorrow–with more still falling! Wouldn’t that be fantastic! Certainly we’d have water in the CDO.
Precip totals ending at 1 PM tomorrow!
These mod forecasts do tend toward the high side, but I would be very pleased if more than my highest estimated amount (1.5 inches) fell.
As you will see, rain’s piling up like mad in central AZ just to the west of us. Amounts, according to radar, already well over an inch just for the last few hours according to NWS storm total radar loops from PHX and Yuma. Hah, Yuma! How often does that radar see amounts over an inch in winter?
I suppose we’ll be complaining soon about too much rain….
Yesterday’s clouds
So much was happening skyward yesterday! So much so, its probably best seen through the U of AZ Weather Department’s time lapse movie here. Its really great and shows all the complications of a day where clouds are moving in at different levels, and there are lots of wave clouds (lenticulars) over the Catalinas to marvel at.
6:59 AM. Altocumulus patches and pastel Cirrus announce a new day.
7:06 AM. A few minutes later, Altocumulus perlucidus join the color display.
11:07 AM. Once again, the rarely seen Cirrus castellanus (“Cumulus in a Cirrus) that I seem to notice every week here…
11:44 AM. Hover clouds (Ac len) over the Catalina, Altostratus above.
1:14 PM. Barging in from the south, the next lower layer, Stratocumulus and Cumulus; bases touched Ms. Mt. Lemmon. Sky darkened rapidly and almost eerily right after this.4:22 PM. The occasionally seen Seattle June sky, overcast with threatening clouds that don’t do anything, and with mild temperatures. Tops 0f these clouds were right at the normal ice-forming level here, -10 C (14 F), and by evening, virga and light rain began to fall from them as they deepened up a bit more.
The weather way ahead
More rain as month closes out. If you don’t believe me, a theme here, check this image out:
Valid for 5 AM AST, November 30th. Of course, I’m not going to show you the actual rain map, I want you to go from this as a bonafide Cloud Maven, Jr. (CMJ). I’ve noticed that some of you have not yet ordered your sophisticated “Dri-Fit” TM, “I heart spaghetti” tee shirts… What’s up with that?
“Better” means wetter, of course. You don’t read this blog to read about DROUGHT! You read it to read about rain and moistness; clouds, too. Let’s leave drought for the other guys…
Here is the latest model permutation from the Canadians, one that successively, and successfully, I might add, jacks up the amount of rain for AZ as the real deal gets closer on the November 21-23rd. Take a lot at these two depictions from Canada for the 22-23rd (sorry about the small size; the Canadians are shy about their model outputs and don’t like to post large gifs or jpegs; also remote areas of Canada mostly have dial up so big files are a problem I’m guessing):
Valid at 5 AM Saturday, November 23rd. Note streamer of heaviest rain in central AZ, The colored regions are for those areas in which rain is forecast by the model for the prior 12 h.Valid at 5 PM, Friday, 22 November. Note streamer of heaviest rain in eastern AZ, and over our area with lots more ahead!
The colored regions are for those areas in which rain is forecast by the model for the prior 12 h.
Note round low near San Diego in the first panel, upper left:
“Round lows out of the flow; no one knows where they want to go.”
This old weather forecasting limerick I just now made up sums this situation well. Round lows sit, spin, wobble and jerk around for awhile, and so they shovel rain and clouds over the same areas for one or two days, sometimes longer.
So, instead of a nice sharp frontal band passing by within a few hours and then its over, as happens most of the time here, bands rev up and keep spinning around the wobbling low, often hitting the same areas and the rain/snow keeps piling up. Remember the giant cutoff low in December 1967, and the MOUNTAINS of snow it produced back then in northern and central Arizona, stranding hundreds? Well, this ones not THAT big, but its big deal anyway with lots of water in it, and not so cold as the one in 1967 when “album rock” was emerging.
So, this could put a real dent in our October-November rainfall deficit throughout Arizona, a real “worth billions of dollars storm” to agriculture! I am pumped, as are you!
Great storm, too, if you’re planning on getting those spring wildflower seeds in the ground; do it just before the storm arrives and you’ll likely get a colorful return in the spring this year.
What are the chances of measurable rain here in Catalina? Oh, right now, I’d say anywhere between 100 and 200 percent. Now the NWS is NOT going to give you those kinds of percentages I might add. You only get them here.
Amounts?
Let’s go for it. I say the minimum (10% chance of LESS) is 0.40 inches, maximum (10% or less chance of more), is 1.50 inches (big top side due to stationary aspects of storm, likely thunderstorms in area). Median of these, which might be the best estimate for Catlanders (those domiciled in Catalina): 0.95 inches, all falling between the morning of the 22nd through the morning of the 24th, likely in pulses. Goodbye dust!
But in those central AZ mountains, with flow more or less perpendicular to them from the south, their best rain producing wind direction, 1-4 inches is very likely. Yay for rain and snow, maybe some TSTMS, too, comin’ right up.
Didn’t mention the US mods but they are “on board” for a major rain event in AZ. Canadian one saw it happening first, so am sticking with it.
Still another pretty good rain chance as the month closes, but a far colder situation than the one coming up.
Yesterday’s clouds
Small ones, Cumulus humilis, no ice, but pretty anyway. Also, a little smidgeon of Cirrocumulus late, with Cirrus, too, invading from the SW, and a pleasant sunset.
5:11 PM. Cirrocumulus blossomed overhead as a moist layer way up top encroached. No ice indicated.2:46 PM. Cumulus humilis dot afternoon skies. No ice indicated.5:32 PM. Cirrus clouds provide target for fading sunlight.
Here, from last night. Has a great solution to weather: all AZ rains beginning the NW portion of the State late on the 21st, spread over the rest of the State the next day (22nd) and continue into the 24th. Not looking at other models since they might be different.
Incoming Pac trough (bend in the upper level winds) curls into low center over southern Cal, then takes a couple of days as it slowly spins east over the US-Mexican border allowing beau coup moisture to flood into AZ from the south.
The End, and pretty easy today; saw what I wanted to and went with it.
A couple of Pima County gauges reported measurable rain yesterday or overnight, but that was about it. But it was a fabulous cloud day yesterday. Heavier spotty rains, one USGS station indicating over an inch, fell in the central and northern mountains, which is good.
Below, a rehash of yesterday’s great variety of clouds.
7:48 AM. Altocumulus lenticularis clouds beyond the mountains to the SE of Catalina. Lenticular clouds indicate a stable layer of air, one resisting being pushed up, the opposite of what the slender Cu below indicated. So, an usual sky for us yesterday morning.8 AM. Towering Cumulus atop Ms. Lemmon indicated how unstable the air was just above mountain top level. Underexposed for dramatic silouhette look. The smooth top on the right would be Stratocumulus lenticularis, again an odd juxtaposition.
10:37 AM. Then you had your Altostratus mammatus/testicularis.3:08 PM. Your Cumulus mediocris topping the Catalinas with a few Altocumulus above; nice shadows and sun quilting.
3:09 PM. And you had your “weak” Cumulonimbus capillatus clouds to the north.
4:19 PM. Here’s a better shot of the Altocumulus perlucidus (here) top side.
4:33 PM. Nice example of glaciating smaller Cumulus remnant north over Saddlebrook. Likely some sprinkles reached the ground under that ice plume. As you know, takes ice to get rain in AZ.4:34 PM. More sunlight and shadow drama due to Stratocumulus and Ac perlucidus above. Was indoors socializing so didn’t see sunset. Hope it was a good one. I am beside myself thinking about how happy you were seeing all these kinds of clouds in one day!
The weather ahead
Models beginning to act quite well now. A little rain is foretold for Catalina and environs on the 21st of November, but Enviro Can make that storm look more significant and slower to move in, on the 22nd. Still two mods, both having some precip? Its all good. First, for your viewing pleasure and because it portends more rain, from Canada, this:
Valid for 5 PM, November 21st. Low and lots of rain shown banging into Cal. Would be here about 24 h later, or on the 22nd.
Also valid for 5 PM AST, November 21st, this depiction of the flow at 500 mb.
An aside: the Canadian model tends to have a westward bias, that is, a storm is foretold to be farther west a few days out than it turns out to be, something I’ve learned since becoming a forecaster yesterday (hahaha, just kidding, if anyone’s reading this far). So you have to figure the Enviro Can depiction of a trough off Frisco, Cal, is really going to be inland that bit. The US mod output shown above, has this same trough going more overland before it gets to us than the Canadian one, and so there’s less cloud water in it by the time it gets here. Root for the Canadian “solution”!
Farther down the road….more illusory water on the hot highway?
And, of course, a heavier rain is once again over Catalina and vicinity as November closes. This model really likes Catalina and SE AZ! Check it out:
6:52 AM. Altostratus with modest downward hanging mammatus1 bulges under lit by rising sun above the Catalina Mountains. Altocumulus clouds are in the background. Was a magnificent sight.6:57 AM. Mammatus protuberances more evident here, and quite lovely I thought. I seem drawn to mammatus formations.
The weather way ahead
Well, the WRF-GOOFUS model has lots of rain for us again as November closes out, with the model rain amounts foretold in November for Catalina now totaling over two inches, or about twice normal. Its been great model month of rain for us. Below the latest rains foretold, beginning on the 27th, continuing into the 29th. Here from IPS MeteoStar, these renderings from our best model, based on last evening’s global obs taken at 5 PM AST:
Valid at 5 PM, Wednesday, November 27th.
Vallid on Thursday, November 28th at 5 AM AST.Valid at 5 pm November 28th. Green areas denote areas where the model has calculated that rain has occurred during the prior 12 h.Valid at 5 AM AST Friday, November 29th.
There is some evidence from the NOAA spaghetti factory that churns out those spaghetti plots that a big change happens in the last week of November, so rain at the end of the month, two weeks from now, is not out of the question. This rain pattern results from a stagnant upper low SW of us which you can see here.
What about the weather immediately ahead?
Global pattern shifting like mad today due to what we call, “discontinuous retrogression” caused by low cutting off out of the jet stream in the central Pacific. Troughs/ridges jump westward almost overnight when this happens. Highs disappear overnight as is happening right now over the whole West! Very exciting, except in this case, while a trough blossoms overnight replacing a ridge in the West, its amplitude (how far south the jet stream in the trough gets) doesn’t seem to be enough to provide us with rain here in Catalina now. Remember that winter rain here is nearly ALWAYS associated with a jet (at 500 mb) to the south of us.
This drastic change in pattern often only lasts a couple of days, too, before reverting to “same old same old” as we had, fair and warm. I wanna cuss here.
The foretold development of a trough in mid-month in the West was a huge, and strong signal, you may recall, in our “Lorenz plots” (I am hoping this name catches on; he deserves it), those balls of yarn I show every so often. So the trough and cold air getting here to SE AZ has been “in the bag” for more than 10 days in advance, according to those strange plots.
However, the rain here in the actual model runs has come and gone in them as mid-month approaches, and lately, there ain’t been nothin’ here. At most, a few hundredths it would now seem, and most likely, nil.
———————–
1Gender-specific naming cloud variety convention: if male, as in the case of the writer, this cloud formation is deemed, “Altostratus mammatus”; if female, the proper name would be “Altostratus testicularis.” Its part of an adjustment similar to the one when only female names were used for hurricanes, and doing that, it was felt, lent a kind of stereotype to female behavior/character. So, male names for hurricanes were introduced by NOAA in the 1970s to “even the score”.
…and maybe points north, too. Lately models have been foretelling rain in Catalina on the 17th or 18th. In case you don’t believe me, here’s the precip forecast from last evening’s (00 Zulu) WRF-GOOFUS1 model run for the morning of the 18th as rendered by IPS MeteoStar:
Valid for Monday morning at 5 AM November 18th. The colored areas are those in which the model has foretold rain during the previous 12 h. As usual, the heaviest amount is foretold for my house here in Catalina/Sutherland Heights.
What are the chances this will really happen so many days ahead? Pretty good. Let’s check out the “Lorenz map2” below:
The Lorenz map, a name I made up but he deserves it since he came up with the Chaos Theory due to which such maps like these are produced by our computer models; where little, itty bitty things can feed into the system and alter the whole thing, like the cliche of a butterfly flapping its wings in Brazil and affecting a tornado in Texas later, as a friend said in a SEA Times article a few years ago, a friend, BTW, that I played softball with on the Dept team and could really hit the long ball3… Oops, where was I? Oh, yeah, this map is valid for 5 AM, Monday, November 18th.
Cold air in Catalina? Having to put your jacket on for a few days? Its in the bag.
Rain? No doubt showers in the area with a pretty low snow level on the 17th-18th, but, with the long overland trajectory as presently indicated, not much, maybe a tenth of an inch or so, kind of marginal.
Yesterday’s clouds, high ones
There was some iridescence in a patch of Cirrocumulus about mid-morning, and then what might have been a bit of a parhelic circle in a patch Cirrus. That was it. More interesting clouds today as streamers of moist air at high levels sporadically invade Arizona, and today should be one of those. Get cameras ready!
10:56 AM. Sublte bright, slightly curved line in the upper part of this photo of a Cirrus cloud patch may have been a “parhelic arc.”
——————————————
1 As the Global Forecast System is affectionately known.
2I think E. N. Lorenz deserves it, a map with his name on it that we currently call “spaghetti plots”, or by the uppity “model ensembles” name. You put little errors in at the beginning of the model run and see how different the end results are. Not too much effect at the beginning because the errors are so small, but usually end up producing a ball of yarn after kitty played with it, as one reader wrote, after a couple of weeks, meaning that the reliability of any specific prediction at that time is nil. You see, all instrumentation has some error factor, so we never really measure the exact state of the atmosphere. This is a technique of adding little errors is to see how much they can affect the outcome. Sometimes, when something really POWERFUL is out there somewhere, those little errors don’t have much of an effect, and that’s when we can make a pretty good prediction for more than a week out.
3In case you don’t believe me again, this time that I actually played on a softball team with someone that might be asked his opinion on something by a newspaper reporter from the Seattle Times, here is a picture of Dr. Nick “Blaster” Bond, my teammate. I took this picture him because I really liked him, and we both liked to play on teams with girls who could really play, too, then we would win co-rec titles because of how well THEY played. It was great! Nick always wore those ripped short-shorts no matter how cold it was, even if it was raining.
Famous scientist, quoted in newspapers, Blaster Bond, looking askance at some lollipop softball pitcher, about 25 years ago. Not the same Bond responsible for “Bond Cycles” in paleoclimate proxies, though I wish he was because then I would be more important as a person having more important friends I could mention.
While waiting for measurable rain to begin piling up in November, let’s look at no rain so far for the current water year which began October 1st:
The observed monthly rainfall is shown by an adjacent column in yellow on the right… (hahaha, trick or treat, there isn’t any yet)
In fact, speaking of piling up, here’s some rain in this forecast from the Canadian GEM model already for the night of November 4th-5th, and, of course, windy on the 4th before the cold front with this barges in. And, I am happy to report that the USA WRF-GFS model is ALSO showing rain during this time, after being rather reluctant until the run from last night at 11 PM AST, seen here. This is lookin’ good now for our first measurable rain in over a month.
Valid at 5 AM AST November 5th. Colored regions in the lower RIGHT panel are those in which the model thinks it has rained during the prior 12 h (overnight, Nov-4-5). You might have to use binoculars to see it.
But wait, there’s more!
Amajor precip episode has shown up in the 11 PM AST WRF-GRS run from last evening! Check out these renderings from that model run from a site I like, IPS MeteoStar:
Valid for Thursday, November 14th at 11 PM AST. Colored regions indicate where rain should have fallen in the prior 12 h. Note heavier blob over us, indicated by darker green! Valid for 11 AM November 15th. Precip for the prior 12 h ending at this time shown by colored regions. Note bull’s eye in this area (likely associated with mountains around here). So, the mod thinks it could be raining over a 12-24 h period.
In the past we have seen numerous examples of “fantasy rain” produced for us here, often involving decaying tropical storms, that turned out to be completely bogus in this time range, that beyond 8-9 days. Its pretty normal for goofy things to show up in these models beyond that time. Just too much chaos going on and using measurements with their inevitable errors, even if fairly slight ones, not to mention that we don’t really have all the answers to how the atmosphere works.
So, what do we do? We deliberately input errors into a few model runs at the very beginning and see what happens, how crazy the key contours and isobars get. “Pretty cool, huh?”, as Bill Nye the science guy might say if he were writing this. Where they remain pretty steady, that’s where a prediction, even one ten or more days out, is going to be very reliable. Here’s is a sample of one of those crazy results from NOAA:
Valid at 5 PM November 10th
The plot above indicates that there is a very strong signal for a big trough and storms along the West Coast 10 days out. The red lines show that there is a strong signal for the jet stream from the subtropics to be a bit south of us.
The main point here is to point out that while the DAY OF THE RAIN on those forecast maps might change in the models, there are still going to be a number of days where troughs and fronts threaten to bring rain yo Catalina over the next two weeks, and one’s likely to make it as a rainy one.
Thinking now, having a rain bias (“truth-in-packaging” note here), that November’s rain will be near or above normal.
Today’s clouds
Look for a few Cirrus and maybe Altocumulus to appear late in the day with the likelihood of a nice sunset shot.
That’s it. Its a kind of news release, best released on the 1st. Its news, of course, you won’t find on other weather sites because maybe they’re chicken, or prudent. Check back on November 30th, and if its rainless again, there will be no mention of this forecast.
But, after the rainless October (we average about an inch here in Catalina), you probably won’t believe me. Check this out from the NOAA spaghetti factory. I got pretty excited when I saw it. I think, you will, too, maybe mention it to your neighbors over coffee this morning, having been pretty convinced yourself after seeing this that storms are a brewin’ for Catalina and vicinity (all of Arizona) in November:
Valid for November 10th at 5 PM AST. Originates with global data obs made at 5 PM AST last evening, and represents a few key 500 millibar height contours after DELIBERATE little errors have been put in and the computer model rerun with them in it.
Thank E. N. Lorenz, a meteorologist for Chaos Theory and maps like the above that show how little tweaks in the original data can change stuff a lot if things are fragile, but not so much if the signal is robust, and things not so fragile. Here a deep trough along and off off the West Coast on November 10th is virtually guaranteed by the blue and red lines that plunge so far to the south off the West Coast. A trough out there, as you know, gives us the best chance for rain as it progresses to the east. The bunching of lines indicates where the forecast, with baby errors, is strongest, like off Asia, and hereabouts, off Baja. Those red lines are pretty much where the south edge of the jet stream will be at this time of year. As you know, we have to be on the north side of the jet during the winter here in old Arizony to get precip, so it looks good for that to happen as we move forward in the month.
BTW, here’s your official forecast for the whole month of November from the Climate Prediction Center (CPC). As you can see, this November is a tough month for them, no real signals showing up for the month as a whole as indicated by the HUGE areas of “EC”, i.e., “equal chances” of above or below normal precip. We’re kind of on the edge of “we don’t know what’s going to happen” (in the popular lexicon, “clueless”) which is good. The signal for continued drought here is not so strong, though it is there. Poor New Mexico, though.
November precip forecast for North America made on Halloween by the CPC.
Cloud photo op coming up
A weak trough ejects from the Pacific and over us beginning tomorrow, and it should bring some great photogenic Cirrus and Altocumulus clouds tomorrow afternoon and evening, likely some “castellanus” if you care. Likely to be some virga (snow falling from the Ac) too, so could be a great sunset shot coming up. With the virga, always a slight chance of a sprinkle-its-not drizzle.
