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?
As you will see from these links, they’re getting pretty worked up, and have issued the SAME “Special Statement” for ALL of Arizona, that’s how big the storm is. We’re all in this together. BTW, the U of AZ model forecast from 11 PM AST last night had as much as 5-6 inches of rain indicated in the central mountains of AZ over the next 24-36 h! Will the washes flow here, eventually as the major rain moves east? Hope so.
But, must point that the range of amounts that will fall here in Catalina has to be considered quite large; something from “just a nice rain” (0.4 inches total) to a gully washer (1.5 inches total) due to the fine-scale of the heaviest rainfall bands rotating around the dawdling low over the next couple of days. Its really not possible to pin it down better than a large range of possible values in situations like this, but it does appear that most of it will fall on Friday night into Saturday.
In the meantime, more pretty skies today before the deeper clouds and rain get here overnight or tomorrow morning. Very little rain is indicated here, though, through tomorrow evening,in this latest U of AZ mod run. while inches pile up just to the west and in the AZ mountains.
Yesterday’s clouds
Had pretty skies all day yesterday, even saw some clouds that as far as I know, have no name, these ones below that LOOK like Altocumulus perlucidus but are all ice at Cirrus levels. Could be called, to make up a name, “Cirrus perlucidus” I guess:
7:46 AM. “Cirrus perlucidus.” It may be hard to tell for most folks, but these flocculent clouds are all ice. There is no WAY I would call an all ice cloud, “Altocumulus.” There’s a patch of Altostratus in distance, and an Ac lenticular to left of pole on horizon.9:49 AM. Altocumulus virgae. Great example of the “upside down” storm; droplet cloud at the top, ice and snow underneath as ice forms amid the droplet cloud, grows like mad and falls out. This finding, first made in the 1950s was surprising because the clouds were liquid at the lowest temperatures. 12:04 PM. Cirrocumulus lenticularis, a bit too thin to be Ac lenticularis.
3:59 PM. This view from atop horsey, an Ac lenticular stack beyond the Gap, in lee of Catalina Mountains. Ac perlucidus in the foreground.4:00 PM. Looking S; buttermilk skies due to Ac perlucidus; lower layer of Ac opacus advancing from the the west below those mottled clouds.5:31 PM. Brief sunset “bloom” due to a small break in the overcast just over the horizon.
The weather way ahead
Valid at 5 AM AST, December 2nd. A near twin of the upcoming situation.
Now showing up on mods, as November closes out, a low center that looks an awful like the situation we’ll have tomorrow and Saturday, another vortex aloft tracks S along the coast, settling in around San Diego, then moving along to the east very slowly. As you know, weather patterns like to get in a groove and repeat themselves for awhile. Could be we’re in that phase where the SW is a low “magnet” and that would mean above normal precip over a spell of a few weeks. Above, a map for December 2nd at 5 AM AST that looks a lot like what we have coming right up. For that reason, you tend to place a bit more credibility than you might otherwise in a forecast that far away. The exact day this occurs will be most likely be off, but it is likely that a troughs/clouds and precip will to affect the SW over the next couple of weeks or more. Good bye dry spell!
If you don’t believe me, check this 10 day outlook from the NOAA spaghetti factory:
“Lorenz plot” from NOAA, valid at 5 PM AST, November 30th. Its pretty plain to see that there is a strong likelihood of a cutoff low in the extreme SW US, if you can find it. (The vast number of contours is due to a software glitch today. Usually only a few upper level contours are tracked.)
Valid for Friday afternoon, 5 PM AST, November 22nd. Arrow points to beau coup eastern AZ precip amounts.
The loop above, generated by last evening’s global obs by the Enviro Can “GEM” model might be the best a numerical model can put out for Arizona. It might even be the best model day of my life ever here (which hasn’t been that long, but still…).
Why?
1. Trough races into the precip “Red Zone”, located immediately SW of AZ. Rain moves in on Friday into Catalina and environs.
2. Trough forms circular, spinning low aloft there, that wanders slightly in place. Cloud and precip rush into Arizona, and it just doesn’t quit as wave after wave of clouds and rain move up from Mexico, the Gulf of Cal-Sea of Cortez, and the Pacific off Baja while the low center dawdles.
3. Low crosses into AZ and departs AZ late Sunday after showery day.
In sum, showery rainy conditions beginning on Friday, continuing into Sunday.
Amounts should be several inches in the mountains of AZ. Here, sans the great U of AZ calcs for the whole storm period, will go with the same “seat-of-pants” estimates of the botttom and top amounts made a couple of days ago: at least 0.4 inches (even if things don’t work out so great; low doesn’t dawdle so long). But as much as 1.50 inches on the high end here in Catalina if it DOES dawdle as this model run from last night shows and we get nailed by recurring rain bands. Best estimate, “therefore” he sez, is the average of the two, or about an inch.
It would seem some thunder now and then would also be in the mix, and BTW, we remind our reader that snow and rain mixed together is NOT SLEET, dammitall! SLEET is frozen raindrops, ones that have frozen on the way down and usually requires two to three thousand feet of below-freezing air temperatures before that happens. Also, they BOUNCE when they hit, are usually clear, and often have spikes where the water was trying to get out since they mostly freeze from the outside inward, and because water expands when it freezes, a spike or ejection of ice splinters results as freezing takes place. Kind of neat really. But its NOT rain and snow mixed together! Sorry, getting into some “sleet rage” here; need to work on it; get it under control. I just don’t want my reader to sound ignorant when rain and snow are mixed together, but rather, “precipitationally erudite.”
Yesterday’s clouds5:20 PM. Jet’s ‘n’ Cirrus. The very short contrails, formed by moisture and carbonaceous crap, oops, black stuff, in the exhaust, are short here because the jets are flying ABOVE the Cirrus.
5:42 PM. OK sunset.
The moon’s been HUGE lately, enough where you can see quite a bit of detail.
“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”.
Some nice CIrrus spissatus and the rare Cirrus castellanus yesterday (something I say a lot here in old AZy). Here is half hour sequence of a patch of heavily precipitating Cirrus spissatus, kind of a cloud oxymoron. I thought it was pretty spectacular even if you don’t care one wit about it. (Hahaha, “wit” instead of “whit.”)
Those Cirrus clouds were up at about 35,000 feet above sea level, at around -50 C (-58 F), but snowing like mad. Don’t let folks tell you its too cold to snow; usually happens that way because here on the surface there’s a high pressure over you, the sky is clear, to wit; a fair weather pattern, and that’s why its not snowing here on the earth when its -58 F, except maybe when there’s a ice haze called “diamond dust“, tiny ice crystals floating/glinting in the air.)
8:48 AM. Cirrus spissatus on the left with the little snowstorm trailing off to the left will pass overhead of Basha’s parking lot there on Oracle in about half an hour, a prediction made in hindsight. 9:07 AM. Taken while not driving down Equestrian Trail Road to Basha’s supermarket.9:21 AM. Basha’s parking lot. Snow, composed of single crystals, not flakes or what we called “aggregates” because they don’t stick together at such low temperatures, pours out of this really cold cloud. The single crystals in the trail would be bullet rosettes, a complex looking crystal consisting of hexagonal columns that stick out from a center point. How much snow falls out? Just a dusting. You could blow it away off any surface. When flying through these icy clouds toward the top where the crystals are simpler, there are sparkles and glints when the sun hits the crystals just right. Very pretty.
The day ended up with lower Cirrus and few Altocumulus clouds with virga as the dry air aloft moved in, providing the clear western horizon that allowed the sun to highlight our clouds. That great sunset, as much as I could see anyway being “on the road” here:
5:37 PM. Heavy Cirrus (spissatus) or Altostratus patch, either name OK, with Altocumulus on the far right horizon.
The weather ahead
Mods still showing rain in the area on Sunday the 17th pretty consistently now. And as we saw from the “errorful” NOAA spaghetti maps yesterday, a trough with cooler weather, clouds and scattered precip is pretty much in the bag for that time period (16th-18th). Can only hope that we get something measurable here. But, even without rain, those days will be pretty ones with Cumulus clouds around.
