Many strange1 and wonderful sights were seen yesterday; I could feel the excitement out there as one cloud microstructural mystery after another regaled our Catalina skies.
How cold are these clouds? Lets look at the TUS sounding, launched at about 3:30 AM yesterday morning.
That bank of Altocumulus was racing at more than 50 mph toward Catalina, and so it got here in a hurry. And, as it got closer, it was also getting more into some airways at that height, possibly descents into PHX since the height of those clouds was below normal jet cruising levels at 23,000 feet Above Sea Level.
Now for the aircraft effects. Hardly a few minutes go by before aircraft began marking up this cold Altocumulus layer. Notice that it doesn’t seem to be producing much or any ice on its own, making aircraft inadvertent seeding lines and holes where tremendous numbers of ice crystals are generated immediately present. Here’s the first of many:
Heading for Catalina, this:
Here’s the south end of that ice canal:
Looking straight up at the icy heart of a hole punch region caused by an aircraft. I am sure you have never done this before! This is gonna be a great blog with all these new things for you!
As the south end of the original ice canal began to enter the refraction zone for simple ice crystals around the sun, usually at the 22° degree halo position, things began to light up with a particularly bright upper tangent arc (more often observed on a halo) or colorful (in this case) partial “reverse halo”. The colors (iridescence) due to the refracting of light within very small ice crystals. Normally iridescence is seen near the sun in Cirrocumulus clouds or the then edges of other droplet clouds. Very exciting.
Then this strange sight:
The day closed out with a lower layer of Altocumulus moving in, this layer, according to the TUS sounding, at “only’ -17° C, and little ice detected. Below, at 2:09 PM:
U of AZ mod thinks so light rain will develop around here in the mid-later afternoon.
1“stragne” above, originally an inadvertent typo, but left in place as another cheap trick to get draw the curiosity of readers who might wonder what stragne is.
Yesterday, whilst disappointingly dry, no rain fell here overnight was a day of rare cloud sightings, most of it involving the rarely seen, “Cumulo-cirrus1“, a cloud fakery situation where extremely cold (less that -40°Ç, -40° F)and clouds at Cirrus levels appear to be ordinary little Cumulus fractus clouds. I hope you weren’t fooled by those impersonators. You’d be pretty embarrassed at the next meeting when we go over yesterday… Yesterday was, in essence, a test for you, and I hope you passed.
Along with the rare “Cumulo-cirrus” sightings, there were intricate patterns in Cirrocumulus clouds that may have caught you’re eye. However, with the wind aloft being so strong (around 90-100 mph at 18,000 feet) you didn’t have a lot of time to enjoy them.
Explanatory figure below:
————— 1Though it fits, I made this cloud name up. Probably would be Cirrus floccus, maybe Cirrus castellanus in the humped up cases.
Oh, well. Was expecting at least 0.25 inches a few days ago, and thought maybe a heavy shower last night might pull that expectation out of the trash bucket. Monthly total now up to 0.70 inches (updated after reading NWS-style and CoCo gauges here), still significantly below average (0.96 inches). Not much else elsewhere, either. Double dang.
Mostly Cumulus humilis and flat Stratocumulus yesterday. Was looking for ice as the temperatures aloft cooled during the afternoon and evening, and only as the sun went down was a slight bit of virga visible to the west. That Stratocu deck over us was deepening upward, and began reaching the magic point where ice begins to form, probably around or a little below -10° C (14 °F) in clouds such as yesterday’s. Let’s look at a sounding from the U of AZ (as displayed by IPS MeteoStar) and see what it says about those evening clouds and see if the above is just a bunch of hooey (I haven’t seen it yet, either):
Still looks like a chance for some light showers before the month closes out, but will be hard to get enough to bring the total to an above average value. Dang.
Will update my reader on December’s early cold outlook as new information that agrees with my assessment comes in. Right now, that information is not available.
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!”
Doesn’t happen every November, thunder, but it sure pounded away at times yesterday. Seemed louder than usual thunder a few times even with the lightning over there by the Tortolita Mountains. Of course, that’s where the heaviest rain fell as several T-storms tracked along a similar path over there just a little to the W through N of us, Bio2, in one of the heavier cloberations receiving 1.17 inches.
Here, in The Heights, we received a disappointing, but nevertheless welcomed final total of 0.24 inches. This brings our total here in Sutherland Heights for November up to 0.60 inches. Average is 0.96 inches1. Here, the regional totals as the storm was coming to an end:
As is proper, let us begin examining the nubilations of our storm by looking at those clouds that preceded the actual rain day yesterday.
Moving ahead to yesterday…..
The great thing about yesterday was that because the upper trough lagged so much behind the cold front, you could be sure it wasn’t over, that is, the rain chances. In fact, as the wind turns aloft from a southerly or southwesterly direction to a more westerly one, we here in Catalina have a better chance of having the clouds pile up over us, even if they’re not full fledged Cumulonimbus clouds, they can still reach depths where they precipitate while upwind, they don’t because they may not be deep enough. The Catalina Mountains provides the lift that helps do this, and we saw that happen later in the afternoon and evening when it began to rain again long after the cold front and it so-so rain band went by.
The End, FINALLY!
1If we don’t get more rain by the end of November, I will delete the sentence of a week or so ago stating that November would have above average rainfall. No use having people see that.
In case you don’t believe me, here’s the model crunch from our very own Banner University of Arizona Weather Department (aka, Hydromet and Atmos Sci Dept). You can watch the storm play out hour by hour here.
However, as you can see, to throw cold water on such a great prediction, we are in the HEART of a rather narrow band of heavy precip, which raises the uncertaintly level a lot on just how much rain will actually fall. Somewhere, these days, there is a Gaussian like distribution of the rainfall at point locations so you can see just what the model spread is in the rain predictions, but I haven’t located it and am too lazy to look right now. If I come up with that, will post it.
So, just as good as that, I will say that measurable rain will fall in Catalina between Sunday evening and mid-day Monday that the least likely amount is 0.15 inches (10% chance of less), which would be a real poop, and the most, 1.00 inches (10% chance of more, a luxuriant rain, washing so much dust off stuff).
The average of those extremes is usually is closer to the actual total, which in this case would be 0.625 (correction! 0.575! Egad, dividing by 2 is still pretty hard for me) inches at my house. The idea here is that we meteorologists often know what’s NOT going to happen better than what is, in the domain of precip forecasts, and so by starting with extrema, to be erudite there for a second, we can narrow our predictions down, not get too carried away as often happens here.
BTW, if you want really great, professional level forecasting besides that by the TUS NWS , see Bob’s discussions! He’s always got great stuff.
The first high clouds ought to be arriving later this afternoon. Have cameras ready. Should be a nice sunset to go with them since there shouldn’t be a total overcast to the west.
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.
Every once in a great while, we have days where fairly thick clouds do not produce even a sprinkle, even though their tops are a little below freezing, but not quite cold enough for natural ice to form. Yesterday was one of those days.
And it was a day you, a cloud maven junior member, could likely have done something about it: rented a small plane or helicopter capable of flying up to around 15,000 kft ASL, taking a bag of commercially available dry ice pellets, then drop them into the fattest, highest Cumulus tops you saw while nipping them in VFR flight mode, and, “violet!”, ice would have formed along the path of the falling dry ice pellets!
So what were the ingredients that made yesterday so special for a little renegade cloud seeding?
The clouds that did not rain were pretty thick for ones that didn’t rain naturally, maybe 5,000 to 6,000 thousand feet thick in their maximum “overshooting” tops, and temperatures at top were a little below freezing, but warmer than -10° C. At lower top temperatures ice would likely have formed naturally. Here’s the annotated TUS sounding from yesterday afternoon from IPS MeteoStar:
Here’s how it works: the dry ice pellets, themselves at -72° C, will chill the air it comes in contact with to -40° C, resulting in the formation of jillions of tiny ice crystals in each pellet’s wake, which are then spread over a wider region in the following minutes due to turbulence in the cloud. In essence, each pellet is creating a tiny, vertical “contrail” in that cloud, as least in those upper parts of the cloud below freezing. (Bases yesterday were a little above freezing, around 2° C, while the highest afternoon tops locally appeared to run between -5° and -10° in clouds that were forming in more haze and smoke than usual (wonder if you noticed that?) Haze and smoke tend to reduce droplet sizes, and in doing that, make it harder to form ice and rain, especially in marginal clouds for that, such as we had yesterday.
What happens next is that the “supercooled” water in the cloud evaporates around those crystals due to the dry ice bombardment, while the crystals take up that evaporated vapor. When the crystals get large enough, they may collide with some remaining cloud droplets, if there are any around. Usually all those crystals that have formed will not left too many droplets in their vicinity.
As the crystals grow in size, and because they are in such high concentrations, they will bump into one another and form clusters of ice crystals we call snowflakes. Cloud Maven Person has, along with Professor Doctor Lawrence F. Radke, the latter the “Flight Scientist” in those days with the University of Washington Huskies’ Cloud Physics Group1 in the late 1970s, made snowflakes the size of pie plates (fluffy light ones without a lot of water content) in Cumulus clouds like yesterday’s here.
IMO you would have created not something of much importance, but rather just an annoying sprinkle or very light shower for those out hiking, horseying around on their horses, biking the trails, on an otherwise perfect day for outdoor activities.
One of the problems, long known about in such seeding experiments as could have taken place yesterday, is that the cloudy air is moving THROUGH the cloud, exiting at the downwind location. That is, lower clouds in particular, move SLOWER than the air itself2.
So, you drop some dry ice in a nice turret, the air you dropped it is, along with that turret’s air, will be moving downwind and is going to go out into clear air eventually. So, if the crystals don’t stay in a turret and upward moving air, but goes out the side of the cloud or into “shelf clouds” like yesterday, those crystals/snowflakes aren’t going to grow much, and will remain “light and fluffy” even though they could be huge because they are like “powder snow” not a lot of water mass in them. When they melted at cloud base, they might end up being just drizzle-sized drop (less than 500 microns across) or very small raindrops. So, that’s why you would likely have gotten just a sprinkle or very light rain shower had you done some unlawful, renegade cloud seeding yesterday. Remember, just like when you hike in the State Land Trust areas, you need a permit to seed legally.
This message brought to you as a public service by CMP.
While warm weather returns to AZ over the next week to12 days or so, there is now, and this goes with climo, a big trough that barges into all of the West Coast in two weeks.
When I say climo, I mean that there is a noticeable tendency for this to happen in mid-November in the longterm upper air records so that in some areas of California, for example, there is a modest increase in the chance of rain in mid-month over other times in the month. These kinds of things in weather are termed, “singularities” like the supposed, “January thaw” back East. This mid-November annual trough passage may be related to the increasing speed of the jet stream in the Pacific as winter approaches, something that changes the spacing between the troughs. Pure speculation.
But in any event, be on the lookout for a major change in weather here between the 17th and 20th of November. Something like this is starting to show up in the models.
——— 1Later renamed the Cloud and Aerosol Research Group.
2Something that was even noticed in small tradewind Cumulus in the Pacific in the 1950s by Joanne Malkus (later, Joanne Simpson) and her colleagues.
We’ve waited a LONG time for a rain day. It was so nice, so photogenic as well. I hope you enjoyed it as much as I did.
Also, you may have seen the Froude Number1 in action as Cumulus congestus and Cumulonimbus clouds developed and went around the sides of the Catalina Mountains instead of developing over them and dumping big shafts of rain on them. The heaviest rains yesterday were due to streamers of showers and with an OCNL TSTMS that were north and south of us, Oracleville, Bio2 area, and Marana, Avra Valley where over half an inch was logged in some places.
Still , we managed a third of an inch here in Sutherland Heights, the first appreciable rain since I don’t know when, though, I could look it up. Too long, though, even for Catalina.
Some regional totals, 3 AM to 3 AM: Precipitation Report for the following time periods ending at: 03:19:00 11/04/16 Data is preliminary and unedited. —- indicates missing data Gauge 24 Name Location ID# minutes hour hours hours hours —- —- —- —- —- —- —————– ——————— Catalina Area 1010 0.08 Golder Ranch Horseshoe Bend Rd in Saddlebrooke 1020 0.12 Oracle Ranger Stati approximately 0.5 mi SW of Oracle 1040 0.08 Dodge Tank Edwin Rd 1.3 mi E of Lago Del Oro Parkway 1050 0.16 Cherry Spring approximately 1.5 mi W of Charouleau Gap 1060 0.16 Pig Spring approximately 1.1 mi NE of Charouleau Gap 1070 0.24 Cargodera Canyon NE corner of Catalina State Park 1080 0.20 CDO @ Rancho Solano Cañada Del Oro Wash NE of Saddlebrooke 1100 0.16 CDO @ Golder Rd Cañada Del Oro Wash at Golder Ranch Rd
Santa Catalina Mountains 1030 0.04 Oracle Ridge Oracle Ridge, approximately 1.5 mi N of Rice Peak 1090 0.16 Mt. Lemmon Mount Lemmon 1110 0.16 CDO @ Coronado Camp Cañada Del Oro Wash 0.3 mi S of Coronado Camp 1130 0.28 Samaniego Peak Samaniego Peak on Samaniego Ridge 1140 0.08 Dan Saddle Dan Saddle on Oracle Ridge 2150 0.16 White Tail Catalina Hwy 0.8 mi W of Palisade Ranger Station 2280 0.04 Green Mountain Green Mountain 2290 0.16 Marshall Gulch Sabino Creek 0.6 mi SSE of Marshall Gulch
Santa Catalina Foothills 2090 0.04 TV @ Guest Ranch Tanque Verde Wash at Tanque Verde Guest Ranch 2100 0.16 DEQ Swan Swan Rd at Calle del Pantera 2160 0.08 Sabino @ USFS Dam Sabino Creek at USFS Dam 2170 0.24 Ventana @ Sunrise Ventana Canyon Wash at Sunrise Rd 2190 0.16 Al-Marah near El Marah on Bear Canyon Rd 2200 0.04 AC Wash @ TV Bridge Agua Caliente Wash at Tanque Verde Rd 2210 0.00 Catalina Boosters Houghton Road 0.1 mi S of Catalina Highway 2220 0.04 Agua Caliente Park Agua Caliente Park 2230 0.04 El Camino Rinconado El Camino Rinconado 0.5 mi N of Reddington Rd 2240 0.04 Molino Canyon Mt Lemmon Highway near Mile Post 3 2390 0.24 Finger Rock @ Skyli Finger Rock Wash at Sunrise Rd
Except for a morning or afternoon sprinkle, no rain in sight, just a warm up back to above average temperatures. Dang.
1The young fluid dynamicist, Richard Penniman, fascinated by the flow around mountains, and who later became known as the rock and R&B entertainer, “Little Richard”, first brought the Froude Number to public attention in his song, “Tutti Froude-e.” The title, after an early release failed to capture the public’s imagination, was later revised for greater “accessibility”, to the song we know today as, “Tutti Frutti.”
2Who can forget “Max and the Storm Troopers” and that great song? I would submit, “everyone.” Of course, few know that after 1968 they changed their name to “Led Zeppelin.” And that, my friends, is “the rest of the story”, as Paul Harvey might say if he was lying about something anyway.
Not much else to talk about, no rain of course; what is that?
But with so many colorful scenes yesterday, we can be partially sated by the lives we lead here sans rain here. October ended with a puny 0.01 inches in Sutherland Heights.
Now, because I grew up in California and remain a little Cal-centric, this brief diversion from AZ:
But droughty Cal got nailed though, from about San Luis Obispo, so we can be happy about that I guess. One station, Gasquet RS, near the Duck border, got just under 28 inches in October; stations in the Santa Cruz Mountains, way down by Monterrey, got between 14-17 inches! From the California-Nevada River Forecast Center, this nice map of October rainfall anomalies in that domain. Red is real dry, and that’s the color we would be in if it was the California-Nevada-Arizona River Forecast Center:
But let us not dwell any more of generous rains that others got, but celebrate the color and clouds of Arizona. Here are yesterday’s glorious scenes, beginning with a spectacular Altocumulus lenticularis under some Cirrus at dawn:
Now, just some nice lighting and color:
In a further celebration of dryness here, let us examine the rainfall cumulative rainfall predictions calculated by the University of Arizona’s Dept Hydro and Atmos Sci computer the period ending at Midnight on November 5th. Says the coming rain in the State misses us here in SE AZ while falling just about everywhere else, of course. Dang. Let’s hope it one of the worst model predictions ever!