Stratus clouds – Cloud-maven

Thunderblasts after midnight awaken sleeping Catalinans with 50 mph winds, graupel, and R++; latest storm total now 1.38 inches!

In case you don’t believe me that over an inch fell, this digital record from Sutherland Heights with writing on it:

20170120-21 rain day — Your last 24 h of rain in the Sutherland Heights, Catalina, Arizona, USA. Total resets at midnight.

Probably a little more to come, too. Got some blow damage, I’m sure. Will be looking for roof shingles around the yard today.

12:45 AM. Your radar and IR satellite imagery for our blast last night from IPS MeteoStar . That tiny red region near Catalina represents hail and/or extremely heavy rain.

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:

Valid for 5 PM, Monday, January 30th. If you've not seen this, you'll be screaming "warm in the West, and damn Cold in the East." Its a common pattern often associated with some of the driest years in the West when it recurs over and over again during a winter. — Valid for 5 PM, Monday, January 30th. If you’ve not seen this, you’ll be screaming “warm in the West, and damn Cold in the East.” Its a common pattern often associated with some of the driest years in the West when it recurs over and over again during a winter.

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:

Valid on Thursday, February 2, at 5 PM AST. Flow from the lower latitudes of the Pac will, in fact, break on through to the other side, as told in song by the Doors1. — Valid on Thursday, February 2, at 5 PM AST. Flow from the lower latitudes of the Pac will, in fact, break on through to the other side, as told in song by the Doors¹. Who knows what they were talking about but here we’re talking about a jet stream….

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….

Yesterday’s clouds

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:

7:21 AM. Altostratus sunrise. Virga is highlighted showing the precipitating nature of Altostratus. Amount of virga can vary.

7:31 AM. Same kind of view, different colors.

7:40 AM. Highlight on the Tortolitas. This is why you carry your camera at all times.

9:04 AM. Pretty much solid gray after that nice sunrise for the rest of the day with cloud bases lowering and raising. Early on, cloud bases were well above 10,000 feet; i. e;, above Mt. Lemmo, and would be called, "Altostratus opacus." The virga is very muted, and there are embedded droplet clouds as well as a droplet cloud layer (Altocumulus) encroaching on the right. Estimated ceiling here: 12,000 overcast." (Pronounced, "one-two thousand overcast" if you want to make your friends think that maybe you were a pilot at some time in your life.) — 9:04 AM. Pretty much solid gray after that nice sunrise for the rest of the day with cloud bases lowering and raising. Early on, cloud bases were well above 10,000 feet; i. e;, above Mt. Lemmo, and would be called, “Altostratus opacus.” The virga is very muted, and there are embedded droplet clouds as well as a droplet cloud layer (Altocumulus) encroaching on the right. Estimated ceiling here: 12,000 overcast.” (Pronounced, “one-two thousand overcast” if you want to make your friends think that maybe you were a pilot at some time in your life.)

12:58 PM. Clouds began to appear on Samaniego Ridge as the moist air above us lowered steadily. However, due to lowering cloud tops, the ice in the higher overcast layer was gone. Here there are two layers above the scruff of Stratus fractus (I would call it) on the ridge. The lower one looks like its a Stratocumulus, and the higher one a solid layer of “Altocumulus opacus.” Its already rained some, and we were in between storm bands.

2:48 PM. Looked like the Altocumulus opacus (stratiformis, if you want to be exactly correct) was breaking up just enough for a sun break. But no, kept filling in as it headed this way from the southwest. — 2:48 PM. Looked like the Altocumulus opacus (stratiformis, if you want to be exactly correct) was breaking up just enough for a sun break. But no; it kept filling in as it headed this way from the southwest. No ice, or virga evident, so tops are pretty warm, probably warmer than -10° C (23° F) would be a good guess. Hah! Just now looked at the TUS sounding and tops were indicated to be at -11° C, still very marginal for ice (absent drizzle drops in clouds, which causes ice to form at much higher temperatures, but you already knew that.)

4:24 PM. Small openings allowed a few highlights to show up on the Catalinas underneath that Altocumulus opacus layer. And clouds were still topping Ms. Mt. Lemmon, indicating a good flow of low level moisture was still in progress.

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.

8:08 AM, January 20th, 2017, btw. "Gray skies, nothin' but gray skies, from now on", by Irving B. — 8:08 AM, January 20th, 2017, btw. “Gray skies, nothin’ but gray skies, from now on”, by Irving B. Stratus fractus underlies an overcast of Stratocumulus. Some light rain is falling toward Romero Pass on the right.

8:10 AM. A really special shot. Stratus with drizzle is a very difficult photographic capture. I can feel how enthralled you are with this view toward Oro Valley. You know, I do this for YOU. — 8:10 AM. A really special shot. Stratus with drizzle, shown here, is a very difficult photographic capture. I can feel how enthralled you are with this scene toward Oro Valley. You know, I do this for YOU. Look how uniform the gray is! It just takes your breath away!

9:44 AM. Before long, drier air down low moved in, eradicating our beautiful Stratus layer, leaving only holdouts (Stratus fractus) along the Catalina foothills below the heavy layer of Stratocumulus.

10:20 AM. The wind had now shown up, and these ragged, shredded shallow Stratocumulus shedding drizzle or very light rain showers stormed across the Catalina Mountains. This was quite remarkable sight, since such shallow clouds as these are more often seen in clean maritime locations like Hawaii. Scenes like this suggest that the cloud droplet concentrations were very low, and that there were larger than normal cloud condensation nuclei on which the drops could form, getting a head start in the sizes needed to produce collisions with coalescene (larger than 30 microns in diameter (about one third to one half a human hair in diameter, for perspective.)

3:12 PM. Lower, drier air moved in, eradicating the Stratocumulus and revealing the rarely seen Nimbostratus precip-producing layer. This layer, considered a mid-level cloud, is usually obscured by, you guessed it, Stratocumulus clouds.

By the end of the day, the clouds had lowered again, and we were about to have a very interesting night!

The End

———————-
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.)

System vanquishes sun for three days! Produces 2.28 inches in The Heights!

While on the first day, January 29th, the sun was only blocked by mid-level clouds, the rainy ones on January 30th and 31st provided a rain amount to remember here in the Sutherland Heights (and elsewhere–numerous records broken), 2.28 inches recorded over 24 h ending at 7 AM for the past three days, beginning with the 30th:

0.19, 1.56, and 0.53 inches, ending this morning.

Weeds and wildflowers really happy, as will be free range cattle and horses that get out of their pens in the days and weeks ahead.

———-experimental module———————–

We have an interesting experiment in progress, one we didn’t know we were going to have re wildflowers this spring.

A local wildflower expert on a public TEEVEE station here was quoted as saying that NOVEMBER rain was critical to wildflower displays. Hmmm. OK, but we had a RAINLESS NOVEMBER here!

So, no wildflowers? A limited display? Some key ones don’t come up at all because November was rainless, while October, December and now January had generous rains?

I don’t think so. My take is that everything will be hunky dory. HELL, no one will be able to tell that November was rainless in our upcoming wildflower displays.

But the reader must be advised royally in this editorial side bar, that the writer is a cloud-maven, not a flower-maven as was expert quoted on public TEEVEE.

So, let the experiment unfold before our very eyes! A chance for all to learn things! Ans, how fun is that?

———————–end of experimental module——————

Too, I wonder how often three sunless days have occurred in southern Arizona? Was probably a rare event that these past three days mimicked Seattle or other Pac NW sites west of the Cascade Mountains in winter so well.

BTW, in an important climate note concerning the Pacific Northwest, it rains more in Eugene, OR, aka Duckville, more than in Seattle, in case you’re a football player and are deciding between the Washington Huskies and the Oregon Donald Ducks prior to the upcoming LOI Day, the National Holiday celebrating when high school kids sign Letters of Intent about where they are going to play college football.

And, continuing a high school theme, don’t forget to watch football today; the Seattle Seahawks, who live right next door to the University of Washington Huskies, will be playing in a big game, so maybe you could get some valuable autographs while playing for the Huskies…. Just a thought.

Back to yesterday……

I think the most surprising part was how nearly stationary rain echoes kept giving all day yesterday. So often, where clouds are almost stationary, they just rain out and thin. But it just kept coming, at least here in Catalina. And, as the storm came to a close, the expected sight of a frosty Lemmon appeared late in the day due to the gradually lowering snow level as the clouds suddenly lifted when a dry north wind rushed in. Should be more of that dry north wind today.

No rain in sight now…. Corrals can dry out, which would be good.

BTW, by later yesterday the local washes were running reel good. In case you missed the flows, here are some floody scenes:

1:48 PM. Here a Catholic priest in non-traditional garb inspects the CDO wash at East Wilds Road. — 1:48 PM. Here a semi-retired Catholic priest in non-traditional garb inspects the CDO wash at East Wilds Road.

1:49 PM. Looking downstream from the CDO wash and E Wilds intersection.

1:56 PM. Perhaps you're a person that prefers upstream views of flooding situations. Well, here it is, the CDO Wash looking upstream at East Wilds Road in Catalina. Trying to please everybody here. — 1:56 PM. Perhaps you’re a person that has a preference for upstream views of flooding situations. Well, here it is, the CDO Wash looking upstream at East Wilds Road in Catalina. Trying to please everybody here, no matter what your preferences are.

Hiked out to the Sutherland Wash yesterday, arriving about 3 PM to take these docuphotos for you. These were taken near the horse crossing that leads to the “Rusty Gate” and the Coronado National Forest boundary on the east side of the Wash.

Had not seen the Sutherland Wash this big before, in person. Was much higher, though, during the September 8, 2014 event, as deduced from debris piles, when 4-5 inches fell in 3 h.

Yesterday’s cloud

It was pretty much the same one all day I think. We begin our cloud soliloquy with an unusual sighting of pure Stratus, present before the rain moved in again.

7:49 AM. Like a wall painted with Seattle gray paint, available at most fine hardware stores. That is the appearance of true Stratus, and we had that yesterday after dawn. Some fog, too, drifted through. Remember, when its on the ground its called, “fog”, while when its above you the same thing is “Stratus.” Estimated ceiling here, 100 feet.

1:08 PM. In the afternoon the Stratus clouds began to break up at times, providing peek-aboo looks at Samaniego Ridge, which was kind of cool. Remember, that the Stratus clouds were not the ones precipitating, but rather the a layer of “Nimbostratus” above them was. However, as you know, a drop falling into a layer of Stratus clouds does not evaporate while it falls through them, AND, can even get bigger if some floating cloud drop can’t get out of the way (those larger than about 20 microns in diameter). So, to continue an educational stream here, while Stratus clouds, and Stratocumulus clouds may not produce precip beyond drizzle, they CAN help increase rain totals when they are present because raindrops are not evaporating when they fall through them, and raindrops may even get larger and the rainfall amount be more than otherwise due to the collection of some of the cloud droplets!

4:14 PM. Its STILL raining! Unbelievable for someone who thought this Nimbostratus layer would rain out and die in place. The low clouds were completely gone, swept away by a dry north wind. — 4:14 PM. Its STILL raining! Unbelievable for someone who thought this Nimbostratus layer would rain out and die in place. This is a really good shot of that layer that produced the rain that fell into lower Stratus and Stratocumulus clouds for most of the day. Some connections between the two did occur in the heavier rain areas, The low clouds were completely gone by this time, swept away by a dry north wind.

5:15 PM. As the Nimbostratus layer lifted, eventually to Altostratus opacus, if you really want to know, frosty The Lemmon came out showing that the snow level had declined during the day.

You may wish to pleasure yourself with another and very unusual occurrence of fog right now (7:02 AM) coming out of Tucson, heading toward Marana, south Oro Valley. Very pretty scene this miniute. Heading out now to capture on film.

The End

1.77 inches in Catalina and counting

….as of 6 AM.

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.

Here are the latest totals for just 24 h from Pima County.

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 Duck^TM 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 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. — 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!

The End.

Another big day; scattered amounts around us of more than THREE inches again; we only got 0.18 inches!

Trying to be excited for those around us who got all that rain yesterday while we received a paltry 0.18 inches here in the upper reaches of Catalina. Still it was another good little rain for our local desert.

The 24 h rolling archive from Pima County rainfall gages is here. Most seen here? 2.01 inches at Finger Rock and Skyline, Tucson. You’ll see that storm in the movies.

Also, check the more comprehensive U of AZ rainfall network here. In fact, you might as well join up, too. It would get you out of your rut. Think how exciting it would be to go out in the morning and see how much rain fell in your gage in the previous 24 hours! Maybe someday you might win the “rain lottery” and have the biggest amount anywhere in the State! The most reported so far this morning is a deluge of 3.17 inches over by Picture Rocks again. Good grief, have they been getting hammered.

What a July this is turning out to be!

Here we are in Catalina, its late afternoon, it has just rained again, the temperature is a chilly 70 F, dewpoint 68 F (almost saturated), with Stratus fractus just above eyeball level lining the hillsides! Its an amazing scene for an afternoon in Catalina and vicinity in July. And so DARK! Here is that odd scene from yesterday afternoon:

SONY DSC — 4:42 PM Stratus fractus is that low bar of clouds in the foreground just behind the tree. Makes you want to run over there and play hide and seek in it.

Relive yesterday, as though you were in the city of Tucson shopping possibly, here in this movie, courtesy of the U of AZ Weather Department. The movie is rated “R”, for violence since the sky goes WILD in the afternoon, winds going every which way.

Also, in this time lapse you will get a sense of how rapidly moist air is flowing across us from the east to east-southeast. This movie, comprised of still shots taken every 10 s shows movement, like the day before, that is phenomenal for summer, more like a winter scene when winds are normally strong. There are even Altocumulus lenticular clouds (almond shaped ones) hovering over and just downwind of the Cat Mountains! Amazing.

But check the CHAOS in the mid and later afternoon. Unbelievable. Areas toward the Catalina foothills, during this chaos, got another 1-2 inches again yesterday.

In contrast, let us now look at the very same day in a time lapse film in Seattle, Washington, where Mr. Cloud-Maven person spent 32 years, most with the U of Washington Huskies Weather Department. Here it is. I sum up the totality of that movie for July 29th below:

Bor-ring!

Those Seattle skies, for the most part, were like eating plain, cooked oatmeal everyday, all day.

Below, the start of our exciting day, the middle, and the end has already been shown above. Lots of nice rain shafts SUDDENLY collapsing down out of clouds. A sequence of the big northwest Tucson storm early in the afternoon that moved off toward Marana is included as part of the middle. That shaft really fell out fast, and how you could detect the icey tops BEFORE the shaft appeared. I try to point out how you might have been able to do that in this sequence, and thus, and quite importantly, impress your friends and gain status and some kind of weather sage.

Today?

Just looked at the latest AZ mod output, as you can here (forgot to past link until now, 8:08 AM). Colored splotches are where it is supposed to have rained that HOUR. That model has a much less active day today, but much more active tomorrow. Cumulonimbus clouds in sight today? Oh, yeah! But, none are SUPPOSED to get us today. But these mods are always slightly inaccurate, so keep watching this afternoon. Should be another photogenic day, if nothing else.

Altostratus: a misunderstood cloud and for good reason

Yesterday afternoon the clouds thickened and dimmed the sun, and our high temperature struggled only into the mid-50s. What cloud was that? Here it is, with Twin Peaks on the horizon.

Our names for clouds, originating with English pharmacist, Luke Howard, are based on visual attributes from the ground. Here, “Altostratus” (As) does RESEMBLE its lower namesake cloud, Stratus, a low fog-like cloud with little definition often found in summer along the West Coast. See a rare example of Stratus (St) hereabouts below. Note that it is topping the Tortolita Mountains to the west, it is that low.

However, about the only thing that these clouds have in common is that they are both relatively smooth looking clouds. Inside them, they are totally different. Also, St is a shallow cloud usually less than 1 km (3,000 feet) in depth, while As is normally 2-3 km 6,000 to 10,000 feet) in depth. In Stratus, you just have cloud drops and maybe, as below, a few drizzle drops (mist-like) falling out. OK, once in awhile in cold locales you have a few ice crystals falling out, but drops rule! On the other hand, in Altostratus, if you were flying in them with a 1998 version of the Stratton Park Engineering Company’s Cloud Particle Imager ($130,000 or so–I’ve added a link in case some of you want to go shopping now), you would find nothing but ice crystals for the most part. Water droplet clouds are sometimes found in them, and, oddly, if the top is not too cold (warmer than about -30 C), at cloud top, the coldest place! So, it is not unusual to see, even in journals, a thin layer cloud consisting of drops called, As. Makes sense really. (A name change of As to “Altonimbostratus” would be helpful to emphasize its internal ice and falling snow particles.)

An example of the kinds of crystals found in a As clouds is shown below, collected over Barrow, AK, in a 1998 project called FIRE/ACE/SHEBA.

These typical crystals, having grown on the way down from simple plates or tiny columns, or sphere-like “germs”, are called “bulett rosettes.”