Cumulonimbus clouds – Page 21

Looking for rain in all the wrong places…like here in Catalina

Another dry day yesterday, a tough one to take, since it appeared that rain hereabouts was a virtual certainty. All the model runs I saw from the U of AZ had good rains at times on the Catalinas yesterday afternoon and into the evening, as they do again for today. Here’s one U of A model output for 2 PM yesterday (WRF Surface (Flash Animation) as an example.

So, when the dense Altocumulus clouds with their spotty sprinkles and light showers finally thinned and the sun burst forth in the afternoon, up went the Cumulonimbus clouds within the hour off in the distance from Catalina to the NE and SE. It was going to be a great afternoon and evening I thought. Tucson International AP reported lightning, thunder, off and on yesterday until after midnight, and even a few drops! Go here if you want to see all of last night’s action in the satellite and radar imagery from IPS Meteostar.

But none here. Check the radar-derived precip from Intellicast.com. You can see light rain was all around Catalina, dang.

2012071112Z_Azpcp — Rainfall for the 24 h period ending at 5 AM AST today.

Cumulus started to form above Ms. Lemmon, and it seemed one of those was bound to explode upward as well. While a brief sprinkle/virga fell out of one of those clouds at one point when it reached the “Cumulonimbus mediocris” stage, one I made up, no full eruption occurred. It was incredible that didn’t happen, and so discouraging when you claim to be a Cloud-Maven, one who is supposed to know stuff.

The full discouraging day can be seen here, if you can stand to review it. Still, these films are pretty interesting no matter what happens when clouds are present.

By evening all Catalina threats were seemingly gone, with no promising, massive clouds approaching from the northeast as they often do here at that time of day in the summer, rolling down out of the White Mountains, blackening the sky behind Charoleau Gap. I missed a great sunset, too.

About today, in view of my poor track record, you might want to check out what Bob has to say. He is one of the premiere scientists in convection, and lives right here in Tucson! I think he has better graphics, too. Also, here is the forecast from our NWS for Catalina, better get that in there for more balance, and maybe more accuracy! They think the chance of measurable rain today in Catlina is but 10%.

However, being indefatigable, imperturbable, immutable, stubborn, I will press on with this forecast space: _____________________ (write in your own forecast; it will likely be better than mine). PS: I think it will rain today.

BTW, even the coarse (as in grid spacing) Nvironment Canada model has a wet Arizona week ahead. So, if not today, tomorrow!

Below, a photo reprise of yesterday.

SONY DSC — 6:59 AM. That promising morning sky. Light showers can be seen beyond the Tortolita Mountains.

Thundery trace; expect more than that today

(A note: I am not getting WYSIWYG in what I am writing and what is posted in WP. This is SO FRUSTRATING! True I am a bit of an amateur at WP, but those spaghetti plots that start the blog are SUPPOSED TO BE AT THE END OF IT as I see them in the draft, not absorbed in the “gallery” as well, dammitall!) Computers and sofware are going to kill me, I am sure. Where are my pills?!

Another promising start to a summer day today in Cat Land, as was yesterday since we have another cloud filled morning, some clouds having weak rainshafts indicating glaciation in the turrets sprouting from today’s layer. And, there’s been a slight uptick in moisture over us, which raises the chances for measurable rain in Catalina today. We also have support for this contention in the great U of A local model forecasts here, based on last night’s 11 PM AST run! Yay!

Below, the photographic diary for yesterday starts begins with the Altocumulus opacus layer, with more than one layer up there. Then, after the usual thinning-dissolution of that layer in the morning, the welcome sight of baby Cumulus beginning to appear over Mt. Lemmon by noon. Those Cu steadily inflated reaching the “glaciation” level by 1:31 PM, a welcome sight after the “dud” Cumulus clouds of the prior two days.

After our first thundery spell, several new thunderstorms developed to the NW and E-SE over the Catalinas late in the afternoon, but again, produced only another trace in a 20 minute or so of “very-light-rain-its-not drizzle” (one of the recurring themes here).

Since I can’t add more captions after the icy sprout, a WP problem, the times of the last few photos are, 1:53 PM, 2:08 PM, and finally, another great sunset sequence, some distant Cumulonimbus to the NW and another blazing sunset underlighting some virga from the remains of our last thunderstorm, these taken at 7:30 PM.

1:31 PM. That icy sprout on the top meant a rainshaft was already fully developed inside that cloud. There’s always some of it falling out.

The Weather Ahead, way ahead:

We’re always on pins and needles this time of year, hoping for the best summer rains we can get, at least I am. The transformation of the desert into green again during the summer, after the spring greening, is one of THE most rewarding aspects about living here in the summer, flying ant swarms aside.

Below are the “spaghetti” plots from NOAA that give us some clue about the reliability of the longer term model forecasts. These are for the afternoon of July 19th, some ten days from now, and the afternoon of July 23rd. Both plots below strongly indicate that the circulation pattern is ripe for good summer rains here between now and the 24th. Doesn’t mean that every day will have rain, but it does mean recurring summer rains are likely with no long breaks. That black region over the SW indicates a high probability (not certainty!) that our big fat SW summer anticyclone will be well positioned for good summer rains here. In contrast, if that black area was OVER southern Arizona, or to the south, it would be a horribly, hot dry spell here that the models were foretelling.

Lemmon bloom

Thunderstorms in the distance crept toward the Catalinas late in the day, and after sunset, an approaching, but thinning anvil of a dead Cumulonimbus cloud (no updrafts remaining to feed the anvil) produced this beauty. With the death of this prospect, any hope of rain moving in here later in the evening went six feet under as well.

The anvil below looks fairly close, but if you go to the U of A time lapse, this anvil comes onto the field of view at about 7:40 PM, and you can get an idea of how much farther the anvil below had to go to be above the Cat Mountains.

For the second day in a row there were virtually no Cumulus clouds over our Catalina mountains, a real disappointment. But, undaunted, Mr. Cloud Maven person will anticipate Cumulus clouds over the Catalinas once again today, following in the same wrong footsteps of the past two days, and will again foretell that these will be ones that will rise high enough to “glaciate”, that is, have their tops convert from liquid droplets to ice crystals.

The result of this “glaciation” process is something coming out the bottom of the cloud, a dense shaft of precip, as a Cumulus cloud transforms itself into a Cumulonimbus one.

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Science Story: This is always an exciting sight and a process that Mr. Cloud Maven person (MCMP) spent some 25 odd years studying with a highly instrumented aircraft at the University of Washington but couldn’t quite figure out how it happened. In fact, MCMP (with his lab chief co-author) were criticized royally (i.e., Blyth and Latham 1998) for what they did report over the years (“royally”; they were two British guys, but working in the US). We “Reply” to their comments in quite substantial fashion in the same issue (Reply to Blyth and Latham)!

BTW, real scientists, like Alan Blyth, are still working on this problem; how clouds glaciate. Its pretty amazing when you think of it. These days the Japanese (asteroid dust Science-2011) can send a spacescraft to an asteroid named, Itokawa, land on it, pick up some dust grains, and bring them back, a process taking more than 10 years, but we really don’t know completely how ice forms in a cloud!

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Back to the local scene:

once again we have our high surface dewpoints, in the upper 50s (58 F here in Catalina) and even 62 F now at Douglas. So the bottom of our atmosphere is OK for Cumulus. And once again, we have an overcast of mid-level Altocumulus clouds. A problem yesterday was the extreme dryness above that surface moist layer, and below the Altocumulus one, a shallow moist layer that was completely obliterated after the sun came up and the dry one and razor-thin moist one mixed together. Its not so dry today above the low humid layer today, and so Cumulonimbus clouds should be able to develop in the area.

Besides the models told me so. Have been a little sloppy and a little, well, arrogant, about reading the early morning sky absent more information.

Here’s today’s TUS sounding, from the Wyoming Cowboys, so you can see for yourself.

The End, unless I find out I am going to be wrong again when more data comes in a couple of hours.

68 F dewpoint in Catalina now; 0.31 inches overnight

68 F dewpoint at TUS, too. With this kind of dampness, it should be an exciting day with clouds topping the Catalinas, and you know when that happens, its another sign of really heavy rain in the area. In fact, we have a little strip of Stratus fractus along the base of the Catalina’s now (5:29 AM).

Let’s go to the National Weather Service’s web page and see if they are excited about today… Yes! They are pumped, with “green” shading designating those areas of southeast Arizona in a NWS flash flood watch!

Here’s the 4 AM map below, courtesy of our University of AZ Wildcats National NCAA Baseball Champions Weather Department. What a great final game that was! (You can get their latest map here.)

After a mostly disappointing day, an unusual summer day in which there were no clouds being launched off the top of Mt. Sara Lemmon, and temperatures were unusually “cool”, there was finally a strong, whitish brightening of the sky to the east, with darkening to the northeast beyond Charoleau Gap, as the sun slid below the horizon.

And if you were looking at the Weather Underground (now having been absorbed by The Weather Channel in some kind of capitalistic power grab) web page for the Catalina area, you saw that the brightening beyond the Catalina Mountains yesterday evening was due to the anvils of an approaching complex of Cumulonimbus clouds. But as we know, they don’t always make it after dark coming from the east, only on some days. They often fade away, or only produce sprinkles.

It began to rain pretty hard right at 9:30 PM, but there had been no lightning preceding it. I was surprised at how hard it was initially raining, thinking earlier that the rain was going to be old stratiform rain from dead Cumulonimbus remains, very steady and light, maybe adding up to just few hundredths. Then “BLAM” this brilliant bolt nearby and two huge booms of thunder setting off a car alarm near us. How great that was! Rain continued to fall until about 2:30 AM. That lack of lightning suggests the rain producing cell was building right over us, finally climbing to heights and with updrafts strong enough to produce the first lightning. Sprinkling again now (for a couple of minutes) from Altocumulus opacus clouds… Very unusual to have morning rain here as you know.

You can get the regional values of rain here from the Pima County Alert gage network and also here from the U of A’s rain measuring network. Three Alert locations had over an inch, and many more in the U of A network! What a great start to the summer rain season!

Here’s a reprise of yesterday’s clouds starting with mid-afternoon and the remarkable absence of Cumulus boiling off the Catalinas. Instead, small Cumulus (“humilis”) were scattered helter skelter around the area as though there were no mountains.

Below, “the brightening” as Stephen King might put it, showing that deep clouds were around, and they were approaching from the east. The anvils, well above 30,000 feet, are still in full sunlight, and the sun is shining through the thin, probably haze-free air up there. Its undiminished light remains white when striking those cloud tops, not having had the shorter wavelengths scattered away by aerosols (until the sun subsides farther below the horizon).

Yesterday’s cloud movie .

Late bloomers and a dry day; but plentiful rains dead ahead

Here’s a brief reprise of yesterday in photos. Expect a similar day today, late rising Cu over the Catalinas, isolated Cumulonimbus off on the horizon, probably NW-NE over the Mogollon Rim, and to the distant SE-S. None are expected to make it here.

4:02 PM. Really haven’t done much, though some turrets poked up to the ice-forming level. Arrows show some ice falling out of an old, evaporating turret.

4:03 PM. Massive anvil appears over the horizon to the SE-S giving hope something could still happen.

5:52 PM. Getting closer!

7:16 PM. Rain complex stays to the S-SW, but provides a nice summer scene with occasional lightning.

7:37 PM. Cumulonimbus capillatus incus (one with an anvil) punctuates the sunset. Somebody got dumped on out there.

Don’t forget to go to the movies to re-live yesterday here, courtesy of our University of Arizona Wildcats.

The rain ahead

One of the great model forecasts of our time came out yesterday from the 12Z global data, and has been pretty much replicated in its results from the new data that came in yesterday at 00Z. These runs have had plentiful rains in SE AZ for just about every day after our little hot dry spell, and both of those US runs with all that rain ahead are supported by model runs by the Canadians using their brand of the Euro model. Here’s the US full run from last night, whilst the Canadian run can be found here.

What’s intriguing is that a tropical wave, sometimes called an “inverted trough” because its upside down compared to our winter troughs, is foretold to move into the State about the 4th of July. An inverted trough would bring extra organization and clustering of Cumulonimbus complexes, which means bigger areas of rain, often accompanied by a large stratiform rain shield that produces hours of rain. It is also true that these can be our most damaging storms.

OK, this big event is “out there”, and you know that this blog is going to jump on the wetter side of the model forecasts. Still, its pretty darn exciting to think of days of scattered showers beginning in early July, and maybe a real drencher just ahead around th 4-5th. The best part is that even if that doesn’t happen, we are embedded in a flow pattern that would keep up that a hopeful possibility of rain day after day, into mid-July.

Tracey

That’s about all we can muster in Catalina these days it seems, just a trace of rain. Several drops came down out of stratiform debris clouds overhead around 7 PM. If you weren’t outside, or driving, you would never have noticed. I guess you could call those dull icy clouds with virga streaks hanging down from them “Nimbostratus cumulonimbogenitus” (derived from Cumulonimbus clouds) if you really want to know.

At the bottom of those were dark looking Stratocumulus droplet clouds that gave a sense of drama and portent, but they were only so dark because it was near sunset, there was a higher layer above them, and likely the high droplet concentrations in our clouds deflected what little light was reaching them back from where it came from (scattered and absorbed that bit of light). They were not dark looking, in this case anyway, because a deep Cumulus turret was piled up on top of those bases. The patchy areas of light and dark help tell you that those dark bases are going to lead to zip.

Below is a reprise of the whole dramatic day, one that had a little fakery in it where for a time it appeared it was going to be a dry day, but ended up with some tremendous storms in the vicinity.

If you don’t want to look at stills, go here to the U of A time lapse movie. The dust storm goes by at about 15:20 if you can make out the tiny time hacks. This is a great movie and really shows how much “action” there is up there, even in those Ac cas clouds shown in the second shot.

The day started with promising heavy clouds at sunrise, then those thinned and disappeared, but there were also some great Altocumulus castellanus clouds that moved up from the S after that.

Those clouds, too, thinned away as well under the blazing sun, and then our little Cumulus began to arise over the Catalinas, early again, just after 9 AM, a timing that is always filled with portent for a good storm day.

By mid-morning, some sharp turrets were “pluming upward” off the Catalinas, though those clouds were “behind” in size from where I thought they would be by late morning, shown next (11:45 AM shot).

Then awful things began to happen. These clouds started to stagnate in size or even wither over the next two hours! Clearly, drier air was moving in, a very discouraging thought.

While I was up on the rise at the Marana landfill to get a better look at the overall situation over the Catalinas, the stagnating Cumulus clouds began to erupt upward into Cumulonimbus clouds! At the same time, a huge complex was moving toward Tucson from the S, one that was to shove a lot of dust up Oro Valley and into Catalina. I started to feel better, get excited.

Here are a couple of photos of that dramatic reversal of cloud fortunes:

Annotated DSCN1932 — 2:15 PM, from the Marana landfill showing a cross section of the Cumulus clouds that were about to explode into thunderstorms.

DSCN1943 — 2:44 PM. A large Cumulonimbus (capillatus) cloud had blown up over the Catalinas.

Today?

Still enough water in the air for Cumulonimbus clouds here and there, but likely not so many as the past three days as we head for a HOT dry spell, as I am sure you all know about by now.

Early to rise

These small fluffs of Cumulus clouds above Ms. Mt. Sara Lemmon, were the first indications that something good, and very different from the previous two days was going to happen yesterday. These clouds appeared no less than 4 h earlier in the day (between 9 and 10 AM yesterday) than those first Cumulus on top of the Catalinas on the previous two days.

The correct emotional response due to this early rising for cloud maven juniors and doscents out there should have been excitement and anticipation; that some big boys with long names (Cumulonimbus capillatus incus) were likely going to be around later in the afternoon and evening hours. No weather maps needed! See AZ Star for confirmation.

While we didn’t get a big dump right here in Catalina, we did at least get a dust-coagulating 0.02 inches. Here are the totals ending at 24 h from around the region from the Pima County Alert gages. The most hereabouts was at the Santa Cruz River at Ina Road with 0.59 inches, with that storm shown in the photo at 4:25 PM below.

Today, with dewpoints once again being in the upper 50s, it should be the case that we see these early precursor clouds on top of Mt. Lemmon, and they will once again lead to the conclusion of a satisfying day of thunder and intense rainshafts, driven by 100 F plus temperatures. It peaked at 106 F here yesterday in Catalina, and it was fairly cloudy when that temperature was recorded! Pretty remarkable.

Here’s your NWS computer generated forecast for Catalina, foretelling similar temperatures for today.

Here are some later shots of those great clouds, and if you want the whole nine yards, go to the U of A time lapse movie here. There’s a lot of rotation at the bottom of some clouds 1:03 before the movie finishes, and an indication of a rope-like funnel cloud, not too surprising given the instability of yesterday.

DSCN1915 — 4:23 PM. Eventually of those Cumulus congestus clouds reached ice-forming heights and produced our little 2 hundredths shower. By the time it reached Saddlebrooke, it had a visible shaft.

DSCN1919 — 4:25 PM: While our little shower passed by, Marana and vicinity were getting the real thing in dumps of more than half an inch.

DSCN1924 — 5:18 PM. Ditto to the NW where heavy rainshafts in this complex created a “haboob” that affected Casa Grande.

Maybe today, with plenty of clouds and heat, it will be our day to get the big dump and wash the dust off our desert plants.

The End.

Model trickeration, Dark Bluster, =s no rain!

You can see what didn’t happen here in the U of A time lapse movie.

I got pretty excited when the U of A Weather Department issued a special report yesterday morning on what the Beo Wolf cluster had come up with in terms of yesterday and today’s weather. These kind of special, technical reports, ones that only I can read, not general people, except in the pictures and everybody can read those and can comprehend, are only issued during the best (worst storm) monsoon days. So, it was VERY EXCITING for me to get in this special post in an e-mail. The many model runs had some great thunderstorms and wind building up to the S and SE of us and roaring in across the Oro Valley-Catalina urban complex during the late afternoon and evening. I was pumped. SOMETHING was going to happen!

And, just as the models were thinking, “anvilation” (first photo) began to appear to the south through soiuthwest by late afternoon before the AZCats won the national NCAA Division I baseball title. Sadly, that complex died out before getting here.

Then, over the Cat Mountains, things began to look more promising just before sunset (2nd shot).Cloud bases began looking more solid, not broken up into dark and light patches, and that solidity suggests an significant updraft over a wide area. I thought, “Here it comes!”, since those dark bases were moving off the Catalinas and toward us, possibly pushed by an outflow wind on the other side. This kind of thing, as you know, happens all the time here.

But no, those bases fell apart, they were merely a phenomenon called “Dark Bluster” which nobody really understands, and the only thing that happened from those clouds was a light rainshower over by San Manuel I think, one that produced a weak rainbow (3rd shot).

Oh, well, at least the evening ended with a nice sunset and a national title.

Today?

Hit and miss showers/thunderstorms likely in the afternoon and evening hours again. Nobody knows exactly where they will be so you’ll have to be watching. Actually this is a pretty good deal for later June, often with no chances of rain at all.

Update at 9:17 AM: Cumulus forming over the Catalinas! This is about 4 h ahead of the past two days. Is a darn good sign of more showers/thunderstorms today.

The End.

Two thunderstorms, but no rain here

A thunderstorm is in progress when you can hear thunder. Yesterday, beginning at 1:20 PM, we were having a thunderstorm in Catalina due to those modest Cumulonimbus clouds on top of the Catalinas. Here are those clouds, ones that streamed northwestward and died. This first photo of an isolated, flat cloud is the remains of what was a bulging Cumulus congestus turret that sprouted over Mt. Lemmon. It was of interest because at this time the tallest sprouts were just reaching the point where ice would form at noon to 1 PM yesterday. Its really unusual to see a marginal ice-producing turret like this dead one in the first shot. Such a cloud is of great interest to researchers studying the characteristics of ice formation since normally turrets ascend quickly through this initial ice-forming level to much lower temperatures, and the onset of ice temperature has to be estimated.

The rainshafts from these Catalina clouds were transparent (“Code 1”) the whole time they were producing, indicative of not much rain having fallen from them.

You can go here to the Pima County Alert site to see the rain totals hereabouts and in Tucson overall. CDO Wash at Rancho Solano (just NE of Saddlebrooke) got the most, 0.43 inches, due to a cell that developed later and is shown below.

This same Cumulonimbus can be seen at the very left edge of the view on the great U of AZ time lapse movie for yesterday here.

As the day starts, you can also see the waves in the atmosphere rippling through those Altocumulus/Ciirrocumulus clouds we had in the morning. Fascinating.

The next event was caused by the rush of winds from a strong cell near Marana that sent rain-cooled air pushing north into Oro Valley. That push of air gave a lift and a life to a developing Cumulus over Saddlebrooke just north of us, and before long, out dropped the load of rain, with occasional thunder with it, too. Here’s the “trigger cell” SW of Catalina with its rainshaft at the max which sent that rush of wind that in turn, pushed up the Cumulus over Saddlebrooke.

The full sequence of that Saddlebrooke cell is shown below.

Not a bad day yesterday–two thunderstorms in one day is always good–but less productive than hoped for here, always the case if there is less than an inch.

What’s ahead?

As you can probably feel, the humidity is still high. Dewpoints here are again in the upper 50s, quite juicy for AZ and that means another day of these sorts of clouds. Yay! I love photographing the bottoms of clouds, ones that are going to deposit a load, but before there is any sign of it coming out. And we will all have a chance to do that again today.

Cumulonimbi sightings; can rain be far behind?

No.

Yesterday saw a gorgeous sight after our long cloudless spell; Cumulonimbus anvils approaching from the south-southeast in the later afternoon, our summer friends with their winds and rain squalls. The bottom of those thunderheads disappeared before they arrived over Catalina, and were just anvils, that icy portion above 30,000 feet or so, but they harbinger a great rainfull day today as degree of moisture improves. The dewpoint in Tucson was only 39 F yesterday at this time, and is now a robust 58 F! Welcome water molecules! This means that if you condensed all the water out of a cubic meter of air today you would get about 8 grams while yesterday you would have only gotten about 4.5 grams, so almost a doubling of water content in the air swirling around us.

And with this, instead of having cloud bases at 14,000-15,000 feet above sea level (about 11- 12 KFT above us) as we did yesterday, they’ll be closer to 10-11 KFT above sea level, or 7-8 KFT above us (maybe even topping Ms. Lemmon). This will mean that less of the precious rain falling out of those Cumulonimbus clouds today will evaporate before it reaches the ground. And with that, some very dramatic skies later today.

Check the U of A local model here to see what the great “Beowulf Cluster” is thinking about rain today in AZ. Looks good. Note some favored areas just to the SW of us might get an inch of rain today! (But, don’t count on the EXACT placement of those strong rain areas; they’re often off by many miles. Its just a good indicator of strong showers very near us today.)

The past two days have seen some rain fall in SE AZ, but the cloud bases were so high, not much reached the ground. So, the chances of a significant rain here in Catalina this afternoon and evening are good, indeed.

Farther ahead…and remembering 1955.

The models are still making it look like a normal uptick in rain chances around the 4-5th of July, pretty usual for us here in Catalina, with a bit of a dry spell before that uptick in rain chances.

One interesting facet of the weather pattern these days is how a cold spring and summer in the Pacfic NW in 1955 translated into a bountiful summer rain season here. This June will be one of the coldest/wettest ever in Washington State. Many of you out there probably remember the great summer rains of 1955 and those string of hits by The Platters. While weather never quite repeats itself, and there hasn’t been a group like The Platters back either, its something to hope for, that is, that the cold in the NW, wet in AZ pattern will recur this summer.

Lots of complainers now in the Pac NW these days with the continuing rains and cool weather there as the longest day of the year has passed, the days beginning to shorten, with no sign of summer yet.

Here are a few shots of those approaching Cumulonimbus clouds from yesterday: