Cloud-maven – Page 28 – About real clouds, weather, cloud seeding and science autobio life stories by WMO consolation prize-winning meteorologist, Art Rangno

Some cloud scenes from yesterday; a forecast map gone awry?

0.07 inches here in Sutherland Heights yesterday afternoon. Much more SW-NW of us, as the photos below show.

A predicted super hurricane?

I now direct your attention to the forecast maps below, produced by the WRF-GFS model last evening’s global data, courtesy of IPS MeteoStar, the usual. The aforementioned extremely strong hurricane foretold in the models 24 hours ago, has acheived in this latest run, mythical strength, possibly a Category 6 or 7 (which don’t yet exist).

We presume the model went berserk, so its kind of fun to imagine how intense, how low the pressure in the center of such a goofy predicted hurricane could possibly be in the panels below.

First, the jaw-dropping -to-weather-nerds like the current writer, predicted height of 540 decameters height of the 500 millibar pressure level! For the pressure of 500 millibars in the atmosphere to be reached at a level that LOW in warm tropical air means that the sea level pressure must be astoundingly LOW to begin with. In warm air, the pressure doesn’t change as rapidly going up as it does in dense cold air.

I don’t believe, in viewing many weather maps with hurricanes that a height that low has ever occurred at 500 millibars. Thus, the pressure at sea level, for whatever reason, must be incredible in this predicted hurricane SW of Cabo. Surf will be up!

The record measured low pressure at sea level is 870 mb in one of the super typhoons (Typhoon Tip) in the Pacific some years ago where winds were estimated at about 200 mph. It is thought that recent devastating Super Typhoon Haiyan, 2013, had a lower pressure, 858 mb, or the equivalent of the density of air at 5,000 feet elevation was thought to have occurred at sea level!

Valid at 5 AM AST, Sunday, July 19th. — The heights of the 500 millibar pressure level predicted for 5 AM AST, Sunday, July 19th. The center of the hurricane SW of Baja is shown to be 5400 meters (540 “decameters”).

2015071000_WST_GFS_SFC_SLP_THK_PRECIP_WINDS_228 — Valid at the time of the above map. The surface pressure lines are too packed to display, but the center pressure would certainly be less than 900 millibars, and in such a tight center, winds, maybe 200-300 mph, tornado-like. Kidding only slightly.

OK, enough fun with a crazy model prediction, though this hurricane will be extremely strong, and the models are still bringing its pathetic, but wet, remnant into California a couple of days later. Many July rain records, though they are not much to begin with, will be broken if this remnant does make it to Cal.

What we really hope for is some aircraft reconnaissance reports during the life of this strong hurricane instead of satellite-derived estimates of strength (though the latter are quite good).

We still look quite wet during this period, too.

The End.

Rainbow “warrior”

This first one grumbled a bit, sent a bolt or two earthward last evening. Dropped a quarter inch on Ms. Lemmon. Hope you caught these brief scenes from two modest Cumulonimbus clouds:

7:31 PM. A different, very modest Cumulonimbus cloud. Note how the orange of the cloud is seen in some solar panels in the foreground. Pretty neat. — 7:31 PM. A different, very modest Cumulonimbus cloud that’s almost totally composed of ice (from this view). Note how the orange of the cloud is seen in some solar panels in the foreground. Pretty neat. Eyeball top, upper 20s, temp -20s.

Spurred from hibernation by these scenes somewhat like the flying ants we have around here by a good rain , AND by the amount of rain indicated in SE Arizona in the latest model run, the one based on the 5 PM AST global data. Here’s what happens in that run:

A tropical storm (what is likely to have been a Category 4 or 5 hurricane earlier in its lifetime) whizzes offshore of Baja in in 11 days or so, rather unusual for July, and lassos a humongous amount of clouds and rain, dragging them Arizonaward.

Here are the ark-like outputs from our best model, the “WRF-GFS”, as brought to you by IPS MeteoStar.

Rain moves in on July 21st. — Rains move in on the night of the 19th-20th. This output showing the 12 h rain areas ending at 5 AM on the 19th.

The panels below are for every 12 h after the one above.

These heavy rains just go on and on, about three days worth in that run. Have NEVER seen so much rain predicted for this area, and while its too far away to have much confidence in it, its still worth considering as a possible event. You might want to perform some leak checks around the house just in case.

While the rainfall predicted above is somewhat moot, the likelihood of a strong hurricane in the Mexican Pacific is almost assured by our ensemble model runs (spaghetti plots). The signal is strong for one to form down there. Really, this kind of forecast is a remarkable thing that our models can do now days!

Such a hurricane will be fueled by the continuing extraordinary and vast areas of sea surface temperature anomalies; the entire eastern Pacific is aflame in unusually warm water. Check it out:

Sea surface temperature anomalies as of yesterday, July 9th.

As far as today’s weather goes, well, you can see those thin low clouds topping Ms. Lemmon this morning. Dewpoints continue high, around 60 F. And with a trough moving in, should be another breezy, pretty day with scattered Cumulonimbus clouds.

But, for a man’s forecast, not a little wispy one like the one above, see Bob’s site for an outstanding analysis! CMP (Cloud Maven Person) does not have the time to do a good, thorough one, if he could.

The End

Anvilations harold the beginning of a new summer rain season

Want to see how many people drop in due to a misuse of words, maybe get more than one reader if a word punctilian drops in to see how bad the rest of the piece is.

Yes, those icy anvils that crept over the sky from the SE were from ejected from distant Cumulonimbus clouds yesterday afternoon and evening. They’ll be closer today, and for the rest of the summer.

The End.

Tweedledee and Tweedledum; ’97 and ’15

This just in from someone else, Nate M¹:

When sea surface temperature (SST) anomalies from the Great Niño of 1997-98 are compared in June 15, 1997 with the one now developing on June 15, 2015 the differences are nil.

That’s it. Hope you like it.

The one in 1997-98 was a “Comprehensive Niño”, that is, it included sea surface temperatures that were much above average in both the Classic Niño locale, just off the coasts of Peru and Columbia, and extended all the way to, and included, the “New Niño” locale, the one way out there in the Pacific along and a little north and south of the Equator (called “Region 3.4” by real scientists²). That 97-98 one was gigantic; earth shaking; the one in progress also appears like a gigantic one, too, so far, to add fudge words.

Take a look for yourself, first June 15, 2015, and below, June 15, 1997.

Not only was it extraordinarily wet in the Southwest that water year, especially in central and southern California (LA had over 30 inches, and mountain stations over 70), but the Great Niño of 1997-98 was also associated with a leap upward of the earth’s temperature. So, be wary of a jump in the earth’s temp during the next year or so. Catalina is already be experiencing a temperature jump; 109 F here yesterday. Egad.

Let’s hope, too, that this Niño is more like the other “recent” Great Niño, 1982-83 rather than the one in 97-98. In the former one, Catalina received more than 32 inches of rain during that water year, October 1, 1982 through September 30, 1983. In 1997-98, we “only” received 24 inches (about 7 inches above average our ~17 inch average here in Catalina). Old timers still talk about how the washes flowed all year in 82-83¹. Recharge those aquifers!

Ninos strengthen the southern portions of the jet stream by increasing the temperature difference between the Tropics and the mid-latitudes, so that low pressure systems are larger and stronger in the middle and lower latitudes of the eastern Pacific (see Bjerknes and “company”, 1960s). Typically, the low pressure centers that accumulate in the Gulf of Alaska are less vigorous, their strength sapped by the shift of the stronger winds aloft toward the south.

Huge plumes of cloud arise over these warmer than average waters from masses of Cumulonimbus clouds where the trade winds of the southern and northern hemisphere are colliding. Those vertical fountains of moisture eject clouds out of the tropics and of middle and high clouds that get caught up in the stronger cool season troughs that come by, enhancing their rain and snow output, and leading to a much cloudier overall cool season. Recall that Biosphere 2 largely failed due to the excessive cloud cover of the 92-93 winter in southern Arizona associated with a Niño.

BTW, It only takes a few degrees of ocean surface warming for clouds to transition from an area of passing light showers with little accumulation, showers that falls from modest Cumulus clouds or clumps of Stratocumulus, to giant, recurring clusters of Cumulonimbus clouds. When cloud bases are warmer, the amount of water being condensed is greatly increased, and that in turn, allows the clouds to be warmer inside, more buoyant, than cloud are when they form over those normally very cool eastern Pacific equatorial waters.

Unfortunately, a lot of wildlife down around the Equator in the eastern Pacific, such as around the normally semi-arid Galapagos Islands and other islands to the west, is severely disrupted by the sudden onset of frequent, heavy tropical rains. The same is true for the coasts of Peru and Columbia where normally very dry areas are awash in water. Fishing gets crappy, too.

Caveat

HOWEVER, note in the plot for 2015 how much the larger the area of above average SSTs in the Gulf and eastern Pacific are compared with 1997. Hmmmm. Not sure how that will play into current Great Niño. It would be prudent to contain our excitement to some extent since weather NEVER exactly repeats itself. Don’t start gathering animals and building an ark just yet.

So, am a little worked up about 2015-2016 water year, as I am sure you are, too. Thanks Nate, I think.

In the immediate future, how will all that excess warm water affect our upcoming summer rain season?

I don’t know. Clueless, really, as are the people who actually study the summer rain season in detail. Could go either way, dry or wet. Lot of uncertainty about how a good Niño affects Arizona weather in the summer.

But we might well have “better”, stronger tropical storm remnants affect us in the fall, maybe like last September and October when what turned out to be a dud Niño was in formation and those wamer waters combined with extra warm waters off the immediate Baja and California coasts (this latter phenomenon now deemed the “California Niño”), that helped sustain tropical storms as they drifted northward.

Once again, ending with a lot of ? and the Mysterians….”96 Raindrops”; “…too many raindrops for one heart.”

The End

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¹Nate M., formerly of the University of Washington’s Climate Impact Group, now at NOAA’s Southwest Fisheries Center, Monterrey, CA. Nate and I used to have “punting wars” right there in the middle of Husky Stadium. Oh, yeah.

²Its the region between 120 W and 170 W longitudes, 5 N and 5 S latitudes), and in the area in between. HOWEVER, in the plots above, note that the longitude has been incremented upward from the Dateline of 180 W, and continues to increase so that 120 W longitude is 240 degrees W longitude. This is not something that Cloud Maven Person did for humor, like claiming that the Equator goes through Hawaii, as he sometimes does to see if anybody notices the error, is reading his blog. Hasn’t been caught yet.

³Heck, add a few more days to that 82-83 water year from Oct ’83, so that the above total would include the rains from Tropical Remnant (TR) Octave, and you’d have a Seattle-like 36 inches of rain here in Catalina! Unbelievable.

Images of heaven

Not is one¹.

But rather these many “Panels of Rain” from our friends at IPS MeteoStar, rendered from yesterday’s 18 Z WRF-GFS model run, these suggesting an earnest few days start to our summer rain season beginning around June 24th.²

Since these are probably wrong….but we can hope.

The End

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¹1980s techno-pop hit. You remember the 80s don’t you? B-52s? Black Flag? Oingo Boingo? Circle Jerks? The Residents? Jello Biafra and the Dead Kennedys and their “Holiday in Cambodia³” hit, celebrating Pol Pot? Of course you do. You probably had a mohawk haircut, too. Maybe acted out on stage during midnight showings of “The Rocky Horror Picture Show”….

²Sometimes mistakenly called the “monsoon.” The “monsoon” actually occurs in Asia, centered around India. Our American Indians did not call our summer rain season, “the monsoon” and neither should we. We don’t call hurricanes, “typhoons” do we? OK, this is a pitiful commentary, but I like it.

³Used it in seminar….that’s right, to set the mood for a cloud seeding talk.

Hihg clouds begin to move toward Catalina! Storm of bullet rosettes ahead!

Misspelling the word, “high” was inadvertent; but leaving it was deliberate, thinking it might work as another cheap attempt to get more than one reader¹, presently my mom. Hi, mom. Glad you enjoyed your mom’s day dinner yesterday, followed by the exciting trip through the Catalina car wash. Really squirts, doesn’t it?

Continuing….people might wonder if “hihg” a new word or acronym they haven’t seen before, maybe wonder if it describes something they should know about. So, I am looking to capture one or two extra folks today.

Our next “storm” will occur mostly above 20 kft above Catalina in the form of light snow showers of single ice crystals from Cirrus clouds, typically those crystals that fall out of Cirrus clouds are bullet rosettes.

What’s a bullet rosette? See below:

University of Washington flight engineer, Don Spurgeon monitors the Stratton Park Engineering Company's images of "bullet rosettes" in flight. — University of Washington flight engineer, Don Spurgeon. monitors the Stratton Park Engineering Company’s images of “bullet rosettes” in flight. Chad Slattery, Smithsonian mag free lance writer, took the shot. Sadly, Don and the other crew members did not get into the Smithsonian article, only Pete Hobbs and me. Pretty sad for them but happy for me! Yes, I was on this flight! Except it wasn’t a flight, we were sitting on the ground at Paine Field, Everett, WA, where our plane was kept, and Don brought up that image so that Chad could take what would appear to be an “action. in-flight” shot in his article.

Oh, there could be an Altocumulus cloud, too, by tomorrow. But that’s about it. Our last storm was not actually a storm, btw, though there were some low clouds. I guess it got pretty windy, but not rain fell here, nor did it snow whatsoever atop Ms. Lemmon, though it was cold enough to. Boohoo.

But, the overall trend for upper cyclonic systems to nest over the Great Southwest continues, insuring a mild May here in Catalinaland, and also a ton of precip in other parts of the SW, with only brief interruptions of hot air, like the kind that comes from this weather keyboard.

The pretty, and high Cirrus clouds should begin arriving this afternoon, except that some are already arriving (5:20 AM)! Cloud maven seems to be on a wrong streak!

Next Catalina rain chance, graciously presented by the Canadians, is overnight, May 14-15th, just a few days from now. Check it out. This graphic been arrowated and texted for your convenience and understanding.

Valid at 5 AM AST, May 15th. Lower right panel shows where The Model thinks that rain has fallen during the prior 12 h, and it includes Catalina! — Valid at 5 AM AST, May 15th from the Enviro Can GEM model. Lower right panel shows where The Model thinks that rain has fallen during the prior 12 h, and it includes Catalina!

The End

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¹Still can’t get over that Atlantic article about, “Blogging for dollars”; its like a song hook, maybe like the one from, The Model, by the very Germanic Kraftwerk techno-pop group, and yet after two years, I have made nothing! With millions of readers, you can make a LOT of money, get some great advertising like the various stuff that precedes the viewing of The Model, which has already accumulated more than 4 million views!

So I continue to reach out for readers and money.

What would a neurotic-compulsive, self-described “cloud maven” do with “a LOT of money”?

Underground power lines in his neighborhood. They obstruct sky and cloud views. Used to be quite a movement around the US to do that, but not so much anymore.

Another Catalina rain day for May 2015

We received 0.08 inches here in “The Heights” for a third day with measurable rain in May already. 0.12 inches fell at the Bridge on Golder Ranch Dr. , while Saddlebrooke got up to a quarter of an inch (as estimated by CMP) in a tiny streak of clouds that erupted into shallow Cumulonimbus clouds, anvils and all yesterday afternoon between 4:30 and 5:30 PM. It was pretty much all over by 6:00 PM, those shower clouds passing off toward Mammoth.

No rain was reported at mountain sites, to give you an idea of how localized that was, localized practically to Basha’s Market parking lot, Sutherland Heights’ Equestrian Trail Road, and Saddlebrooke’s Acacia Drive, to exaggerate some.

The astounding aspect of a tiny line of showers that suddenly erupted over and a little downwind of Catalina was that it was EXACTLY predicted in the University of Arizona’s 5 AM AST model run yesterday morning, one whose results are available by mid-morning! So, there would have been a few hours notice of possible rain here in Catalina.

There is no rain predicted in that model run anywhere else except in extreme NW Arizona, just that tiny ribbon of rain right over us, and the U of AZ “Beowulf Cluster” weather calculator got it right.

However, unless you were in the right spot, you might not have even known that it rained, the shower streak was so narrow.

Below, the astoundingly accurate predictions for 3, 4, and 5 PM for that model run from yesterday morning. No rain whatsoever is shown at 3 PM, as you will see.

To be “fair”, NO RAIN was predicted anywhere NEAR Catalina by that same model crunching the data from 5 PM AST the evening before our little rain event, leading CMP to be a little asleep at the wheel yesterday morning, no blog.

Some cloud shots before and as this predicted (or unpredicted, as the case may be) rain began to happen. Of course, if you want to go to the movies and see this, go here, from the U of AZ: Yesterday’s cloud movie

3:23 PM. Looking upwind. Nada going on, clouds to shallow for ice.

4:04 PM. Hmmmm. Clouds definitely fattening up upwind of us in a nice cloud street from upwind of and over Pusch Ridge to Catalina. Nice scene, anyway, even if nothing happens.

4:12 PM. Cumulus clouds are looking to gather down there at the corner of Pusch Ridge and Oracle Road, Huh. And they’re heading in this direction. Can ice really form in these guys today?

4:23 PM. Clouds over and downwind of Pusch Ridge continuing to gather while heading toward Catalina. Looking for ice now or virga, but don’t see any anywhere.

4:33 PM. Ice begins to show up in even modest clouds! And it started to show up everywhere in the form of virga. But then then the virga became thin shafts all the way to the ground. Cloud Maven Person is beside himself, but must go indoors for a social engagement! Those of you who fancy yourselves as Cloud Maven Juniors, should have recorded this sighting of “first ice” in your cloud diaries for yesterday.

Also at 4:33 PM. Ice is now readily visible in that Cumulus mediocris massing upwind of Catalina and is not about over the south part of the Catalina CDP (“Census Designated Place” that might one day be absorbed by Oro Valley, rumour has it.)

4:41 PM. Just minutes before the first drops fall in Saddlebrooke, and CMP’s last photo of this incoming masterpiece of weather forecasting and little rain band; he can no longer comfortably jump up from dining room table in mid-conversation to say he has to pee again whilst actually taking a photo. You can only say you have to pee so many times in 10 minutes and still have your credibility intact. But, how can you say repeatedly, “I have to go look at some clouds?”, so I can’t hear the rest of your quite interesting story……” Really came down for a couple of minutes several times there in Saddlebrooke between a quarter of five and 6 PM as one little raining cloud formed after another in this cloud stream.

Below, sat view of this cloud streamer with radar, from IPS MeteoStar. The image below is at the same time as the last photo above:

Satellite and radar imagery for 4:40 PM AST. Note the many lines of clouds running almost due south to north into SE AZ from Mexico.

Here some more cloud stuff from the sounding launched at the U of AZ around 3:30 PM AST.

The TUS balloon sounding ("rawinsonde") for yesterday afternoon. Looks like most tops were dabbling with the ice forming temperature of -10 C, but the sounding suggests that somewhat deeper tops could easily have arisen (and did!). Interestingly, the model "knows" when ice forms, and it must have "known" that the ice-forming temperature was going to be surpassed in that little cloud line coming off Pusch Ridge. Astounding, for the Nth time. — The TUS balloon sounding (“rawinsonde”) for yesterday afternoon. Looks like most tops were dabbling with the ice forming temperature of -10 C, but the sounding suggests that somewhat deeper tops could easily have arisen (and did!). Interestingly, the model “knows” when ice forms, and it must have “known” that the ice-forming temperature was going to be surpassed in that little cloud line coming off Pusch Ridge. Astounding, for the Nth time. Bases were pretty cold, 0 C (32 F).

Here’s a diagram of when ice forms in the type of clouds we mostly have in Arizona, “continental” ones with high droplet concentrations, and when ice should form in them. As you can see, ice should form in them soon after the top temperature gets colder than 10 C WHEN the base temperature is about what it was yesterday.

From a survey of the onset of ice formation in continental clouds by Rangno and Hobbs (1995)1 — From a survey of the onset of ice formation in continental clouds by Rangno and Hobbs (1995)¹

“CMP” is not mentioning it at all, but yesterday was another kind of mucked up sky, not a Catalina postcard sky, with lots of aerosols making the sky a whitish-blue, the lower aerosol stuff again from Mexico, but there was also a layer far above the cloud tops, likely a long-range transport event from thousands of miles away.

This higher haze layer still seems to be around if you look toward the horizons right now (5:59 AM).

We’ll be between two jet streams today, kind of a jet stream sandwich, and the stronger one is now approaching from the northwest with that mega upper low over Cal. That means no rain today, subsidence rules, though we’ll have small, non-ice producing Cumulus, and likely some Altocumulus lenticulars, maybe a Cirrocumulus patch here and there. Should be a pretty nice day for cloud photos, haze aside.

The best chance for rain is still after midnight tonight into mid-day tomorrow as the core of the stronger jet stream goes just about over us. Still thinking a tenth of an inch will occur here, though mod run from the U of AZ at 5 PM completely dry. A little snow likely on Ms. Mt. Lemmon, too!

The End, FINALLY! Brain empty.

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¹From “A New Look at the Israeli Cloud Seeding Experiments.”

Hazy, non-perfect skies continue to plague SE Arizona

First some comparisons of clean and hazy skies so’s you’ll have some idea of what I am talkin’ about in today’s title:

5:19 PM. Cumulus fractus and humilis on a hazy afternoon. — 5:19 PM. Yesterday’s Cumulus fractus and humilis form in haze and smoke. Not exactly the same view, but it was the best I could do to give you an idea of how crummy, well, to a clean fanatic, it was yesterday

Pretty clean day from a few days ago, looking toward Twin Peaks area during the afternoon.

Yesterday afternoon looking toward the same area. Note how much whiter the sky is toward the sun side of the photo. This whiteness is due to “forward scattering” of sunlight by tiny aerosol particles. Not much forward scattering in the prior photo.

4:50 PM. Yesterday’s muffin Cumulus (mediocris) over Ms. Mt. Lemmon. No aerosols can be detected in this direction where backscattering of the sun’s light occurs because the aerosols are often dark, Think about when you fly commercially and look out the window away from the sun, say, to the north, and see that ever present black haze line out there, likely the result of black carbon particles. No ice formed in our Cumulus clouds yesterday, either. Top temperatures too warm.

Let us see where this Arizona smog might have come from….. Below a TEN day back trajectory plot which ends over Tucson at 5 PM AST yesterday afternoon at two levels, each below the cloud bases. Notice in the plot below that the model data thinks the air parcels that arrived here at 1945 and 2945 meters above the ground over Tucson (bottom portion of figure) started out at the surface and went a LONG way before rising up as that air crossed Baja, the Sea of Cortez and NW Mexico.

You can see, too, that it wrapped into our upper level trough, coming down the back side, then curling around from the SW–the air in troughs and ridges moves faster than do those features themselves , and that’s also what this plot is showing you.

Using a lower level end point over Tucson, ending around 3000 feet above ground level made no difference:

9:15 AM AST sat observations of aerosol optical depth. Blue is clean, red is awful. You can see a pile of awful air SW of us yesterday morning. — 9:15 AM AST sat observations of aerosol optical depth. Blue is clean, red is awful. You can see a pretty contaminated air (red tones) SW of us over Mexico yesterday morning, and that’s likely what moved up this way to give us our hazy skies.

So, it looks like the air may have picked up some aerosols while it stalled around over northwest Mexico before arriving here since its unlikely that the air was hazy and contained so much aerosol loading coming out of the Pacific offshore of Washington and Oregon. No doubt it would have been out in the Pacific many days before arriving offshore of Washington and Oregon, plenty of time for deposition onto the ocean and washout one would think, leaving that bit of doubt. And of course, this is all dependent on how accurate our back trajectory calculations are. So, with those caveats, we can conclude that the aerosols likely came from Mexico and not the LA Basin as was mused about here yesterday.

Today’s clouds

Get cameras ready. Should be a nice day for patterned clouds, such as Cirrocumulus, maybe some lenticulars as well since the wind remains pretty strong aloft. Also with a minor trough coming through later today, the clouds are likely to fill in during the afternoon, and being that bit colder aloft, some of the Cu that form oughta develop a little ice and snow virga. That means a chance of a sprinkle somewhere in the area today. Right now, as the sun comes up seeing some nice CIrrus castellanus, some mammatus underneath, and a few Altocumulus clouds here and there.

Still thinking about an early cold rain on Saturday morning….

The End

Loud May rain totals 0.47 inches in Sutherland Heights, Catalina

After last evening’s surprisingly heavy rain, we have now met our average for May for Catalina, having received 0.47 inches of rain over the past 24 h, some 0.36 inches during some house-shaking thunderclaps last evening.

Below are the 24 h local totals, ending at 4 AM today from the Pima County ALERT gauges rolling archive , these totals pretty much capturing all of our beautiful storm:

    Gauge    Location
    ID#
    —-     —-       —-        —-       —-         —-       —————–            ———————
Catalina Area
    1010     0.63      Golder Ranch                            Horseshoe Bend Rd in Saddlebrooke
    1020     0.83      Oracle Ranger Station          approximately 0.5 mi SW of Oracle
    1040     0.55      Dodge Tank                   Edwin Rd 1.3 mi E of Lago Del Oro Parkway
    1050     0.75      Cherry Spring                approximately 1.5 mi W of Charouleau Gap
    1060     0.79      Pig Spring                   approximately 1.1 mi NE of Charouleau Gap
    1070     0.39      Cargodera Canyon             NE corner of Catalina State Park
    1080     0.63      CDO @ Rancho Solano       CDO Wash NE of Saddlebrooke
    1100     0.35      CDO @ Golder Rd              CSO Wash at Golder Ranch Dr

Santa Catalina Mountains
    1030     1.18      Oracle Ridge                 Oracle Ridge, 1.5 mi N of Rice Peak
    1090      0.35      Mt. Lemmon                   Mount Lemmon
    1110      1.34      CDO @ Coronado Camp          CDO Wash 0.3 mi S of Coronado,       1130          0.83      Samaniego Peak               Samaniego Peak on Samaniego Ridge
    1140      0.79      Dan Saddle                   Dan Saddle on Oracle Ridge
    2150     0.24      White Tail                   Catalina Hwy 0.8 mi W of Palisade RS
    2280     0.24      Green Mountain               Green Mountain
    2290      0.12      Marshall Gulch               Sabino Creek 0.6 mi SSE of Marshall Gulch

For more rainfall info, go here and here. And here to the USGS, too, not to mention the NWS rainfall tables. Too bad they can’t all be in one gigantic table!

The clouds and weather just ahead

A little cold morning rain, and even snow on The Lemmon, is looking likely for Saturday morning. Presently, the core of the jet stream at 500 millibars or around 18,000 feet associated with a mighty upper cold low that sits on Arizona on Saturday is forecast to be south of us (as was yesterday’s jet), a pretty black and white discriminator for cool season (Oct-May) rain here.

However, if that jet core around the low does not circumscribe TUS, you can forget rain. From IPS MeteoStar, this rendering of the upper level configuration for Saturday morning, showing that it WILL circumscribe TUS:

The 500 mb heights and winds predicted for 5 AM AST, Saturday morning, May 10th. Its gonna a cool Mom's Day, too. One would expect rain here in Catalina with this configuration. Note how max winds are in a band well south of us. That banding circumscribes the deeper parts of the Pacific moisture that came in with this trough. — The 500 mb heights and winds predicted for 5 AM AST, Saturday morning, May 10th. Its gonna a cool Mom’s Day, too. One would expect rain here in Catalina with this configuration. Note how max winds are in a band well south of us. That banding circumscribes the deeper parts of the Pacific moisture that came in with this trough. This rendering is from the global crunch of data taken at about 5 PM AST, yesterday evening. These runs are updated every six hours.

In the meantime, “troughiness” today, tomorrow and Thursday, with secondary jet stream to south of us, will give us some more photogenic high-based Cumulus, maybe with some with virga in the afternoons. Today, as our upper low says goodbye, subsiding air is supposed to keep clouds from attaining tops high and cold enough to form ice. So, no rain today.

Yesterday’s clouds (going deep, as in pedantically)

There were some great scenes yesterday, summer-like ones, odd for May here, with massive rainshafts as the cloud bases lowered, reflected a huge jump in surface dewpoints to summer-like values in the mid-50s. Cloud bases yesterday morning, riding the tops of Samaniego Ridge, were near 7 C, compared with -5 C the afternoon before.

This warming of cloud bases greases the precipitation “wheel” since clouds with warm bases are be able to rain easier than ones with cold bases (say, near or at below freezing temperatures). Droplet sizes have to be larger at any given level above cloud base compared to the clouds of the day before since more moisture is forming in those updrafts at the higher base temperature. And, oddly, the larger the droplets, the higher the temperature at which ice can begin forming in clouds. And when ice forms, snow, then rain, come out the bottom.

To go on too long on this in covering all rain possibilities for yesterday, a base temperature of 7 C here is on the edge of being able to produce droplets big enough so that some begin colliding with one another and sticking together so that drizzle, then raindrops can form, a couple to a few thousand feet above cloud base, and those sizes of drops can really accelerate the formation of ice and then rain out the bottom. Are there any readers left? I doubt it.

Let us go even deeper…. It was hazy, smoky looking yesterday most of the morning, even when some good thunderstorms formed. So what? Well, smoke is bad for storms. Remember when it was reported by Warner and and the U of Arizona’s own Sean Twomey (1967) that sugarcane burning made it stop raining downwind from those fires in Australia? That effect has been verified in satellite measurements by cloud seeding nemesis, Danny Rosenfeld² of the HUJ in Science a few years ago.

Well, too much smoke can choke droplet sizes down and inhibit the formation of rain by collisions, and delay the formation of ice. And so we had that counter effect of smoke from somewhere, maybe LA this time since it was in the boundary layer, not aloft like that smoke layer from Asia was a couple of weeks ago.

So, cloud microstructurally-spekaing, it was an especially interesting day, one, if he were cloud maven person, wishes he would have had an aircraft to sample them.

But let us look now and see what all the fuss is about:

5:40 AM. Dewpoints in the 50s, Stratocumulus clouds top Samaniego Ridge! — 5:40 AM. Dewpoints in the 50s; Stratocumulus clouds top Samaniego Ridge!

6:41 AM. Soft-serve Cumulonimbus forms over west Tucson, Oro Valley. Icy top looks like its comprised of needles and hollow sheaths to me, ice that forms at relatively high temperatures for ice formation, higher than -10 C.

6:42 AM. In the meantime, drama over Oro Valley to the west and north of Catalina as a deeper cloud unloads. Thunder, too.

7:19 AM. Haze and rain. This was a pretty astounding sight, so much haze/smoke in the rain as evidenced by these intense crepuscular rays.

8:19 AM. A real summer-looking sky on a big rain day. Frequent lightning was emitted by this behemoth that went on to pound Saddlebrooke.

8:37 AM. Unusually strong May thunderstorm pounds Saddlebrooke.

3:42 PM. In spite of lots of convection and scattered Cumulonimbus clouds, the sky remained almost an eastern whitish due to smoke, which I will blame on southern California, absent any facts or investigation. No time.

3:42 PM. In spite of lots of convection and scattered Cumulonimbus clouds, the sky remained almost an eastern whitish due to smoke. — 8:37 AM. Unusually strong May thunderstorm pounds Saddlebrooke.

3:42 PM. In spite of lots of convection and scattered Cumulonimbus clouds, the sky remained almost an eastern whitish due to smoke, which I will blame on southern California, absent any facts or investigation. No time.

6:59 PM. Our major evening rain and thunderstorms were developing upstream.

The End

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¹Warner, J. and S. Twomey, 1967: The Production of Cloud Nuclei by Cane Fires and the Effect on Cloud Droplet Concentration. J. Atmos Sci., 24, 704–706.

²Rosenfeld a “nemesis?” See the references and discussion below for kind of an interesting science story aside….

Rangno, A. L., and P. V. Hobbs, 1997a: Reply to Rosenfeld. J. Appl. Meteor., 36, 272-276, and…..

Rangno, A. L., and P. V. Hobbs, 1997b: Comprehensive Reply to Rosenfeld, Cloud and Aerosol Research Group, Department of Atmospheric Sciences, University of Washington, 25pp.

With the publication of voluminous (en toto) commentaries/critiques in 1997 by a few of our peers, but mainly by Danny Rosenfeld of the Hebrew University of Jerusalem, that concerned our 1995 paper reanalyzing the Israeli randomized experiments, yours truly and Peter V. Hobbs, had attained, according the the Technical Editor of the Journal, the status of having become the most criticized meteorologists in the history of weather–well, in the history of the Amer. Meteor. Soc. journals, anyway! How fun is that? Its fun.

Our findings, that the two benchmark Israeli randomized cloud seeding experiments conducted in the 1960s and 1970s were largely misperceptions of cloud seeding effects due to storm biases on seeded days, were independently verified in peer-reviewed publications by researchers at Tel Aviv University some many years later.

Operational cloud seeding has ended in Israel in favor of more fruitful avenues for obtaining the water they so badly need.