An interesting day from a cloud modification standpoint, one that doesn’t happen very often

Every once in a great while, we have days where fairly thick clouds do not produce even a sprinkle, even though their tops are a little below  freezing, but not quite cold enough for natural ice to form.  Yesterday was one of those days.

And it was a day you, a cloud maven junior member,  could likely have done something about it:  rented a small plane or helicopter capable of flying up to around 15,000 kft ASL,  taking a bag of commercially available dry ice pellets, then drop them into the fattest, highest Cumulus tops you saw while nipping them in VFR flight mode, and, “violet!”,  ice would have formed along the path of the falling dry ice pellets!

So what were the ingredients that  made yesterday so special for a little renegade cloud seeding?

The clouds that did not rain were pretty thick for ones that didn’t rain naturally, maybe 5,000 to 6,000 thousand feet thick in their maximum “overshooting” tops, and temperatures at top were a little below freezing, but warmer than -10° C.  At lower top temperatures ice would likely have formed naturally.  Here’s the annotated TUS sounding from yesterday afternoon from IPS MeteoStar:

Ann 2016110500Z_SKEWT_KTUS
The 00 Z (5 PM AST) rawinsonde from TUS, typically launched about 3:30 PM AST. The upward pointing arrow shows what the in-cloud temperature would have been like. The lapse rate, from aircraft measurements is virtually never along the “pseudoadiabatic temperature line (one of which is where the horizontal arrow heads are), but somewhere between that and the dry adiabatic temperature lines that show the temperature drop in a rising dry parcel of air (one of which is where the upward pointing arrow begins). Cumulus protrusions carry the boundary layer air from the surface, that air that forms the Cumulus clouds, into the stable,, and warmer overlying air. So, protruding tops sink like a stone; don’t stay long at their lowest temperature, also hurting the chances that ice will form. That’s why you have to do it.

Here’s how it works:  the dry ice pellets, themselves at -72° C, will chill the air it comes in contact with to -40° C, resulting in the formation of jillions of tiny ice crystals in each pellet’s wake, which are then spread over a wider region in the following minutes due to turbulence in the cloud.  In essence, each pellet is creating a tiny,  vertical “contrail” in that cloud, as least in those upper parts of the cloud below freezing.  (Bases yesterday were a little above freezing, around 2° C, while the highest afternoon tops locally appeared to run between -5° and -10° in clouds that were forming in more haze and smoke than usual (wonder if you noticed that?)  Haze and smoke tend to reduce droplet sizes, and in doing that, make it harder to form ice and rain, especially in marginal clouds for that, such as we had yesterday.

What happens next is that the “supercooled” water in the cloud evaporates around those crystals due to the dry ice bombardment, while the crystals take up that evaporated vapor.   When the crystals get large enough, they may collide with some remaining cloud droplets, if there are any around.  Usually all those crystals that have formed will not left too many droplets in their vicinity.

As the crystals grow in size, and because they are in such high concentrations, they will bump into one another and form clusters of ice crystals we call snowflakes.    Cloud Maven Person has, along with Professor Doctor Lawrence F. Radke, the latter the  “Flight Scientist” in those days with the University of Washington Huskies’ Cloud Physics Group1 in the late 1970s,  made snowflakes the size of pie plates (fluffy light ones without a lot of water content) in Cumulus clouds like yesterday’s here.

IMO you would have created not something of much importance, but rather just an annoying sprinkle or very light shower for those out hiking,  horseying around on their horses, biking the trails,  on an otherwise perfect day for outdoor activities.

One of the problems, long known about in such seeding experiments as could have taken place yesterday, is that the cloudy air is moving THROUGH the cloud, exiting at the downwind location.  That is, lower clouds in particular, move SLOWER than the air itself2.

So, you drop some dry ice in a nice turret, the air you dropped it is, along with that turret’s air, will be moving downwind and is going to go out into clear air eventually.    So, if the crystals don’t stay in a turret and upward moving air, but goes out the side of the cloud or into “shelf clouds” like yesterday, those crystals/snowflakes aren’t going to grow much, and will remain “light and fluffy” even though they could be huge because they are like “powder snow” not a lot of water mass in them.   When they melted at cloud base, they might end up being just drizzle-sized drop (less than 500 microns across) or very small raindrops.  So, that’s why you would likely have gotten just a sprinkle or very light rain shower had you done some unlawful, renegade cloud seeding yesterday.  Remember, just like when you hike in the State Land Trust areas, you need a permit to seed legally.

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Yesterday’s clouds

7:02 AM. Tall, but not so tall as to form ice, Cumulus clouds boil up off the Catalinas. Made you think some Cumulonimbus clouds might form later on. They didn't.
7:02 AM. Tall, but not so tall to form ice, Cumulus clouds boil up off the Catalinas. Made you think some Cumulonimbus clouds might form later on. They didn’t.
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10:26 AM. Disorganzied Cumulus still lurking on on the Catalinas, but the main thing here is how much smoke was in the air when you might have been expecting a very clean morning due to the previous evening’s thunderstorms and rains. Very upsetting to this smoky scene.
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10:27 AM. Looking NE at some Cumulus congestus, no ice evident from this view, but I would not rule it out, Forgot to check radar to see if there was an echo with this cloud.
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2:10 PM. By mid-afternoon skies started to look a little threatening with a Cumulus congestus having formed over and extending downwind from the Tortolita Mountains.
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2:14 PM. Looking for ice to appear in the oldest top portions, now evaporating, top of photo. None seen.
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2:39 PM. Someone needs to get up there on top of this Cumulus congestus, drop a little dry ice in it. Nothing came out, though I thought I would feel a drop at any moment! Some sort of birds can be seen, lower right.
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3:19 PM. Looking downwind at part of the base of this Cumulus congestus cloud line that sat over Catalina for awhile. The top has the base, to the left is the “shelf cloud of Stratocumulus spreading out from other tops and drifing downwind. If precip falls out of the shelf cloud, once part of a turret, you can see I hope that it would fall out of a thicker column of dry air.

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4:01 PM. The scene before a lot writing appears on this photo.
The same photo with a lot of writing on it.
The same photo with a lot of writing on it.

The weather way ahead

While warm weather returns to AZ over the next week to12 days or so, there is now, and this goes with climo, a big trough that barges into all of the West Coast in two weeks.

When I say climo, I mean that there  is a noticeable tendency for this to happen in mid-November in the longterm upper air records so that in some areas of California, for example, there is a modest increase in the chance of rain in mid-month over other times in the month.  These kinds of things in weather are termed, “singularities” like the supposed, “January thaw” back East.  This mid-November annual trough passage may be related to the increasing speed of the jet stream in the Pacific as winter approaches, something that changes the spacing between the troughs.  Pure speculation.

But in any event, be on the lookout for a major change in weather here between the 17th and 20th of November.  Something like this is starting to show up in the models.

The End

———
1Later renamed the Cloud and Aerosol Research Group.

2Something that was  even noticed in small tradewind Cumulus in the Pacific in the 1950s by Joanne Malkus (later, Joanne Simpson) and her colleagues.

Thunderstorms, rain, hail, pummel Catalina finally!

We’ve waited a LONG time for a rain day.  It was so nice, so photogenic as well.   I hope you enjoyed it as much as I did.

Also, you may have seen the Froude Number1 in action as Cumulus congestus and Cumulonimbus clouds developed and went around the sides of the Catalina Mountains instead of developing over them and dumping big shafts of rain on them.  The heaviest rains yesterday were due to streamers of showers and with an OCNL TSTMS that were north and south of us, Oracleville, Bio2 area, and Marana, Avra Valley where over half an inch was logged in some places.

Still , we managed a third of an inch here in Sutherland Heights,  the first appreciable rain since I don’t know when, though,  I could look it up.    Too long, though, even for Catalina.

Some regional totals, 3 AM to 3 AM:
Precipitation Report for the following time periods ending at: 03:19:00  11/04/16
                    
              Data is preliminary and unedited.
              —- indicates missing data
                          
    Gauge     24         Name                        Location
    ID#      minutes    hour        hours      hours        hours
    —-     —-       —-        —-       —-         —-       —————–            ———————
Catalina Area
    1010            0.08      Golder Ranch       Horseshoe Bend Rd in Saddlebrooke
    1020            0.12      Oracle Ranger Stati          approximately 0.5 mi SW of Oracle
    1040            0.08      Dodge Tank                   Edwin Rd 1.3 mi E of Lago Del Oro Parkway
    1050            0.16      Cherry Spring                approximately 1.5 mi W of Charouleau Gap
    1060            0.16      Pig Spring                   approximately 1.1 mi NE of Charouleau Gap
    1070            0.24      Cargodera Canyon             NE corner of Catalina State Park
    1080           0.20      CDO @ Rancho Solano          Cañada Del Oro Wash NE of Saddlebrooke
    1100           0.16      CDO @ Golder Rd              Cañada Del Oro Wash at Golder Ranch Rd

Santa Catalina Mountains
    1030          0.04      Oracle Ridge                 Oracle Ridge, approximately 1.5 mi N of Rice Peak
    1090          0.16      Mt. Lemmon                   Mount Lemmon
    1110          0.16      CDO @ Coronado Camp          Cañada Del Oro Wash 0.3 mi S of Coronado Camp
    1130         0.28      Samaniego Peak               Samaniego Peak on Samaniego Ridge
    1140         0.08      Dan Saddle                   Dan Saddle on Oracle Ridge
    2150         0.16      White Tail                   Catalina Hwy 0.8 mi W of Palisade Ranger Station
    2280         0.04      Green Mountain               Green Mountain
    2290        0.16      Marshall Gulch               Sabino Creek 0.6 mi SSE of Marshall Gulch

Santa Catalina Foothills
    2090         0.04      TV @ Guest Ranch             Tanque Verde Wash at Tanque Verde Guest Ranch
    2100          0.16      DEQ Swan                     Swan Rd at Calle del Pantera
    2160        0.08      Sabino @ USFS Dam            Sabino Creek at USFS Dam
    2170        0.24      Ventana @ Sunrise            Ventana Canyon Wash at Sunrise Rd
    2190        0.16      Al-Marah                     near El Marah on Bear Canyon Rd
    2200        0.04      AC Wash @ TV Bridge   Agua Caliente Wash at Tanque Verde Rd
    2210        0.00      Catalina Boosters            Houghton Road 0.1 mi S of Catalina Highway
    2220        0.04      Agua Caliente Park           Agua Caliente Park
    2230        0.04      El Camino Rinconado          El Camino Rinconado 0.5 mi N of Reddington Rd
    2240        0.04      Molino Canyon                Mt Lemmon Highway near Mile Post 3
    2390       0.24      Finger Rock @ Skyli          Finger Rock Wash at Sunrise Rd

Yesterday’s Clouds

6:50 AM. "Shape of things to come."
6:50 AM. “Shape of things to come1.”  “Nothing could change the Cumulus shapes of things to come” yesterday, to paraphrase here, as evident in this Cumulus shedding ice in the downwind decaying end on the left.
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7:35 AM. Look at this little guy, so full of ice. Another harbinger of the ice-filled clouds about to arise, and with ice, precipitation, snow aloft, graupel (tiny soft snowballs), and even some hail (solid ice). You could guess here from how shallow this Cumulus cloud is that the bases must be at near the freezing level, and tops must be at least as cold as -10° to -15° C, cold for such a small cloud. But what would we call such a small cloud? Cumulus congestus praecipitatio or virgae (since the present of ice absolutely means some precip up there, not likely reaching the ground though. Shoot from the hip estimated depth 2 km, or around six thousand feet.
11:37 AM. Sure enough, as it got warmer, Cumulus congestus/small Cumulonimbus clouds arose trailing ice northwestward in huge plumes of ice. Note to airborne researchers: be sure to sample the older parts of the turrets that have trailed downwind and turned completely to ice even though that trailing portion doesn't look much like a Cumulus cloud. It you only sample the newly risen portions, you will cheat the cloud out of how much ice it can produce since it takes a little time for all the ice to form. Lotta early airborne researchers made this error, reporting too little ice, but, of course, if they were in the cloud seeding business, they wouldn't mind at all since they could report that clouds needed more ice, that from their seeding activities!
11:37 AM. Sure enough, as it got warmer, Cumulus congestus/small Cumulonimbus clouds arose trailing ice northwestward in huge plumes of ice. Note to airborne researchers: be sure to sample the older parts of the turrets that have trailed downwind and turned completely to ice even though that trailing portion doesn’t look much like a Cumulus cloud. It you only sample the newly risen portions, you will cheat the cloud out of how much ice it can produce since it takes a little time for all the ice to form. Lotta early airborne researchers made this error, reporting too little ice, but, of course, if they were in the cloud seeding business, they wouldn’t mind at all since they could report that clouds needed more ice, that from their seeding activities!
11:37 AM. Oh, so pretty, those dark blue skies punctuated by a little muffin Cumulus cloud. Aren't you glad you live here?
11:37 AM. Oh, so pretty, those dark blue skies punctuated by a little muffin Cumulus cloud. Aren’t you glad you live here?
1:25 PM. Showers and small Cumulonimbus clouds trail off the Catalinas north of Bio2.
1:25 PM. Showers and weak Cumulonimbus clouds trail off the Catalinas north of Bio2.
1:25 PM. Showers track westward south of Catalina while the clouds over the Catalinas dissipate or remain disorganized while heading toward us.
1:25 PM. In the meantime, stronger Cumulonimbus clouds and showers track westward south of Catalina  toward Avra Valley while the clouds over the Catalinas dissipate or remain disorganized while heading toward us.
2:33 PM. A voluptous Cumulus congestus in the process of transitioning to a Cumulonimbus calvus (ice is visible but top stil pretty firm and round looking), then Cumulonimbus capillatus (fibrous top)
2:33 PM. A voluptous Cumulus congestus in the process of transitioning to a Cumulonimbus calvus (ice is visible but top stil pretty firm and round looking), then Cumulonimbus capillatus (fibrous top)  AN older turret, looking all ice, leans to the left.  Precip was already dropping out the bottom of this fat cloud.  What kind would it be?  Grauple, without doubt since so much supercooled liquid water  would remain in this cloud amid the ice crystals forming inside.  Those ice crystals, nice and pristine when they first form, would have their pretty forms obliterated by droplets that would freeze instantly on them, making them little snowballs, falling faster and faster, collecting more droplets.
2:46 PM. Moving rapidly away from Catalina, of course, that cloud has now become a Cumulonimbus capillatus (hairy, fibrous top a,most completely composed of ice--some liquid)
2:46 PM. Moving rapidly away from Catalina, of course, that cloud has now become a Cumulonimbus capillatus (hairy, fibrous top a,most completely composed of ice–some liquid may still arrive at cloud top in new turrets before quickly converting to ice.)  A portion of a rainbow can be seen at almost ground level.
2:48 PM. In the meantime, pretty strong storms, now having thunder, rage S through W of Catalina.
2:48 PM. In the meantime, pretty strong storms, now having thunder, rage S through W of Catalina.
3:14 PM. While we didn't have any great clouds near us, at least we had some nice lighting (not LTG) on the mountains from time to time.
3:14 PM. While we didn’t have any great clouds near us, at least we had some nice lighting (not LTG) on the mountains from time to time.
3:41 PM. Finally, the dramatic skies were shifting northward and measurable rain was on the doorstep. Looking SW toward Pusch Ridge and the Tucson Mountains.
3:41 PM. Finally, the dramatic skies were shifting northward and measurable rain was on the doorstep. Looking SW toward Pusch Ridge and the Tucson Mountains.
4:43 PM. Took awhile, but a decent Cumulus with a nice base now transitioning into a Cumulonimbus plopped some big drops and hail down. Streak at right is a hail particle with its fall distance in about 1/400 of a second.
4:43 PM. Took awhile, but a decent Cumulus with a nice base now transitioning into a Cumulonimbus plopped some big drops and hail down. Streak at right is a hail particle with its fall distance in about 1/400 of a second.
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4:47 PM. The hail got a little bigger and I took a picture of one of the stones, a little smaller than pea-sized in case you don’t believe me that some hail fell, too. Sometimes I think people don’t believe what I write, especially in footnotes….
5:02 PM. While the sunset was dramatic, it didn't bring the color hoped for, but this line of dark clouds presaged another bit of rain for Catalina.
5:02 PM. While the sunset was dramatic, it didn’t bring the color hoped for, but this line of dark clouds presaged another bit of rain for Catalina.

Except for a morning or afternoon sprinkle, no rain in sight, just a warm up back to above average temperatures.  Dang.

The End

———————-

1The young fluid dynamicist,  Richard Penniman, fascinated by the flow around mountains, and who later became known as the rock and R&B entertainer,  “Little Richard”,  first brought the Froude Number to public attention in his song, “Tutti Froude-e.”  The title, after an early release failed to capture the public’s imagination,  was later revised for greater “accessibility”,  to the song we know today as, “Tutti Frutti.”

2Who can forget “Max and the Storm Troopers” and that great song?  I would submit, “everyone.”  Of course, few know that after 1968 they changed their name to “Led Zeppelin.”  And that, my friends, is  “the rest of the story”,  as Paul Harvey might say if he was lying about something anyway.

Colorful evening ends day with a colorful morning; a note on the great Cal rains of October 2016

Not much else to talk about, no rain of course;  what is that?

But with so many colorful scenes yesterday, we can be partially sated by the  lives we lead here sans rain here.  October ended with a puny 0.01 inches in Sutherland Heights.

Now, because I grew up in California and remain a little Cal-centric, this brief diversion from AZ:

But droughty Cal got nailed though, from about San Luis Obispo, so we can be happy about that I guess.  One station, Gasquet RS,  near the Duck border,  got just under 28 inches in October; stations in the Santa Cruz Mountains, way down by Monterrey, got between 14-17 inches!  From the California-Nevada River Forecast Center, this nice map of October rainfall anomalies in that domain.  Red is real dry, and that’s the color we would be in if it was the California-Nevada-Arizona River Forecast Center:

Many departures are far over the map color-coding limit of 350%, but are over 1000% of average!
Many departures are far over the map color-coding limit of 350%, but are over 1000% of average!  Note red below normal swath.  This tells you that the mean area of low pressure at the surface and aloft was just off the West Coast.  Pac NW set maximum October rainfall records, too.

But let us not dwell any more of generous rains that others got, but celebrate the color and clouds of Arizona.   Here are yesterday’s glorious scenes, beginning with a spectacular Altocumulus lenticularis under some Cirrus at dawn:

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6:37 AM.
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6:47 AM. Ac len stack.
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10:51 AM. Tiny patch of Cirrocumulus tried to hide in front of some Cirrus. Hope you weren’t fooled and logged this sighting in your cloud diary. Cloud maven person almost missed it himself.
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12:50 PM. There were lenticulars aplenty yesterday. Here’s another one in a location a little different from normal, beyond the Catalinas. Upwind edge is the smoothest one at right. No ice streamers coming out the downwind end, so must have been pretty “warm”. Lenticulars, due to their tiny droplets and those droplets having short life times, have been known to resist ice formation to temperatures well below -30°C -22° F). Pretty amazing.
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2:42 PM. Kind of clouded up in the afternoon, and with breezes, made it seem like something was up. It was, but far to the NW of us. We have been under a streamer of high to middle clouds originating deep in the Tropics for a couple of days. Here some lower level moisture has crept in on cat’s feet, to be poetic for a second, and has resulted in small Cumulus and Stratocumulus clouds underneath the Cirrus and lenticulars standing around. All in all, though the temperature here reached 87° F, a very pleasant day.

Now, just some nice lighting and color:

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5:32 PM. The almost flourescent plant in the foreground is what is known as a “cholla.” The end elements fall off quite easily and attach to things like your pant leg if you brush by them on a horse, or if back into them while walking and correcting your horse for something when he’s acting a little “wild.”  I can report that when seven or eight of them are stuck to the back of your shirt, its really hard to get that shirt off.  In fact, it just about won’t come off without a major scream.
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5:35 PM. The higher Cirrus are shaded by clouds to the west, but the lower remnants of Stratocumulus/Cumulus and a few Altocumulus are highlighted as though they were meant to be for this photo. So pretty.  Notice, too, how there seems to be more than one layer of Cirrus.
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5:44 PM. Cirrus and Altocumulus, the latter with some turreting making those the species, “castellanus”, if you care.
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5:47 PM. A nice flame-out of Cirrus occurred as those pesky clouds blocking the fading sunlight from striking them opened up below the horizon. A few Altocumulus castellanus can be seen, too, but relegated to shadow status.

In a further celebration of dryness here, let us examine the rainfall cumulative rainfall predictions calculated by the University of Arizona’s Dept Hydro and Atmos Sci computer the period ending at Midnight on November 5th.  Says the coming rain in the State misses us here in SE AZ while falling just about everywhere else, of course.  Dang.  Let’s hope it one of the worst model predictions ever!

This really poor forecast is based on the global data from last evening at 5 PM AST.
This really poor forecast is based on the global data from last evening at 5 PM AST.

 

The End.

May to continue into November

Sure, there’s a bit cooler weather heading our way in the next few days, but “May” will reappear after that, and people will be complaining again that they evacuated their domiciles in northern climes or high altitude sites too early when they returned to their winter homes in Arizona.  I am hearing a lot of that kind of complaint.

Heat,  devoid of thunderstorms,  is truly tough to take here in AZ.

Unfortunately the little troughs so well predicted to occur in NOAA spaghetti plots at the end of October did not bring any rain, and this next one, which slipped from late October into the first of November, looks like its going to be dry, too.

Damnug.

October will end with but 0.01 inches of rain here in The Heights.  Our average is 1.13 inches (1977-2015).   Last year we had over two inches in October AND November, setting the stage for a good spring wildflower display!  Below, a reminder:

2015-16 monthly water year totals vs average
The light bars are the averages; red bars the observed.

 

But, “hey”, looks like southern New Mexicans will get a lot of rain, so let us be happy for them this coming week, and not sad for ourselves when we read about all the rain THEY are getting so close to us.  Its only right.

But here’s the killer plot, just out from the NOAA spaghetti factory.  I couldn’t believe how bad it was for us.   You, too, I am sure will be frustrated and mad when you see it:

Valid at 5 PM AST November 12, 2016
Valid at 5 PM AST November 12, 2016 for about 18, 000 feet above us.  Notice how the blueish lines pretty much the heart of the jet stream)  are way up there in Canada, and our area is devoid of lines (see yellow line and south of there).  This strongly suggests an  upper level, warm high center or at least a bulge of high pressure aloft will sit on top of us and the adjacent states, maybe some jet flow way down around Mexico way.  This may be one of the worst forecast maps for AZ of all time, considering the time of year.  Warmth,  with desiccated air,  dead ahead right into mid-November after our little, brief cool down this coming week.  Note, too, the indications (blue lines) that a big trough will populate the East,  bringing cold conditions there.

In the meantime , we can rejoice at the bountiful October rains they are having in California.  Some records will fall.   Some stations in the extreme north will approach 30 inches for the month of October by the time the month ends, and many stations south of those, including ones in the Sierra Nevadas will log 10-20 inches for the month.

Outstanding.  But, it needs to continue, not dry up….to take a real bite out of drought.

The End

 

More odd optics; a Cirrostratus halo with a suggestion of a lower tangent arc

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7:25 AM arrives as usual. Seeming radiating bands of Altostratus stream toward Catalina (little too thick and gray to be “Cirrus”). They also appeared so smooth as to resemble lenticular clouds.
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1:14 PM. Since its summer again in Arizona in late October, not surprising to see afternoon Cumulus clouds originating in air from the Tropics clustering over our mountains again.
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1:38 PM. The curved brightening at the bottom of this otherwise normal halo is likely a “lower tangent arc.”
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1:40 PM. Zooming in with excitement here. Is it really a lower tangent arc? Not positive, but will go with that description anyway.
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2:59 PM. That Cirrostratus thickened into Altostratus (usually, btw, due to the bottom of the cloud lowering) and at the same time the lower moisture, evidenced by these Cumulus and Stratocumulus clouds, also increased. However, none of these lower clouds got cold enough to produce ice, so likely tops were warmer than -10°C (14°F).

DSC_90074:32 PM.  Mix of Altostratus and Altocumulus clouds, with just remnants of the lower Cu.  Here it appears that a liquid layer of Altocumulus now resides at the bottom of the Altostratus, or may be embedded in it.  The globular masses in the middle of this photo represent droplet clouds that appear to have merged into a plate.  In the distance, the telltale sign of lowering tops:  only droplet clouds, with a occasional splash of virga can be seen.

DSC_90115:23 PM.  Just a little before a great sunset,  which I missed due to a social engagement, the shallow Altocumulus droplet clouds are plainly evident around the sun’s position.  Above to center, the backside of the deeper Altostratus clouds with much higher tops,  is about to pass over us.  Here you can see, how much lower the Altocumulus cloud fragments are than the Altostratus layer as they are  illuminated by the sun (upper center highlighted clouds).

All in all, a pretty pleasant day with interesting clouds passing by, though ultimately disappointing since at one time, this was to be a day with showers here.  Oh, well, that’s weather forecasting for you.

Another minimal chance for showers comes up in the middle of next week…

The End

Ice optics extravaganza; Cirrus uncinus fallstreifen going in different directions!

What a day, Mr. and Mrs. Catalina!

Not as good as a rain day with lightning, but yesterday did have its moments in the sky, enough to make the astrologers  on Mt. Lemmon jealous with displays of parhelia (“sun dogs”, or “mock suns”), faint haloes, a rare parhelic circle, something you don’t see but once every year or two,  and fallstreifen (fall streaks) from Cirrus uncinus clouds going in almost opposite directions, an extremely rare sight.

The rare “parhelic circle” is a local brightening often extending out from a parhelia (sun dog) at a sharp angle, which I just learned about here1.  Usually you don’t see a whole circle, just part of one.  

These optic displays are caused by ice crystals, of course, ones not too complex, but rather simple ones like prisms, short solid columns, bullets, and hexagonal plates.  Some examples of these can be seen here.

The bottom of yesterday’s moist layer was just above 30,000 feet at a temperature of -35° C and extended all the way up to about 40,000 feet above sea level where the temperature were around -65° C.

Ann 2016102800Z_SKEWT_KTUS
The balloon sounding launched around 3:30 PM AST yesterday from the Banner University of Arizona.

Some photos documenting the excitement of yesterday

5:30 PM. Cirrus uncinus crystals heading in two very different directions. Wow. Notice the fibers from the contrail that are starting to fall out are going in the "correct" direction, back toward that west.
5:30 PM. Cirrus uncinus crystals heading in two very different directions. Wow. Notice the fibers from the contrail that are starting to fall out are going in the “correct” direction, back toward that west or southwest.
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3:04 PM. Parhelic circle erupts in mostly Cirrus uncinus clouds.
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3:06 PM. The astounding sight continues, but fades away just after this.
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3:33 PM. Local brightening at the position of a sun dog suggests these are tiny ice crystals or possibly even droplets that have just formed, the sizes too small to allow refraction into color normally seen in sun dogs.
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3:32 PM. A zoomed view of that little bright spot. Sure looks like it may have been droplets. Droplet clouds have been reliably reported to temperatures as low as -44° C. Of course, wouldn’t stay liquid long!  I thought this was a pretty exciting shot!  Hope you got it, too.

 

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3:42 PM. Amid all the optical excitement was this ghost-like halo. Can you make out the faint circle around the sun? In ascents through thick ice clouds having complicated ice crystals like bullet rosettes down below the tops, as you climb to the top of such clouds, amazing haloes can be seen where the crystals are newly formed and quite simple in structure, allowing the refraction required for a halo. So, this halo was likely at the top of these thicker Cirrus and Altostratus (dense portions) clouds, though no one would penalize you if you just said they were all Cirrus clouds.

 

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3:59 PM. Another spectacular bright spot at the sun dog location (which is also at the 22° halo location, faintly evident here).
3:59 PM.
3:59 PM. Zoomed view of this sun dog/parhelia. Lots of fine structure evident, which is not usually the case with parhelia.
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4:25 PM. Another finely structured parhelia/sun dog suggesting the ice crystals were newly formed. Fine structure like this can’t last long with the usual turbulence, and so that’s a sure sign this feature has just formed.  I don’t recall seeing so many atypical sun dogs in one day!
5:09 PM. The normal, amorphous sun dog. No really fine detail can be seen here.
5:09 PM. The normal, amorphous sun dog. No really fine detail can be seen here.

Below, examples of cold Cirrocumulus, ones that quickly transition to Cirrus clouds.

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5:19 PM. This group of CIrrocumulus clouds appeared very quickly almost overhead. The tiniest elements are those that have just formed. These are composed of ice crystals in extremely high concentrations, perhaps 10,000 per lilter. Once that ice has formed, its gradually spreads out, much like a puff of smoke would, thinning, some crystals growing large enough to start fall steaks.
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5:19 PM. Some elements are still forming, but the spreading of the older ones is well underway, producing a “blurred” look as the elements merge and thin out.
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5:28 PM. Off to the southwest of Catalina, a promising intrusion of lower moisture indicated by these approaching Altocumulus clouds. Will there be enough today for a sprinkle somewhere?  Not looking so good now, clouds did not lower much overnight.   Well, maybe if it doesn’t sprinkle, maybe we’ll get to see some nice virga and dream about rain…

 

The End

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1I was going to call it something else.  Egad.  Let us remember the words of the B-52s:  “Before I talk, I should read the book.“

Thunderstorms pound Catalina/Sutherland Heights with 0.01 inches of rain! Blog contains a horse photo!!

Well, a partial shot of a horse….

A horse photo will always enhance a blog about clouds.  Expecting a little uptick in readership due to this ploy,  maybe will break out of the single digit  column.

Not much happened early on, a thin film of Cirrostratus covered much of the sky, delaying the expected development of convection, as would be evidenced by the formation of Cumulus clouds, until mid-afternoon.

But they did form, mostly to the S through W of Catalinaland,  upwind of us, and eventually rumbled in on their last legs as weak thunderstorms with gushes of sprinkles and gusty breezes, maybe ones over 15 mph!

Over there in Marana and Avra Valley, those places upstream of us, some spots got more than half an inch.    But, i it seems this year that storms die when they move toward Catalina, and especially, toward MY house and its many raingauges (3).

Still, it was nice to feel cool breezes, air chilled by falling rain, even if elsewhere.

Here are a few dull and disappointing cloud shots from yesterday, including one with a horse:

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10:56 AM. Horse looks ahead, examining the vellum of Cirrostratus cloud overhead, wondering if it means anything. If this was Seattle, such a layer would thicken and lower into a steady rain within hours 70% of the time. Pretty true for most higher latitude locations in the cooler time of the year. (This was horsey’s first true trail ride, going up and down rocky gullies with loose rocks along side the Sutherland Wash. Previously this horse had spent most of its 14 years in a small corral so this was all pretty new to him;  rider tension high.)
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2:49 PM. A soothing gray of Altocumulus undercut the layer of Cirrostratus. Building Cumulus clouds can be seen toward the Mexican border on the horizon. Pusch Ridge is in the foreground. As you can see, no virga is falling from those Altocumulus clouds, so they must be pretty “warm”, warmer than about -10° to -15° C at cloud top.
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3:38 PM. Looking suggestive of rain here in Catalina. However, these storms were in the late, dissipating stage. Note too how the anvils have merged with the Cirrostratus layer and lean far out from the storms toward us, helping to cool the ground, ruin the chances of new Cumulus buildups ahead of them.
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4:19 PM. Not much going on over the Catalinas. Notice how broken up into light and dark patches these otherwise dark looking lower clouds are. Shows there’s no hope for any buildup out of them, though, lower clouds like these under precipitating Altostratus cumulonimbogenitus (that higher cloud here which is really the result of anvils) can help sprinkles get to the ground. That’s because drops or snowflakes falling out of the higher cloud, won’t evaporate while falling though these clouds (representing saturated air with respect to water).
4:33 PM. Nice shaft, some cloud-to-ground lightning strokes toward south Tucson, but who cares? Wasn't moving this way, and would be mostly dissipated by the time it got here anyway.
4:33 PM. Nice shaft, some cloud-to-ground lightning strokes toward south Tucson, but who cares? Wasn’t moving this way, and would be mostly dissipated by the time it got here anyway.
4:57 PM. Eventually some rain with an occasional lighting outrage did reach the southern parts of the Catalinas, making it all the way to Ms. Mt. Sara Lemmon, and SPKLS fell in Catalina.
4:57 PM. Some rain with an occasional lightning outrage did reach the southern parts of the Catalinas, eventually making it all the way to Ms. Mt. Sara Lemmon where 0.24 inches was recorded.   SPKLS fell in Catalina.
5:42 PM.
5:42 PM. Last gasp, last chance for rain here, dying shower with some new bases to the right, offer another slight hope that the new stuff will develop into showers like this one.  It didn’t.

Still have rain chances last few days of Oct into early Nov.

The End

Check it out!

Since my risky forecast, and going beyond professional standards of some days ago seems to be working out, I thought I would update you on it. Of course, if it was not working out, you would hear nothing more about it.  Below, for October 29th, as rendered by IPS MeteoStar.  We seem to be in a bull’s eye for rain amounts.  Wouldn’t that be great!?

But, as you know, gotta get through a heat spell first…

Valid at 11 AM AST October 29th. This was the wettest model output I could find, and, it just came in from the 11 PM AST global data ingest! Wow.
Valid at 11 AM AST October 29th. This was the wettest model output I could find, and, it just came in from the 11 PM AST global data ingest! Wow.  I’m kind of screaming in that annotation.

The End

October 2016 to close out with rain!

Threat!  (omitted portion of the headline above)

Check this out:

Valid at 5 PM AST October 28th. 2016.
Valid at 5 PM AST October 28th. 2016 based on global data from 5 PM AST last evening.

You got yer ridgy flow on the top (“top” meaning, “Canada”, around where that yellow line humps toward the north) and yer broadly cyclonic flow on the bottom (“bottom” meaning,  “Baja Cal and Mexico”) that is, across the whole western part of North America.  This indicates that we will have a configuration that suggests a “split flow” where part of the jet stream and a trough is forced into the Southwest.  Models are showing a big trough and cutoff that brings substantial rains to Arizona!

Of course, model forecasts are pretty dicey at this range, more than 10 days, and so that’s why I am reporting it fully here with great excitement!  That’s what we do here,  go over the edge, not just up to it.

And, for that slight amount of additional credibility, the “WRF-GFS” has been spitting out big storms for Arizona over the past several runs during this late October period.  See Arizona rain below from this rendering from IPS MeteoStar:

Valid at 5 PM October 27th, 2016. The colored regions denote where the model thinks in has rain in the prior 12 h.
Valid at 5 PM October 27th, 2016. The colored regions denote where the model thinks in has rain in the prior 12 h.  The rains are foretold to just be arriving at this time, and continue for a couple of days.  Nice!

Since I ran out of anything more to say, I will post a second version of this same map as a public service for international readers who are clueless about states in the USA:

Same as above, but for international readers of this blog, and others who may be geographically challenged.
Same as above, but for international readers of this blog, and others who may be geographically challenged.

Below, the upper level configuration that goes with the pattern above:

Also valid at 5 PM AST October 27th, 2016. Notice how a lot of the flow comes down this way after extruding into Canada, but some continues on across Canada. Disclosure note: this configuration has more amplitude (and thus a bigger chance for rain in southern Arizona, than was seen in the plot from the NOAA spaghetti factory. Few readers may get this far, so that's why I am placing it here. A announcement that rain might fall in southern Arizona makes people happy, and that's why I will show those models that predict the most rain here, not ones that skimp on a future rain.
Also valid at 5 PM AST October 27th, 2016. Notice how a lot of the flow comes down this way after extruding into Canada, but some continues on across Canada. Disclosure note: this configuration has more amplitude (and thus a bigger chance for rain in southern Arizona, than was seen in the plot from the NOAA spaghetti factory. Few readers may get this far, so that’s why I am placing some element of doubt here.   A announcement that rain might fall in southern Arizona makes people happy, and that’s why I will show those models that predict the most rain here, not ones that skimp on a future rain.  Doubt about a future rain disappoints, makes people sad.  Oh, yeah, and the latest WRF-GOOFUS model run, that from the 11 PM AST global data, had none of this.  What a poop that run was!  Does that later run affect the thought of rain late in the month?  Nope.

So, there are some questions about the magnitude of this event, will it be a spring wildflower energizer with a major rain, or a just a breezy spell with a dry cold front going by?  I’m on the side that a good soaking rain will fall sometime in those last few days of October.

No clouds, so no point in going farther….

The End.