Dry low in spin cycle for two days over Baja; WATER in the Sutherland!

Our latest cut off is now “in place” over northern Baja, California.  Below is the latest map (5 am today) combining satellite images with the 500 mb contours from the U of WA.  Now it will sit and spin before moving off to the ENE and the center passing right over my house here in Catalina Saturday night into Sunday morning.  Makes me feel important to have a low right over me because me and you will be the center of attention as well as under the center of the low on all the weather discussions around the country.

Now, it is true that this low is pretty dry right now, not much going on in the way of rain anywhere (check here), but, sitting where it is, that will change and we should get another “decent” rain out of this beginning Saturday night into Sunday morning.  SOP QPF?  Maybe a quarter of an inch of rain.  “SOP QPF”?   Just a quick eyeball assessment based on patterns, not on models right now.  But our great model output from the U of AZ here will have something to say about this later this morning when the model run is finished.  But why wait for it to finish and have a better forecast?  Because you wanna know NOW, and I have to go on and do something else.  Besides your favorite TEEVEE person and the NWS will have all the gory details when the model run is finished anyway.  So, really, I am of no use whatever here.  I’m feeling sad now.  But I’ll get over it.

Note in that satellite loop how high clouds are appearing in central AZ.  Those will be increasing and appearing more upwind as the low sits where it is, eventually deepening into rain/snow showers over the high terrain in the north and in the western part, and then as it moves off, a nice band of rain should move through here Saturday night.

 

With this low sitting there for awhile, we could see some really interesting Cirrus and Altocumulus clouds in delicate patterns I hope, and great sunsets before the rain gets here.  I really hope to see some Altocumulus castellanus this time.   That will be one of the best parts to this little guy spinning down there.

Another great sight is all the rain and snow predicted for NM and TX as this low finally, and slowly, trudges across the Southwest (seen here–hit the play  button to see the whole loop).   Once again this should do wonders in helping to knock out the awful drought in those areas.

The End.  Maybe some nice cloud shots tomorrow for tomorrow’s harangue.

Actually, its not the end because I just remembered that I forgot to mention that I saw WATER in the Sutherland Wash and one of its tributaries on a horseback ride yesterday!  How great is that?  Below, a former riding partner’s horse that I bought and now ride, “Big JohnT”, romps in a tributary to the Sutherland.

The most interesting clouds–technical discussion ahead; skip now if you have a headache

Well, to me, anyway, those flat, thin ones yesterday (Stratocumulus, and Cumulus fractus, humilis, mediocris, if you want some names).  The thicker versions of these clouds were shedding ice and snow but weren’t very cold and that’s what made them interesting.  Take a look.  If your eye is calibrated you can see that light snow is falling on the Catalina Mountains in the first two photos, and in the third photo, one that better illustrates how thin these clouds were (probably 2,000 to 3,000 feet thick is all), snow is seen falling in the distance from the cloud above and to the right of the white roof of the shed in the foreground.  Quite remarkable.

Why?

According to our TUS sounding data, these clouds, at least at 5 AM LST, were topping out at only around -10 Celsius (14 F), a very marginal temperature for ice formation in clouds in Arizona.  By the afternoon, the TUS sounding was suggesting the clouds near the sounding balloon were as warm as -3 C (28 F), too warm for natural ice formation.  (Where the temperature and dewpoint temperature lines come together, right now, over me.)

If you go to the movies, the time lapse one from the U of AZ here, you will see that the clouds were coming toward TUS from the Catalina Mountains by the time of the afternoon sounding, and therefore its not valid for the heights of those clouds over the mountains–the air has sunk coming off them.  So, the best we can do is probably with the morning sounding and assume the clouds were topping out at the -10 C level with bases about 0 C to -2 C.  You can get base height from where they were intersecting the Catalina Mountains (the cloud, not the snow!).  That was at about 6,000 to 7,000 feet elevation, roughly 4,000 feet above ground level here in Catalina.

So, we had pretty cold bases, and not very cold tops.  When we see ice coming out of clouds like these (and I would estimate from airborne experience at the U of WA, that those concentrations of ice coming out of those clouds were a few to 10 per liter).  If that estimate is correct, then we would say that these clouds exhibited “ice multiplication” or “ice enhancement.”  That’s because we don’t expect concentrations that high in clouds with tops around -10 C.  That is,  unless something “extra” is going on to add to the very few ice crystals that might have formed without “multiplication”; perhaps only 1 in 100 liters at -10 C.

So wha happened?

Our most accepted theory is that the very few lead to the many in collisions with cloud drops.  Those cloud drops, when a bit larger than usual (24 microns in diameter for a number), shed ice splinters, and those splinters go on to populate the cloud.  It takes a long time because the itty bitty splinters have to grow to sizes where they can collide with cloud drops, too.  This ice enhancing mechanism, referred to the Hallet-Mossop riming splintering mechanism, named after two scientists named Hallett and Mossop (hahaha), is known to only occur in the temperature range of -2.5 C to -8 C.

Those temperatures were indeed found in our little clouds.  So, too much ice explained!

Not quite.

In little, cold-based clouds deep into the continent as we are here in Arizona, it would NOT be expected that the droplets inside those thin clouds would be large enough (as big as 24 microns in diameter) so that ice splinters would occur when colliding with the rare ice crystal, the 1 in 100 liters one.

So, that’s the mystery of yesterday.   These clouds DID look kind of “maritime” to me.  In maritime clouds, such as those found in onshore flow along our coasts, drops reach that critical size for riming and splintering just above the bottom of the cloud.  That’s because the air is clean over the ocean as a rule,  and so there are few particles for the moisture to condense on, leading to larger drops right away, and many fewer in a liter than in continental clouds.   A typical maritime cloud has less than 100,ooo drops per liter, whereas a “continental” cloud would have several hundred to a half a million drops per liter and even more in some polluted areas.  So, as a drop, its hard to be a big deal in a “continental” crowd like THAT!

Best thought is that the heavy rains of late cleaned the air hereabouts and those clouds that looked soft and “maritimey” yesterday REALLY were like maritime clouds found over the oceans away from land.  Maritime clouds, as ours might have been,  have large drops in them, and even drizzle and raindrops before reaching the freezing level.  Therefore,  ice forms in maritime clouds at the highest known temperatures for natural ice formation, -4 C to -7 C.

The End.  You might want to rest for awhile if you got this far.

The weather ahead?  More rain, continued below normal temperatures as another “cut off” low rolls off the jet stream table in the north Pacific and falls into the Southwest and Baja area in the next coupla days.


Drought staggering after heavy rain/snow punch, may go down someday; more blows ahead

Any winter storm that drenches the Catalina area, including Saddlebrookians, Oro Valleyians, with more than an inch of rain in 24 h has to be one of the greatest.    Haven’t seen this much winter rain in since the so-called “Frankenstorm” of January 2010 when we got over 2 inches of rain in two days.  Here are the gaudy 24 h totals from the Pima County Flood Control District, ending at 3:34 AM this morning, about 24 h after the rain started Pima rain.  Other interesting rain totals can be found in the network established by the rainlog folks at the U of AZ here.  These totals are a bit smaller than those I culled from the Pima folks since the ob time for the rainlog network is at 7 AM LST, and here, 0.41 inches had fallen in the first few hours yesterday, and then 0.99 inches for the rest of the storm (0.01 inches just now!), for a total of 1.40 inches here in Catalina.  So, the storm totals at rainlog are broken up into two days (the rain pretty much fell in the 18 h from 3 AM yesterday to about 9 Pm last night).  BTW, a nice way to look at the comings and goings of the local rain is via the Weather Underground’s maps with animations of the TUS radar superimposed on a regional map showing our many “personal”  weather stations (e. g., here).  Its interesting that many of you do not have a personal weather station.  Well, the holiday season is here, and the economy can always use some impulsive buying and so maybe now is the time to pick one up before more storms hit.  And they will, as our models continue to show.  BTW2, a rainbow landing on a personal weather station.  Think about it.

In  just 36 h from now another low center barges into Arizona from the NW.  Due to its long overland trajectory, it’s going to be a lot drier than “Frankenstorm Junior”, once again, as another in a winter long series, stagnates in our area as a “cut off” low spinning around flinging rain around its margins for a couple of days (Friday and Saturday mostly).  So with luck, we might pick up another quarter of an inch or so.  Here is a quick look at that whole sequence, and one of the panels below, valid for Friday afternoon at 5 PM LST, for your viewing pleasure.I like this format with the four panels since you got yer upper map in the upper left hand panel showing yer cut off,  and you got yer precip in the lower right hand panel, all  in one jpeg; more cumbersome in the US model presentations I’ve found to have this much info in one jpeg.

So, what about our drought status after all this early winter rain (see below)?

Well, as I have learned from the State Climo office in 2010, not much changes due to a couple of months of wet conditions here, such as we had in 2010 when water was flowing everywhere in southern Arizona later that winter.   Seems for those folks that designate whether an area is in drought, there have to be almost years of wet conditions for the designation of droughty conditions to be removed from their maps.  Its pretty discouraging.  Perhaps it takes wide tree rings to indicate the drought is over (hahahaha, sort of)  ((just kidding!)) (((Really))) ((((Not being sarcastic at all))))

Below is the latest drought map from the Drought Monitors at the University of Nebraska-Lincoln as of December 6th, when they last released a map, we here in southern Arizona were still in an “extreme drought” in spite of all the rain in November and early December.  It will be interesting to see how this map changes after our “Frankenstorm Junior” of the past two days, and with all that rain that has, and will be occurring in the droughty areas of NM and TX.   The longer term model forecasts punish (delight?) those areas with widespread heavy rains over the next two weeks.  Will it remove any of the “extreme” and “exceptional” drought designations for them?  Stay tuned.

At LEAST we have avoided the Climate Prediction Center’s fall forecast of intensifying drought here in AZ over the period of November-January.  Seven weeks into that forecast, we have dispelled that notion, anyway.  It ain’t happening.  It would be hard to take another NDJ like that of 2010-2011 when only December had any rain at all!

Well, Mr. Cloud Maven person had better post some CLOUD photos if he is to remain that and stop squawking about drought…

Here are a couple from the
 storm.  The Catalina Mountains are so wonderful when draped in precip and snow!  I would like to report that I am very happy living here full time in Catalina.

The End, though the image organization will be a mess for awhile, will “publish” now anyway.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Grandson of “Frankenstorm” knocking on Heaven’s door (Catalina, Arizona)

Well, I think Catalina, AZ,  being next to the Catalinas, is “Heaven’s door”.   I think, too, to have a second consecutive thought,  that we’ll get more than an inch out of this Big Boy which is rare here in Catalina for a storm in the wintertime.  Not close in areal extent to the original “Frankenstorm” that struck the West Coast in January 2010 with record setting low pressure, but a potent one anyway.   In the January 2010 storm we received 1.41 inches the first day and 1.18 inches the second to “ice” a fabulous wildflower bloom that year.  We sure seem headed to a fabulous bloom season this year, too.

BTW, there has been a lot of rain in droughty Texas.   We are brothers/sisters in drought relief it seems these days.  How nice; adds to the holiday cheer.  Maybe the price of hay will go down..  It seemed interesting to throw something about Texas in there.  Here is a map showing that great TX rain of yesterday from WSI Intellicast1.  These radar-derived amounts precipitation are pretty much spot on–I’ve checked ground gages a number of times.  We should be seeing “green”,  1-2 inches) over much of AZ in the next couple of days, too.  So, the map below is like a preview for AZ.

Speaking of green, look at the “green-for-rain” in AZ in the lower right hand panel of this forecast for this afternoon ending at 5 PM MST.  During the prior 12 h, beginning at 5 AM MST, the entire State of AZ is virtually covered.   I am just beside myself when I see a map like this!  And look how far to the south of Baja California the circulation of the storm extends.  Its gorgeous to see this.   I guess there could be some flooding here and there, and some “snow birds” might complain about the “crummy AZ weather”, but….you can find people who will complain about anything.  See the whole wonderful model sequence of rain and mayhem in AZ here, and in much more detail from the U of A weather department, here.

Look, too, at how excited the National Weather Service, Tucson is!  They must have 50 bulletins out–be sure to keep reading them.  They are really having a lot of “fun” down there, too.

Late breaking storm bulletin:  We have sprinkles in the area (0425 LST).  Check this radar-cloud map out from IPS Meteostar.  What a great day this is going to be!  Enjoy.   Good chance we’ll see water in the CDO and Sutherland Washes, and maybe some snow mixed in with the rain as the storm closes out Tuesday evening now.

But is this storm the end of our “fun” weather?  Oh, no, my friend.  Another cut off low develops in our area after speeding down as a trough out of the NW in five days.   Another round of significant rain is likely, though not as much as this one.

Some cloud notes from yesterday, including some chat about the unusual streaks.

In that warm afternoon yesterday, it was so great seeing sheets of Cirrus and Altostratus (ice clouds, Altostratus with heavy shading) massing on the horizon, knowing that this time it was NOT just going to be a sky decoration for a nice sunset, but were clouds filled with stormy portent. You probably noticed the lack of sunset color due to the extensive coverage of those clouds upwind. No break allowed the sun to under light them, a sign of extensive clouds upwind to the southwest.

Also, unless you were blind you saw some unusual events in the thin Altocumulus (translucidus) layer yesterday: ice canals and splotches of ice produced by aircraft that flew in them. When so many happen as did yesterday mid-day, its a good bet those Altocumulus clouds, though comprised of liquid droplets, are terribly cold. While the TUS morning sounding did not pick up this mid-day layer, one can be confident that it was likely colder than -20 C or -4 F.

What you also saw was examples of how the presence of ice within a droplet cloud, causes the droplets to evaporate, and the ice crystals to grow and fallout, something that happens on our rain days. However, because there were so many ice cyrstals produced by these aircraft (almost certainly all jets) they compete for the tiny amount of water available at -20 C and form small crystals with little fall velocity.

So the trails of precipitation are very fine and don’t go very far. Here are some examples of that rare phenomenon, rare because for us to see it, takes a thin, cold water droplet cloud, and it has to be high enough so that aircraft are frequently penetrating it. One wonders why, in some of these cases, the trails yesterday were so long with an aircraft probably could have climbed or descended a couple of hundred feet to avoid flying in a light icing producing cloud (the Altocumulus layer composed of supercooled droplets)?  Note “ice optics” in ice canal in the first photo, a weak sun dog so I didn’t just make it up that the canal was ice.  I you wanna know more about this phenomenon, go here and/or here.

On schedule for major AZ storm beginning Monday

Now that the models have reconciled, “come together”,  to show a large storm affecting Arizona and us here in Catland beginning later Monday, it seemed interesting to ME to show you how this one gets here.  This is where our numerical models do things that in the olden days before them we could never anticipate.

Here is a loop from last night’s global data on how a large, vigorous low center forms over San Diego within about 84 from right now.  This loop of the high and low pressures in the middle troposphere (around 15,000-20,000 feet above sea level) from the University of Washington’s “WRF-GFS” model for the West Coast and environs:

Watch what happens in the Gulf of Alaska.  Everything is rolling along FAR to our north, going toward the east, looks like it’ll stay up there with those waves moving one after the other into Canada.  There is no hint of anything moving this way.  Then suddenly, the wave rippling along in the Gulf turns south bound as it hits the West Coast, part of it ripped off and becoming a spinning center just off California and the rest continuing on into central Canada!  Really, its amazing to see such a drastic change like that shown in this sequence.

This type of sequence has been very much like this winter’s past storms have gone through, rippling along in the northern Pacific Ocean, and then suddenly part of those waves shearing off from the main jet,  making a right turn toward the SW US, becoming an isolated, spinning, wobbling center away from the steady strong westerlies of the jet stream.  Some years have had lots of these “cut off” lows, and it seems we are headed in that direction this winter, at least through the first 6-7 weeks.

One of the keys to this happening is how vigorous is the storm immediately upwind of the one that plunges south, oddly.  This influence of upwind storms in perturbing the jet stream downwind was discovered WAY back in the 1950s.  In the current situation, an extremely intense low developing in the central western Pacific sends huge amounts of heat and clouds northeastward behind, upwind, of “our storm” and that heat and moisture (see here protruding into the Aleutians in this loop) helps amplify  the jet stream downwind where our storm wave is by causing the winds shift more to the north downwind of the warm air plume at the backside of our wave).

What it is doing is building,  for a time,  a high pressure ridge aloft within and just ahead of it.  In response to that “ridge building” plume of heat and moisture caused by that intense storm upwind of “our wave”, the jet stream downwind begins to head more to the south, IN our wave.  The intense storm behind our wave is building “amplitude” in the jet stream.  Amplitude in “synoptic” meteorology generally  means the jet stream winds go more to the north and south rather than just east and west. And that’s what you see happen for a time in this loop, and its this greater amplitude that causes a part of the once steadily progressing wave across the Gulf of Alaska to go, “Oops, must go south now” as the winds from the north increase tremendously on its backside.

The assymetry of the winds in these waves tell you where its going next.  If they are stronger on the backside, it will go south or southeast.  If the winds are strongest on the front side, or east side, it will go north or northeast.  If you can see the winds in the above loop, you’ll see that they reach 120 mph from the north on the backside as it plunges S, but the winds on the east side are only about half or less of that.

Hope this is somewhat intelligible.  Still rewriting…!

Personal predictions?  I think we’ll get at least 0.50 inches, probably see some more snow mixed in with the rain by Tuesday morning.  Think about a great wildflower bloom this spring.  In the meantime, enjoy the warmth and cirrus of the next couple of days.  One thing that might help is that disturbance SE of the Hawaiian Islands feeding moisture into the jet stream (seen here in this loop again).  I thought at first that bunch of clouds might be related to the MJO (not a coffee brand, but the “Madden Julian Oscillation” which can have a profound effect on US weather).  But it wasn’t.  The MJO is in the area of the Maritime Continent now.   Go here for the latest NOAA details on this subtle wind regime that travels around the globe toward the east.

Last evening’s “cirrus-ee”, (ice crystal clouds),  sunset.

The End.

 

 

 

“Come together, right now, over me” in Arizona with some rain

This song and refrain by Lennon and McCartney, amended a bit in the title for local interest1 was actually a reference by them to a striking “divergence” in weather model predictions of that day during a droughty time in England;  the models  did “come together” eventually to predict the same thing, and that was for a lot of rain in droughty England in the days ahead.  By the way, you won’t find this kind of historical background information in Wikipedia or in some biography.

As we saw yesterday, one model can show a lot of rain in AZ a few days, and another not.  So, we, too, as did Lennon and McCartney, wanted those models to “come together” and show the needed rain over us;  not one model doing this and another one doing that, as they can do.  I know a lot of you were fretting all day about which one was going to be right, the dry one or the wet one for Arizona?  Well, we have seen them “come together” over the past 24h.

Expect rain and snow!

And a goodly amount of it, in AZ, including Catalina, beginning late on Monday and then continuing off and on for a couple of days!   Wildflowers, here you come!  Maybe you should get that better camera before the spring bloom, and also help the economy along while doing so.

And as you might have speculated, the Canadian wet model run for Arizona, the one one showing a storm pattern similar to the ones we have had intermittently in November and early December, was the one  that won out over yesterday’s model “diffugulty.”  This is great news unless you’re chauvenistic and just that bit peeved that the Canadian model won this event in the “weather model Olympics.”  Oh, well.  The US model, while now predicting storminess  for us is a bit drier than shown here.  Still, its all good.

Here’s last night’s juiciest Enviro Canada panel for AZ, that for Tuesday morning at 5 AM PST showing the storm barging well into AZ (lower right panel).  Exult!  The entire sequence can be seen here.

On a cloud note, we had for a time yesterday, some of the rarely seen Cirrus castellanus, icy clouds with turrets.  Usually its too cold and too “stable” for turrets at heights above about 30,000 feet above the ground, but there they were.  See below.

___________

1In the early original drafts of this song, the reference was to “England”, not Arizona.  As you can see, those part of the lyrics referring to location and rain were a bit awkward and were eventually dropped.


Sunny malaise


2clr4me.  I’ve never texted before, but there it is.

Unfortunately 4me, but fortunately for those “bird people” that come here to avoid real weather, it is going to be sunny except for some passing cirriform clouds over the next few days, a real weather malaise.  However, the good part is that the temperatures are rebounding pretty fast.

However, we can take solace in the fact that clouds and rain are again on the model horizon, not the real one.   Those friendly Canadians up north in their version of the ECMWF model have indicated it will be a whopper, whilst the USA “WRF-GFS” is indicating just a mild event, one that occurs much later than the Canadian “solution.”  (“Solution”, hah!   Nothing is solved here!)  So, once again, we are stuck with a lot of uncertainty partly because it originates with another low that has/will drift away from the main jet stream.  Here is the Canadian view of a whopper for this next Monday.  Note that AZ is as green as a leprichaun below, lower right panel, indicating widespread rain.  Note big upper low center circulation centered over Kingman, AZ (upper left panel).  This would be a very wet scenario for Catalinans.

Next the US model for the same storm and time (Monday afternoon at 5 PM LST) from IPS MEteostar.  Note that a low center is nowhere to be seen in AZ, but INSTEAD two low centers are seen, one over Crescent City-Eureka-I-Found-It, California, and one west of Ensenada, MX.   This is so funny!  Yet annoying.  But no rain has yet appeared anywhere in AZ in the US model at this time!  In fact, as seen in the last map for the exact same time as the Canadian model with all that rain in AZ, the nearest rain to us is sill about 300-500 miles off the California coast!  Amazing!  Yet, annoying.   These are calculations based on physics.  (Well, the “physics” are implemented differently.)   Imagine if your hand calculator said that 2 and 2 was 4 on one day, and the 7 the next.   The world would be discombobulated because no one can do math in their heads anymore.

It takes a coupla more days for the US model rain to get here to AZ, late next week, and then,  its marginal at that.  Well at least the US model has some rain in it someday.  I guess we should be thankful for that.

But what would be a “tilter” in this scenario when you have such “model divergence”?  Persistence might do it.  Look how the Canadian model result below so strongly resembles the kinds of storms we’ve had since the start of November, the isolated low that drifts down into the SW.  This seems to be, at least,  our early winter pattern that we have seen several times now, and when IN a pattern, it may be best in forecasting to “stay the course”, lean toward the model solution that shows the kinds of storms that have already been happening when the models outputs are so different.   It will be fun seeing how this turns out!

The End.

An icy 0.06 inches Catalina dessert

Like most people, I like dessert, especially if its precip in the desert.  Yesterday’s “graupelly” fall of little ice ball showers weren’t expected, a surprise entree.  Even the local model run by the U of AZ weather department on their “Beowulf Cluster” of computers had the showers staying to the north.  So as a weatherperson, you would go with those models; “hey”, they’re the best we can do.  That’s what the TEEVEE weather guys do, too, unless they are really great and can tweak and improve them by knowing the kinds of errors the models make.

A side light:   A professor of weather at the University of Washington recently gave a big lecture about how it is useless for the National Weather Service to try and beat the computer models for tomorrow’s and beyond weather.  As in the humorous take on that old spoken word, how-to-live song, Desiderata,  “Deteriorata”, by the Fire Sign Theatre back in the 70s, this professor told the NWS to, “Give up”;  devote your time to getting the first day right, among other things.  The computers have a tough time in the first 6-12 h, as we saw yesterday.

Yesterday, you could see  the “errors” developing right off the bat.  All of the billions and billions and billions of calculations by the models, to say something Carl Sagan, the astronomer-cosmologist might say if he had been a weatherman, were unraveling; going wrong, incorrect, getting an “F” for rain/snow prediction.    It was going to be a bad day for the computers, who, as we know, generally know more than we do, especially about us and the things we do and buy.

Yesterday, the first exciting hint for me that the showers might reach here rather than just be a little to the north as the models said, was this scene whilst out with the dogs around first light, 7:30 AM.  Look at that shower going by the Charleau Gap!  I thought I might see lightning!  But then I usually think I am going to see more in weather, and in other areas of life, that I want to have happen than actually happens.  I thought, for example, that the Washington Huskies would beat the woeful Oregon State Beavers in football.   Actually fairly confident there.  But, “no”, it didn’t happen.

Back to weather:  the proper weather person would have exclaimed when seeing showers to the left and to the right early yesterday morning (and popping out on the TUS radar) as I did, “Wow”, these clouds have ice in’em!  And that wasn’t supposed to happen!”

So this was the first sign that we had a good chance of showers/snow yesterday.  It was a truly great moment because the computers are so often correct.

But yesterday, they were going down!  Cumulus congestus/weak Cumulonimbus clouds everywhere!

I felt great.  When weather computers fail on the dry side, it makes me feel better as a human.   And  of course, seeing these shafts of precip, you could opine knowledgeably to you friends that the cloud tops are likely colder than -10 C (4 F) (since ice formation in clouds before that temperature is reached would be unlikely here in AZ).

Here are some additional shots from that glorious day yesterday, including, for Oregon State fans (“hey”, the former company team is going to a bowl game!) a closeup of “graupel” for your viewing pleasure.  The last shot is when subsiding air arrived and squashed the Cumulus down over the beautiful Catalina Mountains into “humilis” versions late in the afternoon.

The weather ahead?  A strong storm still shows up in about a week.

The End, except for trying to get this layout right!

 

Cumulus with Stratocumulus; hold the ice

Mr. Cloud-maven person hasn’t said much about clouds lately, which is kind of ironic since he deems himself a “cloud maven” and not much more.  Rather, he has been obsessing about POSSIBLE storms in AZ 15 days away which is kind of futile anyway.

So, as an excuse to show more cloud photos from that gorgeous day of snow and cloud shadows on the Catalinas yesterday, will go into a cloud lecture, a post-mortem so to speak.   Here are some cloud shots from yesterday, most below the one at left.  Note, not one cloud shows any virga yesterday, and some of them got, at least moderately humped up.  A promiscuous cloud maven person might have called one or two of the cumulus clouds, a “Cumulus congestus” (though they would be WRONG).  Well, maybe not that wrong–see the 1987 World Meteorological Organization International Cloud Atlas that I can’t stand because they goofed up on their cloud designations as you will see if you could only find one of those yourself.  Still kind of bummed out by that atlas, but one member of that cloud selecting panel told me they were too busy in their Paris meeting going to the Eiffel Tower and such rather than paying attention to getting the cloud photos they had properly named.   Now, where was I?

Right, I was talking about yesterday’s clouds….   Well, here are some cloud shots, ones that I was going to post 15 minutes ago before getting upset again over the 1987 WMO cloud atlas.  (Really, I could have done a better job than the WMO all by myself; it was a real boondoggle, that meeting of “cloud experts”, yeah right.)   OK, photos!

Now looking at ALL of these, you see no fibrous material falling out, even though some of the clouds look pretty dark in these perty scenes.   I was so happy to be alive and live here yesterday, feeling very, very lucky.  So, remembering the University that Bullwinkle Moose went to play football as the “Frostbite Flash”, “Whatsamatta U.”, we might say the same thing to these clouds, “Whatsamatta U?”   How’s come there no precip falling out, and those who read this silly site will answer immediately, “Them clouds ain’t got no ice in’em”, which would be correct.

But why?  It was awfully cold yesterday, and even Mr. Cloud-maven person, who does not even have the Master’s Degree, was wondering.  So, off to the TUS “99 Luftballoons” sounding data for yesterday afternoon, posted by our great U of A Weather Department below (where the lines come together are where the clouds were located).  Didn’t seem possible to me, but those cloud tops were hardly as cold as -5 C (23 F).  Ice does not form in clouds, even though they are below freezing, at this temperature in the natural state except in very special circumstances.  Ice formation in clouds, still not WELL understood, is known to be a function of drop sizes AND temperatures.   Over the oceans where cloud drop sizes are large,  it happens.  Usually, someone can get a whole scientific paper out of a cloud that formed natural ice when the top has never been colder than -4 C!

Here in Arizona, what we would call a continental cloud forming environment.   Cloud drops “is” smaller because there are so many more particles for the drops to condense on, and so the concentration of drops is higher, meaning the drops have to be smaller to condense out the same amount of water as over the oceans where the air has fewer particles for clouds to form on.   In a nice cumulus off the Washington coast of the sizes we had here yesterday, the cloud drops would be as large as half the diameter of a human hair (“wow”, huge, he sez, 30-50 microns in diameter, for the sake of a number) here in AZ in those clouds yesterday would be lucky to have drops in them as big as 20-25 microns, too small to activate ice forming processes, known to be related to drop sizes.   Oddly, the bigger the cloud drops, the HIGHER the temperature at which ice forms, especially if drizzle drops have formed.  The drops in our clouds yesterday were too small to have an appreciable fall speed, so they don’t fall out either.

Since I have published a lot of critical work on cloud seeding, one might ask if these clouds could have been made to snow by artificial means?   Even as a long time critic, the answer is an unambiguous “yes.”   With a small plane, and a little dry ice, you could have made a little snow fall out of these clouds because the tops were cold enough for that.  Dry ice, the substance you would have used,  has a temperature of -78 C, and when pellets falling, they leave a jillion ice crystals in their path as they cool the air momentarily to -40 C and below, the spontaneous nucleation temperature.  And, with ice in these clouds, the drops would be evaporating and the water molecules depositing themselves on the ice crystals.   Ice crystals in clouds of water drops are like little low pressure centers; the water molecules leave the drops and goes to ice, and ice crystal gets big enough to fall out.  Our natural precip here is like this most of the time.

So, summing up this little cloud-ice lesson, our clouds did not get cold enough, and at the temperature the tops DID get to, the drops weren’t big enough to trigger natural freezing.  Tell your friends.

The End.

“…goin’ down in the first round”

As Muhammad Ali might say, referring to the Climate Prediction Center’s three month outlook that was for dry conditions in Arizona from November to January.  So, the first round, November into early December, has delivered quite a punch against drought with another 0.40 inches here in Catalina last night.  Our December total is already 0.82 inches!  Rains have been bountiful, too, during this period in some parts of NM and Texas, horribly stricken with drought, so its been great run of drought smashing weather.   Check the latest 30 day US precip totals here (does not include the heavy rains of yesterday in TX, however).   And from WSI Intellicast, this 7 day total precip map.   Excellent.    In Catalina we now have had 2.63 inches since the beginning of November.

Below, the CPC forecast for November through January for the US issued last October 20th.  These predictions are weighted by the “moderate” La Nina event now going on in the central and eastern Pacific.  A La Nina leads to greater chances of dry conditions throughout most of the southern US.  Hence,  this forecast.  However, the correlations between a La Nina and the map shown below leave plenty of wiggle room, especially early in the winter.  Later in the winter is when the great southern US storm deflecting property of a La Nina has its greatest power, so it’s really good that we’re getting slammed early by decent rains; it might be a very dry late winter and spring.

Remember 1971-72?  And how wet it was in November and December in the SW, and then poof, almost nothing in the way of precip after January 1st?  It was awful. (I was weather forecasting in Durango, CO, then.  ((Hay! Not for TEEVEE, but for a randomized cloud seeding experiment!))


Had some pretty Cumulus clouds yesterday before the gray Nimbostratus layer moved in.  Here are a couple of shots around the Catalina area.  Always nice to see snow on the Catalina Mountains.

The last one is from today showing the gorgeous scenes, changing by the minute as the cloud shadows roll by, of the low level on the snow on the Catalinas.   Even here at just under 3200 feet elevation, last night’s rain ended with light snow for a few minutes.

Mods (from U of AZ Wildcats) don’t see precip from this next cold trough, one that lands on us tomorrow.  Darn.

Suddenly, it occurred to me that I want you to look at these forecast maps from IPS Meteostar for the next 15 days.  Just changed this to the intermediate model run, updated at 06 Z, 11 PM LST.  Much more “interesting”–means this writer saw MUCH more precip in AZ on the updated model run just now.  Check out the massive trough 12-15 days out and cross fingers.  Man, this is an exciting new change!

The End.