More Cirrus on tap today

No, Cirrus is NOT a microbrew as you may have thought from the title and if you were visiting this site for the first time.  (and to continue being juvenile from yesterday’s “Dusty Parhelia” submission because that’s who I am….)

In fact, Cirrus clouds are the exact opposite of a microbrew. Cirrus is a high CLOUD, 15,000 to 45,000 feet above ground level, lower in the Arctic or when its cold, higher in the Tropics or when its warm, like today here in Catallina.  They’re composed of ice crystals with some momentary exceptions at the time of formation.   To continue a theme, there are no “ice crystals” in beer; beer is also generally found at ground level.

Q. E. D.

BTW, if you’re still interested in beer and clouds, get this book:

Clouds in a Glass of Beer:  Simple Experiments in Atmospheric Physics by Professor Craig Bohren.  In spite of having an interest in beer or perhaps because of it, he is a Distinguished Professor Emeritus of Meteorology at Penn State University, one of the leading party schools in America.  Writes about optics, too, a real atmo optician. Kidding aside, his book is one of the best you can get on how the atmo works.

To sum up, it should be another fun day of Cirrus cloud viewing for you and me.  What kind will we see?

Yesterday’s clouds

Man, yesterday was great!  Some unanticipated Altocumulus castellanus and floccus, middle-level clouds with little turrets, many having long fall streaks of snow (virga) rolled in during the afternoon underneath the higher Cirrus clouds, keeping the temperature down a bit.  Here are some shots of what went overhead, in chronological order, in case you missed the “show.”

The show ended with dessert, another one of our gorgeous sunsets; they are particularly so when two or more cloud layers are present.  In those case,  you see the residual scattered light that has passed through the lower part of the atmosphere when the sun sets, turning the lower clouds gold or orange (the longer, “redder” wavelengths of light are still making it through) while the higher ones, where the sun’s light is not so scattered in passing through the atmo, are that bit lighter in color, white before this last photo.  The greater the height difference in the clouds, the greater the differences in sunset colors between them.  When you add shadows and highlights where the sun is striking the clouds, well, it doesn’t get any better than this.  OK, I am feeling lazy now about captions; been up since 3 AM something.  Can YOU name these clouds?  If not, just enjoy.

The End.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 



Plethora of storms ahead; Catalina snow day still being foretold for Feb. 25th which is only nine days away now!

To help understand that odd word, “plethora” in the title in case you are befuddled by it, I have added a YouTube teaching module to help you out:   “What is a ‘plethora’?”

Well, one of the great model runs of our time has come out once again last night after yesterday’s great model run of our time  based on the that morning’s data.   SEVERAL rain days foretold in the next couple of weeks!  One of these is actually a snow day, Feb, 25th, first predicted by the models about a week ago.  This would be the “real deal” here in Catalina, not some “diabatic” (a weather term opposite of “adiabatic”) fluke as was our inch or so of snow two days ago, one that happened due to extremely heavy precip in the clouds above us, thus drawing the freezing level downward.

The first rain day is today, likely beginning after 5 PM AST, and then continuing into tomorrow for a second day.  Here are some rainy/snowy snapshots from our friends in Canada at the EnviroCan weather service where they use a modified version of the ECMWF (European) forecast model here. The first panel is valid for 5 PM today just before the rain is supposed to begin.  (If you don’t click on the panels below, you’ll need binoculars to see what I am talking about.)

Does this pattern look familiar in that first panel?

Yep.  “SOSO” as we have been seeing all winter when storms strike. In the lower left panel you will see all that moisture streaming (colored regions) into our today’s cut off vortex from the south from the Mexican Pacific and linking up with a moist plume from the Gulf.  Interesting to see that.  Also, as it gets cut off, and great for us, it begins to dawdle while edging eastward along the US-Mexican Border, allowing those moist plumes to “filler up”,  just like at a gas station.  So, the rainy areas with this low should be expanding/appearing as clouds are enhanced; deepen up and begin to precip. Very exciting.

What’s been great is seeing the amount of precip predicted in Catalina from this low increase gradually over time as the models were seeing that it was not going as far south as they thought earlier.  Here is another panel for this storm, valid for tomorrow afternoon at 5 PM AST.  While the low has gone by to the south during the day tomorrow, this model suggests that it likely will have rained on and off during the day.  This is because so much moisture arrived in this low that it has developed a “wrap around” band of rain to its north and west, good for us, kind of like a sucker punch.  You should be able to see that happening today and tonight in this great IPS sat and radar link, as well as clouds “appearing” over the deserts to the west and south of us, and then developing echoes as they deepen.

Our local U of AZ Wildcat Weather Department has this great depiction of this “wrap around” development from their own model run here.  Nice!

 Here are the additional days ahead with more rain, and also, low snow levels.  Mt Lemmoner’s rejoice!  Below, the next panel, Sunday afternoon into Monday morning, this next trough.

Brrrrr, another cold blustery day Sunday, but notice this one is NOT a cut off and so will move through rapidly.  Then, 4th panel, a dollop on Tuesday, just a minor trough passes by, and then, after a break, the Arctic iceberg on the 25th.  Check this trough out in the last panel.  Awesomely cold!

With luck, and a little verification of these predictions, maybe the washes will run later this spring!

The Cloud Report part of blog

Had some complicated, but nicely detailed Cirrus clouds float over in the early afternoon, a part of our invading storm’s circulation.  This was followed by a large clearing  and then encroaching Altocumulus patches trailing virga (ice crystals) in gorgeous, fine strands that wiggled this way and that in the setting sun’s light as that falling snow responded to slight changes in the wind below those little flakes of Altocumulus cloud.  Enjoy.

The End.

Sprinkles! (coded as “RW- -” if you are keeping a weather diary!) (Its not drizzle!)

Pretty excited up there, as usual.

The Cumulus and Stratocumulus clouds began filling in yesterday, and some shed ice/snow virga in the late afternoon.  With that a few drops of rain (melted snow, of course) plopped down on Catalina.  In case you missed those drops, here they are.

Also, here are a few shots of those clouds, ones based about 7,000 feet above us, judging from their height above Mt. Sara Lemmon.

Note the trails of virga dropping out of Stratocumulus clouds near and over the Cat Mountains in shots 3 and 4.  That was the “worst” of our “storm”  right then when the clouds got their deepest, which wasn’t all that deep, maybe 3,000 feet or 1 km.

By now, too, you will know instantly that the top temperatures of those clouds, to be able to produce ice, were lower than -10 C (14 F).  This kind of knowledge about local clouds and ice, is also a great “ice breaker” at parties and barbecues.  In fact, the TUS sounding suggests that the general top was about -12 to -13 C, with likely momentary tops protruding to -15 C or so.  This would suggest marginal ice formation in clouds with bases as cold as ours were, about -7 to -8 C (about 18 F).  (Strangely Believe It:  warmer cloud bases with the same top temperatures as we had yesterday, leads to more ice formation, and precip.)

Below the photos is the mid-level weather map for the time the sprinkles occurred from the University of Washington.  Since the wind follows the green contours on this map, you can see two things.  The wind maximum at this level (500 millibars) is south of us over northern Mexico, and that the wind was on the verge of shifting to the WNW above us at map time (5 PM AST yesterday).   That wind shift line is referred to as a trough, and at, and ahead of the wind shift line, clouds and precip are stimulated, while behind it, the air gets drier and clouds are mashed down or disappear.  You could even see that happening to the west of us yesterday afternoon while the clouds were heavy and precipitating over the Catalinas.  Those clouds over the mountains, too began to whither, and the virga ended, not JUST because it was heading toward evening and getting cooler, but also because of that trough was passing to the east at that time and the drier, descending air was moving in over us.

In this map, you will also see the much stronger trough over northern California, one that is racing toward us and will bring rain as early as tomorrow morning!  Yay!  However, the U of AZ massive Beowulf Weather Calculating Computer Cluster foretells only about a tenth of an inch from this next storm (here).  Boo!   I will suggest that might be a little on the light side, but that’s because I am biased and strongly want more rain than a tenth from this new storm; I’ll venture 0.25 inches or so here in Catalinaland by Wednesday morning.

More storms after this next one?  Oh, yeah!

The End

Some more of that Catalina climo

Here is a 35 year record showing what days have had measurable rain in January.  Sometimes “singularities” in weather show up in these kinds of charts of tempearture or precipitation, such as the “January thaw” that seems to occur with some regularity in the East but is “unexplained.”  You would be looking at our chart for Catalina for example,  a cluster of days with higher or lower precipitation and it MIGHT be a singularity, something that Nature likes to do at that time of the year rather than a statistical fluke that represents nothingness.  Here’s January, a month that averages 1.65 inches in Catalina.  These data are almost totally due to the careful measurements made at Our Garden organic orchard here in Catalina–only the last few years here are from measurements on East Wilds Road.

Not much to see here.  That peak on the 6th looks more like a fluke rather than a singularity.  You would never say that one day represents a singularity, but maybe 5-10 days.

The reason why I wanted to see this was because of the striking changes that were foretold by the “WRF-GFS” model 36 h ago and were shown here yesterday.  Was there a singularity that might support a greater chance of rain in SE AZ in mid-January, and therefore, cast that bit more credibility on such a huge model change?

I would have to say “no.”  And, not surprisingly, that huge change has gone bye-bye in the models.  Nothing like it is shown now, though they do have a rain situation developing for here by the end of the 15 day run (around January 20th and beyond).    But this rain comes out of the lower latitudes of the Pacific, a completely different direction than was shown just yesterday, and if the models are correct in this pattern breakdown, it means flooding in California as the flow breaks through to the coast from the Pacific.

Below, what the models came up with based on last night’s global data, again, from IPS Meteostar, whose renderings I favor.

These are exciting times for those of us who peruse the models.

Why?

These vast changes indicate that there is something far, far upwind, perhaps a data sparse zone, errors in reported measurements that is causing a problem for the models and that more changes in their outputs may come down the line until that problem is better “resolved.”  (They are never perfectly resolved.)

So, every 6 h update of the models is a “must see”, with the persuser (me) holding his breath with excitement.  In these cases, its all “good” because a rain situation is foretold for us.  Take a look at where the jet stream is compared to where it is now, up around British Columbia.   You can see it barging into southern California and major rains ALWAYS accompany this pattern.  Also, you can probably count on at least two storms breaking through before this pattern changes much.   The reservoirists in Cal will be very excited to see this pattern develop since most of their holdings have much below capacity.  And these kinds of storms usually produce significant rain in Arizona, too, though here we would be a little far south to get the brunt of those storms in this scenario.

Pretty clouds yesterday

Can’t leave without a little cloud excitement.  I wonder how many looked up and saw this little beauty go by (shown below)?  So pretty and delicate-looking, as unusually thick virga (snow) fell from this little cluster.  It would be called, “Cirrus uncinus” at this stage.

That snowfall probably began developing one-two hours before it came over us, and the cloud patch would likely have been fluffed up on top that bit and as a mostly liquid water cloud, that is, an “Altocumulus castellanus” before becoming this “uncinus.”

Below we saw the dying remnants of that patch, the snow to finally stop falling out with the parent cloud mostly gone, and that snow continuing to dry up on the way down.  Lots of nice cloud sights yesterday, in fact.

Enjoy.

 

 

 

 

 

Invasion of the water molecules

At least more of them….   Overnight (take a look here), the dewpoint temperature, a measure of how much frost would build up in your refrigerator freezer and/or drip down the walls of it if you left the doors open and the refrigerator on, climbed a whopping ten degrees early this morning!  

Yay,  “mo better” humidity for storms!  This will mean lower cloud bases today, and that in turn means that the rain that falls out of the thunderheads with their anvils (aka, “Cumulonimbus capillatus incus” clouds, if you want to impress your friends) will reach the ground in torrents; the  rainshafts will be opaque under those clouds.   This will be quite unlike yesterday, where rain fell,  grudgingly it seemed,  from the isolated, high-based, and rather shallow Cumulonimbus clouds seen around Catalina.   This is the first day that, to focus on MYSELF for a second, I….have waited for all year!  I am not one of those little babies that can’t take a little heat and humidity of the Arizona summer and have to head off to his/her mountain palaces or shacks, as the case may be.

Now, of course, if you have any photographic documentation inclinations, you’ll definitely want to get some “before” shots of dusty cacti, dust-covered mesquite trees, your car, check the amount rocks around the little hill your house is on (I don’t think we have enough, for example) and be ready to get some “after” shots once our summer summer’s rains begin and the dead desert springs to life, one of nature’s big miracles around here.  In fact, it would be that bit better if you had a time lapse camera set up so that we could see this change take place over a period of a month or two.  Thanks in advance for doing this! I look forward to seeing your work.

Below, an example of dead desert taken during a horseback ride yesterday.    Also note in the second photo,  some large black birds in formation on the top of telephone poles, wings out.   Sometimes they extend for miles on top of telephone poles.   They do this when the relative humidity is about to go up in some kind of homage.  (OK, I made this up.)

How much rain can fall in our most intense rainshafts, the kind that you can’t see through, are virtually black, and also have just dropped down from the cloud?  (In “conversational meteorology”, when this happens, you might exclaim to dinner guests, “What happened to the view of the Tortolitas?  Just a minute ago there was only a dark cloud base over them, and now, 2 minutes later you can’t see them at all!  Man, look at that shaft of rain over there!”  A murmur develops among your guests…  They’re impressed by your interest in natural events.

Well, we have our measurements here in Arizona.   And once in a great while, something extraordinary like this “bottom drops out” situation hits a hi res gage.  Well, Floridians, you don’t have that much on us.  Our gages have indicated that a whopping  1-2 inches of rain can fall in but 15 minutes!  Unbelievable!  In those cases, its pretty much a whiteout inside the heart of that newly fallen shaft, and your roof will become the equivalent of Bridal Veil Falls, Yosemite.

Please note black dots on top of telephone poles in second photo.  They’re birds.  A close up follows, so that you can see I did not just make this up.  The clouds?  Center:  Altocumulus opacus virgae (has some stuff falling out it) with some “perlucidus” thrown in.

The End, except for the photos below.

The Twelve…rain drops in Catalina, that is

Well, maybe there were about 27, but anyway….not very many; still,  those drops were to be treasured after not seeing a single  “hydrometeor” display in SE AZ in so–ooooo LONG A TIME!

———————————-

PG-13 advisory; DRIZZLE is discussed

I have to warn you at this point.  That rain event yesterday WAS NOT DRIZZLE!!!!!!!!!!!!!!!!!!!!!!!!!!!  I will be ROYALLY PO-ed if I hear someone in my social network or a TEEVEE weather presenter say that it “drizzled” yesterday!

Why make a BIG THING out of the correct type of precipitation?

I have to tell you a true story (well, I don’t have to, but I am going to anyway) about the importance of drizzle (i. e., fine, close together drops that appear to FLOAT in the air).   This event happened during my cloud seeding “vigilante” adventures (see Publications for samples).   A well-known professor of cloud seeding in a foreign country asked me to leave his office and never come back after I told him it had been “drizzling” outside, “10s per liter” in the air.

Drizzle is a profound indicator of cloud structure overhead, and the presence of drizzle falling from the clouds in that professor’s region’s meant his numerous reports of how clouds were, ripe for cloud seeding,  were in substantial error.   So you can understand why a report of true “drizzle” would naturally be upsetting to that professor.  Man, am I digressing here!  Yikes.  My apologies. (BTW, those reports WERE in error, confirmed by aircraft years later!   (Spiking football now, with a proper amount of decorum, of course!)

——————————-

OK, back on task….

With the sky full of low (“boundary layer”) clouds by mid-day (f you’ve forgotten, that was yesterday, May 10th, 2011) and with RW— in the air  (“triple minus”, extremely light rain showers) by 1:30 PM,  with gusty winds,  temperatures in the mid-60s, it turned out to be quite a “storm.”  It just as well could have been but a mostly sunny day with just a scattered Cumulus clouds here and there the way some models were “telling it.”

Here’s a pictorial on how it went, from a Catalina, AZ, perspective:

1) 09:29 AM, itty bitty Cumulus (Cumulus “fractus”) starting to appear,

2) 12:03 PM, larger Cumulus growing up into Cumulus “mediocris” beyond Tortolita Mountains on the horizon,

3) 12:29 PM, virga and rain visible to the NW horizon!  Now I am getting apoplectic since the best models in the world did not have this precipitation over thataway!   But there it is, bigger than watermelons.  The models have to be really red-faced about this! Not everything in the world is predetermined by numerical models; you can  say things that might be right and those models are WRONG!  Just like in the 1970s when a lot people thought global cooling was underway and that’s where we were headed!  But they were WRONG!  Who were those clowns anyway?! (hahaha, sort of).

4) 1:25 PM.  Now where was I before all that excitement?  Oh, yeah.  Here’s some ice for you.  See the frizzy top parts of this cloud in the center of this photo above the dead tree that the birds like to sit in?  Well, them’s ice crystals, and likely snowflakes that have formed in that medium-sized Cumulus cloud (above the dead tree) and its in the upwind direction.  Behind that is more ice and precip falling from a wide area of a Cumulus-Stratocumulus complex.

—–

Mini-diversion

Quiz.  How cold does the top of THAT cloud have to be to look like that (have that much ice in it, probably a few per liter to maybe 10 or so, not a tremendous amount but significant)?  Well, with bases as cold as they were, near freezing by this time of day at around 7, 000 feet above the ground or 10, 000 feet above sea level, around -15 C (or about 5 F).  Amaze your friends with cloud trivia like this!  Well, maybe not.

—-

5)  1:25 PM.  Here it is, a band of precipitating clouds overhead.  Now the ONLY question remaining, as you gaze upwind at Twin Peaks clearly visible through the precip and virga is, how much will there be?  None? Or as much as a “trace”?   Measurable is out of the question,  looking at this scene below the clouds.  Most of the visibility degradation is due to dusty air, not precip.  Darn.   (Amaze your friends with skills like this!  Well, maybe not.)

6) 3:03 PM.   The End is Near

7) 7:06 PM.  Nice sunset with traces of Cirrus and Ac len on the horizon, driblets from a storm striking the Pac NW.  Isn’t there always a storm striking the Pac NW? I digress again.

Man, I could go on about the weather maps of yesterday, but will quit here.

The end.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

If you REALLY want to see how it went, take a look at the U of A time lapse video here.

Yet another nice sunset

This shot, yesterday just after 7 PM.  Light snow (virga) is falling from relatively thick Altocumulus (opacus) clouds.  Just above the horizon you can see some little turrets poking up from a row of cloud bases making those  clouds Altocumulus castellanus.

Bases of these clouds, according to the balloon data obtained from Tucson Int AP indicated that the bases of these clouds were at about 13,000 feet above us here in Catalina, and the temperature was about 15 degrees F (about -10 C).  The tops of the clouds were about 18,000 feet above us, or at a chilly -5 F (-20 C), hence the thin, red-orange curtains of light snow illuminated by the setting sun below these clouds.

The clearing on the horizon marked the last of this “mid-level” moisture that streamed over us here in Catalina yesterday as an upper level bend in the winds, called a “trough” was passing by.

Below is a weather map of the winds (blowing along the green lines) at around 30,000 feet (300 “millibars” of pressure) and the clouds as shown on the satellite imagery.   If you look closely where the TUS data is, you can see a little fluff of cloud that made our sunset. A loop of the whole sequence can be found here from our friends at the University of Washington Huskies’ Department of Atmospheric Sciences.

Speaking of the Huskies, here’s what it was like today in Seattle, my former home.

The end.

 

In case you missed it…yesterday morning’s sunrise

A belated post, to be sure

Yesterday morning’s sounding when the Altocumulus clouds were overhead.  Bases about -18 C, tops -27 C.  Lots of ice visible along with widespread virga.  Whenever you see this much ice in small Altocumulus clouds like these, you should automatically assume that the temperature at the top is less than -20 C.

Usefulness of this information in everyday conversation, a module I call,  “Conversational Meteorology.”

The scene:  you’re walking/hiking with a friend on a warm morning when sunrise occurs.  You see these clouds.  The conversation has died off since you’ve been walking for several hours. You’re looking for something to say to re-energize the conversation.  Suddenly, you look up and see this scene below and blurt out, “Man, those clouds are cold!”  The volume of your blurtation has surprised even you, and startles your friend who was thinking about that tortoise on the trail ahead of you.  You rattle on about how cold the clouds with a followup, “Man, they must be at least colder than -20 C!”  Your friend seems puzzled at your excitement, but listens politely’ after all he is your friend.  You quickly add, “Almost every cloud has some snow coming out of it, no matter how small it is! Wow!”  Your friend, now saturated with your exuberances, asks if you saw the last episode of NCIS last night?

The end.

 

Exit right (or to the east)

Here’s what happened on top of us yesterday, that gorgeous snow day with so many wonderful sights to see. These maps below,  courtesy of San Francisco State University , for 500 millibar pressure level, about 18,000 feet above sea level, for 5 AM LST as the snow band moved through Catalina, and then 5PM LST,  a little before sunset:

 

 

A visual on what the clouds did as this happened yesterday is below. Interpretative cloud statements on the following gallery: shallow, deeper (precip begins in distance), deepest (small, soft hail falls here and there from miniature cumulonimbus clouds), less deep (barely-able-to-precip stage again), shallow, nil. Pics 1,2, 3, 4, 5, and 6, respectively.  If you want all the visual glory of yesterday, go to the U of A time lapse movie here.  However, you’d better hurry, these wonderful films are overwritten each day.  You can really see the clouds flatten out after about 3 PM LST here, and there are some spectacular snow showers going by on the Catalinas.

The end.

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“Send in the clouds”….then the wind, the rain, the cold front, the snow

Too bad Steven Sondheim wasn’t a meteorologist.  He might have written some great weather songs.  Instead, he chose to write about “clowns.”

Hmmmm.  Perhaps he WAS thinking about some weatherman in those days when he used the word “clowns.”  Who can forget that the LA Times  headline about weather forecasting in 1981;  the headline that declared that weather forecasting in the media consisted of,  “Clowns and Computers.”   Personally, I think humor has no role whatsoever when talking about weather….   Oh, well, I digress.

Today will be really exciting for us weather buffs (buffoons?)  We WILL be excited as mom Nature gives us a reprieve from the steady diet of glorious days, sunrises, and sunsets (this morning’s at left), paradise really,  with a blast of wind and then cold, likely to inflect more damage on our probably dead palms here in Tucson-Catalina-Saddlebroke.  Also this will be punctuated by a really exciting cold front passage, one where the temperature is likely to drop at least 10 degrees Fahrenheit within minutes as the wind shifts to the W  then NW after those bruising S-SW winds.  Probably here on the knob, we’ll see 40 mph or more in momentary gusts. Good-bye dead palm fronds.

When will the rain/front hit?

Well, lets say you don’t have a supercomptuer, a Cray, a Fujitsu, or access to thousands of PCs for parallel computing purposes to solve all the euqations in your 57-layer nested grid model using GFS-WRF outer boundary conditions, etc.,  for your subdomain.  What the HECK would you do, besides peruse the internet for answers, which can take a LOT of time?  Besides, we know that the internet is loaded with bad information…

Here’s what I do in this “bind.”   You get out a little piece of paper or Hollerith card (2nd photo), and you use the technique of “extrapolation.”  You got to the internet and check out the recent movement of the cloud band feature upwind of you by marking where the leading edge was, say, 4-6 hrs ago, then where it is currently, and move the two marks forward so that the back one (the old edge) is at the front of the feature and look at where that 4-6 hrs of past movement puts it  4-6 hrs from its present position.  Presently, the middle of this mass of Altostratus clouds (last photo) we have over us, will be around Noon to 1 PM using that technique.   However, there is no precip in that fat band of clouds, though one would think they would be thickening up as they approach us due to the Cat Mountains and overall effect of the Mogollon Rim.  So, maybe there will be some sprinkles around.  Our best models suggest the main rain band and front will not arrive until well after dark., and “extrapolating”, using the past 13 h,  suggests the front won’t hit until dawn tomorrow!  So, it”ll be a long time comin’, but “a change gonna come, yes it is.”

In the meantime, the biggest conundrum in today’s forecast is is what are these Altostratus layer clouds going to do (last photo), the ones at presently  zooming above us in winds of nearly 100 mph, bases at 20-22, 000 feet?  There are no radar echoes in Arizona to the west of us here in Catalina, yet as you can see they are drooping precipitation down at us in the form of virga.  As the air moistens below these clouds, as it should given the approaching system, that virga will tend to hang down lower and lower.  I would guess with this scenario that some very light rain or sprinkles will start reaching the ground this afternoon into this evening in Catalina ahead of the main rain area, the one due in well after dark. Our best model for this area is, of course, at the U of A, right here, and you can see the precip creep in then.  I think I would use them (U of A and NWS since the last time I used the “extrapolation” technique described above was in 1989 I think.  However,  you’d be surprised, when timing fronts coming in off the Pacific (where I was forecasting then), how well this simple, simple technique worked.)

Don’t be surprised if a bit of a clearing comes up toward later this afternoon to sunset.  Its not unusual to have a vast amount of quasi-threatenbing cloud go overhead all day, maybe with a few sprinkles, and then have a thin slot or brief clearing before the heavy clouds and rain move in later in the evening.  That appears to be suggested in the satellite imagery today.  We shall see! What an interesting two days ahead!

Still looks like a little snow in Catalina Sunday morning.  U of A mod indicates that the total amount of precip will be around half an inch.

 

BTW, while you’re digesting all of the above, here is where the weather records that were set for yesterday are.   You can see that a LOT of records were set yesterday!  Generally low temperatures and record snowfalls for the day in the northern half of the US beginning in the Mid-West and “thence” westward to the Pacific Coast.

 

OK, enough rambling!