Cloud-maven

I guess that title is a little long…

Yesterday’s lack of much temperature change during daylight hours here in Catalina reminded those of us from the Wet Life in Seattle and other locales west of the Cascade Mountains of our fall and winter and early spring days.   Its not unusual in those locales for the temperature to stay about the same all day due to the weak sun.  Here  temperature as Cat mtn profile is our Catalina temperature record for yesterday, one that resembles a west to east cross section of the Catalina Mountains.

However, and only about 10% of the size of the shower line I expected later in the day yesterday, clusters of “mild” showers,  not really having good shafts,  moved across that had a tiny pellets bouncing off the hard surfaces.   Nice.  When they’re as small as they were at my house (about 1/8 inch in diameter is all) they’re generally referred to as graupel, or soft hail.  These originate as ice crystals or snowflakes that collect a lot of cloud droplets on the way down and end up being little snowballs.   The process is the same as opaque rime icing on aircraft, or when clouds are below freezing on mountain tops and the trees collect ice from the impacting cloud drops.   You can usually crush soft hail/graupel in your hand.  On the other hand, if they originate from much larger drops, the icing is clear.   Won’t go into drop size differences here.  Some nice examples of rime ice can be found here from a “Romantic Asheville” (NC) website that popped up under a “rime icing” search.  Hmmm, “romantic”….

Next, while viewing the time lapse movie of clouds over the Catalinas and over us from the  U of A campus, I noticed a nefarious cloud making machine that I did not know about before this morning.  Take a look at this movie here and see this little plume on the far left of the picture tooting little clouds up into the lowest layer of clouds yesterday,  beginning about 40% into the movie.  At that time ther is an eruption of much lower clouds from the southeast.   What kind of weather making experiment are they doing to us now?   (hahahha, just kidding)

Looks like a steam plant plume ejecting a moist and heated plume right into those lowest clouds, adding some density to them.  Kind of neat to see that.  Also, you can see how the wind changes during the day yesterday.

BTW, some of the tallest buildings in Seattle (We calls’em, “cloudscrapers”) also put out little cloud forming plumes, adding to the body of clouds already in place.  “Great!”-sarcastically spoken.

The End.

Nice rainshower starting right this second at 4:03 AM which will likely add to this total.  Just did add 0.01 inches.  I was hoping for an inch or more from this situation, and it can still happen before its over by late today.   But,  in the desert,  you always have to prepare to be disappointed when it comes to rain.  However, that 0.38 inches (now at 5:18 AM) is significant and will keep prospects for a great spring wildflower bloom going.   Local 24 h amounts can be found here, FYI.  BTW, when you see in this list that Mt. Sara Lemmon has a ludicrous “zero” precip, as in this list today,  its because its snow, not rain, and isn’t melting into the gage.

BTW, a great way to observe what’s going on around here is via the Wunderground maps here where you can animate the radar.  Also, if you pay them a very small fee, you can get these maps advertising-free.  These guys do a great job I think.

First, when you open this map, you will be surprised at the number of “personal” weather stations being displayed around SE AZ, especially if you drill down.  Almost certainly you will begin wondering whether YOU should have one as the herd instinct begins to activate.  That would be great if you got one!   It is pretty remarkable how folks get all wound up about weather and decide that the number of official reports aren’t good enough for them; they must have a station next to the BBQ grill in the backyard to REALLY know what happened, and what is happening while the grill is heating up.  I have one, if that helps in your decision process.  Its here.  You have to drill down on the Wunderground map, linked above, for it to show up, though.

Cold Dead Ahead

A second atmospheric “iceberg” is shooting down out of the north at us and winds up just to the northwest of us.  The USA NWS “WRF-GFS”  (I pronounce it, “WURF-GOOFUS”)  model (whose output is shown below) had that second low too far to the east for much of any precip here in prior runs.  But last night, that model has produced a forecast that raises our chance of precip from this second blast of cold air.  Eerily, these maps eventually resemble that horrible cold spell of last early February, though fortunately it will not nearly as cold this time.  Still, you get goose bumps looking at that historic pattern recurring again.

Here is a color-coded temperature forecast from the WRF-GFS at the 500 millibar level, around 18,000 feet.  Below, a couple of snapshots from that model run based on last night’s data.   The first map below is what this morning was supposed to look like over us.   This first map is just a 12 h prediction so its likely that there are few errors and it will look pretty much exactly like this.  (Remember though that the little errors that ARE there at the outset grow into mighty oaks in errors in a few to ten days out making those forecasts unreliable in details.)

Note on the first map, that “incoming”, namely, that purple blob of low temperatures approaching the USA border from Canada.  It will be extruding southward right to AZ while our present, overhead cold low spinner drifts off to the east, passing overhead of my house about 7 PM tonight.  I will be looking up then to see what it looks like.

The second map, valid for Saturday afternoon at 5 PM LST,  shows how that blob of purple approaching the US now, has spun off an “iceberg” that is shown sitting over Kingman, AZ, pretty much where the current cold low shown on the first map is sitting.  That means we have a very slight chance of more showers, some mixed with snow here as that one goes overhead on Monday.  The chances of precip are down because this blob of upper cold air has such a long overland trajectory.

Finally, its the last map that is eerily similar to the awful cold wave situation we had last February.  It brings shudders just looking at it, reminding one of all the damage that February cold snap caused.

You can see on this last map how the very lowest temperatures (purple areas) have extruded (I love that word!) all the way down into Colorado, while another vortex has formed in AZ.  Probably too dry for anything but a tiny chance of snow flurries here on Monday morning, maybe a couple of shallow glaciating Cumulus clouds in the afternoon is all we’ll see.

The following Tuesday morning will be awful cold.  Check NWS forecast for Catalina here.  You’ll see some temps below freezing are expected, and if you live in a gully, it will be much colder than those shown here on the clear nights ahead!  Check out the minimum temperatures some time as measured at the Catalina State Park (here, pluck the morning reports for Cat SP) in the CDO wash on clear nights.  Unbelievably low sometimes, as much as 10-15 deg colder than here at my site on a hill side.

Enjoy some more rain today!

The End

Hi, again,

Go here for as good as the timing on the incoming rain gets, graciously provided by the University of Arizona Department of Atmospheric Meteorology.  This model run, now in progress says that rain begins to move into the Cat Mountains by 3 PM tomorrow.  Exciting.   Also you will notice in this “total accumulation of precip” presentation, that we’re expected to get a very nice rain, looks like half inch to an inch by Friday, 2 PM, and even then it ain’t over.   Also you’ll see that by that time, areas to the north of us get SEVERAL INCHES according to this model.   However, those indicated amounts have to be used with caution since they originate with imperfectly known cloud and precip processes that we try our best to represent in models, but still come up short most of the time.  In this case, there is a “tendency” in this model to over-predict the precip.   And the onset timing could be off some as well.

Also, if you like to see time lapse of the clouds you might have missed yesterday, they have this U of A campus site with the roof cam pointed at the appropriately named Cat Mountains.  Us in Catalinaland are just behind Table Mountain, Pusch Ridge in that time lapse.  This time lapse will REALLY be interesting in the next few days.

You will also see, if you look closely, why we think of Cirrus clouds as “precipitating” clouds.  In the time lapse you will see trails of ice crystals falling out.  They are virtually dust like in size (well, they run 100-300 microns in diameter, those ones falling out), but if in it, you would hardly notice that kind of precip.   You would only see glints of crystals going by, and a dust like coating on the ground (if you were on Mt. Everest or K2).  So, once out of the body of the cloud they start to evaporate, fall even less slowly, and the trail becomes almost horizontal.   Sometime horizontal (flat) layers have precipitating Cirrus above them constantly dropping new crystals into the flat, constantly thinning layer in kind of a quasi-equilibrium.

Oops, enough of that.  Here’s is yesterday’s Cirrus-induced sunset, definitely more interesting than the above.

The End and waiting for the RAIN!

Who can forget rock band, Foreigner?   Remember that other hit song from that album about desert people like us, “Hot Blooded”?  I do.  But I was in Seattle then (1980s) at the U of WA, never dreaming I was going to be in hot blooded in Catalina, AZ, especially in the summers.

Today’s amazing progs with such wonderful sights maybe think of that song title because two of the same kind of upper cutoff lows are forecast to sit and spin over the Southwest in the next few days, with noticeable weather happenings,  like the wind picking up as early as Windsday (hahhaha).   What’s weather website without juvenile humor now and then?  But seeing this model output has made me quite happy, feeling good about myself and the world around me.

Again, I start with the Canadian’s (whom I sometimes tease since my relatives there might be reading this blog) model output (in totality here) from last night’s 5 PM LST global data.  The first panel is last night’s initial weather maps just to show you how drastic the change in the weather is going to be.  Look at how there is nothing but “high pressure” all over the West.

Then here’s what we see in just 60 and 132 h from that map, that is,  just this Friday morning at 5 AM LST, and Sunday morning at 5 AM (second and third maps).  Look in the upper left panels and note how similar Friday and Sunday are!  Amazing!  And the positions predicted are great for huge dumps of snow in the north parts of AZ and good rains here.  The aspect of this that really helps us is that the rains/snow won’t just come in ONE several hour spell, but should recur after they start because cut offs by their nature don’t move much but kind of wobble around like they look like on the upper maps, spinning tops, ones that initiate new bands and blobs of rain while they sit and spin.  And we will be dealing with TWO of those! Fantastic.

Now, for fun, the thing to do is NOT look at any more model runs, they could hardly be better than these, so why look?) and just watch the sky change over the next five days or so, dreaming about what will be, what COULD be.  Enjoy it all.  No matter what, the clouds will be great, the rain treasured, as will those sunrises and sunsets from time to time.

What a life we have here!

Starts with the starting model map since that seemed to be a good place to start, then Friday and Sunday maps follow, respectively:

Droughtbusters! (When you have a drought)

Kind of exciting today as another complex, hard-to-predict upper low center breaks off from the main jet stream and circulates down into the Southwest on Thursday and then sits and spins for a couple of days.  What so exciting to trigger a blog in the afternoon?

One of the enigmas has been that the Canadian model, often shown here because most of my relatives are Canadian, and the USA ! model have had large differences in where this upper low center will end up once in the Southwest and cut off from the main flow.   Once in place, it sits and spins for a while, which means that if you are in the right place, it might rain off and on for a couple of days. A cut off low in the SW is one of my favorites patterns of all time, not that you care.   Remember that low of December 1967 in Arizona?   The one that nearly buried the State in snow when it sat around for a couple of days in almost the same spot?

Well, this incoming one is not as gigantic as that 1967 one, but, it has potential to produce a lot of rain in the State for the same reason: sitting and spinning like a record player somewhere in the SW for a couple of days before moving on.

Today’s model runs were exciting because now the USA and Canadian models are in sync.   Previously the USA model had the low in a spot in which most of the rain would miss us, while the Canadian one had a pretty wet scenario for us.

Now, from this morning’s global data, they BOTH see the low ending up over southern California, drifting very slowly eastward, and BOTH have good rains predicted for the State!   Imagine a couple of days of good rains.  Wow.  Droughtbusters!  (in the plural because two models have this scenario now.)

Well, of course, it doesn’t guarantee it will happen just because both models are showing the same thing over several days, but it is very encouraging.  Fingers crossed.

Below, an example of this cut off low, well away from the main jet, sitting over about San Diego.  This depeiction is valid for Friday morning at 5 AM LST.  The whole loop can be seen here.  Enjoy.

The End.

Gorgeous day yesterday with lots of…Altocumulus opacus with castellanus clouds here and there.   But you knew what kind of cloud those were already.  And our upper trough and clouds situation closed out overnight with a decent 0.23 inches of rain here in Catalina.   “Nice”,  since it wasn’t a sure thing that we’d even get rain when the tropical plume from former hurricane Kenneth (R.I.P.) was slipping by to our SE across Douglas, AZ and into NM.  Dang.  So, it WAS a 24 h to be thankful for.

There was also, ever so briefly yesterday, the “flying saucer” cloud, an Altocumulus lenticularis, apparently hovering above but really a bit downwind of the Catalina Mountains.  This photo is one of the better of that cloud variety I have taken.  Also, while it may LOOK like its hovering over Samaniego Peak, its really quite a ways downwind from there. You’ll see that in the U of A time lapse movie for yesterday here.  It appears about one minute into the movie, or just after 9AM if you can read the time signature in the lower right hand corner.   Lenticular clouds usually form when the winds aloft are quite strong, and the air at the level of the cloud is “stable”, resists moving up and down so you get laminar flow instead of turrets and bumps on the top.  Below a couple of other shots characterizing the day.

Ahead?  A LONG dry spell.  Dang#2.

The End.