Lots of nice Cirrus clouds yesterday, but no Altocumulus castellanus later in the day yesterday as it was asserted there would be. Only a flake or two of Altocumulus “uncastellanus”, (flat-as-you-can-get lenticular) clouds off in the distance (see bottom of page). BTW, I obsess over being right. I thought you’d want to know that about me since you come here every day and I am part of your life now. So, I made up the word “uncastellanus” because it sounds like in some way I might have been right about yesterday if you are reading quickly.
BTW#2, as per usual tendencies, the bottom of the moist layer where the Cirrus clouds were yesterday did slide down toward us during the day, from about 24 kft above the ground at 5 AM and -34 C to 21.5 kft and -27 C at 5 PM, the latter still pretty cold for clouds comprised of droplets, but they were there.
Below are a few “character of the sky” photos from yesterday. If you want the whole day, go here to the U of A time lapse. In this movie for yesterday are a few spectacular Cirrus castellanus clouds just after 11 AM AST. You’d swear they were real Cumulus clouds at first, but then you see them moving along at the same speed as the Cirrus clouds, glaciated with fall streaks beginning to come out as they go by.
You’ll also see in this movie, a lot a wind shear, changes in wind direction and or speed, with height, quite at lot visible early on. It will be easy to see how those trails of ice crystals get skewed away from the parent cloud producing these sometimes incoherent patterns when viewed from below.
Expecting castellanus TODAY, dammitall!
I think you can kind of sense my ferocity here about getting things right… A LOT of weatherpersons are like this, so its not just me.
As a potent trough blasts into Cal today, AZ will be in the rising motion part of that trough. So what happens? The air temperatures aloft begin to fall as the subsiding air pattern over us lessens and moves off to the east. With that tendency for subsiding air gone, some layers of the atmosphere will develop larger drops in temperature (lapse rate) as you go higher, a situation ripe for castellanus clouds, ones that look like miniature clouds that have been on a growth hormone. Those clouds (Ac cas) are probably my most favorite clouds, itty-bitty towering Cumulus clouds and so I do have a tendency over predict them based on a desire to see them. You can see what the TUS sounding is supposed to do here from the U of A model run. You’ll see the temperature falling just that bit over us late in the day. Well, it will be interesting to see what really happens!
Lots of other kinds of clouds are likely, too, such as a patch of Cirrocumulus, more Cirrus, and a lenticular here and there as the winds continue to increase over us. Gee, with the air coming from so far to the south, maybe even a scruff or two of small Cumulus clouds may show up, too, though Mr. Model doesn’t think so! Quite a cloud day possible.
Due to the high altitude the Altocumulus are likely to be at today, above 15, 000 feet above the ground, they’ll likely be cold enough (tops colder than -10 C, 14 F) to produce ice crystals and snowflakes, which we will see as virga coming out. Again, a fabulous sunset is possible because of the presence of more than one cloud layer.
Still only a dusty cold snap in the offing as the main upper trough bashes Cal Thursday and Friday before settling in over AZ on Saturday and Sunday.