Being a fussy type, I will complain that the sky has not been quite right lately with a continuing, though slight, smoke layer aloft. The sky has not been as blue as it should be. A couple of days ago when it was windy, it was good ole’ Arizona dust made the sky not so blue,most of that brought in from the northwest of us. Dust as a rule, is not up high in thin layers like smoke can be. Dust particles are usually too big for that (several to 10 microns or so in size). They fall out quicker. The period in this sentence, font size (12), is about 100 microns. Hmmmm. Wonder if that translates well to your screen? Probably not. Oh, well.
Today, however, we will see some interesting Cirrus clouds (it’s dawn now and they’re already here), probably some uncinus types with tufts and long interesting twisty trails hanging down. Later, before the clearing, these ice clouds will likely be thick enough to call them “Altostratus”, those ice clouds thick enough to produce widespread gray shading. Only one kind of Cirrus is allowed, in our cloud definitions, to have gray shading and that is the species, “spissatus”, and they can only be patchy clouds that don’t cover a lot of the sky like an Altostratus cloud would.
Here’s where you can see this hook shaped arc of Cirrus coming at us in this 24 h loop from the University of Washington Huskies Weather Department. Also, you can see it on this map below, also from the Huskies. Of course, this is a “man’s” (read, adult person’s) weather map, not one of those Mickey Mouse types you see on TEEVEE so much.
What’s the payoff today? A great sunset as the back side of this blob of ice clouds should be over us by late afternoon. That will allow the sun to underlight the bottoms of the Cirrus-Altostratus clouds, the latter likely with virga which will add to the effect by having something like stalagmites hanging down in that underlit time. Well, we are out on a limb here with so much detail, but that’s what I would hope for.
Dust, then sprinkles ahead
In the meantime, the models have been revving up the strength of a trough of cold air headed this way. Tomorrow it generates the dreaded Tonopah, Nevada, low pressure center, and again, as last week, it will be intense, lots of isobars around it. Lows like to nest around Tonopah and so that phrase, “Tonopah Low” has been around for decades. Tomorrow, as the wind picks up in the afternoon, you’ll see the usual coating of dust start to build up on your car, etc. I wouldn’t wash it until Thursday.
That’s because now, the jet stream at 500 millibars (18,000 feet above sea level or so) will finally get a little to the south of us, and the wind maximum at that level marks lower clouds and precip to the north, and much drier air to the south.
As that jet passes over us tomorrow night, it should mean that by Wednesday morning we have some lower clouds like Stratocumulus and Cumulus a plenty, and with the lower freezing level that comes with troughs, those clouds should be able to produce ice, which in turn means snowflakes that melt on the way down into raindrops. Well, really stretched that out. But, then again, I am not a TEEVEE weather presenter who would short change you on technical explanations because they think you are too dumb to take it. Oops, going over the line here.
Enjoy 1) the sunset. 2) the dust tomorrow afternoon and evening–really, there’s nothing you can do about it; 3) some “glaciating” clouds on Wednesday, maybe with enough stuff coming out to produce a few hundredths even. Fingers crossed.