White holiday season day still in the cards

“Cards” in title referring to computer models, not some kind of goofy fortune telling thing, though, in fact, the models can be kind of goofy, too.

Also by talking about the exciting weather ahead here in Catalina (how many inches will it pile up?), I wanted to deflect attention from error.  No rain here in Catland yesterday, as thought likely a couple of days ago (thanks to Enviro Can’s GEM model), though a couple of light showers and even a thunderstorm were close by.  There was even a lightning strike from the cell shown below according to the National Lightning Detection Network, one that’s off limits for the tax payers who paid for it.  (Must go through private weather providers or work at a university to see the NLDN directly, quite an outrage, as was the case in the early years of Doppler radar data.)

4 PM AST.  Radar and satelllite IR image from IPS MeteoStar.
4 PM AST. Radar and satellite IR image from IPS MeteoStar.  Arrow points to Cumulonimbus cloud that briefly erupted to the SE of us.

While Yesterday’s Gone, for Chad and Jeremy1, here are some clouds shots anyway…

First of all, the long foretold and then bailed on Altocumulus castellanus (and floccus) showed up yesterday morning:

11:09 AM.  Altocumulus floccus and castellanus.  Floccus has a ragged base.  From the taken- while-not-driving collection though it looks like it.  Professional course, do not attempt.
11:09 AM. Altocumulus floccus and castellanus. Floccus has a ragged base; cas a flat base, not that it matters that much. From the taken- while-not-driving collection though it looks like it.  Professional course, do not attempt.

 

2:59 PM. Later in the afternoon, scattered Cumulus clouds were aplenty under some remaining Altocumulus, but did not attain the ice-forming level, with a couple of exceptions, which of course, I will have to show.
2:59 PM. Later in the afternoon, scattered Cumulus clouds were aplenty under some remaining Altocumulus, but did not attain the ice-forming level, with a couple of exceptions, which of course, I will have to show.

 

3:44 PM.  Moderate Cumulus (mediocris) over the Catalinas.  Can you find the remnant puff of ice from the highest turret formerly in this grouping?
3:44 PM. Small and moderate Cumulus (humilis and mediocris) over the Catalinas. Can you find the remnant puff of ice from the highest turret formerly in this grouping?  That ice puff up there tells you that one of these rained on someone earlier. Hope you logged it in your clouds and weather diary…

 

Same photo as above except with annotation and s... like that.  I don't cuss but it sounded funny to write that, detracting just that bit from erudition.
Same photo as above except with annotation and s… like that. I don’t cuss but it sounded funny to write that, detracting just that bit from erudition; stepping out of character for humor.  I laughed anyway.  Maybe this blog is just for me anyway.  That’s what my brother says.

 

4:40 PM.  Dramatic scenes like this on the Catalinas closed out our dry day.
4:40 PM. Dramatic scenes like this on the Catalinas closed out our dry day.

 

5:19 PM.  Fading clouds and drier air move in from the southwest.  All threat of rain is gone, but not of a great sunset.
5:19 PM. Fading clouds and drier air move in from the southwest. All threat of rain is gone, but not of a great sunset.

 What’s that about white stuff?

Here’s the latest 500 millybar map (flow around 18,000 feet above sea level):

Valid at 5 AM AST, Friday, December 20th.  Those bowls in the SW are going to be SO COLD!  Poor guys.
Valid at 5 AM AST, Friday, December 20th, rendered by IPS MeteoStar. Those bowl games in the SW are going to be SO COLD! Poor guys.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Big U-turn in jet stream shown over AZ and all the way to Canada!  On the east side of the U-turn are clouds and precipitation and sh…  like that. (hahahaha, to continue an out of character theme for a second for humorous purposes…)  In the middle of the U-turn are the lowest freezing levels, on this map,  low enough in AZ for snow here has either already occurred, or is on the doorstep or already here.  On the backside of the U-turn, where the wind is blowing out of the north, the air is mostly subsiding, drying out, clearing off, allowing huge amounts of infrared heat to escape from the earth’s surface into space.

Here’s something else…  See how much stronger the wind at this level is over CA, OR, and WA than in the eastern part of the U-turn?  That means the U-turn itself is going to push farther S as time goes on, a mechanical thing.  This would be a VERY cold episode for us, hard freeze variety, when the clouds and precip clear off.

While the amount of precip here has varied as the exact configuration and placement of the jet has varied in model run to model run, the OVERALL pattern of very cold air getting here has remained in place.  Be ready!

Note, too, in the map above that the strongest winds at this level are WELL south of us, and so its already preciped here.  Now I will look and see when the precip starts with this gargantuan trough and record cold (in part of the West) pattern first takes hold:  OK, looks like the night of the 19th-20th, starting out as rain, changing to snow as storm ends, IMO.

Terribly cold weather will impact the whole West, and punish the northern Rockies and Plains States again.  You’ll be reading/hearing about this one during the through the runup to Christmas, so similar to the blast of cold air that broke so many low temperature records last week.  Will be tough on travelers.  Not so happy about that prospect.

BTW, just to make a point about those crazy NOAA spaghetti factory plots:  they have been pointing confidently, as readers of this blog will know, for more than ten days or so, to another pretty extreme weather event here and throughout the West, and that’s where they come in as an important tool for weather forecasters, when a strong signal shows up.  Normally, weather forecasts go pretty bad after five days to a week.  But “Lorenz”-spaghetti plots can help us see through the fog of middle range forecasting sometimes.  That’s why you look at them everyday to see what’s up beyond the first five days or so.

BTW#2, all of this crashing down of the jet stream suddenly into the West after our nice spell of weather, is due to that jumbo storm that erupts in the western Pacific, builds a high pressure ridge ahead of it, and then that causes the mild-mannered jet crossing the coast in British Columbia to go into a southward, buckling rage, dragging record cold air behind it as it does so from northern Canada.  That key gigantic eruption in the western Pacific has also been predicted with confidence day after day.

Really going overboard today, got up too early I can see that….  Below, the first the “la-dee-dah” spaghetti plot valid just two days from now:

See how the illustrative contours are piling into BC and northern Washington State?
See how the illustrative contours are piling into BC and northern Washington State?  Over us and the WHOLE West, is a big fat ridge.  No problems.  Toasty weather, here too, for December.  Note also, how small the errors are that are deliberately introduced at the beginning of the model test (or “ensemble” runs)!  They hardly make any difference in a 48 h forecast (the lines run on top of each other).  The giant low in the western Pac has not yet erupted, so there’s not much amplitude to the jet stream, its just pretty much west to east flow, la dee dah.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

But look below at the waviness (amplitude) of the flow in the Pacific AFTER the giant low erupts, forming a big ridge downstream!

Valid at 5 PM AST, Thursday, December 18th; pattern caving in.  Wrote all over this, got too excited about what's ahead.
Valid at 5 PM AST, Thursday, December 18th; pattern caving in. Wrote all over this, got too excited about what’s ahead.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Whew! Quitting here, got a little over worked today about the weather way ahead.  Too long to proof, too….  But HELL, its the internet; don’t have to be a great writer to be on the internet2!

The End, except for historical culture footnote below.

————————

1Part of the “British invasion”.  If you’re a kid, have your parents explain to you that it was not a military thing to reclaim America except in terms of music.   Pop music here wasn’t good enough (Beatles were better than the Beach Boys I guess) in the mid-1960s, and so they came, and they came and they came from that little island nation with their weird hair styles and great hooks and dominated the air waves.  Pretty soon, everybody had weird hair styles.

2

From Saturday Review...
From The Atlantic Magazine…