FROPA! (plus some corrections in red….)

2:26 AM, Catalina:  S- (light snow), 33.9 F, 0.01 inches so far.  Precip not registering on Wunderground map site for some reason.

3:20 AM:  S– (very light snow), 34.8 F.  Temperature beginning to recover following precip, snow almost over, just a “skiff”, 0.3 inches.

6:20 AM:  Total now a measly 0.02 inches, less than expected, but in keeping with jet “rule of thumb”; nil precip until 500 mb core goes by1, and its just getting here now–120 mph wind now at just around 18,000 feet over TUS, an extremely exceptional event for winds that strong to be that low!

Correction on storm total:   Mr. Cloud Maven person forgot that when it snows, the small orifice into which the rain water usually flows without hesitation is clogged by that SNOW and the tipping bucket does NOT tip until the snow melts.  It began melting in mid-morning, and by the time it was done melting, there was a total of 0.10 inches, 0.14 inches at the Sutherland Heights gage.   This is a lot better than 0.02 inches.

County ALERT gage totals disappointing, too, just a few hundredths to a tenth of an inch; most with zeroes.  Mountains reports missing since it fell as snow.   (As with my own gage, the snow is melting into the buckets in the ALERT gages and they are now showing precip! )

(Here, the snow has melted and dribbled into the gage–NO it hadn’t!!!!) ((Shoulda looked inside the funnel before writing that!))

Only expecting small Cumulus today, but its cold enough that they could have some ice in them.  It would be something for you to watch for.

Here’s the temperature and pressure traces for this dramatic cold front passage (FROPA) here in Catalina last night around midnight with the chart below beginning around 7 PM, this from a pitiful jpeg of computer monitor since the software I use will not print two parameters on the same graph (please fix this, Lightsoft Weather Centre, UK!):SONY DSC

You can’t read it, but the temperature dropped from 50.x F to 33.x F in about an hour, with period of very light snow, no accumulation at the end of that hour.  And you can see what we meteorologists call a “pressure check” when a cold front goes by; starts rising immediately.

Yesterday’s clouds

Lots of lenticular formations around, beginning with this rosy specimen just downstream of the Catalinas at dawn:

7:17 AM.  Altocumulus lenticularis downstream of the Catalinas.
7:17 AM. Altocumulus lenticularis downstream of the Catalinas.

Lenticular clouds downwind of the Catalinas persisted for hours yesterday.  Its sometimes hard to tell that they are not over the mountains, but you can see that in the U of AZ time lapse for yesterday.

BTW, if you want to know how the UFO thing got started, legend has it that it was due to a hovering Altocumulus lenticularis cloud downstream of Mt. Rainier in the 1940s.

Viewing this U of AZ time lapse movie will tell you why lenticulars have sometimes been reported as UFOs.   It really does look like a hovering “vehicle” in the morning hours in the movie, and a “hovering”, which is what we know alien spacecraft do; hover.  In the face of the strong winds up there yesterday, hovering is, for most folks, unexpected, suspicious behavior.  Check it out.

SONY DSC
8:38 AM, below: CIrrus castellanus and floccus, i. e., “cumulocirrus”, Cirrus showing a lot of instability up there, steeper than usual decrease in temperature with increasing height. Makes things bubbly.

Finally, after the heavy mid-level overcast in the mid-late afternoon, a brief sunset bloom due to a distant clear slot beyond the horizon (way down at the bottom).

 

12:28 PM.  Here's comin' at you; Cirrostratus way up top, below, Altocumulus lenticulars, and Cirrus spissatus (thick ice clouds)
12:28 PM. Here’s comin’ at you, looking to the west; Cirrostratus way up top, below,  Altocumulus lenticulars, and Cirrus spissatus (thick ice clouds possibly evolved from glaciating lenticular patches.  Very complex scene. Thought about omitting it because what I couldn’t name and explain things?)
1:02 PM.  Altocumulus opacus invaded sky rapidly from the west.  Bottom looks pretty much like a lenticular, but it was scooting along, something true lenticular clouds don't do.  Hmmmm.  Maybe I should omit this one, too.
1:02 PM. Altocumulus opacus invaded sky rapidly from the west. Bottom part looks pretty much like a lenticular, but it was scooting along, something true lenticular clouds don’t do. Hmmmm. Maybe I should omit this one, too.
1:27 PM.  ACSL is back again downwind of the Catalinas! (Altocumulus Standing Lenticular)
1:27 PM. ACSL is back again downwind of the Catalinas! (Altocumulus Standing Lenticular)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5:46 PM.  A heavy layering of Altocumulus (opacus) is under lit by the sun for just a few moments.  Like me, you may have initially given up on a "bloom", by, by golly, it happened!  BTW, as often happens, these heavy looking clouds were a lot higher than you might think, about 17,000 feet above Catalina (from the TUS sounding.)
5:46 PM. A heavy layering of Altocumulus (opacus) is under lit by the sun for just a few moments. Like me, you may have initially given up on a “bloom”, but, by golly, it happened! BTW, as often happens, these heavy looking clouds were a lot higher than you might think, about 17,000 feet above Catalina (from the TUS sounding.)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

What’s out there beyond the present cold spell and the warming after that?

This is kind of intriguing to me even though its kind of a waste of time, too. We’ll be reel cold for awhile, then it will suddenly warm up to seasonal temperatures for a few days.  We know that.   But then what?

Our models have been churning out wildly different forecasts toward the end of the month, and with those, wildly differing weather occurs here, naturally. These model forecasts are like a 5-foot wide puddle of water on a pot-holed street like the ones we have here in Catalina that they only repair in the most rudimentary way, throw some asphalt crumble in the hole, that its pretty much what they call a “repair.”  Maybe its because we’re considered “po’ folk.”  Let’s see, where was I?  Oh, yeah, that puddle could be an inch deep or three feet deep. You just don’t know for sure.

One way to “dip stick” that “puddle” is in our NOAA spaghetti plots. At the end of this is the latest one from last night’s global data. You can see how wild (humorous) the forecasts are in the yellow and gray lines, indicating exactly opposite conditions in the West at the end of the month for those model runs at 00 Z (5 PM AST) and 12 Z (5 AM AST yesterday). Pretty bad.

The spag plot below from last night’s data suggest the warm ridge has the edge at this point (note clustering of blues lines to the northern US; red lines still confused).  With a ridge holding forth, it would be a comfy time in AZ late in the month, not cold and blustery.

Valid for 5 PM AST January 25th.
Valid for 5 PM AST January 25th.

Still, its not the final word, remembering that the atmosphere remembers. It will be interesting if it remembers enough to bust our venerable spag plots.  That’s what makes it so darn interesting!

The End.

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1Its interesting that such an old style methodology, of the type used by forecasters  before the rise of weather computing models, would seem to have equaled our best models in 2012.