Jet stream band of clouds delivers a sunset to remember; its snowing now…

at 6:30 AM…

The sunset? This one:

4:18 PM.  Near stationary band of high and middle clouds, clearing to west.
4:18 PM. Near stationary band of Cirrus, Cirrocumulus and Altocumulus emanating from beyond Kitt Peak, with a “pre-storm clearing” to west sets the stage.
SONY DSC
5:56 PM.
6:06 PM.
6:06 PM.
6:06 PM.  More overhead and zoomed view of the phenomenal ribbed structure in those clouds.  Had never seen this before, waves in the flow spaced like this ("undulatus" as we would term it).
6:06 PM. More overhead and zoomed view of the phenomenal ribbed structure in those clouds. Had never seen this before, waves in the flow spaced like this (“undulatus” as we would term it).

 

6:09 PM.
6:09 PM.

 

Raining pretty good now, 5:01 AM, thank heavens.  Now, to get that bottom prediction of 0.08 inches…  Always worry when foretellling rain amounts.  Over is good, under is awful.  Can’t look at radar, either, which would tell me what’s just ahead.  Just listening to it on the roof, sort of “enjoying” the suspense in the morning darkness.

Back to the clouds at sunset…   Would tell you how high they were, except that they were misssed by the TUS rawinsonde balloon.  It appears it went up outside and ahead of this little moist plume up there, but indications and my own estimate, and even though these clouds were termed “Altocumulus” in the first photo, they were almost certainly above 22,000 feet above the ground (25,000 feet above mean sea level, or above 350 “millybars.”)  ((That may seem exceptionally high for Ac clouds, but it happens1, excessive footnote, detracts from the main discussion and that’s why you put stuff like this in as a footnote because it doesn’t look so bad as just a little, itty bitty number.  There’s a period just below this in case you lost trackl.

5:23 AM:  Oh, my gosh, temp down to 35 F now!  Wow.

On to some an illustrative figure of what was going on last evening, this from the Weather Department at the University of Washington, a 300 mb map.  There’s a tremendous number of arrows and amount of writing on it, I hope that’s OK.  It is kind of pretty, though, with all the colors on it.

300 millibar (30,000 foot level in the atmosphere) for 5 PM AST yesterday, the 8th.
300 millibar (30,000 foot level in the atmosphere) for 5 PM AST yesterday, the 8th.

Back to stream of conscientiousness:  6:11 AM.   Quiet now, no rain.  Only 0.06 inches so far, need two more.  What the HECK is happening?  Went out with flash light and its SNOWING!  Oh me, Mr. CMP wasn’t thinking snow at 3200 feet today! Dang.  But, like the map above, it could be quite pretty, likely precip will get over 0.08 inches now, too.   Just won’t go in gauge and tip bucket until later when it melts.  Temp now 33.5 F in light snow.  Was 47 F before front and rain began to hit, so its down almost 14 degrees now.  No wind, either.

Rest of today; now looking at data:

Looks like precip, snow melting on contact mostly, maybe a skiff to an inch at most, will continue for the next 3-5 hours before the clouds lift into a higher layer of Stratocumulus toward mid-morning (this from the Hollerith technique illustrated a couple of days ago).  Probably will be some gorgeous Stratus fractus along the snow-covered Catalinas, too.  Later the sky should devolve into scattered to broken coverage in Cumulus and shallow Cbs with virga and passing light showers, probably will barely measure.  Now, lets look at the U of AZ model and see if this has ANY credibility….  Seems to be about the same, rain/snow precip ends by 9 AM here in Catalina.  However, no passing showers are indicated in this model after that.

Should be a memorable day with the Catalinas in some snow again, and passing clouds and shadows on them.

The End.

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1During our (Cloud and Aerosol Group’s study of aircraft-produced ice holes and canals in Ac in the early 1980s when Reagan was President and just after he fired all of the air traffic controllers, we were able to talk to guys at the Air Traffic Control Center in Auburn, Washington, working the jets coming into SEA-TAC! We were able to get from them real time heights of Altocumulus cloud layers in which holes or canals due to ice formation occurred due to an aircraft.  While Mr. Cloud Maven person has won cokes off pilots who questioned his estimates of how high clouds were, who then, following a bet,  took off and measured them, even HE was surprised at how high some Altocumulus cloud layers were.  Some were well over 20,000 feet above ground level!  In the days before heights were measured by machines, now up to 12,000 feet above ground level,  it was almost routine for human ground observers at weather stations, when seeing Altocumulus clouds, to put down “12,000 feet” or “15,000 feet” above ground level for the estimated height of those clouds in aviation weather reports.  Older pilots will know this, having heard the sequence in verbal “transcribed” aviation reports, something like, “Five thousand scattered, estimated one-two thousand broken, two-five thousand overcast….”  Oh, yeah, that’s how it was so long ago.