It seems we’re heading into another “trough bowl”, a persistent collection area for cold air in the upper levels over us during the next couple of weeks. In the meantime, something about today’s great weather, if you like a little drama.
The wind starts blowing pretty hard later on this morning or certainly by mid-afternoon. As it gets gusty and dramatic, its only natural for our heads to start swiveling around, looking skyward, knowing something ominous is happening; something’s changing drastically, like the barometer. That gut reaction comes not from the gut, as popular lore would have it, but from the deep responses to fear located in the amygdala, that ancient piece of brain that knows scary things1. And it would be right.
Here is the scary stuff that going to happen, first from the NWS, as told in their latest (as of 4:30 AM) very “Special Weather Statement“, FYI. Have goose bumps now!
Also shown at that link is a “Special Statement” from the Albuquerque office of the NWS, one in that I particularly liked because of their use in their own Special Statement of the word, “potent” to describe this incoming storm. Its a great word to employ, and apt in this case; and its a word that conveys power. A “potent” this or that is something tremendous! “Po-tent”; fun word to say, too. Think, too, of the devastation when just two little letters are prefixed to that word.
Today is the precursor day for our “potent” storm, a day with potent winds, likely reaching 40 mph in momentary “puff gusts” (lasting just a second or two) here in Catalina, especially in the hills overlooking our little berg. The air gets squeezed against the Catalinas today as it races northward into a large Great Basin low center. Should be gusty here right up to when the potent cold front hits tomorrow morning. When that front hits, we should see light to moderate rain for a couple of hours, along with our usual temperature drop of about 15-20 degrees in an hour, too. And, as it always does, the wind will drop off dramatically, turning to the northwest for awhile before returning from the southwest.
BTW, since we haven’t had strong winds in so long a time, there will likely be more dust raised today and tonight than would normally be the case. Also, you tend to see more branches break off trees after a long non-windy period such as we have had.
All the mod outputs I’ve seen from overnight (3, USA, Canadian, and the downscaled U of AZ one) have rain here tomorrow morning followed by the chance of a passing, brief shower in the afternoon. Those passing shower clouds would be Cumulus congestus converting to small Cumulonimbus clouds. Very pretty to see in the winter.
The chance of measurable rain here in Catalina tomorrow?
Oh, 100%. We don’t mess around here; but then we don’t have any particular responsibility to anyone either.
U of AZ mod has us on the edge of the 0.25 inches region, slightly less than was forecast yesterday at this time. SOP from this keyboard: minimum 0.08 inches, maximum 0.38 inches, middle ground, 0.23 inches, same forecast as yesterday. However, as a person who suffers from a desert version of precipophilia, I love it when its MORE than I think it could possibly be. (Didn’t really have this syndrome in Seattle…)
Rain chance here HAS to be near 100% due to our position near the Catalinas, and how those frontal band clouds will be fattening up as they approach them, especially to the point tops are fattened up to BEGIN raining in the trailing part of the frontal band (requires the formation of ice up there, as you know). The trailing parts of storm bands is where we in Catalina Census Designated Place pick up an additional amount of rain over outlying areas in fronts like the one coming tomorrow.
So, in sum, tomorrow will be a fun day and a dramatic one with rain pounding down in the early morning, and, with the snow level plummeting to below 3500 feet during the rainy part of the storm, and a scenic one when the leftover, non-raining Stratocumulus clouds begin to break open, build into scattered Cumulus and small Cumulonimbus clouds. Those snow covered mountains will come fully into view. So, a VERY photogenic day ahead tomorrow, particularly in the afternoon. Charging camera batteries now.
First, as we saw at sunset yesterday, Cirrus clouds, lots of different varieties/species today, probably including the patchy thick versions with shading called Cirrus spissatus. Most likely these clouds will thicken enough in coverage to be termed, Altostratus, widespread gray looking ice clouds. Below those, maybe a brief Cirrocumulus or maybe an Altocumulus lenticularis–again, look to the northeast of the Catalinas for that. These latter clouds can have the best, really delicate patterns embedded in them on days like this. But, they may only last minutes if they form.
Our high cloud spawning grounds have been doing their work overnight, as you will see in this infrared satellite loop from the University of Arizona. You will see that high clouds have spawned from clear air in the lee of both the mountains of southern California and those in northern Baja California. Those cloud spawning zones have quit for the most part now as the air dries out aloft over them, but the shield of clouds they launched now extends over the middle of Arizona, some are over us now, too, so a good chance of some sun rise color. That nice plume of ice clouds launched by those mountains is wrapping around our coming upper level low center as it marches down the California coast.
As you know, those high clouds are “decorations” in a sense because they will have nothing to do with the surge of lower clouds and rain that blasts into Catalina tomorrow morning. But they do present us with the chance of great sunrise and sunset color. Just now I saw that the U of A model foretells drying at Cirrus levels over us near sunset today, meaning that the huge clear slot that (oddly) precedes storms so many times, may arrive just as those Cirrus/Altostratus clouds depart around sunset. Hope so.
The weather ahead and far ahead (beyond 10 days)
This is great news and not so great news (if you’re snowbirding in Arizona); the coming rejuvenation of winter. The mod output from last night’s 5 PM AST global data crunch (can be seen here) has a series of troughs of cold air dropping southward from the Pac NW into the Southwest US, meaning multiple chances for rain, but even if no precip, lower than normal temperatures. In other words, it appears that we are entering another spell where we are in a trough bowl, a nesting place of sorts for cold air aloft and the storms that come with them.
Below, from our TUS NWS, is an example of what it means to be a thermometer going in and out of “trough bowls”, that region where one or more upper level troughs find us for a couple of days or more, this graph for January. You can see that if you were a thermometer, it would be like being in the ocean with big swells driving you up and down, up and down. That’s what’s ahead now, that same temperature roller coaster we saw in January appears to be ahead for us through the remainder of February.
But, with troughs come chances to joyfully fill our February rain gauges and see our desert vegetation spring to life. So, really, snowbirds aside, its all good.
Would refer you to our venerable error-filled NOAA ensembles of spaghetti plots to support or weaken these longer term conclusions, but I haven’t been able to get in, seems site must be down.
1May be some kind of “first” here, seeing the word amygdala in a weather briefing. Tell your friends.