Plethora of storms ahead; Catalina snow day still being foretold for Feb. 25th which is only nine days away now!

To help understand that odd word, “plethora” in the title in case you are befuddled by it, I have added a YouTube teaching module to help you out:   “What is a ‘plethora’?”

Well, one of the great model runs of our time has come out once again last night after yesterday’s great model run of our time  based on the that morning’s data.   SEVERAL rain days foretold in the next couple of weeks!  One of these is actually a snow day, Feb, 25th, first predicted by the models about a week ago.  This would be the “real deal” here in Catalina, not some “diabatic” (a weather term opposite of “adiabatic”) fluke as was our inch or so of snow two days ago, one that happened due to extremely heavy precip in the clouds above us, thus drawing the freezing level downward.

The first rain day is today, likely beginning after 5 PM AST, and then continuing into tomorrow for a second day.  Here are some rainy/snowy snapshots from our friends in Canada at the EnviroCan weather service where they use a modified version of the ECMWF (European) forecast model here. The first panel is valid for 5 PM today just before the rain is supposed to begin.  (If you don’t click on the panels below, you’ll need binoculars to see what I am talking about.)

Does this pattern look familiar in that first panel?

Yep.  “SOSO” as we have been seeing all winter when storms strike. In the lower left panel you will see all that moisture streaming (colored regions) into our today’s cut off vortex from the south from the Mexican Pacific and linking up with a moist plume from the Gulf.  Interesting to see that.  Also, as it gets cut off, and great for us, it begins to dawdle while edging eastward along the US-Mexican Border, allowing those moist plumes to “filler up”,  just like at a gas station.  So, the rainy areas with this low should be expanding/appearing as clouds are enhanced; deepen up and begin to precip. Very exciting.

What’s been great is seeing the amount of precip predicted in Catalina from this low increase gradually over time as the models were seeing that it was not going as far south as they thought earlier.  Here is another panel for this storm, valid for tomorrow afternoon at 5 PM AST.  While the low has gone by to the south during the day tomorrow, this model suggests that it likely will have rained on and off during the day.  This is because so much moisture arrived in this low that it has developed a “wrap around” band of rain to its north and west, good for us, kind of like a sucker punch.  You should be able to see that happening today and tonight in this great IPS sat and radar link, as well as clouds “appearing” over the deserts to the west and south of us, and then developing echoes as they deepen.

Our local U of AZ Wildcat Weather Department has this great depiction of this “wrap around” development from their own model run here.  Nice!

 Here are the additional days ahead with more rain, and also, low snow levels.  Mt Lemmoner’s rejoice!  Below, the next panel, Sunday afternoon into Monday morning, this next trough.

Brrrrr, another cold blustery day Sunday, but notice this one is NOT a cut off and so will move through rapidly.  Then, 4th panel, a dollop on Tuesday, just a minor trough passes by, and then, after a break, the Arctic iceberg on the 25th.  Check this trough out in the last panel.  Awesomely cold!

With luck, and a little verification of these predictions, maybe the washes will run later this spring!

The Cloud Report part of blog

Had some complicated, but nicely detailed Cirrus clouds float over in the early afternoon, a part of our invading storm’s circulation.  This was followed by a large clearing  and then encroaching Altocumulus patches trailing virga (ice crystals) in gorgeous, fine strands that wiggled this way and that in the setting sun’s light as that falling snow responded to slight changes in the wind below those little flakes of Altocumulus cloud.  Enjoy.

The End.

By Art Rangno

Retiree from a group specializing in airborne measurements of clouds and aerosols at the University of Washington (Cloud and Aerosol Research Group). The projects in which I participated were in many countries; from the Arctic to Brazil, from the Marshall Islands to South Africa.