“And I think its going to rain today”

Well, how can we forget that mournful Leonard Cohen song?  And the sweet rendition of that tune by Judy Collins?  It was played a lot in Seattle, of course, where I’m from.  But, it also looks like it might be apt for late today right here in Catalina.  Check out this “incoming” here from the U of AZ Weather Department’s model output here.  This loop of rain areas will show you how the precip creeps toward us during the day, eventually overrunning almost the whole State of AZ.  “Oh happy day”, to quote another song title.  Just hope we get more than the tenth of an inch the model projects, all of which falls overnight tonight after midnight.  (Hmmmm.  Seems a little slow to me.)

Here’s a loop of satellite imagery and the surface pressure maps for the past 24 h from the University of Washington.  The interesting thing about these maps, is how one hurricane-like center with lots of isobars off the Pacific NW coast crashes into British Columbia while a new low develops off the California coast and is now pummeling central and southern California while heading to the southeast and toward us.   Reminds me of someone getting a “spare” in bowling by knocking two widely separated pins to the left and right to get it.

Why would storms divide in their paths like that?  You have to look aloft at the steering by the jet stream.  Low centers separating like that always means there is a split, a dividing point in the flow.   Higher level pressure maps from the UW shows that.  Below is a 300 millibar  pressure map (about 9 km above sea level or around 30,000 feet), a level where the jet stream is just about the best developed.  Notice how part of the flow whirls around the big vortex in the northern Gulf of Alaska and toward BC, while a more powerful branch dips toward California.  Its that trough,  that bend in the winds just now off California, that will come barreling through here tonight bringing that surface low center now near SFO with it–well, what’s left of it after it gets wrecked by mountains.  The next chance for rain/snow is in early February.


Nice clouds again yesterday.   Here are a few shots, including another nice sunset.  The haze you saw was dust, leftover from the strong winds of the previous day in western AZ.  The first, Cirrus over dust.  The second, some Altocumulus with Cirrus, and finally, Altostratus with some  under lit Altocumulus in the distance.