Weekend slider, cloud excitement ahead, more about spaghetti

Check out these forecast maps from IPS Meteostar from last night’s 5 PM AST global data (less data from GOES-15, the satellite that covers the eastern Pacific and western US, which has gone belly up lately):

A ludicrous baseball metaphor for today; after all,  its almost baseball season:

Let’s say your a very tall person with a bat a few hundred miles long standing in the batter’s box somewhere around Hermosillo, MX.  A trough, like a baseball, has been thrown by the Pacific Ocean.  Its coming down the “middle of the plate” (see panel 1) with the trough easing into southern California with a lot of rain).  This one is gonna be jacked (will bring rain to all of Arizona!)   It can’t miss.   If it rains in southern California it can’t miss bringing rain to AZ!

You take a mighty swing (forecast rain), to go back to this silly metaphor.   You didn’t noticed the “red dot”, something batters can see on the spinning ball when a pitcher throws a “slider”, a curving ball that,  from a right handed pitcher to a right handed batter, veers away from the plate.

In this case the “red dot” to stretch this metaphor, is that the north winds on the backside of the southern California trough will be weakening as a new trough from the Gulf of Alaska roars down toward California and begins to catch up to it.  The “ball” (trough) veers suddenly to the outside corner of the “plate”, Arizona, and spins into the dirt over Nevada and Utah.  But you have swung anyway and struck out with the bases loaded (if you had thought rain from southern California was going to get here and water our wildflowers).  The fans are booing now.

Well, enough baseball for today.  The season is too long anyway.

Recall the  AZ “jet rule”; no jet here and to the south of us as troughs go by; no rain no how in this cooler time of the year.  Whilst the jet is south of our latitude on Sunday’s map  (first panel), you can see that by Monday night at 11 Pm AST, the high velocity core has oozed over the NW corner of AZ (brownish regions in the second panel).  The strongest winds are now on the east side of that trough, telling you its going to rocket off to the NE.

 Cloud prognostication:  get yer cameras ready!

The great thing about our “missed” storm is that the skies should be especially fabulous over the next three days (make sure all cameras are charged) because of having marginal moisture in the mid and upper levels of the troposphere as our “miss” goes by.  That should mean interesting and photogenic clouds of all kinds up there:  Cirrus, Cirrocumulus (fine grained clouds), Altocumulus (probably castellanus, lenticulars), and probably a spate or two of Altostratus clouds.  Gee, you’ll have to get a cloud chart to know what I am talking about here!  (Maybe you should get this one;  it seems better than some of the other ones I’ve seen, and I don’t just say that because if you do get it, I will get some money.)  ((Or go here, if you like to shop around)).  Is this crass or WHAT?

The great thing, too, is that the Altocumulus clouds are likely to have nice virga trails, and it that kind of cloud (Altocumulus castellanus virgae) or Altostratus occur at sunrise or sunset, you can get the MOST fabulous photos.  I like’em during the daytime, too, though.  OK, so very excited about the cloud prospects ahead.   Will be scanning skies.

The weather ahead

Another giant cold spell has erupted in the models.  Check this big boy out over Az, valid for Sunday morning, 5 AM AST, nine days from now.  Yep, you got yer low snow levels again, some showers, too.  But the really interesting part is that it gets cut off out of the stream and sticks around for a few days.  Look at the second panel, for FIVE days later!  A remnant of it is still there, producing showers!  In April?  Seems unlikely, but could happen.

How do we check out how likely this cold spell and rain/snow is?

We think about spaghetti.  Now remember, too, with GOES-15 out, there is also the fact that the models are working without as much information as they usually have.  So, right off the bat, you have to downgrade anything “strange”, more than you normally would.OK, here’s some spaghetti for 168 h out, valid for a week from last night.  This map was SHOCKING to me, because its telling you that the set up for our big boy is virtually guaranteed!  I couldn’t believe it, its amazing!

So what am I ranting about?

This plot below says that a gigantic trough in the eastern Pacific between Hawaii and the mainland is virtually guaranteed.  Look at how closely the contour lines are spaced in the eastern Pacific!  This closeness says that the “signal” for this to happen is huge in the global data.  Compare this spacing in the eastern Pacific, with the bowls of rubber  bands, say, in the Atlantic and western Europe.   The models are clueless about what is going to happen there.   Conclusion:   a few days before our forecast trough shows up, it is out there, and at least has the potential to be realized here in AZ two or three days later.  Somebody on the West Coast is going to get whacked, little doubt about that.

But what happens on the days we are concerned about, April 1st and beyond?  See next panel of spaghetti plots (2) for the afternoon of April 1st.  The yellow lines are a couple of the contours in the forecast map for April first above.

The confidence factor has gone to HELL!  Sorry for having to cuss.  In the western Pacific, you can still be pretty confident of where the troughs will be, but look at the MESS now in the central Pacific to Moscow!  Nothing is assured.  All is hazy, fuzzy, out of focus, dimly lit, a drunken spider’s web, DAMMITALL, to cuss that bit more.  While our trough has been foretold as of last night’s data, and it will maintain itself right up until reaching the West Coast (spaghetti 1), after that its anyone’s guess.  Chances are good for a cool spell, but will it be historic with rain and snow, or a slight drop in temperature under sunny, breezy skies?

No one knows, but that first dish of spaghetti (1) has to make you at least hopeful that something strange will happen in early April here.  Go here if you want to see the full animation.

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.