Clouds before the storm

First, let’s see how excited the NWS is about our upcoming major, drought-denting storm, now “in the bag”:

Tucson, here and a nice NWS YouTube presentation here.

Phoenix

Flagstaff

As you will see from these links, they’re getting pretty worked up, and have issued the SAME “Special Statement” for ALL of Arizona, that’s how big the storm is.  We’re all in this together.  BTW, the U of AZ model forecast from 11 PM AST last night had as much as 5-6 inches of rain indicated in the central mountains of AZ over the next 24-36 h! Will the washes flow here, eventually as the major rain moves east?  Hope so.

But, must point that the range of amounts that will fall here in Catalina has to be considered quite large; something from “just a nice rain” (0.4 inches total) to a gully washer (1.5 inches total) due to the fine-scale of the heaviest rainfall bands rotating around the dawdling low over the next couple of days.  Its really not possible to pin it down better than a large range of possible values in situations like this, but it does appear that most of it will fall on Friday night into Saturday.

In the meantime, more pretty skies today before the deeper clouds and rain get here overnight or tomorrow morning.  Very little rain is indicated here, though,  through tomorrow evening,in this latest U of AZ mod run. while inches pile up just to the west and in the AZ mountains.

Yesterday’s clouds

Had pretty skies all day yesterday, even saw some clouds that as far as I know, have no name, these ones below that LOOK like Altocumulus perlucidus but are all ice at Cirrus levels.   Could be called, to make up a name, “Cirrus perlucidus” I guess:

7:46 AM.  "Cirrus perlucidus."  It may be hard to tell for most folks, but these flocculent clouds are all ice.  There's a patch of Altostratus in distance.
7:46 AM. “Cirrus perlucidus.” It may be hard to tell for most folks, but these flocculent clouds are all ice. There is no WAY I would call an all ice cloud, “Altocumulus.”   There’s a patch of Altostratus in distance, and an Ac lenticular to left of pole on horizon.
9:49 AM.  Altocumulus virgae.  Great example of the "upside down" storm; droplet cloud at the top, ice and snow underneath as ice forms amid the droplet cloud, grows like mad and falls out.
9:49 AM. Altocumulus virgae. Great example of the “upside down” storm; droplet cloud at the top, ice and snow underneath as ice forms amid the droplet cloud, grows like mad and falls out.  This finding, first made in the 1950s was surprising because the clouds were liquid at the lowest temperatures.

12:04 PM. Cirrocumulus lenticularis, a bit too thin to be Ac lenticularis.

 

3:59 PM. Ac lenticular stack in lee of Catalina Mountains. Ac perlucidus in foreground.
3:59 PM. This view from atop horsey, an Ac lenticular stack beyond the Gap, in lee of Catalina Mountains. Ac perlucidus in the foreground.
4:00 PM. Looking S; buttermilk skies due to Ac perlucidus; lower layer of Ac opacus advancing from the the west below those mottled clouds.
4:00 PM. Looking S; buttermilk skies due to Ac perlucidus; lower layer of Ac opacus advancing from the the west below those mottled clouds.
5:31 PM.  Brief sunset "bloom" due to a small break in the overcast just over the horizon.
5:31 PM. Brief sunset “bloom” due to a small break in the overcast just over the horizon.

The weather way ahead

2013112100_CON_GFS_500_HGT_WINDS_276

Valid at 5 AM AST, December 2nd. A near twin of the upcoming situation.

Now showing up on mods, as November closes out, a low center that looks an awful like the situation we’ll have tomorrow and Saturday, another vortex aloft tracks S along the coast, settling in around San Diego, then moving along to the east very slowly. As you know, weather patterns like to get in a groove and repeat themselves for awhile. Could be we’re in that phase where the SW is a low “magnet” and that would mean above normal precip over a spell of a few weeks. Above, a map for December 2nd at 5 AM AST that looks a lot like what we have coming right up. For that reason, you tend to place a bit more credibility than you might otherwise in a forecast that far away.  The exact day this occurs will be most likely be off, but it is likely that a troughs/clouds and precip will   to affect the SW over the next couple of weeks or more.  Good bye dry spell!

If you don’t believe me, check this 10 day outlook from the NOAA spaghetti factory:

"Lorenz plot" from NOAA,  valid at 5 PM AST, November 30th.  Its pretty plain to see that there is a strong likelihood of a cutoff low in the extreme SW US.

“Lorenz plot” from NOAA,
valid at 5 PM AST, November 30th. Its pretty plain to see that there is a strong likelihood of a cutoff low in the extreme SW US, if you can find it.  (The vast number of contours is due to a software glitch today.  Usually only a few upper level contours are tracked.)