Rain shows up here in a model run!

Looky here, valid in only about 9 days, that is, just off the forecast confidence horizon, predicted rain for SE AZ!  Valid for April Fool’s Day, at 5 PM AST.  We hope its not another model cruel joke, since time is running out on the chances of cool season (Oct-Apr)  rains.

Ann gfs_namer_240_1000_500_thick

SInce I know you love spaghetti, here’s some for about that same time, the evening before the map above, and it has a strong indication of a strong trough moving into the SW from the Pacific.  Count on it.  At the least, it will get real windy when this happens, count on it, and with a little more luck, there will be enough amplitude in the jet stream, that rain WILL occur.

Valid at 5 PM, the day before the predicted map, that is, 5 PM on March 31st.
Valid at 5 PM, the day before the predicted map, that is, 5 PM on March 31st.

The last batch of spaghetti was disappointing, that shown here about two weeks ago. Sure, there’s been  a “trough bowl” in the SW as was predicted way back then; that’s what was producing the pretty clouds we’ve been seeing, the passages of weak troughs aloft over us, ones that have been also keeping the temperatures reasonable.

But, that predicted “trough bowl” so far back did not have the amplitude necessary to bring rain as was thought could happen back then.  “Trough bowl” turned out to be more of a “plate”, than a “bowl.”

Here’s what I mean, below, from the first panel of spaghetti from last evening:  see the little dent toward the south in the contour lines passing over Arizona? That represents a trough where clouds like to form, such as yesterday’s Cirrus clouds..

spag_f000_nhbg
Map for last night as model runs begin.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

But we need the big polar jet stream over us to get rain in the cool season, not a wispy jet up at Cirrus levels as we have been having. You may have noticed how fast the Cirrus clouds were jetting along up there. Well, for the past couple of days, they were zooming along at over a hundred miles an hour.

What we need are deep, cold troughs where the red height contours (5700 meters in the above map) are way south of us.   Here’s why rain is predicted in the first map, as an example.  Below is the configuration of the jet stream for that day that rain is predicted, showing that the 5700 meter contour and the core of the jet stream is over central Baja California.  Now THAT is a rain map for AZ!

Ann 2014032300_CON_GFS_500_HGT_WINDS_240
Valid at 5 PM AST on April 1st from an IPS MeteoStar rendering of the NOAA NWS model. Note to mod: don’t pull another cruel hoax on us.

 Yesterday’s clouds

Let us begin by breaking up the weather talk monotony with a photo of a bee evaluating a thistle1, this from a hike yesterday to some weather petros2, to resume the weather talk.

10:31 AM.
10:31 AM.  “Sentient Bee-ing and Thistle”  $1800.  (See link to Sci Am article below if you don’t think bees think about stuff.)
DSC_0179
8:46 AM. Crossing strands in CIrrus fibratus. Indicates that they have formed at different heights in layers of air with vastly different wind shear (change of direction with height). Rarely do you see this because at Cirrus levels (here around 30-35 kft above ground level, the wind direction usually does not change much.  The strands running from left to right across the photo is the higher Cirrus cloud.

 

9:14 AM.  Several species of CIrrus here; fibratus, uncinus, and spissatus (lower right).
9:14 AM. Several species of CIrrus here; fibratus, uncinus, and spissatus (lower right).

 

9:35 AM.  After the delicate Cirrus forms passed, lower blobs of dense Cirrus spissatus followed.
9:35 AM. After the delicate Cirrus forms passed, lower blobs of dense Cirrus spissatus with some castellanus *turreted” versions) followed.

 

9:45 AM.  Cirrus fibratus radiatus--last of the delicate Cirrus clouds left a memorable scene.  However, the look of radiating fibers may be due to perpspective, not sure.
9:45 AM. Cirrus fibratus radiatus–last of the delicate Cirrus clouds left a memorable scene as they disappeared past the Catalina Mountains. However, the look of radiating fibers may be due to perpspective, not sure.

 

11:32 AM.  Strands of Cirrus fibratus mimic the branches of a mesquite tree, both seemingly reaching out.  A blob of the rarely seen Cirrus castellanus is on the horizon, lower left.
11:32 AM. Strands of Cirrus fibratus mimic the branches of a mesquite tree, both seemingly reaching out. A blob of the rarely seen Cirrus castellanus is on the horizon, lower left.

The cloud day pretty much ended with a brief appearance of Cirrocumulus overhead, enhanced by iridescence:

12:07 PM.  CIrrocumulus and iridescence.
12:07 PM. CIrrocumulus and iridescence.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The End.

 

 

 

 

 

 

 

 

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1Apparently bees think a lot more about stuff than we think.

2Below, an early weather forecasting icon petroglyph indicating that the forecaster was anticipating a sunny day except for some Cirrostratus clouds, ones expected to produce a halo.  Pretty sophisticated I thought.

10:17 AM.  One of several weather forecasting petroglyph icons.
10:17 AM. One of several weather forecasting petroglyph icons.

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.