Nice sunset; slight rain due in Thursday morning

In case you missed it:

6:09 PM.  Not so long ago, this kind of thing happened at 7:09 PM...
6:09 PM. Not so long ago, this kind of thing happened at 7:09 PM…  Altostratus here; too thick to be Cirrus.

Some rain to fall on Thursday, most likely between 5 AM and 11 AM. Both the US models and the Canadian one have rain for us now, not much, but likely measurable. Best personal guess from the “pattern”: between 0.02 and .20 inches. This “pattern” is one where the Catalina Mountains are at the southernmost extension of much heavier rain/snow to the north, the clouds bank up on the west side of our mountains, and little Catalina-its-not-Tucson gets measurable rain whereas Tucson and places south do not.  Jet core at 500 millibars (18,000 feet or so above sea level) will be passing just about overhead Thursday morning, and the wind at cloud levels during precip southwest to west-southwest.  In the cooler half of the year, that jet core usually demarcates a sharp line between no precip (to the south) and precip on the north side of it when the core is oriented west to east.  From IPS MeteoStar, this rendering for mid-day Thursday for illustrative purposes:

Forecast winds at 500 millibars (halfway through the atmosphere in terms of mass) 11  AM Thursday.  Recall sea level pressure averages 1013.6 mbs.
From last evening’s 5 PM AST global data, the WRF-GFS model forecast winds at 500 millibars at 11 AM,  Thursday, October 10th, Julie B’s birthday. I liked her a lot (late 70s) but it didn’t work out.   Recall sea level pressure averages 1013.6 mbs and so this level is about halfway through the mass of the atmosphere above us, and around 18,000 feet above sea level.  Likely that any precip here is ending here about this time as the trough over us shuffles off to ‘Braska and vicinity.

Adding to the rain excitement in the meantime will be scattered interesting clouds, windy conditions in the afternoons, and much colder air arriving during the daytime on Thursday.

To keep you occupied while waiting for rain, I now present an enigma. I shot this during a return flight from our B-23 aircraft as it ferryied back to Paine Field in Seattle after a study of emissions from the Mohave Power Plant near Kingman, AZ, September, 1983.  Not sure of the location, might be eastern California or southern Nevada.  On these kinds of ferry flights after a big field project, often with two bumpy, low-level flights a day, you don’t care where you are on the way home, you just wanna be home!

Might be a satellite calibration field of some kind.  Even today this grid in rough terrain still amazes:

September 1983, over eastern California or southern Nevada.
Late September 1983, over eastern California or southern Nevada.  Not sure; half asleep.

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.