Dust cloud day

Sample frame from a video running when the peak gust hit, estimated at over 60 mph by “yours truly”, if that is, in fact, the case.  Some roofing material blew off, too.

gust
Equestrian Trail Road spewing dust, estimated peak puff gust, in this King of the Gusts, 60-70 mph. Only lasted a few seconds. Not mashed plants due to winds.

Cloud Maven Person was doing other things, not thinking about weather, when he finally began to notice that the winds in “The Heights” were approaching 100 mph1; great clouds of dust suddenly rose up from our dirt streets;  dogs blowing ahead of him on his dog walk when going westbound on a dog walk,  sandy grit sanding off the hair on the back of his legs. You get the picture.

Well, it was caused by an unusual situation of wind coming OVER the Catalina Mountains, which usually block east winds from us quite well, while the city of TUS gets ripped.

Too, yesterday might have been like that situation some of you remember that affected  California’s San Joaquin Valley in December 1977.   Winds, forced OVER the Sierra Nevadas,  then collapsed down on poor Bakersfield and vicinity, the air accelerating as it fell down the Sierra mountainsides going faster and faster, driven by a HUGE high pressure inland over Nevada, and lower pressures offshore, peaked at 130 mph!

Something similar to that situation may have been what happened yesterday here in Sutherland Heights.   Both Froude and Richardson Numbers, to throw in some high sounding terms that characterize flow,  along with the strength of the winds piling up against the Catalinas on the east side, were just right so that the air went OVER the Catalinas instead of around them.  End of potential explanation.

Below is yesterday’s TUS U of AZ launched sounding from IPS MeteoStar, which still isn’t charging anything to look at their stuff even though they said they would:

Ann 2015031512Z_SKEWT_KTUS
The TUS balloon sounding for 5 AM AST yesterday morning as the winds were picking up.  The arrows are point to stable layers where the air, as the winds piled it up against the Catalinas, were resisting being lifted, and under less forceful winds, likely would have gone around the Catalinas instead of over.  But those two layers being raised up by the wind,  the air more impetus to go down the west side of the Catalinas after it was forced over the top.  Those wind barbs of the right indicate that the winds were banging against the Catalinas as 40-50 mph near the top of Mt. Lemmon, and 50-60 mph not much higher above the top.

 

Corroborative data: on 2 h dog walk just after sunrise, taking them on the ridge on the east side of the Sutherland Wash2 , the wind on the ridge was coming right at us from Ms. Mt. Lemmon, of all places! Very unusual.  Closer to The Heights, the wind turned more more from the northeast.

Oddly, just down on Swan below us, the wind were not unusual at all, only 20-30 mph, one experienced observer reported. That kind of microscale thing happens in these situations,  when the air finds channels in canyons and gulleys, so “oddly” really doesn’t apply, and I don’t know why I said it.

Well, that’s what I think happened;  air accelerated downhill after being pushed over the top of the Catalinas,  and gave us extra strong gusts.

Did you notice that during the winds, it could almost be calm, but you could hear another gust approaching like the roar of a gushing river out there in the desert?  That was cool.

The weather ahead.

Mods continue to indicate a showery SE Arizona for a few days beginning tomorrow in the extreme SE as weak troughs in the southern band of the jet “influx” some mid-level and higher moist layers to begin with.  Water vapor already increasing over us, so maybe we’ll see an Altocumulus cloud later today.

Aerosol forecast:  Look for enhanced smog with this air mass coming from the south and southeast.  Dang.

The End.

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1If you round up from 60 or 70 mph in those momentary, less than 1 or 2 second blasts.

2Which still had water in it in some parts, but not at the Cottonwoods anymore.

The Sutherland Wash at the Rusty Gate horse crossing.
The Sutherland Wash at the Rusty Gate horse crossing yesterday morning.  The water disappeared here, too.
The Rusty Gate.
The Rusty Gate.