Augustober weather continues on October 18th

Truly LATE breaking news,  untimely really,  but Augustober 18th was too special a day to ignore:

Giant clouds, dense rain shafts,  frequent lightning in the area throughout the afternoon,  dewpoints in the high 50s to 60 F; can it really be after the middle of October?  Or, is this some kind of preview of climate change we can look forward to in the decades ahead, that is, if you’re thunderphilic?

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5:05 PM. An amazing scene, and thunderstorm with such powerful updrafts that when those updrafts are blocked by the inversion at the base of the Stratosphere, they force the winds at that level to slow or backup and the anvil protrudes upwind (center left), something that is common with severe thunderstorms. This was significant here because the winds at 40,000 feet were around 50 kts, far stronger than anything we have here during a typical summer rain season.  Summer  Cumulonimbus  cloud anvils  can splash outward easily against weak winds up there in summer when they hit that barrier at the top of the tropopause.  This just in from Mark A:  severe thunderstorms, I have just learned here on the 20th , were observed in the PHX, and the NWS has a great link going describing all the mayhem it produced.  I did not know this until just now in the middle of writing this first caption when I read Mark’s e-mail.
1:40 PM.
1:40 PM.
1:56 PM.  Anvil of the Cumulonimbus over west Tucson, drifts overhead of Catalina, and in three minutes, rain drops started to hit the ground.  This is amazing because those drop had to fall from at around 20, 000 feet above the ground (estimated bottom of this thick anvil) and could only have happened if those isolated drops had been hailstones ejected out the anvil, something that also only occurs with severe storms with very strong updrafts in them.
1:56 PM. Anvil of the Cumulonimbus over west Tucson, drifts overhead of Catalina, and in three minutes, rain drops started to hit the ground. This is amazing because those drops had to fall from at around 20, 000 feet above the ground (estimated as bottom  height of this thick anvil) and could only have happened if those isolated drops had been hailstones ejected out the anvil, something that also only occurs with severe storms with very strong updrafts in them.  So, if you saw those few drops fall between 2 and 2:05 PM you saw something pretty special.

 

 

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6:26 AM. Early portent: Cu congestus, aka, “heavy Cumulus) piling up this early.
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6:29 AM. Mammatus of the morning., an extraordinary scene for mid-October, pointing to the possibility of an  unusual day ahead with strong storms. as was the scientific basis for giant clouds on the 18th  in the amount of CAPE predicted, over 1,000 units of Convective Available Potential Energy, later that day from computer models.   That is a lot for mid-October, take my word for it.
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3:45 PM. Strong storms did not form over or near the Catalinas yesterday, but they did get something. As you can see the top of this guy (Cumulonimbus calvus) is very subdued compared to the giants that formed elsewhere.
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5:53 PM. Peakaboo Cumulonimbus calvus top east of Mt. Lemmon provided a nice highlight after sunset. And to have convection like this going on this late was remarkable. Some heavy showers and a thunderstorm formed downwind of the Catalinas about this time,, too.
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5:51 PM. Pretty nice, summer-looking sunset that day, too.

 

 The weather just ahead, and this might be it for precip for the rest of October

A nice-looking upper level trough is ejecting over us from the SW this morning but the computer model says its going to be a dry event.  A second low center  forms just about over us in the next day.  AZ model doesn’t see much rain for us throughout these events, and rain doesn’t begin here until after dark today.

I think that is WRONG; bad model.  Watch for some light showers this morning, then a break and rain overnight (which the models do predict).   Due this quite bad model forecast,  as seen from this keyboard, I feel must interject for the blog reader I have,  an improved rain prediction for Catalina over that rendered by a computer model.

Feel like guesstimating a minimum of 0.25 inches between now and Thursday evening, max possible, 0.60 inches, so the median of those two, and maybe the best guestimate being the average of those two, or 0.425 inches here in Catalina.   When you see a prediction of a rainfall total down to thousandths of an inch, you really know that the person predicting it knows what he is doing…..

Below, your U of AZ disappointing, but objective, take on the amount of rain based on last evening’s data and one that is the result of billions of calculations.  One must remember that cloud maven person’s calculation of the rainfall amount for Catalina is only based on three.

From the 5 PM AST run executed by the U of AZ Beowulf Cluster.  Billions of calculations were involved with this model prediction; it should be kept in mind that cloud maven person's prediction is only based on three when he opines that this is not enough for us here in Catalinaland.
From the 5 PM AST run executed by the U of AZ Beowulf Cluster.

The End.

One thought on “Augustober weather continues on October 18th”

  1. Those are some great photos of clouds there, Art. I especially liked the one at 1:40 pm. These remind me of a series of pictures I took back in June 2013 here in Vancouver of a large Cb with an anvil north of my location along the mountains. I might send them to you in the future if you’re intrested.

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