River of Wind

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rdrobson
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River of Wind

Post by rdrobson »

I had something weird happen last night. I was out flying on a gorgeous evening over the lakes country of northern Minnesota. The winds were light, 10 knots or less aloft, and not a cloud around. Very smooth air.

Anyway, we were flying at about 2000 ft AGL when I noticed that we had to really increase the crab angle to hold a straight course. The GPS was reporting a +45 knot crosswind but there was no change to the smooth ride we were having. Then suddenly things were back to less than 10 knots again. The whole event covered less than 7 nm and less than 3 minutes of flight time.

I've never noticed that before, wondering if anyone else had.

--Ron
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Colin
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Re: River of Wind

Post by Colin »

You are describing a very mild version of what happened to me when the AHRS failed (5 bent pins in the connector). The details are in the blog entry and I will be curious what you find.
Colin Summers, PP Multi-Engine IFR, ~3,000hrs
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rdrobson
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Re: River of Wind

Post by rdrobson »

I don't think it had anything to do with an avionics failure. We were close to the ground so it was very easy to confirm that our track continued straight as we corrected for the crosswind. (FlightAware shows a straight track as well.) All of the data downloaded from the G1000 agrees with what was experienced.

-- Ron
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RMarkSampson
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Re: River of Wind

Post by RMarkSampson »

Ron,
As a former Navy Meteorologist, I'll throw out a hypothesis - but I did not do any real analysis nor did I check the "synoptic weather" at the time your river of wind was running at flood stage. That would require me to set down my beer and pull the data. Much easier to gander a guess. Any my best guess - a low level wind maximum, also known as a low-level wind jet.

I'm a Navy guy so I've seen these things off the coast of California and around the maritime environment. Googling a bit for Minnesota I found this article on "wind shear" - beside the Thunderstorm variety it also discussed this: "Another way that low-level wind shear can occur is when a “nocturnal” or nighttime inversion sets up as the lowest levels of the atmosphere “decouple” from the upper levels and stronger winds. A nocturnal inversion is basically a layer of warm air that develops in the lowest few thousand feet of the atmosphere as the planetary boundary layer becomes decoupled or “disconnected” from the stronger winds just above it."
Here is the link I am looking at: http://www.crh.noaa.gov/Image/lmk/pdf/L ... 0Shear.pdf

It would have been interesting if you climbed through it and encountered any turbulence/wind shear above it. But then again I'm glad you avoided that - it sounds uncomfortable and sometime dangerous. Best to exit out of it on the side. So my guess is you went through a low-level jet that is of the non-thunderstorm variety. My best recommendation is to turn downwind, take a picture of your ground speed and post it to this blog so we all can ooooh 'n ahhhh with envy.

Cheers, Mark
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Lou
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Re: River of Wind

Post by Lou »

Low level jets are common up here, and are charted in the Nav Canada GFAs, but on a calm evening, not so much. They usually precede an incoming system.
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ultraturtle
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Re: River of Wind

Post by ultraturtle »

Most folks would be surprised that Minnesota is is amongst the richest wind power resources in the nation. Take a look down next time you fly during the day, and you will see more wind farms than pretty much anywhere East of isolated mountain passes of the west (too small to be indicated on this map):
Wind Speed.jpg
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