Swirling Winds and mountain airports

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Alexb2000

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Alexb2000
Yesterday when arriving in Taos the winds were not very strong maybe 8-10 gusting to 15-18. The interesting thing was they were swirling around the airport. Listening to the weather machine they were moving 30 degrees every report or just changing direction entirely. Landing became a function of timing the swirl so that you were touching down at a time when the winds were at least somewhat down the runway. When I initially listened at 20 NM out they were 320 at 10 to 15 so I planned runway 4. At 10 miles they had shifted to 060 so I continued for runway 4. On short final for runway 4 I could feel the winds were a tailwind now, so I listened again and checked the sock. 260 at 15. Around we go. Kept listening as I made a loop around to a long final for 22. While outbound the winds went to 350 again favoring runway 4. I still flew the pattern for runway 22 and by the time I was on short final they were about 270 10-15. So I landed uneventfully.

I have encountered this many times in mountain airports never in the flat lands except near a storm front (which is obvious). So I make it a habit of not just checking the weather machine once and coming in, rather I let it play for 10 minutes or so in the descent and see if the winds are shifting.

There was a visiting 172 from CA on the ground listening to all this. They had tried to take off earlier and aborted due to shifting winds. The pilot kicked the passengers, had them drive down to SAF, and then took off right after I landed. Smart move if you're not familiar with the situation.

Here are a few of the weather reports during that timeframe:

SA 12/05/2013 20:55->
METAR KSKX 122055Z AUTO 15008KT 10SM BKN110 22/M02 A3032
RMK AO1 57024=
SA 12/05/2013 20:35->
METAR KSKX 122035Z AUTO 15008G18KT 10SM BKN100 21/M02 A3032
RMK AO1=
SA 12/05/2013 20:15->
METAR KSKX 122015Z AUTO 32006KT 10SM SCT100 22/M03 A3033
RMK AO1=
SA 12/05/2013 19:55->
METAR KSKX 121955Z AUTO 23006KT 200V270 10SM SCT100 22/M03
A3033 RMK AO1=
SA 12/05/2013 19:35->
METAR KSKX 121935Z AUTO 35007G16KT 10SM FEW095 21/M03 A3034
RMK AO1=
SA 12/05/2013 19:15->
METAR KSKX 121915Z AUTO 31009G16KT 210V340 10SM SCT085 20/M02


Hopefully useful information for those that haven't seen kind of thing before.
 
tonycondon said:
was there strong thermal activity?
Click to expand...

I don't think so, the daytime temps haven't gotten high enough yet. At night we are just now above freezing consistently so the ground is still pretty cool.

In another month or two, you bet.
 
it doesn't have to be "hot". as long as there is a good sized temperature difference from the overnight low to daytime high and "cool" air aloft, the heated surface air will want to rise. There have been 18K foot thermal days in Moriarty already this year.

just curious as strong thermals can have the same effect on the wind in a particular location, especially when the general wind is light.
 
tonycondon said:
was there strong thermal activity?
Click to expand...

Sounds to me like vortex shedding off an upwind mountain range.

That happens with flow past the edge of an obstruction, at moderate rates, as it starts to separate from the surface. It's the same thing that makes your aircraft shudder in the approach to stall.

Vortex shedding is purely mechanical, and it's more likely in stable conditions. As one of these vortices crosses the airport, you'll get a lot of variability over a timescale of a few minutes.
 
tonycondon said:
it doesn't have to be "hot". as long as there is a good sized temperature difference from the overnight low to daytime high and "cool" air aloft, the heated surface air will want to rise. There have been 18K foot thermal days in Moriarty already this year.

just curious as strong thermals can have the same effect on the wind in a particular location, especially when the general wind is light.
Click to expand...

Well then maybe so, you would know a lot more about it than I do. I would guesstimate the difference as ~ 30-40 degrees F. I can't find any way to predict it.
 
well were you feeling thermal activity?

just general mountainous influence is a pretty reasonable conclusion too
 
tonycondon said:
well were you feeling thermal activity?

just general mountainous influence is a pretty reasonable conclusion too
Click to expand...

No thermal activity I could feel. It is usually very obvious up here.

I guess it's just a mountain thing.
 
The first rule of mountain flying::

Fly EARLY in the morning!!! What was the WX at 0630 local?


Check the wind at Date: 05/12/13 12 UTC
KSKX 121235Z AUTO 00000KT 10SM CLR 03/M03 A3045 RMK AO1
 
Last edited:
kgruber said:
Relevance? No. Why should I care what some fool does in New Mexico.
Click to expand...

I was simply asking how that relates to the topic? Or were you suggesting that I get up at 0200 to be here by 0630?

Posting on POA is starting to become a zero sum game. There are just so many people out there spoiling for an opportunity to be needlessly rude. Is this the way you talk to people face to face?
 
Alexb2000 said:
Here are a few of the weather reports during that timeframe:

SA 12/05/2013 20:55->
METAR KSKX 122055Z AUTO 15008KT 10SM BKN110 22/M02 A3032
RMK AO1 57024=
SA 12/05/2013 20:35->
METAR KSKX 122035Z AUTO 15008G18KT 10SM BKN100 21/M02 A3032
RMK AO1=
SA 12/05/2013 20:15->
METAR KSKX 122015Z AUTO 32006KT 10SM SCT100 22/M03 A3033
RMK AO1=
SA 12/05/2013 19:55->
METAR KSKX 121955Z AUTO 23006KT 200V270 10SM SCT100 22/M03
A3033 RMK AO1=
SA 12/05/2013 19:35->
METAR KSKX 121935Z AUTO 35007G16KT 10SM FEW095 21/M03 A3034
RMK AO1=
SA 12/05/2013 19:15->
METAR KSKX 121915Z AUTO 31009G16KT 210V340 10SM SCT085 20/M02
Click to expand...

Light and variable!

The weather along the Front Range Thursday through Saturday was "interesting" for sure. I wanted to get out of ALS on Friday afternoon but had to wait until Saturday morning. The air was definitely unstable over the front range and the plains. Plenty of storms moving north to south which is a little unusual. Saturday morning was fine with an overcast layer limited to covering the highest mountain ranges only. Pikes Peak had little clouds all around it which was interesting. It was like it couldn't commit to making all the weather it had room for..
 
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