Wind Drift, Up Slope Thermals

[B_Reynolds_AK]

I've been shooting my Barrett Fieldcraft/Nightforce NXS rifle out to a thousand yards plus for a while now, mainly in the mountains using a vitals size steel that I'll place in various realistic situations. I'm getting more comfortable with wind calls doing this.
Fast forward to my sheep hunt this year. 30 degree down angle at 6000 ft on a steep face. 650 yards.
I have a secure shooting position and feel confident in the shot. I compensate for what I feel is a full value 5 mph thermal.
However, the thermal is coming more from below than left to right.
I take the shot on my sheep... and miss considerably high over his back.
Fortunately he came toward me and I am able to get a direct hit at 518 at a 40 degree down angle, directly below me.

So, I have never read anything specific about up slope wind in relation to wind calls. It seems that the wind effectively held my bullet aloft longer, causing the POI to be around a foot high. Am I wrong in my assessment? What would be the method of factoring in wind that is coming from below?

 

[Tumbleweed]

You're talking about a condition known as lift. It can be a bugger to predict. Here's a fantastic video by a man highly qualified to share his experience on the topic of wind over terrain.

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[B_Reynolds_AK]

You're talking about a condition known as lift. It can be a bugger to predict. Here's a fantastic video by a man highly qualified to share his experience on the topic of wind over terrain.

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Great. Thanks Tumbleweed!

 

[B_Reynolds_AK]

Alright I completely understand the principle. Now time to go out and put it to use in the mountains and practice.


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[wind gypsy]

This is an interesting topic. Also Interesting - the number of folks that will tell you they are proficient to take 600+ yard shots out west but only one response with a related link as it pertains to this topic.

We've gotten to a point where it is relatively simple to shoot bugholes at 100 yards and have good ballistic data/calculators. It is easy to make hits a long ways out AFTER you see where the first shot lands. I'd say most of us who have plastered steel on square ranges have a long ways to come in relation to these vertical winds or reading wind in general as it relates to actual mountain hunting conditions.

 

[B_Reynolds_AK]

This is an interesting topic. Also Interesting - the number of folks that will tell you they are proficient to take 600+ yard shots out west but only one response with a related link as it pertains to this topic.

We've gotten to a point where it is relatively simple to shoot bugholes at 100 yards and have good ballistic data/calculators. It is easy to make hits a long ways out AFTER you see where the first shot lands. I'd say most of us who have plastered steel on square ranges have a long ways to come in relation to these vertical winds or reading wind in general as it relates to actual mountain hunting conditions.

Yeah definitely true. I feel like I could have corrected and made a hit after the first shot if the ram stayed stationary.. but it did not. I was certainly fortunate that things worked out in a way that allowed me to take him with an ethical shot. It surprised me as well that it took quite some time for a response. The video that was shared was quite informative and contained info & theory that I have never heard before.


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