Stumped by cross canyon wind

[cwright]

Shooting 400, 500, and 600 yards last weekend we dialed in our rifles and were hitting the "gongs" consistently. Had a 2-3 MPH wind but at a near zero value, coming from the 5 o'clock position. Next morning, same place, same targets, same shooting platform, we have a 2-3 MPH breeze at shooting location, and no visible signs of wind down range. Grass blades still, etc. I calculated the 3 MPH left to right, aimed left and missed the gong. Several attempts, still no hit, no splash detectable by my spotter(s). One shooter keeps adjusting aiming point left until he finally hits the gong at 400, and based on his gun's particulars, his successful adjustment would be correction for 10MPH wind. Next shooter adjusts for 10 MPH wind and hits targets at 400, 500, and 600. But we didn't have 10MPH wind. Maybe 2, maybe 3 where we shoot from, hardly even spun my anemometer. POI on a 300 H/H Mag shooting 190 gr. Berger VLD's was almost 20 inches right at 600. Good group, just 20" right.

Reading and googleing on "canyon wind", I'm anxious to hear thoughts from this forum about the predictable affects of shooting cross canyon, in light winds. Can it be howling down the canyon, say 400 feet above canyon floor, but not be blowing on the sides? We're starting to think we need to release a helium filled balloon to see what's happening at our bullets path, because we're not seeing it on the ground. Can anyone offer up any science here. Thanks in advance.

 

[BrentM]

The number 1 issue of mountain shooting is wind. Over the past several years I have been shooting in various terrain and over multiple terrain features. I have found that you can never trust the wind at the shooter location to be the same as target or between. I do rely on prevailing wind to give me bullet flight path data and then I look at how the terrain shapes the winds direction......which flows a little like water in a stream. Complete with eddies, cycling/flushing, and up/down drafts.

It is very likely you were in a deadzone due to pressure differentials at the shooter and the cross wind above the rim and below the rim were in fact much stronger. In a case such as this, I tend to try and "predict" the wind the entire time I am out, not just the time I am ready to send it. The whole challenge of terrain shooting for me is getting wind dialed in the first time to make first round hits. This requires constant wind monitoring. It drives my wife nuts sometimes. We'll be on hike and she is watching me as I stare off into the landscape.....she asks me what I am looking at...then says, never mind, you are studying the freaking wind again..... and walks off.

 

[FearNoWind]

Brent obviously has considerable experience with wind doping. It is not a science; it's an art. With a zero value 3 mph wind behind you there may be a full value 10 mph wind half way to the target. It may be 2 - 3 mph at ground level and 15 mph at the height of the arc of your bullet's patch. You're on the right track comparing vegetation movement at your shooting position to that at the target's location but when you're shooting over a canyon or similar terrain there can be wind shifts that are nearly impossible to judge. Energy tends to concentrate in terrain like canyons so air movement differs from what we experience over ground that is relatively flat. Canyon walls heat and cool at a different rate than surrounding plains. The type of vegetation, concentration of rocks, presence of or absence of water, amount of moisture in the vegetation, etc. will all affect wind. I'd suggest learning all you can about doping wind over flat ground. Once you've become an "artist" at that you may have some success at making wind calls over uneven terrain. I have never mastered it and some of the guys I shoot with who believe they have are more than likely simply blessed with greater luck than I have.

 

[BrentM]

Have you watched the movie Shooter with Mark Wahlberg? I made my wife watch it a couple of weeks ago during some down time. She noticed right off the get go you have to be a little nuts to be a shooter. I am thinking shooting LR in terrain makes you a little nuts.

 

[4xforfun]

Just a little FYI on windage values. A 5 Oclock wind is just a tad under 50% of full value....not "near zero".

 

[FearNoWind]

Just a little FYI on windage values. A 5 Oclock wind is just a tad under 50% of full value....not "near zero".

Thanks ... I neglected to mention that.
Here's some instructional data that can be helpful.

https://www.google.com/search?q=sho...ooting-tips%2Fshooting-in-the-wind%2F;250;242

Also, estimating the angle of the wind relaltive to point of aim can be tricky.

 

[Wedgy]

A hill top that is one of my favorite spots to glass from has the wind in your face at 13mph facing East and it's going the opposite 10mph in the bottom of the canyon almost every morning. The warm air rises and the cool air is going down. The other side of the canyon is 800 yards away and is the same wind in the face every morning. It's over 300 yards deep and I have no idea what is going on in between but it shoots as a full value 3mph wind shooting straight across so I think the wind just hits the tops of the hills and not the space in between. I would love to see some fog blow thru there in those conditions.

 

[royinidaho]

It took me a long, way too long for a smart fella, to learn that wind velocity "is usually" higher and more consistent in the center of the canyon than at the edges. Similar to water flow in a river.

This became visible when I started videoing all shots. The bend in trajectory in the middle was quite visible which was at the apex of the trajectory which is at a much higher altitude than either the shooting point or target.

When shooting at that spot I multiply measured wind speed by 1.25 and get spot on first shot. Well, some times.

 

[WildRose]

Shooting 400, 500, and 600 yards last weekend we dialed in our rifles and were hitting the "gongs" consistently. Had a 2-3 MPH wind but at a near zero value, coming from the 5 o'clock position. Next morning, same place, same targets, same shooting platform, we have a 2-3 MPH breeze at shooting location, and no visible signs of wind down range. Grass blades still, etc. I calculated the 3 MPH left to right, aimed left and missed the gong. Several attempts, still no hit, no splash detectable by my spotter(s). One shooter keeps adjusting aiming point left until he finally hits the gong at 400, and based on his gun's particulars, his successful adjustment would be correction for 10MPH wind. Next shooter adjusts for 10 MPH wind and hits targets at 400, 500, and 600. But we didn't have 10MPH wind. Maybe 2, maybe 3 where we shoot from, hardly even spun my anemometer. POI on a 300 H/H Mag shooting 190 gr. Berger VLD's was almost 20 inches right at 600. Good group, just 20" right.

Reading and googleing on "canyon wind", I'm anxious to hear thoughts from this forum about the predictable affects of shooting cross canyon, in light winds. Can it be howling down the canyon, say 400 feet above canyon floor, but not be blowing on the sides? We're starting to think we need to release a helium filled balloon to see what's happening at our bullets path, because we're not seeing it on the ground. Can anyone offer up any science here. Thanks in advance.

Since it was morning you probably had up slope wind as well and just could not see it; provided of course the sun was already hitting the canyon.

If it wasn't there's a good chance you had a down slope wind.

When the sun first hits the ground it creates updrafts. Those updrafts will act differently in a canyon than the will on flat ground because those updrafts and down drafts for that matter tend to follow the contours of the ground.

 

[WildRose]

The number 1 issue of mountain shooting is wind. Over the past several years I have been shooting in various terrain and over multiple terrain features. I have found that you can never trust the wind at the shooter location to be the same as target or between. I do rely on prevailing wind to give me bullet flight path data and then I look at how the terrain shapes the winds direction......which flows a little like water in a stream. Complete with eddies, cycling/flushing, and up/down drafts.

It is very likely you were in a deadzone due to pressure differentials at the shooter and the cross wind above the rim and below the rim were in fact much stronger. In a case such as this, I tend to try and "predict" the wind the entire time I am out, not just the time I am ready to send it. The whole challenge of terrain shooting for me is getting wind dialed in the first time to make first round hits. This requires constant wind monitoring. It drives my wife nuts sometimes. We'll be on hike and she is watching me as I stare off into the landscape.....she asks me what I am looking at...then says, never mind, you are studying the freaking wind again..... and walks off.

Emphasis mine.

Really right on.

 

[AaronEdwardJames]

Did you check your zero before you started shooting the second day, in areas like that you can get swirling , aggressive fish tailing wind and wind switches down range try putting up some wind flags t variou intetvels down the line if fire might give u a better indication of what's going on

 

[Greyfox]

Canyon shooting is by far the toughest for me to get a solid wind dope. I have had to pass on LR shots on a bunch of good animals over the years because of uncertainty in this condition. I agree with Brent that understanding the prevailing wind speed and direction, and applying it to the orientation of the canyon is a very useful approach. As a general rule, when shooting across canyons where the elevation is a few hundred feet or more, I will many times double the correction that I determine at my location. Not very scientific, but there aways seems to be a venturi type of effect in canyon formations that accelerates the wind.

 

[AaronEdwardJames]

Wind in a canyon will be accelerated due to it all being funneled Dow the canyon following the path of least resistance like a river it flows and when it gets unbelted to a tight spot it speed up

 

[AaronEdwardJames]

When the win bounces of canyon walls it will cause it to swirl and if there are Any alleys ways in the canyon it will create crosswind which differ from the prevailing wind, it's a experience thing I reckon the more you shoot in a canyon the better understanding you'll have of what happens to dial in correctly