Another lesson over the weekend. I was hunting wolves and cats and spotted a shootable cat. It's a long story so I will cut to the point-
600 yard shot. Backside of mountain and back side of wind direction. The wind mainly had been, as facing down the finger/ravine, blowing left to right and it was gentle (3-4 mph). During my hold and target area observation it appeared the wind was NULL in this protected area. ?? Sent it, the hit was 6-9 inches left. Cat was slightly angled toward me. When I got to the area I noticed the wind was now right to left and coming up the ravine. Should have held 1 moa right, from my new calculations.
Later I shot uphill at 900 yards. When I took the wind reading at my spot it was right around 6mph (2.6 moa) but a little gusty. Wind was right to left. As I hiked up the slope I was trying to take note of the wind but it was minimal in most spots, until I got close to the target. At the strongest point it was 8mph. My impact was vertically good, horizontally it was left 9-12 inches. I needed 3.4 moa according my program based on 8mph vs the 6 mph I input. The strike and the new calculation look about right. When I got the saddle, above this test shot, the wind was 12. Crap.
I am not new to the mountains of course but reading wind for hunting game seems significantly different than shooting. I have noticed all sorts of weird things with the wind lately such as the way it builds up, holds it's breath, then lets it go. I call it flushing. I see rivers do the same thing behind a rock.
Is there a good site that helps describe wind flow and mountain terrain? I am feeling pretty inadequate and need a better wind reading education.
Thanks guys. I know I need to field test and learn but I can not get reloading supplies here in Boise and don't have enough left to do much practical shooting. I tend to do well with in-field training and reading or researching. I am finding there may be a pattern to this mountain wind currents and am looking for any advise I can get.
Thanks. We have hound guys that will run for us anytime but my buddy I prefer spot and stalk. It is tough, cats are super sneaky, and can hide with some mad skills. I have only wanted to shoot one other cat in the past 20 I have spotted. The only reason I didn't shoot it was due to not knowing if the female quota had been met yet. It was much larger than this one so I assumed it was a male, but passed on the shot. I did get pictures though. : )
This cat seemed much larger at the time I was estimating size, not very good at that for sure, but it seemed like a shooter and well, it all managed to work out. Whew!
OK, about wind: What I am observing is back drafts and low pressure areas. I call these hides. Hides is the area of the terrain the wind is confused and trying to find balance. If you look at wind at the very top of a mountain it curls over the lip and tumbles into self, like a cartwheel. Further down the mountain there is back draft area where the wind is actually going up the mountain, then the transition or hide area, then the area where the wind is going back down again.
What I have observed is a few different wind directions in a 1000 yard plus target range. For example, near the top the wind may be generally blowing down and to one side, the next area it is coming back up, the hide area is confused and swirling, the bottom is coming back up the mountain etc. I also notice the surge, calm, and then flush. The cycle starts over again. To complicate this even further it depends if the target is one side or the other of the down range ravine.
On front sides of the terrain to the wind direction calculating windage seems pretty straight forward and consistent. However, it is kind of rare you have a target that stays within that terrain feature. Another fun one I encountered Sunday was a down draft on side of deep ravine and I noticed an updraft on the other side. I have no clue what is was doing the middle. I assume the hokie pokie.