I have also had varied results in snowy conditions. IMO, if the laser won't work either get closer or try the reticle-rangefinding system. I have tested RR on deer and antelope and have had great results to about 500 yds. and OK results beyond that. When it comes to reticle-rangefinding the best system u can use is the modified mil-ranging formula that will work with any multi-stadia reticle out there once it's subtension (stadi to stadia measurements are known). Here's the formula in it's most basic form (inches to yds.)--
tgt. size (") x range of reticle subtension measurement (usually 100 yds.) / reticle subtension (") / quantity of "gap" tgt. occupies (decimal equivalent) = range (yds.)
Coyotes in my area of operation measure right around 11" back to brisket (back to brisket is the most consistent presentation you're gonna get on a game animal). So if i'm using my TMR reticle by Leupold that has .2 mil (.72 inch per 100 yds.) subtension units and say the coyote occupies 4.7 of those here's what it calcs out to be--
11 x 100 / .72 / 4.7 =325 yds.
Now here's that particular entry in my ranging sticker that i put into a Butler Creek BLIZZARD objective scope cap cover--
4.7-325
...see how it works? Better practice with it some to see how it works. Remember as range increases so does the error--geometrically, and it all comes down to how well u can guess tgt. size accurately, and how well u can interpolate (guess) between stadia accurately.