I'm not sure which section of the madison you will be on, guessing probly the upper though. I spend a lot of time on the lower and have found it comes down to three basic approaches...baetis dry flies and emergers, buggers in black, brown or olive, and nymphs (pt's, hares ear's and princes are usually the best bets). I like to use a beatis sprout emerger, usually in 18 or 20, which can also be usued during a midge hatch in smaller sizes. If I dont see fish rising then I use a bugger. I rarely use nymphs but they are effective. I didnt get on the Madison as much last fall as the past few years. Hope this helps you out some, these are just my observations and others may have more to add. The best bet would be to check any fly shop in W. Yellowstone (Blue Ribbon Flies my choice), Bozeman (Greater Yellowstone Flyfishers my favorite), or Ennis.

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Take care everyone and cya around. Mark