Everyone was talking about winter storm Harper late last week. The storm was moving across the Midwest on Friday and was expected to make landfall in Pennsylvania on Saturday afternoon. The weather report was telling me I was going to have a four or five hour window on Saturday to fly fish. The air temperatures were supposed to hold steady in the mid-30s into Saturday morning and this was actually an increase from earlier in the week when overnight temps were dipping into the low 20s. My experience is that any gradual and sustained increase in temperatures in the colder months can mean active brook trout.