Storm & Flood Damage Recovery in Jamestown, NY

That is an ice dam and it is a heat problem rather than a weather one. The upper roof is warm enough to melt snow while the eave stays below freezing, so the meltwater refreezes at the edge and backs up under the covering. Two houses on the same street can differ entirely depending on attic insulation and air sealing. Raking the eave treats the symptom; sealing attic bypasses is what stops it recurring.

In balloon framing that is normal and it is one of the reasons this stock is deceptive. The stud cavities run uninterrupted from sill to roof, so water entering at an upper window or roof junction falls the full height inside the wall and appears at the bottom with nothing wet in between. Tracing it means starting at the top of the cavity rather than at the stain, and opening a small area high up usually saves a lot of guessing.

Clear the gutters, check that the attic hatch and any recessed lights are sealed, and look at the insulation depth at the eaves rather than in the middle of the attic. Those three determine whether a dam forms. It is also worth knowing where the roof has leaked before, because a dam will find the same weakness every year, and a repair made in October costs a fraction of the ceiling work in February.