Every fall, the same weather pattern plays out: a cold front stalls east of the Wasatch, pressure builds, and wind pours down the canyons like water from a tipped bucket. On the benches below Millcreek, Big Cottonwood, and Little Cottonwood canyons, gusts past 70 mph are a near-annual event — and the morning after, the chainsaws sing.
Why the bench gets hit hardest
Canyon outflow winds accelerate as they squeeze through the canyon mouths, which means the neighborhoods directly below them — Millcreek’s Canyon Rim, Olympus Cove, Cottonwood Heights, east Sandy — take winds 20 to 30 mph stronger than the valley floor sees in the same storm. A tree that would shrug off a storm in Rose Park can lose half its crown on Wasatch Boulevard.
Which trees fail, and how
Three failure patterns account for most of the damage we clean up:
The overloaded limb. Long, horizontal branches with years of end growth act as levers. The wind adds load at the worst angle, and the limb tears out at the trunk — usually the limb over the roof, because that’s the one that was never lightened.
The sail crown. A dense, never-thinned canopy catches wind instead of letting it through. The whole tree rocks, and either a major limb snaps or — in shallow-rooted species like blue spruce — the root plate lifts and the tree goes over entire.
The hidden defect. Codominant stems with included bark, old topping cuts, decay pockets: weak points that hold fine on a calm day and fail at 60 mph. These are the failures that surprise people, and the ones an inspection catches.
The three things that work
- Thin the crown. Selective interior thinning lets wind pass through. It’s the single highest-value job for a big bench tree — here’s how we do it without stripping the tree.
- Reduce end weight. Shortening overextended limbs back to strong laterals takes the lever arm away. Your roofline limbs should be first in line.
- Fix or remove the known weak points. Deadwood comes out, bad unions get corrected or cabled, and a tree that’s genuinely past saving comes down on a calm day — on your schedule and your terms, not the storm’s.
The timing matters: all three belong in late summer and early fall, before the first big event. If your yard sits under a canyon mouth, a pre-season walk-through costs nothing — and it’s a far better call than the one your neighbors make the morning after.