Grand Teton – Owen-Spalding Route

The Owen-Spalding route spans from roughly 6,800 ft at the Lupine Meadows trailhead to 13,775 ft at the summit, and this forecast hits hard above 10,000 ft. Today and tonight bring WSW winds at 22–26 mph at valley level — figure 44–52 mph at the Upper Saddle and summit ridge. That's well above the threshold for comfortable technical climbing on exposed terrain, and with a 45–48% chance of snow showers both periods, new loading is ongoing. Do not attempt the Upper Mountain today or tonight.

Tuesday is the worst window of the trip: 70% probability of snow showers, temps at 24°F, and sustained WSW winds 14–23 mph at basecamp. Extrapolated to ridge elevation, that's 28–46 mph with new snow actively depositing on lee aspects. The Bridger-Teton Avalanche Center has no current rating for the Tetons — their off-season — but their discussion specifically flags watching for cracking, collapsing, and recent avalanche activity. With fresh loading on top of a 35-inch snowpack and no stability data, treat the couloirs and the Valhalla Traverse as suspect on Tuesday. The Owen-Spalding avoids the most loaded cross-slope terrain on ascent, but the approach through Garnet Canyon and the Upper Exum Ridge traverse still cross below loaded headwalls. Move fast through those sections and probe for hollow sounds.

Tuesday night clears significantly — only 19% precip chance and winds dropping slightly. This is your alarm clock: if skies open by midnight, a Wednesday predawn start (2–3 AM from the Lower Saddle) puts you on the summit in the early morning before Wednesday afternoon's next 48% snow shower cycle moves in. Wednesday's temps hit 29°F with 13–17 mph SW winds at the surface, so plan for 26–34 mph at the Upper Saddle — cold and blustery but manageable for technical terrain if you're moving well. Be off the summit and below the Black Dike by noon Wednesday to stay ahead of the returning precip.

Stream gauges in the data are California stations — irrelevant here. Lupine Meadows approach will have consolidated spring snow; the 35-inch snowpack at lower Teton elevations means Garnet Canyon will be well-covered and straightforward for travel. Nearly 14 hours of daylight gives you enormous margin — use it, but structure your summit day around the Tuesday night clearing window, not Monday or Tuesday daytime.