Glacier NP — Highline Trail to Granite Park

The Winter Weather Advisory from NWS Missoula (issued April 21, active until 6 PM today) is the headline, but the storm pattern extends well beyond the advisory window. Highs of 36-39°F and lows of 20°F persist through Saturday night, with snow likely every day and night of your trip. Snowpack at this elevation is already significant — 52 inches of depth at the trailhead area — and you're adding to it daily through the weekend. The Highline Trail traverses exposed alpine terrain above 6,000 feet with no real bailout once you're past the Loop trailhead. In these conditions, post-holing through fresh snow on top of a consolidated late-season pack is likely, trail markers will be buried, and route-finding between the Garden Wall and Granite Park Chalet becomes genuinely committing.

Avalanche data is unavailable for this forecast zone, but that doesn't mean avalanche terrain is absent — it means there's no formal forecast. The Highline Trail traverses directly beneath steep north and northwest aspects on the Garden Wall, which are exactly the slopes that load during north-wind snow events like this one. You're getting heavy snow on top of a 52-inch base with sustained north winds. Without a forecast, you're operating without a safety net on terrain that historically produces slides in these conditions. Cross carefully under any steep chutes and move quickly through exposed avalanche paths — the cliff bands above the trail don't give you much room.

Stream crossing data in this briefing is from California gauges and does not apply to Glacier NP — disregard those numbers entirely. What does apply: warm days followed by cold nights all week means snowmelt will be minimal and daytime runoff will be limited. Stream crossings on the Highline route should be lower than their May peak, which is a relative positive. That said, any stream running through snow on north aspects will still be cold, fast, and slippery on an icy substrate.

Fires are clear, no smoke issues at all. Daylight is generous at 14-plus hours with sunset at 8:38 PM, which is your biggest logistical asset if you do go. If you proceed, leave the Logan Pass trailhead by 8 AM to maximize daylight for route-finding in low visibility and build in time for slow travel through fresh snow. Carry poles, be ready to turn around if you lose the trail, and know that the Granite Park Chalet is not staffed this time of year. The window does not improve until Sunday at the earliest — if your dates are flexible, a 48-hour delay could be the difference between a slog and a great trip.