Snow Predictions: Route-level forecast for a GPX track

Snow is one of the biggest reasons a route that looks great on a map turns into a miserable (or unsafe) day out. TrailSplits ships Snow Predictions as map tiles and as a route-level summary so you can quickly sanity-check a GPX track.

What the map layer is

TrailSplits publishes a snow overlay as raster tiles:

• GET https://api.trailsplits.com/tiles/v1/snow/current/{z}/{x}/{y}.png
• GET https://api.trailsplits.com/tiles/v1/snow/current/metadata.json

The metadata includes freshness and pipeline context when available.

What the route forecast does

A map overlay is great for exploration, but for a GPX route you usually want an answer like:

• “Mostly clear” vs “mostly snow”
• “Mixed / uncertain” (clouds / coverage gaps)
• “New snow likely in the next 24h”

TrailSplits exposes a route summary endpoint that accepts sampled points along a route:

• GET https://api.trailsplits.com/tiles/v1/snow/route-forecast?release=current&z=13&encoding=mapbox&points=lat,lon|lat,lon|...

The response includes:

• Observed snow percentages (when snow tiles are available)
• A fused estimate that fills gaps using a simple terrain + freezing-level prior
• A coarse 24h/48h evolution driven by weather at the route centroid
• A runner feasibility summary (runner / runner_fused)

Try it with a GPX

The easiest way is the website tool:

• /tools/snow-route-forecast

It processes your GPX locally and sends only sampled lat/lon points.

Notes and limitations

• This is a route-level heuristic, not an avalanche forecast.
• Cloud cover and missing satellite coverage can increase uncertainty.
• The 24h/48h forecast is intentionally simple and should be treated as a “heads up,” not a guarantee.