Snow Forecast Accuracy: What 'Expected 40 cm' Really Means

A weather model is a grid. Each grid cell is typically 9 km wide and assumes one elevation. A real ski resort spans 1,200 m of vertical and three or four exposed faces, often inside one model cell.

That means the model under-predicts orographic snowfall on the windward side and over-predicts on the leeward side. Anyone who tells you their 7-day total is accurate to the centimetre is bluffing.

We publish 24-hour and 7-day forecast totals for upper mountain elevation. We deliberately do not publish hour-by-hour precipitation graphs, because at 9 km grid resolution they are noise dressed up as signal.

• 24h total — useful for 'should I book a powder day?' decisions.
• 7-day total — best signal-to-noise ratio for trip-planning a week out.
• Powder alerts — triggered at ≥20 cm in 24 h or ≥30 cm in 7 days, with a 5-day cool-down per resort to avoid spam.

Most public forecasts give snow at the model's reference elevation. A village at 1,400 m and a peak at 2,800 m do not get the same amount. We apply a per-resort altitude correction using the upper-mountain elevation we hold in our catalogue.

This is the same reason a generic 'Tignes' forecast on a consumer app under-predicts what falls on the Grande Motte glacier above.

Compare 7-day totals across nearby resorts before fixating on absolute numbers. The relative ranking — 'Engelberg is forecast 80 cm, Andermatt 40 cm' — is far more reliable than the exact value at either site.

Then cross-check with current snow depth. A resort forecast to get 40 cm on top of a 220 cm base is a much safer bet than the same forecast on a 60 cm base.