The composite score weights snow reliability against the historical baseline, pulls in live conditions where available, then adjusts for how much hassle the trip actually is for your group.

01ERA5-Land hourly grid → daily SWE & snow depth at the resort cell.
02Bias-correct against ground stations (SLF / Météo-France nivôse).
03Build per-week climatological percentile · 35 winters.
04Anomaly = current week vs. cell's own 30-year baseline.
05Snow-sure read at the highest-snow cell within ~15km. When most resorts are bare, ranking shifts toward this, surfacing glaciers in shoulder seasons.
06Weight + rank against your origin & vibe profile.