The trail moisture index is a running total of rainfall that decays as trails dry out: each day the index keeps 82% of yesterday's value, loses moisture to measured evapotranspiration, and gains that day's rain. It's seeded from the last 7 days of observed rain at Uki (−28.41, 153.34) via the Open-Meteo API, then projected forward with the forecast.
Bands: index under 12 mm-equivalent = Ride; 12–30 = Caution (soft patches, avoid skidding); over 30, or 20 mm+ in the last 24 h = Too wet — riding damages the surface and makes work for the dig crew.
Topsoil moisture (0–7 cm, satellite/model estimate) is shown as a cross-check. This is an estimate, not gospel — official closures and local knowledge win.