Every cell is NOAA HRRR (3 km, hourly‑updated, CONUS, 48 h) — no other model is blended in. Arrows point downwind, the way the air is moving; hover or tap any cell for the direction it blows from, given in degrees the usual way — 000° = north, 090° = east, 180° = south, 270° = west. Heights are feet AGL, recomputed from each level's geopotential height minus field elevation, so they shift a little as the air column expands and contracts.
Colour is risk, not raw speed: the surface rows and the rows aloft use different thresholds, because 18 mph on the deck and 18 mph at 4,000 ft are not the same problem. The gust row is shaded on gust minus sustained, since a spread is what knocks a wing down. Thresholds follow the Powered Paragliding Bible 7 — they are a planning aid, not a go/no‑go call.