Colors show modeled near-ground smoke concentration (or whole-column haze) from NOAA's HRRR forecast model, refreshed from the freshest hourly run (~18h ahead). Bands line up with EPA PM2.5 thresholds but this is a forecast, so treat it as guidance; where a real monitor is nearby, its latest reading is shown next to the modeled value — from AirNow (regulatory) or the denser PurpleAir network (low-cost, EPA-corrected). If a sensor near you reads worse than the forecast, the guidance says to trust the sensor. SUMMIT (in the Model picker — beta, in training) is our bias-corrected view: it blends HRRR and RRFS, each nudged by that town's recent sensor-vs-model ratio, and the town readouts, stripe and table show the corrected value with its difference from the raw blend (the stripe's dashed line is the raw HRRR+RRFS average). Where a real sensor sits within ~10 mi of a town, SUMMIT also anchors to that live reading near the present hour, relaxing to the pure forecast over the next several hours (sensor now → model later). Pick HRRR or RRFS to see a single raw model instead. The map's colored shading is always the raw base model — a per-town correction can't repaint an image — so trust the town numbers over the shading in SUMMIT mode. (A fuller machine-learning corrector — SUMMIT, Sensor-Updated Mountain Model for Inversions & Terrain — using elevation, valley trapping and upwind smoke is trained and being wired in.) For official air quality, see AirNow.gov. Times are Colorado (Mountain). ▲ = mountain town, ● = city, 🔥 = satellite fire detection, blue dot = you.