There is no basemap. The only ink is the Interstate system itself, drawn on the Albers equal-area projection (standard parallels 29.5° and 45.5°) the 1957 Yellow Book used, tinted by the NWS NDFD forecast sampled at 5,580 points along the pavement. Pick a layer, scrub the timeline seven days out, and hover or tap any mile for the value there and the nearest numbered exit — on an Interstate, the exit number is the milepost.

Radar slides the live MRMS reflectivity mosaic underneath the network — the same 2-minute national mosaic that drives forecastdbz.com, rewarped from its native web-mercator tiles onto this map's Albers plane so the geography stays honest. Alerts drapes the current NWS warning and advisory polygons over the top, tinted by severity; tap inside one for its headline. The forecast layers stay on the timeline; radar is always now.

Road Temp and Pavement come from our own physics model (pavecast — a METRo-style pavement column at every sampling point), not the air forecast: the road surface can hold ice hours after the air warms, and a clear night can frost a deck under above-freezing air. Road Temp pivots its colour ramp at 32° always; Pavement is the modeled surface state — dry, damp, wet, slush, snow, ice, black ice, frost — for untreated pavement (no salt, no plows), so real winter roads usually run better than shown.

Snow, ice and rain are six-hour buckets, not instants, and the scrubber labels them as the window they are. Both carriageways of every divided route are drawn — the pavement doubling when you zoom into a city is the road, not an artifact.