Riding weather

About the data

• Riding areas use the automated gauges (USGS and HADS) within 8 miles of each trailhead, up to the 5 nearest. Each number is the median across those gauges. A gauge reading far less than its neighbours over the past week, or less than half of what radar saw at that gauge, is assumed to be clogged or broken and is crossed out (hover it to see why).
• The rating adds up the last 7 days of rain, counting older rain less as the trail dries: Ride under in, Caution under in, Too wet above that. Each area has its own drying speed, and everything dries slower from November to March. These are rough guesses to tune, not trail reports: check closures and local trail-condition posts too.
• Forecasts come from the National Weather Service for each trailhead's grid cell: hourly chance of rain and expected amounts. “Rideable around” adds the forecast rain to what has already fallen, so it moves as the forecast changes.
• Radar estimates come from NOAA's MRMS radar mosaic (via the Iowa Environmental Mesonet) at the exact trailhead, updated hourly. Radar reads low in the mountains because ridges block the beam, so the number is scaled by how much the nearby gauges caught versus what radar saw over those same gauges. It's a cross-check; the rating still comes from the gauges.
• Creek crossings use USGS stream gauges. “Normal” is the median flow for today's date over 90+ years of record; “High” is above the 75th percentile, “Very high” above the 90th. Hover for details.
• USGS automated rain gauges report every 15 minutes. “Today” is rain since local midnight; 3 and 7 days include today plus the previous 2 or 6 calendar days. Data is provisional.
• Gauges used lists every gauge the riding-area cards draw on, with its distance from each trailhead. Crossed-out gauges were set aside as probably broken (hover for why). Mountain rainfall varies a lot over short distances, so compare the nearest gauges, not just the medians.
• HADS gauges are automated stations relayed by NOAA and served by the Iowa Environmental Mesonet: Forest Service and NC fire weather stations (RAWS), county flood-warning gauges and others. They report every 15–60 minutes.