How it works
Every call has a source, or it says unknown.
Today's call
Each morning at 6:40 a job pulls snow depth from NRCS SNOTEL stations, rain from NWS airport sensors and SNOTEL gauges, the NWS forecast, and closure pages from the Forest Service, Nevada State Parks and the Tahoe Rim Trail. Fixed rules turn that into one call per trail. No AI touches the call.
- Closed when an official page names the trail and a closure.
- Snow when a SNOTEL station near the trail, at a similar height, has 2 in or more at or below its high point.
- Muddy after a quarter inch of rain in 48 hours at the nearest gauge.
- Dry only with proof on both counts: a bare station near the high point and a complete, low rain record.
- Unknown when any of that is missing or stale. Then the page says what's missing and where we looked.
The dry-by forecast
Starting from today's call, dryline runs the NWS forecast forward a day at a time with a small water budget. Snow at the trail's high point melts with warm days. Rain and meltwater soak the ground, then sun, warmth and a south-facing slope dry it out. North faces hold water longer. The first day the ground drops back under the muddy line is the dry-by day.
It's a guess, and the numbers it uses are all in the code. Closed and unknown trails don't get one.
How often it's right
Scored against the next mornings' calls, across 8 mornings since Oct 16:
| Days ahead | Matched | Calls | Hit rate |
|---|---|---|---|
| 1 | 68 | 68 | 100% |
| 2 | 33 | 33 | 100% |
| 3 | 31 | 36 | 86% |
| 4 | 18 | 33 | 55% |
| 5 | 5 | 33 | 15% |
| 6 | 0 | 36 | 0% |
| 7 | 0 | 18 | 0% |
That's a small sample from one storm, so read it as a start. Rider reports are the real test, and they get scored here as they come in.
Rider reports
Anyone can say how a trail actually was: dry, tacky, muddy or snow, plus a short note. Reports show on the trail's page for two days, and they're the ground truth the forecast gets tuned against. No account, no tracking.
What it won't do
It won't guess when the data isn't there, and it won't scrape sites that ask not to be scraped. It isn't safety advice. Snow, closures and fire change fast, so check the land manager before you go.