About & Methodology
Windfield is a SummitFlux project built on the USFS WindNinja engine. Here's what it is, the three ways to run it, and its limits.
What WindNinja is
WindNinja is a diagnostic wind model from the USDA Forest Service's Missoula Fire Sciences Lab. It computes a terrain-adjusted wind field for a specific place and time, accounting for the way hills, ridges and valleys speed up, slow down and redirect airflow. “Diagnostic” means it solves one physically consistent snapshot rather than forecasting how wind changes over time. The core solver is mass-conserving: it adjusts an initial wind field so air mass is conserved at every grid cell, given the real terrain underneath — see Credits for the project's source and the data this runs on.
Three ways to run it
- Simulate — you set the wind speed, direction, height, vegetation and mesh detail yourself.
- Current conditions — we pull live weather for the area you've drawn and run WindNinja with that.
- Forecast — a weather model drives the wind over the next several hours, with a time slider to step through each hour.
Structures
You can draw a building, wall, barn or any polygon/circle shape directly on the map, give it a height (or mark it infinitely tall), and WindNinja will raise the terrain under it before solving — useful for seeing how wind bends around a specific structure rather than just the open landscape.
Limits
There's no fixed area-size cap — instead, every run is budgeted by total grid cells, run time and memory, so a big area at coarse detail and a small area at fine detail are both fine, but a huge area at fine detail isn't. The panel always shows a live estimate (“≈ N cells · ~S s · terrain M m”) before you run, and if a custom mesh would be too fine for the area, the app offers the coarsest setting that would fit.
- Up to 2 runs process at once, up to 20 queued, 2 in flight per visitor.
- Job files are kept only while you keep the page open (roughly 5 minutes after you close it or move on) — share links rebuild the run rather than pointing at files kept forever.
Results are a model, not a forecast. WindNinja estimates a physically plausible wind field for the inputs and terrain it's given — it does not know the actual weather at any given moment unless you chose Current conditions or Forecast, and even then it's only as good as its weather source. Treat it as a planning and situational-awareness aid, not a substitute for an official forecast, especially for life-safety decisions.
Data sources
Elevation comes from AWS Terrain Tiles (a blend of SRTM, USGS NED/3DEP, GMTED and ETOPO1); basemaps from OpenStreetMap, OpenTopoMap and Esri; live weather from Open-Meteo and the NOAA National Weather Service; forecasts from NOAA's GFS/HRRR/NAM models; place search from OpenStreetMap Nominatim. Full attribution and links: Credits.
No accounts, nothing gated
Everything here is free: no login, no paywall, no feature gating.