How PowMeet snowfall forecasts are made

Where the data comes from

PowDensity™ is PowMeet’s own snowfall forecasting algorithm. Its inputs are ECMWF IFS open data (© ECMWF, CC BY 4.0, modified) and NOAA GFS global forecasts (modified; no NOAA endorsement).

Regional weather forecasts in Japan come from the Japan Meteorological Agency. 出典：気象庁ホームページ（加工して作成）.

Resort names, locations, runs and lifts come from OpenSkiData (© OpenStreetMap contributors, ODbL), Skimap.org and Who's On First; PowMeet maintains the Japanese and Chinese resort lists. 3,024 resorts in 60 countries and regions are listed.

Snow or rain, and how much

PowDensity™ looks at the temperature at each level of the air above the mountain to tell snow from rain and how light the snow is, then sums the result into daily new snow (cm) on the resort’s own reporting basis.

The same amount of precipitation builds a deeper layer as dry snow in cold air than as wet snow, so centimetres of new snow are not a fixed multiple of millimetres of precipitation.

Summit and base, worked out separately

Each resort has two heights, base and summit, and PowMeet computes new snow at each. Resort pages show both elevations and the vertical between them.

Air gets colder with height. With a few hundred metres of vertical it often snows at the top while it rains or sleets at the bottom. Resorts without both heights show a single value.

Model grids are coarser than a ski area, so the summit value describes that height in general, not a measurement on any particular run.

Forecast range

Free: daily snowfall and weather for the next 9 days. PowMeet Pro adds the daily forecast for days 10–14, the PowDensity™ heavy snow forecast and side-by-side forecast models.

Updates and expiry

Forecasts are updated daily. Every forecast carries a publish time and a validity period, and pages show when the forecast was updated.

Once a forecast passes its validity, PowMeet stops showing its numbers and says no forecast is available: an out-of-date number misleads more than a missing one.

Snowfall numbers on resort, country and region pages are read in your browser from the latest data; resort facts (elevation, runs, lifts) show the date they were updated.

Limits

Forecasts are guidance only. Actual snowfall can be more or less than forecast, and forecasts several days out change more.

Wind strips and loads snow, and local terrain makes totals differ from the forecast.

A forecast is not a substitute for avalanche bulletins, the resort’s own updates or on-site judgement.

Resort information (runs, lifts, links) is gathered automatically and not manually checked; PowMeet pages are not the resorts’ own websites.

Who publishes this

PowMeet (app name PowMeet Ai) is operated by 上海玩态科技有限责任公司 (Shanghai, China), on the web at powmeet.app and as the WeChat mini program “滑雪天气PowMeet”.