About PowderCast

Free, open-source snow forecasting for every mountain.

What is PowderCast?

PowderCast is a snow forecasting tool that blends multiple weather models to generate accurate snowfall predictions for 200+ North American ski resorts. Instead of relying on a single model, we combine GFS, ECMWF, ICON, and GEM forecasts into a confidence-weighted blend that outperforms any individual model.

The result is a 14-day snowfall forecast for each resort, complete with confidence scores and forecast ranges that let you know how certain the prediction is. We also integrate SNOTEL ground-truth data to validate and improve our forecasts over time.

Data Sources

Open-Meteo

Free weather API providing GFS, ECMWF IFS, ICON, and GEM model data. Forecasts are fetched for the mid-mountain elevation of each resort with 3-hour resolution.

SNOTEL / NRCS

USDA Natural Resources Conservation Service SNOTEL network. Automated snow telemetry stations measuring snow depth, snow water equivalent (SWE), temperature, and precipitation across western mountain ranges.

National Weather Service

NOAA National Weather Service provides supplementary forecast data, avalanche alerts, and winter weather advisories.

Methodology

1

Multi-Model Fetch

Every 6 hours, we fetch 14-day forecasts from 6 weather models (GFS, ECMWF, ICON, GEM, HRRR, NBM) for the mid-mountain coordinate of each resort.

2

Model Blending

Individual model forecasts are blended using performance-weighted averaging. Models that have been more accurate for a given region in the past receive higher weight.

3

Confidence Scoring

Model agreement determines confidence. When all 4 models agree on snowfall amounts, confidence is HIGH. Significant disagreement yields LOW confidence and wider forecast ranges.

4

SNOTEL Validation

Forecasts are compared against real-time SNOTEL observations. This feedback loop helps calibrate model weights and identify systematic biases by region and elevation.

5

Daily Summary

Hourly blended data is aggregated into daily summaries with snowfall totals, temperature ranges, wind conditions, and a human-readable confidence label.

Weather Models

GFS(NOAA / NCEP)

Global Forecast System. American model, updated 4x daily.

Resolution: 0.25 deg

ECMWF(ECMWF)

European model. Often considered the gold standard for medium-range.

Resolution: 0.25 deg

ICON(DWD)

German model with higher resolution. Strong for complex terrain.

Resolution: 0.125 deg

GEM(ECCC)

Canadian model. Valuable for northern and Pacific patterns.

Resolution: 0.25 deg

Open Source

PowderCast is open source. The full data pipeline, forecast engine, and frontend are available on GitHub.

View on GitHub