How our forecasts work
Start with the place, then check the elevation and the time. Those three details make a big difference when you read a mountain forecast. Here is how the numbers on SnowReportMeteo reach your screen, and what they can—and cannot—tell you.
Two models, two views of the weather
We use GFS, produced by the US National Centers for Environmental Prediction, and IFS forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF). SnowReportMeteo processes these model data for the locations shown on the site; we do not run a separate global weather model. Comparing them helps reveal uncertainty. Two models agreeing is useful information, but it does not make a forecast certain or turn the comparison into a full ensemble forecast.
Your location and elevation matter
Models describe the atmosphere on a grid. We use the site's coordinate interpolation to obtain a forecast for the selected point. Mountains are smoothed in model terrain, so the model's ground elevation can differ from the elevation you choose. Our altitude processing uses the available model information to estimate conditions at that height. In the ECMWF view, temperature is interpolated between available atmospheric levels; outside that profile, a 5.5°C per kilometre temperature adjustment is used. Precipitation is interpolated horizontally, without a separate simulation of each slope's terrain.
Rain, water equivalent and fresh snow
Check the units and the period beside each value. Precipitation in millimetres represents an amount of water; model total precipitation can include the water equivalent of snow. It should not automatically be read as liquid rain alone. The snow row in centimetres is an estimate of fresh snowfall during the stated interval, not the depth of snow already on the ground.
How the snow estimate is made
The GFS and ECMWF forecast tables use a shared empirical conversion based on precipitation, temperature and a wind-direction adjustment. The snow-to-water ratio varies with the conditions used by that routine. For example, at −4°C, 10 mm of precipitation with a 10:1 depth ratio gives 10 cm of estimated fresh snow before any applicable wind adjustment. It does not give 100 cm. This simplified method cannot fully describe melting layers, mixed rain and snow, settling or wind redistribution, so small changes near freezing can change the result substantially.
The freezing level is not a snowline
The freezing level indicates where air temperature reaches 0°C in the model atmosphere. Snow can survive below it, depending on the air beneath, precipitation intensity and humidity. It is therefore not a promise of snow cover at that elevation. Where the available vertical profile cannot resolve a crossing, the display may show a boundary or an estimate; consult the forecast notes and tooltips.
Model run time and website update time
The model run time identifies the forecast cycle. The site update time tells you when its processed data became available here. They differ because model production, publication, download and processing take time. The countdown is an estimate of the next site update, not a guaranteed arrival time. Use the times shown with the selected forecast and pay attention to the displayed timezone.
Reading totals and the longer outlook
A compact day's total groups forecast intervals; a detailed value covers its stated interval. Do not add the compact total to those same detailed values. A partial day does not cover a full 24 hours. GFS can provide an outlook up to 16 days, while the available range and time steps depend on the model and data received. Farther ahead, use the forecast to follow possible trends rather than to plan around an exact hour or snowfall amount.
What our station comparison score means
The comparison pages use matched temperature and rain records over the displayed period, usually the last 24 hours. Wind is excluded from the overall score. The percentage is our agreement scale, not the probability that tomorrow's forecast will be correct. Missing data and station exposure affect the comparison; the page explains the scoring and available forecast ages. These comparisons do not automatically change the forecasts.
Before heading into the mountains
Read the forecast alongside current observations, camera timestamps and the resort's operating information. For hazardous conditions, follow official weather warnings, local avalanche bulletins and instructions from the relevant authorities. A forecast on this site is not an avalanche assessment or confirmation that a route or lift is open.