At Sknowed.com, we believe users should understand where weather information comes from, how it is presented and what its limitations are.
Sknowed presents numerical weather-model data in a format designed for skiers and snowboarders. We do not employ meteorologists and do not issue official weather forecasts.
This guide explains the data displayed by Sknowed, how we present it and how it should be interpreted when planning a ski trip.
1. Where Our Weather Data Comes From
Sknowed uses numerical weather-prediction data produced by established national and international meteorological agencies.
Our primary long-range forecast currently uses the Global Forecast System (GFS) operated by the United States National Oceanic and Atmospheric Administration (NOAA).
-
Weather model: Global Forecast System (GFS)
-
Forecast period: Today plus the following 15 days
-
Model updates: GFS produces new model runs four times daily at 00Z, 06Z, 12Z and 18Z
-
Sknowed updates: Sknowed retrieves updated model data several times each day after new model runs become available
Numerical weather models divide the atmosphere into a grid. As a result, neighbouring ski resorts may sometimes receive similar forecast values, particularly where the model cannot fully resolve individual mountains, valleys, ridges and other local terrain features.
Model resolution and forecast characteristics vary depending on the weather model being used.
2. Elevation-Based Forecasts
Sknowed displays forecasts for different elevations at each ski resort, normally representing the bottom, middle and top of the ski area.
The underlying model data is processed for the requested resort coordinates and elevations before being displayed by Sknowed.
Sknowed does not independently apply a proprietary temperature lapse rate or manually modify temperatures for individual slopes, ridges or valleys.
The elevation forecasts are intended to help users compare likely conditions at different parts of the mountain. They should not be interpreted as measurements taken at those exact locations.
3. Snowfall and Other Derived Variables
Not every value displayed by a weather service is necessarily a variable directly produced by the original numerical weather model.
Some values may be derived from underlying atmospheric variables such as temperature, humidity, precipitation and pressure.
Sknowed currently displays the model-based data supplied to its forecasting system. Unless specifically stated otherwise, Sknowed does not independently:
-
convert precipitation into snowfall using a proprietary snow-to-liquid ratio;
-
apply historical bias correction;
-
adjust snowfall for slope direction or individual terrain features;
-
modify forecasts according to local resort observations; or
-
create a consensus forecast from several weather models.
Where snowfall is displayed, it should be understood as model-based forecast snowfall, not measured snowfall, settled snow depth or a guarantee of conditions at the resort.
4. AI-Generated Model Summaries
Some Sknowed pages include a written outlook generated from the numerical weather data displayed on the page.
The purpose of these summaries is to make the underlying model information easier to understand.
A summary may describe expected:
-
snowfall;
-
rain;
-
temperature;
-
wind;
-
freezing-level trends; or
-
changes during the forecast period.
- Other
The summary does not create a separate numerical weather forecast or alter the underlying model data. It is an automated plain-language interpretation of the model information displayed on the page.
Users should consider the numerical values and charts as the primary source of forecast information and report any apparent inconsistency between the written summary and the displayed data.
5. How to Read Our Charts
Snowfall
Snowfall values represent forecast accumulation during the stated period.
They do not represent existing snow depth and do not necessarily indicate how much snow will remain on the ground.
Actual accumulation may be affected by:
-
wind;
-
temperature;
-
compaction;
-
melting;
-
terrain;
-
exposure; and
-
local weather conditions.
Rain and precipitation
Precipitation represents forecast water falling from the atmosphere.
Rain and snowfall values indicate how that precipitation has been classified within the forecast data supplied to Sknowed.
Temperature
Maximum and minimum temperatures are modelled values for the selected location and elevation.
Actual temperatures can vary, particularly around:
-
exposed ridges;
-
sheltered valleys;
-
forested areas;
-
south- or north-facing slopes; and
-
rapidly changing mountain terrain.
Freezing level
Where available, the freezing level represents the approximate altitude at which the atmospheric temperature reaches 0°C.
It can help indicate whether precipitation is more likely to fall as rain or snow at different elevations, but the freezing level should not be treated as an exact rain–snow boundary.
Wind speed and gusts
Wind information can help identify potentially exposed or uncomfortable conditions.
Lift operators make their own operational decisions based on local conditions and safety procedures. Sknowed cannot predict whether an individual lift will open, close or be placed on hold.
Weather symbols and probabilities
Weather symbols provide a simplified representation of model conditions.
Where precipitation probability is available, it represents forecast uncertainty and should be considered together with the expected precipitation amount.
6. Why Forecasts Change
Numerical weather forecasts are calculations of how the atmosphere may develop.
Each new model run starts with updated atmospheric information and can therefore produce a different result.
Forecast uncertainty generally increases with time.
A forecast for tomorrow will normally have greater confidence than a forecast for two weeks from now.
Long-range forecasts are therefore best used to identify:
-
broad weather patterns;
-
warming or cooling trends;
-
possible storm periods;
-
potential snowfall windows; and
-
general travel-planning conditions.
They should not be treated as precise predictions of snowfall amounts or timing many days in advance.
Mountain weather is particularly difficult to forecast because conditions can vary significantly over short distances.
Weather may differ between:
-
the base and summit;
-
neighbouring valleys;
-
opposite sides of the same mountain; and
-
ski resorts located only a short distance apart.
7. Historical and Future Data
Where available, Sknowed's extended weather tables may display:
-
the previous 15 days;
-
today; and
-
up to the following 15 forecast days.
Past days are provided to give recent weather context.
Future columns represent the current numerical-model outlook.
Historical information should not be mistaken for part of the future forecast.
8. Verification and Limitations
Sknowed does not currently claim to have completed formal forecast-skill studies across all resorts and models displayed on the website.
We therefore do not publish unsupported claims such as:
-
forecast accuracy percentages;
-
model bias figures;
-
Mean Absolute Error figures; or
-
claims that one model is universally more accurate than another.
We intend to improve forecast verification as suitable observation data becomes available.
Any future performance claims should clearly identify:
-
the weather model;
-
resort or location;
-
forecast lead time;
-
observation source;
-
variable being tested; and
-
evaluation method.
For important or safety-related decisions, users should consult official meteorological services, resort announcements, avalanche information and local authorities.
Sknowed should be treated as a ski-trip planning resource rather than an emergency-warning service.
9. Additional Weather Models
Sknowed currently uses GFS as its primary long-range numerical weather model.
We are also introducing additional weather models where they can provide useful regional improvements.
For Japan, this includes the Japan Meteorological Agency Meso-Scale Model (JMA MSM) for higher-resolution short-range guidance.
JMA MSM provides substantially finer spatial resolution over Japan than a typical global forecasting model and can therefore provide additional detail for mountainous areas.
Where different models are used for different forecast periods or products, Sknowed will identify the model being displayed and explain the relevant forecast period and limitations.
Our goal is not to hide differences between weather models, but to make it clear which model is being used and allow users to understand the information they are viewing.
10. Corrections and Feedback
We want Sknowed's weather information to be presented accurately and transparently.
If you notice:
-
an incorrect resort elevation;
-
inconsistent forecast values;
-
an incorrect written summary;
-
missing data;
-
a chart problem; or
-
another issue,
please contact us.
We welcome corrections, recommendations and suggestions for improving our forecasts, charts and weather information.
Conclusion
Sknowed organizes third-party numerical weather-model data into resort-specific forecasts, charts and summaries for skiers and snowboarders.
Our aim is to make numerical weather information practical and easy to understand without overstating its accuracy or presenting it as an official meteorological forecast.
Weather models are valuable planning tools, but they are not guarantees.
For the best understanding of upcoming conditions:
-
check the latest model run;
-
compare conditions at different elevations;
-
pay attention to forecast uncertainty;
-
expect longer-range forecasts to change; and
-
consult official local information before making safety-critical decisions.
If you would like to learn more about meteorology, check out this great video that explains all the basics. It is a great starting point to read and learn from and it will most certainly provoke you to delve more into each subject it covers.
