A weather forecast is an estimate of the future weather conditions at a specific location. Two things are needed to make a weather forecast:
Factors which affect the accuracy of a weather forecast include:
Short-range forecasts (0-72 hours) are generally accurate. In medium-range forecasts (3-7 days), trends and patterns are handled well, but the details (precipitation) may be off the mark. Beyond 7 days weather forecasts become highly probabilistic and incorporate climate data.
Forecasting from observations are primarily in the short-term (0-12hrs). In addition to local weather proverbs, the following general rules of thumb may forecast weather changes:
The mountain snowpack evolves over time under the influence of weather. The accuracy of an avalanche forecast is largely related to the accuracy of its weather forecast. The most important weather parameters affecting snow stability include:
Be familiar with how local topography affects weather. The orientation, elevation, and proximity to water sources are key factors. It is possible to see significant variations within the same mountain drainage. Familiarisation also helps identify patterns leading to significant weather events. Detailed and consistent weather observations help correct the nearest weather forecast to your area.
Avalanche Canada Mountain Weather Forecast (ACMWF) – Synoptic Based.
Avalanche Canada Public Avalanche Forecast – Local Based.
Private Meteorological Consulting Services.