The PowDay Algorithms
An inside look at our two distinct scoring models: the classic PowScore for powder days and the Spring 'Corn' Score for late-season conditions.
The PowScore
For forecasting classic powder days based on new snowfall.
- Freshness: More recent snowfall scores higher, with value decaying over time.
- Storm Temp: Colder temps during the storm produce lighter, higher-quality powder.
- Depth: More new snow is better, with diminishing returns after a certain point.
- Post-Storm Temps: Consistently cold temperatures since the snowfall preserve quality.
- Rain Damage: Any rain since the snowfall is highly detrimental and is heavily penalized.
- Sun Effect: Solar radiation degrades snow. We model its impact based on aspect and tree cover.
- Base Depth: A deep, established snowpack provides better coverage and a more resilient surface.
- Melt-Freeze Crust: A hard layer from melting and refreezing is penalized heavily.
- Sun Crust: A thin, breakable crust from intense sun is also penalized.
The three core components are combined using a weighted geometric mean, which heavily prioritizes the quality of the snow itself.
- Base Snow Quality 60%
- Snowpack Preservation 20%
- Base Depth & Surface 20%
This parallel 1-10 rating asks 'Is it worth it?' It balances snow quality with weather comfort, acknowledging that great snow often trumps bad weather.
- PowScore (Snow Quality) 75%
- Weather Comfort (Wind, Temp) 25%
The Spring 'Corn' Score
For forecasting perfect "corn" snow—the holy grail of spring skiing.
- Overnight Low: Ideal refreeze occurs when temps drop well below freezing.
- Cloud Cover: Clear nights allow radiant cooling, creating a firmer snowpack.
- Dew Point: Low dew points help the snow surface dry out and freeze solid.
- Afternoon High: Temps must rise enough to soften the frozen surface, but not so much it turns to slush.
- Sunlight: Strong sun is crucial for efficiently transitioning the snow to a 'corny' texture.
- Wind: High winds can accelerate melting or keep the surface frozen, disrupting the cycle.
- Timing & Duration: We estimate when the corn will be perfect and for how long. A longer, well-timed window scores higher.
- No-Freeze Penalty: If the snowpack doesn't freeze overnight, a true corn cycle is impossible.
- Overall Depth: A deep snowpack is more resilient to warm temps and provides better coverage.
- Melt Rate: We analyze the forecast to determine how quickly the snowpack is shrinking.
- Hard Floor: A penalty is applied if the base is too thin to support the cycle.
The four spring components are combined to produce the final score, with the highest importance placed on a solid overnight refreeze.
- Overnight Refreeze 35%
- Daytime Transition 30%
- Snowpack Longevity 20%
- The Corn Window 15%
Our scores are sophisticated estimates based on cutting-edge weather modeling. However, mountain weather is notoriously unpredictable and microclimates can create variable conditions across a single resort. Always ski or ride with caution, be aware of your surroundings, and respect all mountain safety guidelines.