Forecast

Powder Alert?

Where snow comes from, and how Saildrone Forecast tracks it.

By
Saildrone
,
on
January 28, 2020

Snow—perhaps no weather phenomenon has inspired as many memes. As a concept, snow is extremely divisive; like the mountains vs. the beach, skiers vs. surfers, skilled winter drivers vs. everyone else, people either love it or they hate it. “Snow is, okay…” said no one ever.

snow memes

But as a science—how snow forms, where and why it falls, its moisture content, and the shape of an individual snowflake—there is no disputing that snow is fascinating, if not a little bit magical.

The majority of precipitation that falls over land is moisture that evaporated from the oceans. Snowsports lovers in North America equate the El Niño weather phenomenon with significant snowfall in the mountains, but it’s not a snow-specific weather event. El Niño and its antithesis La Niña are two opposite phases of the El Niño-Southern Oscillation (ENSO), a small fluctuation in sea surface temperature (SST), only 1°C to 3°C, in the Equatorial Pacific.

Water evaporates from the ocean and rises in the atmosphere as water vapor. As moist air rises, it cools, forming clouds. Wind carries the clouds over land. The air can only hold so much moisture, depending on the temperature and pressure of the atmosphere; it’s primarily vertical motion that affects these properties. When the air exceeds the amount of moisture it can hold, it releases water vapor as a liquid or a solid—rain or snow, or sometimes a mixture of the two.

Japow snow alert Saildrone Forecast
When cold Siberian air crosses the relatively warm Sea of Japan, moisture evaporates from the surface of the ocean forming clouds that dump incredible amounts of “Japow” on the Japanese Alps and Hokkaido.

So, snow in the Rocky Mountains represents the transfer of heat and moisture between the atmosphere and the ocean thousands of miles away. When the temperature of the ocean changes, like during El Niño, it can affect evaporation locally and cause global changes in temperature and precipitation—a lot of snow in Colorado and a drought in Indonesia, for example.

More than 70% of the planet is covered by ocean, and ocean processes are a key driver of global weather and climate. That’s why Saildrone operates a global fleet of ocean drones equipped with sensors to detect small changes in sea surface temperature, salinity, currents, atmospheric pressure, and wind speed and direction—all important metrics for weather prediction and climate modeling.

Saildrone Forecast leverages the same expertise we use to manage our global saildrone fleet to deliver accurate global weather forecasts in an easy-to-use iOS app. The Saildrone Forecast app combines temperature and altitude with high-resolution weather models to forecast rain, snow, and mixed accumulation.

Saildrone Forecast weather map views
Toggle the Saildrone Forecast Weather Graph to see the whole map or data only.

If you’re a skier or snowboarder, Saildrone Forecast will help you determine the best days to hit the slopes—and the best slopes to hit. The map provides an animated look at local and regional weather using an intuitive color scheme. For the most precise forecast, tap the desired location and click “Go”—data for that specific point will be shown as daily averages in the 7-day forecast and hour-by-hour forecasts in the Weather Graph.

Tap the Settings wheel to customize your preferred map units or long-press the Precipitation icon to change the opacity of the layer. Drag the scrubber left and right for a precise look at location and intensity of forecasted precipitation. Tap the play button to animate the forecast in three, six, 12, 24, 48, or 72-hour intervals (tap the time period to change the length of the map loop).

Toggle between map layers by pressing the weather icons for clouds, precipitation, temperature, wind, and currents (available for oceans, seas, and bays). Whether you long for winter or dread it, Saildrone Forecast provides the information you need to weather any conditions.

Download for free from the App Store for iPhone and iPad or access on the web at forecast.saildrone.com.


Main photo: Arctic air picks up moisture from the Pacific Ocean blanketing the Olympic Mountains in copious amounts of snow every winter.