Fathoming the Snow Depths
Jamie Hinrichs, Pacific Southwest Region
January 17th, 2023
The person behind the map, Cartographer Brian Moran, January 2023. (USDA Forest Service photo by Andrew Avitt)
In California, the new year arrived on the wave of an atmospheric river, carrying water nearing the daily flow that discharges from the Mississippi River. Much of this aerial stream has fallen as rain, but some has touched down as snow.
This is glad tidings for snow seekers. And on national forests, snow lays the foundation for an abundance of activities — including snowmobiling, skiing, snowboarding, peak bagging, and snowshoeing. But before enjoying these activities, we need to know where to go for snow.
“I came up with the snow-depth map because I know people interested in recreation always want to know how much snow there is and know what elevation the snow starts,” said Brian Moran, Cartographer with the Pacific Southwest Region of the USDA Forest Service.
The art of cartography and an enduring fascination with weather merge in the snow-depth map. Inches of snow are represented in neon hues of purple, blue and pink. Viewers can interact with these fluorescent features by zooming into the landscape and switching to the topographic base map.
Moran has been making maps and atlases – folded-paper, spiral-bound, and digital – for the Pacific Southwest Region since 2007. But he came into cartography through his first love: the weather.
“I was a big weather geek as a kid. I kind of still am,” Moran shared. “I went to school thinking I was going to be a meteorologist, but then discovered that I was more into the spatial and visual aspects of weather data and maps. So I switched over to geography and then discovered GIS and cartography.”
For more details on the snow-depth map, switch to the topographic base map — like this example of the Inyo and Sierra national forests. (USDA Forest Service photo)
Cartography is a science too. Since he started making the map in 2018, Moran uses public data from the National Oceanic and Atmospheric Administration (NOAA). By merging satellite, airborne, and ground observations into a mathematical model, NOAA updates snow-depth mapping imagery daily.
“There's a whole bunch of different factors you want to know about when you're heading up there to the winter sports,” Moran points out.
“I just didn't see another site that was using this public snow depth data and displaying it in a consumer friendly way.”
As a reminder, snow-depth data is averaged over a square kilometer of ground. Use the map as a general planning tool rather than for precise measurements. Add the snow-depth map to your Know Before You Go resources to find a great spot for your winter wanderings on national forests.