In early-December an alumnus, Rud Platt, shared with me a project that he’d been working on, snowEvaluator. Its chief function is creating snow coverage maps, i.e. where there is snow, or where there was snow on specific dates in the past.
If you’ve ever been uncertain about whether you’ll encounter snow on an upcoming backpacking or camping trip, this tool will provide a fairly definitive yes or no. At least for this purpose, it’s a better predictor than other resources I’ve mentioned in the past, such as SNOTEL and the National Snow Analyses.
snowEvaluator is more robust than just a static map of current conditions. Features include a:
- Calendar view, so that you can easily look up historical snow coverage (by 1-week increments); and,
- Snow Index (screenshot below), which plots snow coverage over time and reveals exactly when an area become covered (or uncovered) by snow.
snowEvaluator creates the maps using high-resolution Sentinel satellite data, which is also used by CalTopo and GaiaGPS, as I discussed here. For comparison, below are screenshots of snowEvaluator and then CalTopo, depicting Yosemite in June 2019.
SnowEvaluator has several advantages over CalTopo:
- Its false color image better distinguishes snow from clouds. Snow is represented in an unmistakable red color.
- It automatically displays the least cloudy images, if multiple images were taken of the same area in a given week. This is especially helpful at high latitudes where there is a lot of overlap between neighboring image paths.
- It’s free forever, whereas CalTopo and Gaia may make it part of their premium subscriptions.
I wouldn’t expect an abandonment of CalTopo, however. In that platform, the snow coverage data can be helpfully overlaid atop topographic layers like USGS and USFS quads. And, in general, it’s a much more robust trip planning system.