How to Distinguish Snow Cover on Visible Satellite Imagery

Yesterday, the Louisville National Weather Service  posted an image illustrating how the snowfall from Sunday night into Monday can be seen on visible satellite imagery. This is a common occurrence all across the country during the winter months and the big question is how can we distinguish snow cover from clouds on visible satellite images? It can be difficult to tell the difference as both clouds and snow cover appear white on a visible satellite image, but let’s go over a few strategies that can help distinguish between the two.

The first (and most obvious) way to tell the difference between clouds and snow cover is to put the satellite image in motion. Clouds tend to move while snow cover stays in motion. There are a few exceptions to this rule, one being in mountainous regions where clouds formed by orographic processes can sometimes remain stationary. Also, animated visible satellite images are not always available.

When looking at a still visible satellite image, it is important to note the topography. Snow cover tends to hug the topography, and it is possible to see mountains, valleys, forests, as well as unfrozen rivers and lakes. These features would be obscured by clouds on a satellite image.

These techniques can prove very useful to any meteorologists examining satellite imagery. NOAA uses snow cover on visible satellite images to create their daily U.S. and Northern Hemisphere Snow Cover maps.