The Ishawooa Horse’s Head is actually a pattern in the snow. It starts with the head and flowing mane, and clearly showing reins. The trappers in the area used that as a signal of sorts. When the reins broke, that meant the majority of the spring runoff was over and the high mountain passes to Jackson Hole would be open enough to get through.  Many have told me that the ‘reins’ break usually around Father’s Day (since at least the 1940s).

It’s now a fun little phenology project for the snowpack each year.