Do I Summit That Mountain? Tips on Weather

Once summer comes, we get the itch to summit mountains. All the mountains. We make a checklist of 14ers (and 13ers, and basically anything with a summit) at the beginning of the season, then methodically check them off as the weeks progress.

Unfortunately, peak-bagging season is also thunderstorm season. If you don’t come off the mountain by midday, you run the serious risk of hearing the rumbling of thunder or even being struck by lightning.

Cumulonimbus clouds—the birth of thunderstorms

What They Look Like: Cumulonimbus clouds are likely the most famous types of nimbus clouds. A cumulonimbus cloud has a broad base because air is being drawn toward the primary updraft before being forced upwards. The strong updraft creates localized low pressure underneath the storm, which causes the storm to act like a vacuum, sucking up the warm, moist air around it, with collision and coalescence happening at the base of the cloud over a broader area than the main updraft area. At the surface, this can also lead to brisk straight-line winds, both preceding the thunderstorm and occurring again after it departs.

What they say about the weather: Often called towering cumulonimbus for the heights that they can reach, these clouds mean only one thing—thunderstorms. The violent updrafts that cause these storms tend to occur when the surface (or the area just above it) is warm and humid. Thunderstorms emerge from the strongest updrafts and can offer some of the most dangerous, but also the most visually captivating, of all weather scenes.

How to safely summit mountains in the summer: You need to commit to setting an early alarm and getting an alpine start. For taller, more notorious lightning-strike peaks like Longs Peak, you need to be hitting the trailhead by 2 a.m. If you can make it to the summit and down before clouds start to form overhead, great! If not, turn around and head back to the car. It’s not worth the risk and you can try again another time!