Happy (& Safe!) Storm Watching
Summer storms showcase the beauty and power of nature
By Capt. Weatherly
Picture yourself relaxing on the beach on a picture-perfect summer day. Blue skies, wispy clouds, gentle waves, birds calling, and children running along the sand. An unexpected rumble rolls past. You’ve just finished a snack, so it can’t be your stomach. You turn and see a wall of black clouds approaching from mainland.
Within minutes dark clouds cover half the sky, spiraling upwards with the highest tendrils stretching closer and closer to the beach. Over the ocean is still perfect blue. The wind picks up. The temperature drops. You know it’s time to go.
This scene is all too familiar to us along the coast. As I write this, the 10-day weather forecast shows an average 25% chance of rain (ranging from 18-49%). In most places, that would mean a 25% chance of rain. But in Charleston, I like to think of it as “it will rain, only over 25% of the area.”
As a boat captain, I don’t start worrying until the forecast has held over 50% for several days. These storms blow in fast and blow out just as quickly and the post-storm sunset is one of the best around.
But why do these intense thunderstorms pop up so often in summer? Recently our high temperatures have been in the 90s with a heat index over 100. Coastal areas are lucky to be slightly cooler than inland, thanks to the ocean.
Photo: NOAA.gov
Water has a higher specific heat than land, meaning it can absorb more energy without a big temperature spike. Wind from the ocean also creates convective cooling along the coast. That’s why, as the day heats up, air over land rises more quickly than air over water. Something needs to fill that space and in rushes that cooling ocean breeze to save the day!
This creates a pressure gradient and eventually a pop-up thunderstorm. But don’t let their fast start fool you. They can bring wind gusts over 50 mph (for reference, tropical storms start at 39mph sustained winds), hail, tornados, and waterspouts.
You may be wondering – what about the Folly Bubble? Thanks to a curve in the coastline, the same SW ocean wind that helps form these storms inland tends to hold them over downtown, James Island, and Mt. Pleasant. When I’m on the water, I’m far more concerned about a small, dark cloud over the ocean than a massive cloud over Summerville!
Some of my most vivid childhood memories involve racing against storm clouds in ocean swells, hoping to make it to the dock in time. Our old Hydra-Sports boat was an absolute tank. We’d lie as far forward as possible, hoping the high sides would protect us from hail – only to be launched into the air by each wave. It was a 50/50 shot of making it back. Apparently, the excited grin on my dad’s face as he got blasted by rain was contagious because decades later, I’m still grinning at the first rumble of thunder.
No cloud gets me more excited than a shelf cloud. It’s exactly what it sounds like. Instead of towering fluffy formations, a shelf cloud looks like a solid cliff rolling across the horizon. If you spot one, email me a photo. I’d love to see it!
Happy and safe storm watching!
P.S. If you’re into storm watching, we recommend the afternoon Salt Marsh Adventure or Sunset Cruise!
