Portland, Oregon Raindrop Size: Why They’re So Big Right Now

The Northwest is famous for drizzle. This is where tiny water droplets barely big enough to see fall from the sky. But the Oregon and Washington storm that’s moving through right now is a real slap in the face. One huge raindrop at a time!

Here are three things to consider about our large northwest raindrops right now:

1. Warm moist air from the SW is helping to create a buoyant and somewhat turbulent atmosphere so there are a lot of raindrop collisions happening right now in the sky above us. When two small drops collide they create a larger drop.
2. Small drops are typically round because surface tension holds them into a ball like shape. Water is amazing this way.
3. Big drops often flatten on their way down to earth. As they’re falling it’s like the air underneath is pushing up against the drop & the result is often a drop that doesn’t look like a drop at all. More like a blob or a flattened pancake. These hit with a real ‘splat’ on windshields and heads all over the northwest.

Can raindrops keep getting bigger, eventually resembling a pumpkin falling from the sky? Uh, no. Drops bigger than 6mm (just less than 1/4″) almost always split apart on their journey to earth. Here’s an explanation of raindrop size and splitting. And expect more raindrops of every size this winter as La Nina powered storms hit Oregon and Washington.