In the distance you see the cloud--grand, puffy, colorful, pretty.

And malevolent.

It is the rain, seen below the cloud, which tells you that a squall is likely coming. As it gets closer, one sees smaller, usually faster-moving clouds of rain coming down from the main cloud. As the clouds drop the rain and rise, surface air moves in quickly, causing intense gusts of wind.

While the gusts are usually short-lived, one wants to reduce sail before they arrive, when its much easier to do so.

When I was a teenager, working on a training ship, I learned an old sailors rhyme about handling squalls: When rain comes before the wind, topsail sheets and halyards mind When wind comes before the rain, hoist your topsails up again

The squalls we have seen have been minor, as tropical squalls usually are. In the higher latitudes, when the air is cold, the wind is stronger and the rain hurts when it hits, one pays even more attention in squally weather. It's nice to be in the tropics for a while :).