When you look at a satellite image of a tropical storm, it's sometimes possible to tell whether it'll strengthen into a hurricane or just fizzle out. One sign of weakening is that the storm is showing, loosely speaking, "its underwear". Sounds strange - let me explain what I mean.

Think of a tropical storm's "underwear" as its cloud circulation in the lower atmosphere, within a few thousand feet of the ground. Most of the time, you can't see these low-level clouds on a satellite image because the view is blocked by taller thunderstorms - the "pants" of the storm, if you will. But if high-altitude winds are strong, they can blow these taller clouds away from the low-level circulation, exposing the storm's "underwear." When this separation occurs, it's curtains for the storm.

This is exactly what happened two weeks ago with Tropical Storm Edouard off the East Coast of Florida. In this satellite image, strong high-level winds have blown all the heavy thunderstorm clouds off to Edouard's east, exposing the low-level circulation. Though Edouard did move across Florida with heavy rain, it was never anything more than a weak tropical storm.