The Hazard of Heavy Rain - An Important Operational Article

You awake in the hotel room, turn on The Weather Channel and see red- and orange-colored warning areas promising thunderstorms on your return flight. A last check of the WSI weather screen when leaving the FBO shows the line of CBs growing in size and intensity, directly on your route home. Throughout the flight you keep adjusting the weather radar to pick your way around the cells.

Finally, you're in the terminal area and see a fairly significant CB growing right over your field, and the sage, familiar internal voice questions whether you should try to make it in before that intimidating cloud begins spewing lightning, torrents and perhaps a microburst or two. So far the tower isn't reporting any wind shear or rain, but you suspect that dark behemoth could let loose at any moment and you're alert for any telltale signs of trouble. You're also thinking about the possible loss of visual reference and runway contamination if the thunderstorm suddenly materializes.

For the past hour, meanwhile, the cumulus cloud has been hauling significant amounts of low-altitude moisture to its upper elevations, and now the thundercloud is so saturated up high it can no longer hold another drop. At that point, moisture droplets in the high altitudes begin descending, colliding with droplets below, forming ever bigger drops, and descending at faster speeds. Up until this point, there have been no signs of wind shear at the surface.

You decide to  .............     READ MORE:    Aviationweek.com