Quote:

---

I too noticed the phenomenon, that nothing that was already on the ground was moved.

---

Surface winds in tropical cyclones are highest slightly above the surface due to friction at the earth's surface. This is why wind speeds are usually higher over open water, as opposed to land, because land has more friction than water.

On land, the maximum wind speeds usually reach the surface in the form of gusts, not sustained winds. This usually happens during downdrafts in rain squalls, which transport the higher winds above the surface to ground level. This might explain the downward force of wind on trees and buildings.

Meso-vortices, or mini-swirls, in the eye wall of hurricanes also can bring maximum wind speeds to the surface. Just like tornadoes, these vortices bring powerful winds right to ground level. This happened in Andrew, where we discovered narrow bands of catastrophic damage right next to areas with much less extreme damage. This is common in major hurricanes.

I am located about 4 miles inland from the Gulf Coast. When Jeanne passed just to my north this past weekend, I recorded wind gusts of 65mph in my neighborhood. However, just a 4 mile trip to the coast revealed a different situation. Winds right on the water were sustained at 60mph, and gusting to 75-80mph.

During Hurricane Jeanne, most areas slightly inland from the immediate coast likely did not see sustained winds near 120mph. These winds, and even gusts above 120mph, were realized mostly in the form of downdrafts and mini-swirls. Such wind distribution over land leads to the disparate levels of damage we see in areas struck by hurricanes.

Ronn

Post Extras