Breakdown: Why hurricanes weaken when moving across land

Updated: Oct. 10, 2018 at 9:57 PM CDT
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MEMPHIS, TN (WMC) - Hurricanes, they strengthen over water and weaken over land. Have you ever wondered why this is the case?

In this episode of the breakdown, we will explain the reason why hurricanes weaken over land, and some myths associated with tropical cyclones that move over land.

Tropical cyclones, they thrive in ocean waters due to the rich amounts of moisture and the heat sources that the seas provide.

The more heat and moisture the storm encounters, the stronger the storm will grow, the more storms will form and the greater intensity of the storm. In the picture below the red and purple colors indicating very strong winds as Michael moves on shore. Wind speeds up to 150 mph.

Once a tropical system moves inland, the storm will usually weaken rapidly. This is due to the lack of moisture inland and the lower heat sources over land. Notice in the picture below, as the storm moves north and more inland the stronger winds indicated by the red and purple shades diminish.

According to the Atlantic Oceanographic and Meteorological Laboratory, the depletion of moisture and heat hurts the tropical storms ability to produce thunderstorms near the storms center.

The lack of thunderstorms or convection will cause the collapse of the eye of the storm and as the eye fills in the storm will weaken and start to dissipate.

Some misconceptions about tropical systems weakening onshore is that it is due to friction of the land. This is some what contradictory. While the sustained winds are reduced because of the dampening effect of larger roughness over land.

The reason why the gusts are stronger because turbulence increases and acts to bring faster winds down to the surface in a short burst.

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