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 HABYTIME MINI LECTURE 55: HURRICANE AND SHORE POSITION

METEOROLOGIST JEFF HABY

The wind speed experienced from a land falling hurricane can vary dramatically even over a few miles. The strongest wind is experienced in the eye wall of the storm. This represents a donut shaped region of the strongest winds that surround the much weaker winds within the eye of the storm. The forward motion of the storm and the position of the water and land also play a key role in the wind speed experienced. Both of these will be explained next starting with water vs. land.

There is less friction over water than land. Because of this there is less slowing of the wind at ground level over water. Thus, the winds flowing from the water to the land will generally be higher than the wind flowing from the land to the water. The trajectory of the wind flowing from the water to the land is what also helps bring in the storm surge.

The forward motion of the hurricane will add wind speed on one side of a hurricane while subtracting wind speed on the other. The diagram below shows a hurricane moving from the east to the west at 20 knots. The hurricane is going to strike a beach that has a north-south trajectory. To the right of the hurricane motion, the forward motion is adding to the hurricane wind. This increases the hurricane winds of a 100 knot hurricane (if it was motionless) to a 120 knot hurricane. To the left of the hurricane motion, the forward motion is subtracting from the hurricane wind. This decreases the hurricane winds of a 100 knot hurricane (if it was motionless) to a 80 knot hurricane.

The right side of the hurricane landfall has it worst off in three ways. First, the wind direction is bringing in the storm surge. Second, the storm motion is adding to the hurricane wind to make it stronger. And third, there is less of a slowing force from friction. The damage from a land falling hurricane can be dramatically worse in the area where the winds are flowing from the water toward land. This is one factor to consider as a hurricane is approaching land.