|WHY ARE CERTAIN REGIONS|
OF A HURRICANE STRONGER?
METEOROLOGIST JEFF HABY
hurricane is a spinning mass of thunderstorms. These storms form in bands that spin around the center of
circulation. The winds are strongest near the center of circulation. This region is called the
eye wall. The
closer a place is to the eye wall the stronger the winds can be expected to be.
The onshore region of a hurricane tends to be stronger. When a hurricane makes landfall the wind will be coming
from the ocean toward the land (onshore) on one side of the hurricane and the wind will be coming from the
land toward the ocean (offshore) on the other side of the hurricane. The onshore winds are stronger because
there is less
friction over the ocean surface. The storm surge is the strongest in this region also since the
winds are piling ocean water toward the land.
On the onshore side of a hurricane the hurricane's forward motion combines with the storm relative wind velocity. Thus,
this also contributes to winds being stronger on the onshore side especially for faster moving hurricanes.
As air moves from the water onto land it is sheared. The land slows the wind down somewhat while the wind speeds
aloft remain at a stronger intensity. This produces vertical
speed shear. Friction also turns the wind more toward
lower pressure over the land. This produces vertical directional shear. This enhanced shear with the presence of
thunderstorms increases the likelihood of
tornadoes. Thus, it is common for a
tornado watch to be issued
for the Northeast quadrant of a hurricane. This quadrant is the region that often experiences onshore flow.
In a hurricane situation keep close tabs on updates from the Tropical Prediction Center.