ORLANDO, Fl. – Helene was a historic storm, marking the strongest landfall in the Florida Big Bend region since 1851. As it approached Florida’s coast late Thursday, it wobbled before hitting land near the mouth of the Aucilla River.
Before landfall, Helene rapidly intensified over the northeastern Gulf of Mexico on Thursday.
Its eye didn’t have the typical round shape seen in many strong hurricanes before landfall; instead, it looked elongated and jagged. Hurricane eyes can be oblong or oval, especially in weaker storms.
In stronger hurricanes, the eyewall can take on shapes like pentagons or hexagons. These shapes are often caused by eyewall mesovortices — smaller swirling air patterns inside the eye that can create very strong winds. On the radar image above, you can see the mesovortices within the eyewall making it appear jagged and oblong.
The reason for this phenomena is that the sea surface temperatures in the Gulf of Mexico were around 87° — well above the 79° needed for storms to strengthen. Since Helene’s eye passed over these warm waters and there was little wind shear, the storm continued to gain strength.
During this intensification, mesovortices often form in the eyewall, making the eye look jagged and elongated.
These mesovortices can remain nearly stationary relative to the hurricane’s center, rotate around it, or even pass through the center of the storm.
Every storm is different, and hurricane eyewalls can change in size and shape as the storm evolves.
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