JACKSONVILLE, Fla. — With a tropical storm churning right off the First Coast, one might think Jacksonville would get more rain than it did. We did get some spritzing showers, and a few downpours, but the heavier storms stayed offshore.
We are thankful for that! But why?
It has to do with wind shear.
Simply put, wind shear is a change in speed or direction with height in the atmosphere.
Tropical cyclones do not like shear. They develop best in regions with little to no wind, so their thunderstorm clouds can build nice and strong.
However, with wind shear, and in the case of Isaias passing Florida's east coast as a struggling tropical storm, tears cyclones apart.
As Isaias was moving north-northwestward just offshore, winds were blowing at roughly 30 knots out of the west at around 30-thousands feet in our atmosphere. Since Florida's east coast runs from north to south, this wind shear was ideal to help the storms stay mostly off into the Atlantic - at least the strongest ones.
We watched as Isaias was torn apart from the west-southwest as cloud tops would get blown off and away to the east.
Without this shear, the storm's thunderstorm clouds would have been able to build vertically allowing the cyclone to breath. Therefore, the storms would have been able to wrap around the core more easily and rotate onshore.
So, it's as simple as shear! Shear helped to keep the storms off our coast as a tropical storm skirted on by. Crazy to think how all of the different variables of the forecast lined up in Jacksonville's favor this time around.