Water and wind typically are the main impacts of a hurricane, but time and time again, tornadoes have proven to be a real, but sometimes overlooked threat in landfalling hurricanes.
Lesson 5: Tornado Threats
Our severe weather outbreak this past April that produced over a dozen tornadoes was historic for both their power and their quantity. You see tornadoes are fairly rare in the Lowcountry and a good chunk of our tornadoes don’t occur in spring- but autumn as hurricanes move onto land.
We see this time and time again with tropical systems-in fact it’s rare for a hurricane to not produce tornadoes after landfall! The majority of these don’t form in the eyewall, but in the intense outer bands that can extend over 200 miles away from the storm’s center- usually in the front right quadrant- or to the northeast of the hurricane’s eye.
This “sweet spot” for tornado development comes down to spin, or shear. At the surface, we’re battered with strong southeast winds as the storm’s bands circulate counter-clockwise. But higher up in the atmosphere, the wind comes from the nearly opposite direction! This vertical wind shear only increases after landfall as winds at the surface slow down due to friction over land- increasing that tornado threat. Spin ups can happen quickly-so be alert and ready to move to your established “safe place,” preferably an interior room on the first floor of your home without any windows or outside facing doors.
Thankfully these tornadoes are short-lived and generally weak compared to springtime supercells like the Lowcountry experienced this year.
While tornadoes pose a much more isolated risk compared to wind, rain, and storm surge in tropical systems, they’re still worth planning for- especially for tropical systems that crash into the Florida Panhandle and move north- placing us in the front right quadrant. This pattern with Irma in 2017 produced 4 tornadoes in the Charleston metro and 13 with Frances in 2004- both of which were tropical storms by the time they reached us.
This goes to show that you should be prepared for any system, even tropical storms, whether it’s your first or fortieth hurricane season!