With the devastating strength and power these hurricanes were bringing, the last thing on anyone’s mind was these hurricanes throwing additional blows to areas that seemed outside of their “cone.” However, those of us that went through Hurricanes Harvey and Irma (and even those watching from areas outside those directly affected) recall all the news stations announcing tornado watches and warnings for over 24-hours with each storm. I recall the meteorologists’ predictions of which storm cells in the bands of these hurricanes had rotation and were producing tornados.
I was watching the news channels and waiting on the edge of my seat hoping that my home wouldn’t be in the cross-hairs of Irma’s tornadic activity. In Irma’s aftermath, the signs of tornadic activity can be seen throughout Florida.
Tornadoes are a common phenomenon that accompany a strong hurricane that makes landfall. Particularly when the landfall is over such a wide area and for such a significant time as that with Hurricanes Harvey and Irma.
So how does a hurricane cause a tornado? Tornadoes are formed due to the instability in the opposing vertical and horizontal forces in the wind. These highly unstable low altitude tropical storms produce small superstorm cells. The storm cells are formed because of the high vertical shear force (or perpendicular force) acting on an already chaotic system. The turbulent wind direction changes, coupled with the high vertical force because of the low attitude, form a supercell storm.
Tornadoes form over land in most cases. The increased wind resistance that land offers on one side increases shear forces, spawning tornadoes. This factor propels tornado formation during hurricanes after they make landfall.1
Mother Nature can unleash a wrath with two swirling vortex storms combined in one. Those in Texas and Florida that have gone through Harvey and Irma have a fresh recollection of this.
The tendency to experience these tropical tornadoes is greater in the right front quadrant of the hurricane due to the dramatic change of wind speed and direction with wind shear.2
The tropical tornadoes from Hurricanes Harvey and Irma are real and there will be significant damage that occurred from them.
1 The Science Behind Hurricanes Causing Violent Tornadoes Explained, www.ibtimes.com, Suraj Radhakrishnan, 9/12/17.
2 Dissecting the parts of a hurricane, www.washingtonpost.com, Matthew Capucci, 9/10/17.