Message from a meteorologist: Why you should not ride out Hurricane Irma.

2017-09-06 10:30 a.m. By Timothy Wright, M.Sc.

I have heard through the news media and from several friends and acquaintances that they will “ride out” Irma rather than evacuate. Bad idea.

Research has shown that people do not heed evacuation warnings when they have “rode out” other hurricanes. They think they can ride this one out too. This issue was brought to light during Katrina and to some extent, recently, with Harvey. During Katrina, the storm surge and rainfall overcame the levees and pump system surrounding below-sea level New Orleans, resulting in massive flooding, hundreds of deaths, and thousands of rescues. Harvey was a slow-moving flooding rain producer. The resultant floodwaters inundated Houston and surrounds. Rescuers were also able to navigate the floodwaters and make thousands of rescues, but still many deaths occurred. The challenges of Irma will be different because of the storm’s powerful winds and storm surge. For those who remember Andrew, it will be like that, but worse if it strikes as a category 5 (155 mph sustained winds and higher). This, of course, assuming landfall as a category 5.

Irma is a large and powerful storm. Forecast consensus is that it will remain at least a powerful category 4 upon landfall. However, the official forecasts have been consistently under-forecasting the strength of this system. You may have heard as one of the most powerful to hit the Atlantic. True. Let’s put this in perspective. The current winds near the center are 185 mph sustained, with gusts as high as 225 mph. For comparison, an EF4 tornado has winds 166-200 mph and an EF5 tornado > 200 mph. So, in effect, this hurricane has winds as powerful as the higher-class tornadoes, but is much, much larger, and lasts much, much longer. These catastrophic winds strip leaves from trees, trees from the ground, rooftops from buildings, toss cars, turn everyday objects into deadly missiles. Some graphic examples in Figure 1 below. As a meteorologist, I have always wanted to “chase” a hurricane, as I have done tornadoes, but I will sit this one out.

As I write this article I hear that Rick Scott, governor of Florida is taking this seriously and will order mandatory evacuations. Good idea! The forecast path is to strike Florida, but this forecast is still not completely certain. Regardless, with the size of the storm, its effects will certainly be felt in Florida even if it does not make a complete landfall there. Also to note, Irma may turn northward and strike Georgia and the Carolinas after laying waste to the east coast of Florida. See Figure 2 below. The governors of those states and all local municipalities in the path should keep a close eye and consider Florida's actions as the next steps to take.

I also just read that billionaire Richard Branson will ride out the storm on Necker Island in the British Virgin Islands. Bad idea! This is in the path of the front-right eyewall (strongest winds in the storm because the forward motion of the storm combines with the winds rotating around the eye). See Figure 3 below. He may have a concrete bunker of a wine cellar and possibly sufficient supplies for himself and those hunkered down with him, but who knows if they will be trapped inside said bunker or on the island with few resources until rescue comes. We will see. For those who do not have a concrete bunker and ample supplies to survive days to weeks after the storm strikes, I suggest evacuating out of the path of Irma – for your own good.