Mandatory evacuation orders have been plastered up and down both Florida coastlines for those most at risk from Hurricane Irma. Forecast by the National Hurricane Center to sweep through the Keys en route to a landfall in southwest Florida as a Category 4 nightmare, the threat is extreme for a potentially highly destructive event. The National Weather Service Office in Key West tweeted that “this is as real as it gets,” and urged that nobody should remain on the island.

The uncertainty in Irma’s path still leaves a wild card as to who will experience the storm’s eyewall, where the storm’s fiercest winds concentrate. Depending on where the eye moves ashore, winds sustained at well over 100 mph and gusting above 140 could spread over a rather substantial area. While one can only hope that residents living in areas susceptible to gales of that magnitude have already evacuated, that’s not necessarily possible for everybody. So it’s important to have a plan in place before the onset of extreme hurricane eyewall winds to keep yourself and your loved ones safe.

Most folks have at one point in their lives witnessed wind gusts exceeding 70 mph,  maybe even 80. But when winds gusting to nearly 140 mph are expected, how can we compare? One important thing to note is that there is an exponential increase in damage and force as speed ticks up. In other words, 140 mph winds won’t be twice as strong, but rather four times as strong as winds of 70 mph.

For anyone sheltering in place from the Keys to Tampa, the advice that follows is particularly important as you are likely to be in the core of Irma’s strongest winds.

The precautions that need to be taken are the exact same that come to mind when sheltering for a tornado — but this only applies to residents who will not encounter a damaging storm surge. It’s possible to hide in your home from wind, but water will always find you if you’re in the danger zone.

If you’re safe from surge but find yourself facing extreme winds, seek shelter in the most interior room on the lowest floor of your home or business, and avoid windows; a basement would be preferable. This only applies to site-built homes. Outbuildings, mobile homes, vehicles, and any other unanchored structures will not suffice, and the consequences could be deadly. Mobile homes will disintegrate in extreme winds, with shrapnel acting as lethal projectiles, jeopardizing the lives of anyone nearby.

But what if you don’t have a basement? It’s not ideal, but it’s the reality for many. The advice still holds: get as low to the ground as you can, and put as many layers between yourself and the outside world as possible. Hunker down in a central bathroom, haul a mattress inside, and use it to cover yourself and any family members to protect against possible building collapse.

Bryan Norcross, the broadcast meteorologist who helped Miami through Hurricane Andrew in 1992, extolled the use of a mattress as a lifesaving measure. “Over the past 25 years, I’ve heard from hundreds of people who said they rode out [Andrew] under a mattress in a central hallway, closet, or bathroom. When the wind died down, they moved the mattress and saw the sky [since the roof had blown away],” he told The Washington Post. “A mattress is the ultimate defense from wind for people staying in a house.”

Before Superstorm Sandy struck the Northeast in 2012, Norcross offered some additional helpful advice on sheltering from the wind on Facebook:

If you’re riding out the storm in a house surrounded by trees, Norcross said, “Stay on the opposite side of the house from the wind on a low floor. Close the curtains to cover windows facing the wind, but still be very careful near any glass that could break.”

You should also think about trees when parking your vehicle. If possible, place your car in garage or, at the very least, as far away from anything that may fall on it as possible.

If you’re riding out the storm in a high rise, Norcross said: “It’s especially important that you stay away from the windows. If something flies off a neighboring building, it can smash windows downwind. Besides that, the wind is stronger because you’re higher in the air, and the air gets squeezed between the tall buildings. The high wind stresses the glass, and makes it break more violently if something hits it.”

If you can’t shelter safely in a basement, bathrooms tend to be the most stable rooms in most homes due to the complex web of pipework woven in the walls. If bicycle helmets are available, use them — children are especially at risk, and this would be an extra level of added protection.

As the hours tick by, the threat draws nearer. No amount of luck, prayer, or hoping the forecast is wrong will change where Irma goes. The only thing you can do now is to take action.

Get ready. In the words of Norcross, “This is it.”

Ride along with the 'Hurricane Hunters' as they fly straight into the heart of Hurricane Irma, collecting vital data that will help Meteorologists' forecasts. (Billy Tucker/The Washington Post)

(Capital Weather Gang’s Jason Samenow contributed to this post.)