Here’s why so many hurricanes are heading toward the U.S. Masters said “the Atlantic is primed for making major hurricanes”right now due to three major ingredients.
First, and most pertinent, is weak wind shear. Hurricanes lose potency when winds near the ocean surface blow at one speed and direction while winds in the upper atmosphere blow another. This difference — or shear — causes a hurricane to physically tilt, like a top, which dampens the force of the winds emanating from it.
“Right now, the shears are pretty low, and as you can see the storm looks pretty symmetrical,” Philip Klotzbach, an atmospheric scientist at Colorado State University, told the NewsHour.
The other two ingredients are warm Atlantic ocean temperatures that extend deep underwater and high levels of moisture in the air. Irma is brewing where sea temperatures hover around 85 degrees Fahrenheit, which are ideal for fueling intensification. Meanwhile, the air has 55 percent relative humidity, which is a little on the dry side, Masters said, but still enough to make a strong storm.
Irma is following on the heels of Harvey, because of a change in air pressure along the East Coast, Klotzbach said.
"Typically, over the last 10 to 12 years, we tend to have a ridge of low pressure along the east coast, which has helped steer the storms away,” Klotzbach said. But this invisible ridge has pushed westward this year, leaving the eastern seaboard, the Caribbean and the Gulf of Mexico exposed to hurricanes.