It seems like we have been faced with an endless string of natural disasters this year, with Hurricanes Harvey, Irma, and Maria all hitting back-to-back. Maria has left Dominica’s rainforests ripped to shreds and Puerto Rico could be without power for months. Comparisons to the 2005 hurricane season a dozen years ago are abundant. So, what gives? Why is this season so bad for U.S. cities?
The U.S. National Oceanic and Atmospheric Administration (NOAA) and the Weather Channel both estimated that we’d be seeing more hurricanes than usual this year. NOAA’s Climate Prediction Center forecasted we’d see between 14 and 19 named storms and five to nine hurricanes this season, National Geographic reports.
Unfortunately, atmospheric conditions were hurricane-friendly this year—and combined with rising sea temperatures, it’s the perfect storm. The Climate Prediction Center says that multiple conditions have aligned to make “the Caribbean Sea and part of the tropical Atlantic…particularly well-suited to hurricanes.”
According to National Geographic:
Kerry Emanuel, an atmospheric scientist at MIT who studies hurricanes, says that two factors stand out. For one, there’s currently little difference in wind speeds near the surface and those roughly 10 miles up, which ensures that miles-tall hurricanes can form and remain stable. What’s more, the tropical Atlantic is exhibiting high “thermal potential,” meaning that water can rapidly evaporate into the atmosphere.
“[Thermal potential] is a thermodynamic speed limit on hurricanes,” Emanuel says. “The greater the speed limit, the more favorable conditions are for hurricanes to form, and the more powerful they can get.”
What’s more, El Niño is stuck in neutral this year, improving Atlantic hurricanes’ prospects. When this warming of the equatorial Pacific is active, there tends to be more wind shear and less thermal potential over the Atlantic, hurting hurricanes’ chances of survival.
We can only hope the disasters die down, especially as wildfires hit the West Coast.
Source: National Geographic