This has been one heck of a hurricane season and "it can always get worse" seems to be the rule at the moment. It's the middle of November. We're on our unprecedented 30th named storm. And Hurricane Iota, now a category five hurricane with 160 MPH sustained winds, is on track to make landfall in almost the exact same spot in Nicaragua where category four Hurricane Eta made landfall two weeks ago. Come on.
Iota rapidly intensified into a scale-topping hurricane on Monday morning as it encountered near-ideal conditions in the western Caribbean. The region features a deep reservoir of warm waters, light winds aloft, and ample moisture, all the necessary ingredients for a storm to thrive. The only limitation on the storm is that water temperatures—even a steamy 84°F—will only allow storms to intensify so far.
The latest forecast from the National Hurricane Center puts the storm into the Nicaraguan coast at full intensity. The only thing that could weaken the storm right now is either a hiccup in its internal structure that causes it to temporarily weaken, or the beginning of an eyewall replacement cycle that has the same effect. Time is running out for that to happen, though, and the storm is so strong that the catastrophic effects are essentially baked in at this point.
The National Hurricane Center's 10:00 AM EST discussion succinctly sums up the threat:
This is a catastrophic situation unfolding for northeastern Nicaragua with an extreme storm surge of 15-20 ft forecast along with destructive winds and potentially 30 inches of rainfall, and it is exacerbated by the fact that it should make landfall in almost the exact same location that category 4 Hurricane Eta did about two weeks ago.
Hurricane Eta killed more than 100 people in Central America after multiple feet of heavy rain triggered flash flooding and mudslides. It's always difficult to outline the true worst case scenario for any one region when a hurricane makes landfall, but Central American countries preparing for a category five hurricane just two weeks after the devastating winds and flooding of a category four hurricane has to sit pretty high up on the list.
Adding insult to injury, there's a chance that another storm will form in the western Caribbean later this week. Indications point to the potential system not being quite so strong, but even a gentle shower over areas hit by these two hurricanes would make a horrible situation worse.
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| An infrared satellite image of Hurricane Iota on November 16, 2020. | Source: NOAA |
The tropical Atlantic usually starts shutting down by the middle of November. The end of hurricane season isn't a hard deadline—it's based on climatology that shows waning tropical activity in the Atlantic as the cool, dry, and hostile winds of autumn start to call the shots in the northern hemisphere. While that's what usually happens, that isn't the case this month.
In addition to warmer-than-normal waters in the western Caribbean, Hurricane Iota likely managed to strengthen as a result of La Niña in the Pacific and a ridge of high pressure over eastern North America.
La Niña, a period of cooler-than-average waters in the eastern Pacific, subdues thunderstorms over the eastern Pacific that could send strong wind shear eastward over the Caribbean. The ridge of high pressure over eastern North America, the one responsible for the relatively warm and calm weather we're experiencing today, further calmed the atmosphere over the Caribbean, fostering an environment where Iota could build itself up as much as possible.
It's also difficult to ignore the influence of climate change in a situation like this. We can't "pin" any one storm on climate change, but when you see rapid intensification in one storm after another, year after year, it becomes a worrying trend that could signal that we've crossed a threshold when it comes to warmer ocean waters and more favorable atmospheric conditions for rapid intensification.
Oh, and just in case you're keeping track...
Hurricane Iota is the 30th named storm of the season. The previous high water marks were 28 storms in 2005, 20 storms in 1933, and 18 storms in 1995.
We exhausted the list of 21 names back in September. Iota is the ninth letter of the Greek alphabet.
Hurricane Iota is the latest category five hurricane on record in the Atlantic Ocean.
This is the sixth major hurricane this season.
This is the fourth storm to reach at least category four intensity this season.
This is now the fifth season in a row we've seen at least one category five hurricane in the Atlantic.
This is the eleventh storm this year to undergo rapid intensification, having jumped from 105 MPH to 160 MPH in just 12 hours. (Rapid intensification occurs when a storm strengthens about 35 MPH in one 24-hour period.)
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