Hurricane Outlook 2021: Penn State Group Expects More Typical Season


2020 was the most active hurricane season on record in the Atlantic, with a total of 30 named tropical storms. Together, they caused 60 to 65 billion dollars in damage and over 400 deaths. 12 storms made landfall in the us, the most out of any other year. The Earth System Science Center at Penn State releases a hurricane outlook every spring. They’re calling for a more typical season this year, but that doesn’t mean we can let our guard down.  

“If we’re wrong, it’s likely to be because the actual number will be greater than what we predict.”  

And that’s exactly what happened… Dr. Michael Mann of the ESSC talked about the potential for a very busy season last year. His group predicted up to 24 named storms, the highest of any major group’s forecast.  

“This year…Atlantic is a little cooler. We are in the neutral phase of El Nino, which isn’t as favorable for hurricanes. So, our forecast scheme predicts a slightly above normal season, with 12 named storms, give and take 3 or so.”  

This year features more uncertainty because of trends in the central Pacific Ocean. La Nina (or cooling of pacific waters) has officially ended, which means we are now in a neutral El Nino state. A La Nina phase usually brings less vertical wind shear over the Atlantic, which is more favorable for tropical development. Whether we remain in a neutral phase or transition back to a weak La Nina will have implications on the strength and number of storms. 

“Part of the challenge here is that the hurricane season depends on what’s happening with the El Nino phenomenon during the late summer and early fall. And we have to make a prediction here in April or May. There’s a spread among the current model predictions. Some models predict neutral conditions. Some models predict a return to moderate La Nina conditions. The average of the models is pretty close to that neutral state.”  

The ESSC prediction is less than other group’s forecasts, but if La Nina does re-develop, the ESSC calls for slightly higher activity, with 9-17 total storms in this scenario and a best guess of 13. Either way, water temperatures in the Gulf and Atlantic are again warmer than normal, and earlier rapid intensification of storms is becoming more of a concern. 

“There’s this thing called the beta effect. It causes those storms to track more poleward…to track toward the north pole. The stronger they get, the more they want to go north. That’s a trend to look out for, especially if you live in the mid-Atlantic and New England.”

Even with the lower numbers this year, it’s important to remember none of these groups predict the number of landfalling storms. All it takes is for one major hurricane to hit a metropolitan area to wreak havoc. For abc27 news, I’m meteorologist Adis Juklo.

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