Forecaster upgrades 'hyperactive' season forecast

The early arrival of Hurricane Beryl, which caused at least 10 deaths and as much as $1 billion in damage, is a harbinger of a “hyperactive” Atlantic hurricane season. 

Colorado State University, one of the oldest and most respected bodies in the hurricane prediction business, made the comment as it increased its hurricane season estimate this week. 

“Hurricane Beryl, a deep tropical Category 5 hurricane, is also a likely harbinger of a hyperactive season," CSU said. "This forecast is of above-normal confidence. We anticipate a well above-average probability for major hurricane landfalls along the continental United States coastline and in the Caribbean. "

It added: “While early season storm activity in the western Atlantic typically has little relationship with overall basin-wide activity, deep tropical hurricane activity in the tropical Atlantic and eastern Caribbean (such as we saw with Beryl) is often associated with hyperactive seasons.”

CSU increased the number of predicted named storms to 25 from 23, the number of hurricanes from 11 to 12 and the number of major hurricanes from five to six. 

CSU said the probability of one major hurricane – classified as a category 3 or stronger storm - making landfall was 57% compared to the historical average of 43%. 

The likelihood of a major storm hitting the US East Coast including  Florida was put at 31%. CSU also said the probability of a major storm striking the Gulf Coast from the Florida panhandle to Texas was put at 38%. The historical averages for those two strikes is 21% and 27% respectively. 

“We anticipate that cool neutral ENSO or La Niña conditions are likely at the peak of the Atlantic hurricane season,” CSU said. “Cool neutral ENSO or La Niña typically increases Atlantic hurricane activity through decreases in vertical wind shear. 

“This year’s sea surface temperatures across the tropical Atlantic and Caribbean are much warmer than normal, with temperatures averaged across the Main Development Region currently measuring ~1°C above the 1991–2020 average. 

“This warmth favours an active Atlantic hurricane season via dynamic and thermodynamic conditions that are conducive for developing hurricanes.”  

CSU added: “As with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season. Thorough preparations should be made every season, regardless of predicted activity.”

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