Expect another more active hurricane season in 2021, with 17 named storms, including eight hurricanes, with four of those being major, Category 3 or above, climatologists with the Colorado State University Tropical Weather and Climate Research team said Thursday.
The forecast also says there’s a 44% chance of at least one major hurricane making landfall somewhere along the Gulf Coast from the Florida panhandle westward to Brownsville, Texas. The average for such a landfall over the last century is 30%.
The chance of a major landfall on any part of the U.S. coastline is 69%, compared to an average 52% over the last century. The chance on the East Coast is 45%, compared to a 100-year average of 31%.
Climatologist Phil Klotzbach, who leads the research team, said the absence of El Niño conditions in the eastern Pacific Ocean is a key factor for the more active season.
El Niño conditions mean that the average surface water temperature is higher than normal. When present, those conditions often create westerly upper level wind shear in the Caribbean Sea and tropical Atlantic Ocean that disrupts the formation of the thunderstorms that can form into tropical storms.
Klotzbach said sea surface temperatures in the tropical Atlantic are near long-term averages, while subtropical Atlantic sea surface temperatures are much warmer than average. The warmer subtropical water temperatures occur in an area where tropical storms are likely to get their start, and are another factor in the prediction for an active season.
The forecast says that weak La Niña conditions — cooler than average sea surface temperatures — are occurring in the central and eastern tropical Pacific.
“While these waters may warm slightly during the next few months, CSU does not currently anticipate El Niño for the peak of the Atlantic hurricane season,” the forecast said.
Computer modeling used to develop the seasonal forecast indicates the 2021 conditions seem to be tracking conditions that occurred in 1996, 2001, 2008, 2011 and 2017.
“All of our analog seasons had above-average Atlantic hurricane activity, with 1996 and 2017 being extremely active seasons,” Klotzbach said.
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