COLORADO -Hurricane researchers in the Department of Atmospheric Science at Colorado State University (CSU) have increased their forecast, predicting now “an extremely active” 2020 Atlantic hurricane season.
“Sea surface temperatures averaged across the tropical Atlantic are much warmer than normal, and vertical wind shear is well below average,” said forecasters Philip J. Klotzbach, Michael M. Bell and Jhordanne Jones in a statement.
“Current cool neutral ENSO conditions may transition to weak La Niña conditions by later this summer. We anticipate an above-normal probability for major hurricanes making landfall along the continental United States coastline and in the Caribbean.
“As is the case with all hurricane seasons, coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them. They should prepare the same for every season, regardless of how much activity is predicted,” the researchers aid.
They noted that the Atlantic has already had nine named storms and two hurricanes through August 4, predicting that 2020 will have an additional 10 hurricanes (post-July 31 average is 5.9).
Their outlook calls for 24 named storms, 12 of which are expected to become hurricanes, and five of those hurricanes becoming major hurricanes – Category 3 or higher (115-plus-mph winds) on the Saffir-Simpson Hurricane Wind Scale.
The NCU forecast is almost double the 30-year (1981-2010) average of 13 named storms, seven hurricanes and three major hurricanes.
The prediction is four storms, three hurricanes and one major hurricane more than NCU last outlook in early July.
“We expect Atlantic basin Accumulated Cyclone Energy (ACE) to be approximately 190 percent of its long-term post-August average. his forecast is based on an extended-range early August statistical prediction scheme that was developed using 38 years of past data,” the researchers said, adding that analog predictors are also utilized.
They said the tropical Atlantic is much warmer than normal, and that vertical wind shear across the tropical Atlantic and Caribbean has been much weaker than normal.
“Warmer than normal water across the tropical Atlantic provides more fuel for tropical cyclones and also is associated with lower than normal pressure (as was observed in July) and increased instability – all of which favour more hurricane activity.
“Vertical wind shear in July has been extremely low, and there is typically strong persistence between July vertical wind shear and August-October-averaged vertical wind shear,” they added. “Lower vertical wind shear allows hurricanes to better vertically couple and also inhibits entrainment of dry air into the circulation,” they added.
The hurricane forecasters said sea surface temperatures averaged across the eastern and central tropical Pacific are slightly cooler than average, adding that it appears likely that there will be either cool neutral ENSO or weak La Niña conditions during the peak of the Atlantic hurricane season.
“All of these conditions in combination point to a high likelihood of an extremely active hurricane season in 2020. Coastal residents are reminded that it only takes one hurricane making landfall to make it an active season for them, and they need to prepare the same for every season, regardless of how much activity is predicted,” they added.