Cooler ocean waters in the Atlantic Ocean and Caribbean Sea and stronger wind shear and increased stability of the atmosphere are among the conditions that have resulted in forecasters predicting a less active hurricane season for the balance of 2018.
Seasonal forecasters with the National Oceanic and Atmospheric Administration’s Climate Prediction Center have increased the likelihood of a below-normal Atlantic hurricane season to 60 percent, which is up from 25 percent in May. The probability of a near-normal season is now at 30 percent and the chance of an above-normal season has dropped from 35 percent to 10 percent.
For the full season that ends on November 30, NOAA predicts a total of up to 13 named storms of which four to seven will become hurricanes with winds of 74 mph or greater including up to two major storms with winds of 111 mph or greater.
“There are still more storms to come — the hurricane season is far from being over,” said Gerry Bell, Ph.D., lead seasonal hurricane forecaster at the National Oceanic and Atmospheric Administration’s Climate Prediction Center, in a statement.
So far, the season has seen four named storms, including two hurricanes. An average six-month hurricane season produces 12 named storms, of which six become hurricanes.
The update is for overall seasonal activity and is not a landfall forecast. Landfalls are determined by short-term weather patterns that are only predictable within a week of a storm reaching a coastline.
The August 10 update said that El Nino is more likely to develop with enough strength to suppress storm development during the latter part of the season. NOAA’s Climate Prediction Center updated its forecast to a near 70 percent likelihood of El Nino during the 2018 hurricane season.
Additionally, sea surface temperatures across the Atlantic and Caribbean regions have remained cooler than average. This combined with a combination of stronger wind shear, drier air and increased stability of the atmosphere in the region where storms develop should further suppress hurricanes.
“Today’s updated outlook is a reminder that we are entering the height of hurricane season and everyone needs to know their true vulnerabilities to storms and storm surge,” said Federal Emergency Management Association administrator Brock Long in a statement. “Now is the time to know who issues evacuation orders in their community, heed the warnings, update your insurance and have a preparedness plan.”
NOAA also urges coastal residents to have hurricane preparedness plans in place and to monitor forecasts frequently.