Revisions have been made to the 2018 Atlantic Hurricane Season according to Colorado State University (CSU). CSU is expecting the season to be less active than originally thought, which would lead to a below-average hurricane season for the Atlantic. This is according to an updated outlook (July 2nd, 2018) from CSU.
The main variable in the predicted reduction of named storms is due to cooler Sea-Surface Temperatures (SSTs) across the tropical Atlantic (see Fig. 1). Below-average SSTs have persisted throughout the early hurricane season and has expanded since May. Below-average SSTs in this region tends to lead to a less-active hurricane season.
Fig. 1: Sea-Surface Temperature Anomaly Map From Tropical Tidbits
Another variable that may influence the hurricane season is the potential return of El Nino conditions later this year. The waters near the equator across the eastern Pacific and central Pacific have warmed to above-average (see Fig. 2). While not technically reaching the El Nino threshold yet, wind shear has been abnormally strong over the southern Gulf of Mexico and Caribbean Sea thus far during the hurricane season. This along with the equatorial-Pacific waters warming, typically is indicative of the development of El Nino.
Fig. 2: Sea-Surface Temperature Anomaly Map From Tropical Tidbits
The new outlook from CSU now includes 11 named storms, which includes already named Subtropical Storm Alberto, for the 2018 season (see Fig. 3). Of the 11 named storms, four hurricanes are expected with one of the hurricanes reaching major status (Category 3 or higher). The previous outlook from CSU called for 14 named storms (6 hurricanes with 2 being major hurricanes).
Fig. 3: Updated 2018 Atlantic Hurricane Season Outlook
Firsthand Weather is also forecasting an average to below-average season for the Atlantic. Regardless of the number of named storms in a hurricane season, it only takes one storm making landfall to cause significant impacts.