The 2018 Atlantic hurricane season is expected to have a near-average number of hurricanes and tropical storms, according to an updated outlook released Thursday by the Colorado State University (CSU) Tropical Meteorology Project. CSU projects that another 13 named storms will form during hurricane season. When accounting for Alberto’s preseason development in May, the final season total is expected to be 14 named storms.
Six of the named storms are forecast to attain hurricane strength, and two of those are expected to be major hurricanes (Category 3 or higher intensity). Those numbers are a reduction from the original CSU forecast issued in April which called for seven hurricanes and three major hurricanes.
The primary reason for the forecast change is the cooling of sea-surface temperatures (SSTs) in the tropical Atlantic Ocean, according to Dr. Phil Klotzbach, a tropical scientist at CSU. You can see this patch of below-average water temperatures shaded blue and highlighted by the black box in the tweet below from Klotzbach. “Overall, the SST anomaly pattern now is less conducive for an active Atlantic hurricane season than was present in late March,” the CSU outlook said.
The cooler-than-average waters in the tropical Atlantic are being driven by northerly winds around the eastern periphery of a strong area of high pressure over the eastern and central Atlantic Ocean. On the western periphery of this high, southerly winds have led to above-average water temperatures off the U.S. East Coast. Another factor that can be detrimental to hurricane formation is the development of El Niño in the tropical Pacific Ocean during hurricane season. This typically causes stronger-than-average winds aloft over parts of the Atlantic basin, shredding potential tropical cyclones apart.
The CSU team does not expect a significant El Niño event to develop during the peak of the 2018 hurricane season (August-October). CSU did caution that a large amount of uncertainty still remains surrounding this potential factor.
Additional adjustments to the CSU forecast are possible in future updates.
“If the tropical Atlantic were to remain anomalously cool or if El Niño were to develop unexpectedly, the seasonal forecast would be lowered with our July or August updates. However, if the tropical Atlantic were to anomalously warm and the tropical Pacific were to remain neutral, the seasonal forecast could be increased in future updates,” CSU concluded.
Other Hurricane Season Forecasts
Other seasonal forecasts issued in the last few weeks for named storms (NS), hurricanes (HU) and major hurricanes (MH) include:
The Weather Company, an IBM Business: 12 NS, 5 HU, 2 MH
NOAA: 10 to 16 NS, 5 to 9 HU, 1 to 4 MH
North Carolina State University: 14 to 18 NS, 7 to 11 HU, 3 to 5 MH
Tropical Storm Risk/University College London: 12 TS, 6 HU, 2 MH
What Does This Mean For the United States?
There is no strong correlation between the number of storms or hurricanes and U.S. landfalls in any given season. Residents near the coast should prepare each year, no matter what seasonal outlooks say.
A couple of classic examples that show the need to prepare each year occurred in 1992 and 1983.
The 1992 hurricane season produced only six named storms and one subtropical storm. However, one of those named storms was Hurricane Andrew, which devastated South Florida as a Category 5 hurricane.
In 1983, there were only four named storms, but one was Hurricane Alicia. The Category 3 hurricane hit the Houston-Galveston area and caused almost as many direct fatalities along the Texas coast as Andrew did in South Florida.
(MORE: Sudden-Developing Storms/Hurricanes Near the U.S.)
In contrast, the 2010 hurricane season was active. There were 19 named storms and 12 hurricanes that formed in the Atlantic Basin. Despite the high number of storms that year, no hurricanes and only one tropical storm made landfall in the U.S.
In other words, a season can deliver many storms but have little impact, or deliver few storms with one or more causing major impacts to the U.S. coast.
The U.S. averages one to two hurricane landfalls each season, according to NOAA’s Hurricane Research Division.
It’s impossible to know for certain if a U.S. hurricane strike, or multiple strikes, will occur this season. Keep in mind, however, that even a weak tropical storm hitting the U.S. can cause major impacts, particularly if it moves slowly and triggers flooding rainfall.
Hurricane season runs from June 1 through Nov. 30 in the Atlantic Basin.