The Colorado State University (CSU) Tropical Meteorology Project Team is predicting an “above average” Atlantic hurricane season this year, with 17 named storms. This includes eight hurricanes, four of which are predicted to become major hurricanes.
The CSU team bases its forecasts on models that use 40 years of historical hurricane data and evaluates conditions including:
- Sea surface temperatures
- Sea level pressures
- Vertical wind shear levels (the change in wind direction and speed with height in the atmosphere)
- El Niño
- Other factors
The CSU team cites the likely absence of El Niño as the primary factor for an above-average season. El Niño is a climate pattern in the Pacific Ocean that breaks normal conditions. Hurricane frequency declines in El Niño years due to increased wind shear over the Caribbean and Atlantic, which can tear apart hurricanes as they begin to form.
The 2021 hurricane season is exhibiting characteristics similar to 1996, 2001, 2008, 2011 and 2017, says CSU. These seasons all had above-average Atlantic hurricane activity, according to Phil Klotzbach, research scientist in the Department of Atmospheric Science and lead author of the report.
The CSU team predicts that this year’s hurricane activity will be about 140%t of the average season. Last year’s “above average” season saw about 170% of the average season.