The 2017 Atlantic hurricane season is forecast to be more active than historical averages with regard to the number of named storms, according to the latest forecasts released by Colorado State University, the National Oceanic Atmospheric Administration and The Weather Company, an IBM Business.
The Colorado State University (CSU) Tropical Meteorology Project outlook headed by Dr. Phil Klotzbach updated its forecast Thursday, calling for an above-average number of named storms with 14 expected. CSU forecasts an average number of hurricanes this year, with six expected in the Atlantic Basin. A below-average number of major hurricanes – two – is also anticipated.
The 30-year historical average (1981-2010) for the Atlantic Basin is 12 named storms, six hurricanes and three major hurricanes. A major hurricane is of Category 3 strength or higher on the Saffir-Simpson Hurricane Wind Scale.
NOAA issued its forecast at the end of May and called for:
- Eleven to 17 named storms – including April’s Tropical Storm Arlene.
- Five to nine of which would become hurricanes.
- Two to four of which would become major hurricanes.
An important note is that Tropical Storm Arlene, which formed in April, is included in the seasonal forecast numbers in the outlooks.
Numbers of Atlantic Basin named storms, those that attain at least tropical storm strength, hurricanes, and hurricanes of Cat. 3 intensity forecast by The Weather Company, an IBM business, NOAA, and Colorado State University compared to 30-year average.
According to NOAA, “The outlook reflects our expectation of a weak or non-existent El Niño, near- or above-average sea-surface temperatures across the tropical Atlantic Ocean and Caribbean Sea and average or weaker-than-average vertical wind shear in that same region.”
Strong El Niños typically lead to increased wind shear in parts of the Atlantic Basin, suppressing the development or intensification of tropical cyclones in the Atlantic, so the prediction for weak conditions increased the chance for more activity this season.
“The climate models are showing considerable uncertainty, which is reflected in the comparable probabilities for an above-normal and near-normal season,” NOAA added.
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