2017 Atlantic Hurricane Season Update: More Active Season Predicted

Jon Erdman
Published: July 5,2017
The number of tropical storms and hurricanes forecast to develop in the 2017 Atlantic hurricane season has increased in the latest forecast issued Wednesday by the Colorado State University Tropical Meteorology Project.
(MORE: Hurricane Central)

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 and Colorado State University compared to 30-year average.

At total of 15 named storms and eight hurricanes are now expected in the Atlantic basin, according to the CSU forecast which is headed by Dr. Phil Klotzbach. Three of the eight hurricanes are forecast to be Category 3 or stronger on the Saffir-Simpson Hurricane Wind Scale.
April's Tropical Storm Arlene and June's Tropical Storm Bret and Tropical Storm Cindy are included in the seasonal forecast numbers in the outlook.
The updated forecast is above the 30-year historical average (1981-2010) for the Atlantic Basin of 12 named storms, six hurricanes and three major hurricanes.
CSU's latest forecast is a bit higher than the last update from June 1 that called for 14 named storms and six hurricanes. It's significantly greater than the initial April forecast of 11 named storms and four hurricanes.
Warm water temperatures in the tropical and subtropical Atlantic Ocean along with the dwindling chance of El Niño's development later this summer are the reasons why the forecast has steadily nudged upward.
"A warmer-than-normal tropical Atlantic is generally associated with lower surface pressures, increased mid-level moisture and weaker trade winds, creating a more conducive dynamic and thermodynamic environment for hurricane formation and intensification," said the CSU team.

2017 Atlantic hurricane season names.

Widespread and hostile upper-level winds typically associated with El Niño will also be a no-show during the heart of the hurricane season ahead. That said, unfavorable winds aloft still occur at times each season in the Atlantic basin no matter whether El Niño is present or not.
CSU found six years since 1950 that most closely resemble what is expected in the atmosphere above and waters of the Atlantic basin during August-October 2017. Those years included 1953, 1969, 1979, 2004, 2006 and 2012. The average of those six seasons is very close to CSU forecast for 2017.
The Weather Company, an IBM business, updated its seasonal forecast in June and also expects a total of 15 named storms, eight hurricanes and three major hurricanes this season. This is an increase from its earlier forecasts as well, mainly due to the same factors stated in the CSU outlook.
The official Atlantic hurricane season begins June 1 and runs through Nov. 30. Occasionally, storms can form outside those months as happened this year with Tropical Storm Arlene. This also occurred last season with January's Hurricane Alex and late May's Tropical Storm Bonnie.
(MORE: 10 Things We Remembered Most About the 2016 Season)

What Does This Mean For the U.S.? 

There is no strong correlation between the number of storms or hurricanes and U.S. landfalls in any given season. One or more of the additional named storms forecast to develop this season could hit the U.S., or none at all. Therefore, residents of the coastal United States should prepare each year no matter the forecast.
A couple of classic examples of why you need to be prepared each year occurred in 1992 and 1983.
The 1992 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 of them was Alicia. The Category 3 hurricane hit the Houston-Galveston area and caused almost as many direct fatalities there as Andrew did in South Florida.
In contrast, the 2010 season was active. There were 19 named storms and 12 hurricanes that formed in the Atlantic Basin.
Despite the large number of storms that year, not a single hurricane and only one tropical storm made landfall in the United States.
In other words, a season can deliver many storms, but have little impact, or deliver few storms and have one or more hitting the U.S. coast with major impact.

The named storms that affected the U.S. in 2016 were clustered in the Southeast.

The U.S. averages one to two hurricane landfalls each season, according to NOAA's Hurricane Research Division statistics.
In 2016, five named storms impacted the Southeast U.S. coast, most notably the powerful scraping of the coast from Hurricane Matthew, and its subsequent inland rainfall flooding.
(MORE: Hermine Ended Florida's Record Hurricane Drought)
Prior to that, the number of U.S. landfalls had been well below average over the previous 10 years.
The 10-year running total of U.S. hurricane landfalls from 2006 through 2015 was seven, according to Alex Lamers, a meteorologist with the National Weather Service. This was a record low for any 10-year period dating to 1850, considerably lower than the average of 17 per 10-year period dating to 1850, Lamers added.
Of course, the record-breaking 2005 hurricane season was outside that current 10-year running total. It was also the last season we saw a Category 3 or stronger hurricane (Wilma) hit the U.S., the longest such streak dating to the mid-19th century.
(MORE: 10 Reasons the U.S. Major Hurricane Drought is Misleading)
The bottom line is that 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, resulting in flooding rainfall.
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