By Skip Rigney
The 2020 Atlantic basin hurricane season is expected to have above-normal activity according to an extended range outlook issued Thursday by atmospheric scientists at Colorado State University (CSU). The hurricane season for the Atlantic basin, which includes the Caribbean and Gulf of Mexico, runs from June through November, with the peak of activity usually in August, September, and October.
The CSU research team, led by Dr. Philip Klotzbach, predict that there will be 16 named storms, four above the historical average of 12. They forecast that eight will become hurricanes, which is slightly above the long-term average number of 6.4 hurricanes per year in the Atlantic basin.
Of those eight hurricanes, four are expected to reach major hurricane status, which means maximum winds greater than 110 miles per hour. Historically, there are on average two or three major hurricanes in the Atlantic basin each year.
The Gulf Coast has a 44 percent chance of seeing at least one major hurricane make landfall according to the CSU outlook. That’s up from the annual average of a 30 percent chance based on historical data for the last 100 years.
This is the 37th year that the Tropical Meteorology Project at CSU has issued a long-range preseason outlook for hurricanes in the Atlantic. They use a combination of models based on statistics and physics of the atmosphere and upper ocean.
The models are refined each year in an attempt to improve these seasonal predictions. The outlook synthesized by the researchers does not attempt to forecast the occurrence or location of specific storms, but instead predicts general trends of the number of tropical cyclones, their severity, and the risk for large swaths of coastlines.
One good predictor of Atlantic hurricane activity is the sea surface temperature pattern in the tropical Pacific Ocean.
When those SSTs are warmer-than-average the pattern is known as El Nino, which, through the connections between the sea surface and the atmosphere, results in far-reaching changes to large-scale weather patterns across the globe for months.
But we are not in an El Nino pattern this year. Instead sea surface temperatures in the tropical Pacific are near average and may actually cool over the next several months. That will likely result in large-scale wind and pressure patterns, such as less wind shear over the Atlantic, favorable for increased hurricane formation.
The other major factor driving the expectation of above-average hurricane activity is a warmer-than-normal sea surface temperature pattern over most of the tropical and subtropical Atlantic basin. The Gulf of Mexico is especially warm for this time of year. If that pattern persists, it would provide an abundance of fuel for tropical systems entering the Gulf.
More information about CSU’s 2020 seasonal hurricane outlook as well as past forecasts and verifications are available online at http://tropical.colostate.edu. They will be issuing seasonal updates in the first weeks of June, July, and August. Other groups will be issuing their outlooks over the next couple of months, including the National Oceanic and Atmospheric Administration in May.
Of course, as the CSU report reminds us: “It only takes one hurricane making landfall to make it an active season. Prepare the same for every season, regardless of how much activity is predicted.”