Below-Average Atlantic Hurricane Season Predicted

FORT COLLINS, CO — Weather researchers at Colorado State University said they are predicting a slightly below-average 2019 Atlantic hurricane season. The university's Tropical Meteorology Project team said the 2019 season will be about 75 percent of an average season.

The researchers are predicting 13 named storms during the upcoming hurricane season that starts June 1. The Atlantic hurricane season runs through Nov. 30.

"Of those, researchers expect five to become hurricanes and two to reach major hurricane strength ... with sustained winds of 111 miles per hour or greater," researchers said Thursday, adding that they are referring to storms that would be a category 3, 4 or 5 storm. "The team bases its forecasts on a statistical model, as well as a new model that uses a combination of statistical information and forecasts from a dynamical model."

Researchers said both models are built on roughly 40 years of historical data and evaluating conditions that include Atlantic sea surface temperatures, sea level pressures, vertical wind shear levels, El Niño and other factors.

“It takes only one storm near you to make this an active season,” cautioned Michael Bell, associate professor in the CSU Department of Atmospheric Science.

Researchers also calculated the probability of major hurricanes making landfall as follows:

• 48 percent for the entire U.S. coastline (average for the last century is 52 percent)
• 28 percent for the U.S. East Coast including the Florida peninsula (average for the last century is 31 percent)
• 28 percent for the Gulf Coast from the Florida panhandle westward to Brownsville (average for the last century is 30 percent)
• 39 percent for the Caribbean (average for the last century is 42 percent)

Researchers cited the relatively high likelihood of a weak El Niño as a primary factor in the 2019 forecast.

"Tropical Atlantic sea surface temperatures are currently slightly below their long-term average values and are consequently considered an inhibiting factor for 2019 Atlantic hurricane activity as well," researchers said. "A weak El Niño has recently developed in the tropical Pacific. CSU anticipates that these weak El Niño conditions are likely to persist through the peak of the Atlantic hurricane season."

Researchers said that a weak El Niño tends to increase upper-level westerly winds across the Caribbean into the tropical Atlantic, tearing apart hurricanes as they try to form.

"The tropical Atlantic is slightly cooler than normal right now. Colder-than-normal sea surface temperatures in the tropical Atlantic provide less fuel for tropical cyclone formation and intensification," according to Colorado researchers. "They are also associated with a more stable atmosphere as well as drier air, both of which suppress organized thunderstorm activity necessary for hurricane development."

The CSU team will issue forecast updates on June 4, July 2 and Aug. 6.

Researchers caution that the prediction is only intended to be a best estimate of hurricane activity during the upcoming season — not an exact measure. This is the 36th year that the CSU hurricane research team has issued an Atlantic basin seasonal hurricane forecast.

The team said the 2019 hurricane season thus far is shaping up to be similar to 1969, 1987, 1991, 2002, and 2009.

"1987, 1991, 2002 and 2009 had below-average Atlantic hurricane activity, while 1969 was a very active hurricane season,” observed Phil Klotzbach, research scientist in the Department of Atmospheric Science and lead author of the report.

The 2018 hurricane season was about 120 percent of the average season with Hurricanes Florence and Michael which devastated the Carolinas and portions of the Florida Panhandle.

Visit the Landfall Probability website for information on all coastal states as well as 11 regions and 205 individual counties along the U.S. coastline from Brownsville, Texas, to Eastport, Maine. Landfall probabilities for regions and counties are adjusted based on the current climate and its projected effects on the upcoming hurricane season.

The National Oceanic and Atmospheric Administration WP-3D Orion aircraft flies directly into hurricanes. Photo by Paul Scicchitano.