Hurricane Forecast Downgraded By Colorado Researchers

FORT COLLINS, CO — Weather researchers at Colorado State University said Thursday they are downgrading their prediction for a slightly above-average Atlantic Hurricane season in 2018. The university's Tropical Meteorology Project team is now calling for a "near-average" season. In the wake of Subtropical Storm Alberto, the researchers are predicting 13 additional named storms during the upcoming hurricane season that starts Friday. The Atlantic hurricane season runs through Nov. 30.

"The primary reason for this decrease is anomalous cooling in the tropical Atlantic," researchers explained. "The tropical Atlantic has anomalously cooled over the past two months and is now colder than normal."

In addition to providing less fuel for tropical cyclone formation and intensification, Colorado researchers said that cooler tropical Atlantic sea surface temperatures are associated with a more stable atmosphere as well as drier air, both of which suppress organized thunderstorm activity necessary for hurricane development.

See also Forecasters Predict 1 To 4 Major Hurricanes In 2018 Season and FREE Glass Of Wine When You Sign Up For Patch's FREE Newsletter

Last week the National Oceanic and Atmospheric Administration predicted a "near or above normal" hurricane outlook for the upcoming 2018 season. In releasing their annual Atlantic outlook, officials said they anticipate 10 to 16 named storms with winds of 39 mph or higher. Of those, five to nine storms could become hurricanes, including one to four major hurricanes with winds of 111 mph or higher.

In releasing their initial predictions back in April, Colorado researchers called for 14 named storms during the Atlantic season. Of those, researchers expected seven to become hurricanes and three to reach major hurricane strength.

Now, in the revised forecast, researchers expect six to become hurricanes and two to reach major hurricane strength, which would be a category 3, 4 or 5 storm with sustained winds of 111 miles per hour or greater.

The Colorado team bases its forecasts on more than 60 years of historical data that include Atlantic sea surface temperatures, sea level pressures, vertical wind shear levels (the change in wind direction and speed with height in the atmosphere), El Niño (warming of waters in the central and eastern tropical Pacific) as well as other factors.

"So far, the 2018 hurricane season is exhibiting characteristics similar to 1986, 2001, 2012, and 2014," observed research scientist Phil Klotzbach in the Department of Atmospheric Science and lead author of the report. "Nineteen eighty-six and 2014 were below-average hurricane seasons, while 2001 and 2012 had above-average activity.”

The CSU team will issue forecast updates again on July 2 and Aug. 2.

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 35th year that the CSU hurricane research team has issued an Atlantic basin seasonal hurricane forecast.

"The team predicts that 2018 hurricane activity will be about 100 percent of the average season," researchers added. "By comparison, the extremely active 2017 season was about 245 percent of the average season."

The report also included the following revised probabilities of major hurricanes making landfall:

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

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.