Forecasters are predicting a more active end to what has been a relatively quiet Atlantic hurricane season.
The final months of the season are expected to bring 12 named storms, including six hurricanes and two major hurricanes, according to forecasters with the Colorado State University Tropical Meteorology Project.
The 5 Aug. forecast anticipates seven hurricanes overall for the season, up from five hurricanes predicted in the initial 4 April forecast.
The US National Oceanic and Atmospheric Administration is also forecasting a more active season. While Colorado State University predicts a near-average year, NOAA forecasters have said conditions are now favourable for above-normal hurricane activity.
NOAA now predicts the season will bring 10 to 17 named storms, including five to nine hurricanes. Two to four of those are forecast to be major hurricanes.
El Niño conditions, associated with lower hurricane activity in the Atlantic, had discouraged hurricane development until now. The effect produces eastward winds in the Caribbean, diminishing storm formation.
NOAA forecasters say the El Niño effect has now subsided, creating more conducive conditions in the Atlantic.
“El Nino typically suppresses Atlantic hurricane activity but now that it’s gone, we could see a busier season ahead,” said Gerry Bell, lead seasonal hurricane forecaster at NOAA’s Climate Prediction Center.
“This evolution, combined with the more conducive conditions associated with the ongoing high-activity era for Atlantic hurricanes that began in 1995, increases the likelihood of above-normal activity this year.”
Colorado State forecasters say the eastern tropical Atlantic is cooler than normal, while the central tropical Atlantic is slightly warmer than normal. Vertical wind shear, associated with lower storm formation, continued across the Caribbean over the past month.
“During July, the tropical Atlantic was moister than normal, while the Caribbean was drier than normal,” the forecasters said.
“More active Atlantic hurricane seasons are generally characterised by lower shear, more moisture and warmer sea surface temperatures, so current conditions in the tropical Atlantic and Caribbean present mixed signals for the remainder of the season.”
Despite weakening El Niño conditions, the forecasters say they believe warmth in the central tropical Pacific should continue, and will likely prevent upper-level winds from becoming too favourable for hurricanes in the tropical Atlantic and Caribbean.
An average Atlantic hurricane season produces 12 named storms, including six hurricanes.
So far, 2019 has produced two named storms – Subtropical Storm Andrea, which formed before the official 1 June start of the season, and Hurricane Barry, a category one hurricane that hit the south-central Louisiana coast in July.
Both NOAA and Colorado State University forecasters added the caveat that it is impossible to know how the season will unfold, despite improved sophistication in weather modelling.
“Landfalls are largely determined by short-term weather patterns, which are only predictable within about a week of a storm potentially reaching a coastline,” a NOAA media release read.
Residents of coastal areas should remain prepared, regardless of how much activity is predicted.