Weak hurricane season forecast in Pacific
On Thursday, the National Oceanic Atmospheric Administration released its 2024 hurricane season outlook. The agency predicts an active season in the Atlantic hurricane region, with its most aggressive May forecast on record. The Atlantic hurricane region includes the north Atlantic Ocean, Caribbean Sea and Gulf of Mexico.
Below-average hurricane activity is expected in the eastern Pacific hurricane region, which includes the western coast of Mexico. NOAA’s eastern Pacific outlook indicates a 60% chance of below-normal activity, 30% chance of near-normal activity and only a 10% chance of abovenormal activity.
In the eastern Pacific basin, NOAA calls for 11 to 17 named storms, or tropical cyclones, which includes hurricanes and tropical storms. Four to nine of these storms are predicted to reach hurricane strength, with one to four reaching major hurricane strength. A normal year averages 15 named storms, eight hurricanes, and four major hurricanes.
The eastern Pacific hurricane season officially runs from May 15 to Nov. 30.
Last year, the eastern Pacific hurricane season was extremely active with 17 named storms and 10 hurricanes. Six tropical cyclones made landfall in Mexico, including Hurricane Otis, which rapidly intensified before making landfall near Acapulco, and Hurricane Hilary.
While El Niño’s influence helped fuel an active 2023 hurricane season in the eastern Pacific, an emerging La Niña is forecast to do just the opposite.
Vertical wind shear — changes in wind with height, either in direction or speed — is the kryptonite of hurricanes, causing the storm to tilt, ultimately leading to its demise.
Wind shear is typically stronger in the eastern Pacific during La Niña, while it is weaker over the Atlantic. During El Niño, these patterns are flipped.
With weak wind shear likely over the Atlantic this summer and fall, conditions for tropical cyclone development are expected to be favorable. In addition, sea-surface temperatures in the Atlantic basin are currently 2 to 3.5 degrees above normal, providing extra energy for hurricanes, which are fueled by ocean heat. Across the eastern Pacific hurricane region, near to below-normal sea-surface temperatures are predicted later this summer.
It’s for these reasons that NOAA forecasts well abovenormal activity in the Atlantic, with 17 to 25 named storms, eight to 13 hurricanes and four to seven major hurricanes.
“The forecast of named storms, hurricanes and major
hurricanes is the highest NOAA has ever issued for the May outlook” for the Atlantic region, said NOAA Administrator Richard Spinrad in a news conference Thursday.
NOAA also released the central Pacific hurricane outlook, for the waters between 140 degrees west and the international dateline, including Hawaii. The forecast calls for one to four tropical cyclones across the central Pacific region. A normal year has four or five tropical cyclones.
Probabilities favor belownormal activity, but also a 30% chance of normal activity and just a 20% chance of above-normal activity. NOAA notes that the outlook “does not predict whether or how many of these systems will affect Hawaii.”
Tropical cyclones are becoming more intense due to humancaused climate change, according to NOAA, and rising sea levels are putting coastal communities at higher risk of storm-surge flooding.