Why This Hurricane Season Has Defied Forecasts—So Far
Tropical Storm Francine heads for the Gulf Coast after an unexpectedly quiet month
By Eric Niiler
Sept. 10, 2024
Francine—the first tropical storm to form in four weeks—is expected to bring up to a foot of rainfall, damaging winds and a storm surge from High Island, Texas, to the Alabama-Florida border with some areas receiving five to 10 feet. Coastal residents are being urged to evacuate.
The storm’s arrival at the midpoint of the official hurricane season breaks a dry spell that has puzzled forecasters.
Federal officials had warned the nation to expect a record-breaking Atlantic hurricane season with up to 25 named storms. In June, Hurricane Beryl became the earliest Category 5 storm. By mid-August, conditions shifted.
Unexpected weather patterns offset warm ocean temperatures and favorable winds that were supposed to create a blockbuster hurricane season. The lengthy pause in tropical storms hasn’t been seen since 1968.
Hurricanes begin as thunderstorms blowing across western Africa. Tradewinds drive the storms over the Atlantic.
Normally, the storms cross over humid jungles and pick up moisture along the way.
This year, monsoon winds pushed the storms farther north over dry desert, removing the storms from their source of energy.
Normally, once the storms reach the coastal waters off Africa, warm water fuels their growth.
But, being farther north this year, the storms passed over cooler water, which slowed their development.
Higher up, cooler air allows heat to transfer from the ocean to the atmosphere, feeding potential hurricanes.
This year, unusually warm and stable air aloft has been blocking the development of storms fed by warm ocean temperatures below. And an unusual pattern of strong winds has sheared the tops off developing storms before they turn into hurricanes.
Weather patterns now are returning to what meteorologists had anticipated. Tropical Storm Francine formed in the Gulf of Mexico, while two other disturbances are forming in the Atlantic.
Source: Phil Klotzbach/Colorado State
Graphic: Adrienne Tong and Carl Churchill/WSJ
Every year since 1984, Colorado State University has put together seasonal forecasts of how many storms it expects. The computer models used to come up with these forecasts are pretty accurate, but this year has been an anomaly, according to Phil Klotzbach, senior research scientist at CSU’s Department of Atmospheric Science.
Even with the unusual pause, meteorologists say this year will be above average.
“Hurricane season is not over till Nov. 30,” said Matthew Rosencrans, lead hurricane forecaster at the National Oceanic and Atmospheric Administration’s Climate Prediction Center. “I’m urging people not to let their guards down.”
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