Technology boosts hurricane forecasts, aids preparations
WEST PALM BEACH, Fla. – The boldest forecast in the history of the National Hurricane Center was made at 11 a.m. Aug. 26, 2021, when a newly formed tropical depression was predicted to rapidly intensify to near-major hurricane strength before reaching the marshy fringe of the Gulf Coast.
It was the first advisory for what would become Hurricane Ida, which deepened to a 150-mph Category 4 beast that walloped Louisiana on Aug. 29 and then maintained major hurricane muscle for eight hours after landfall.
Forecasting for rapid intensification – defined as a harrowing ascent in wind speeds of at least 35 mph in 24 hours – was nearly unheard of 10 years ago. But technology has given tropical meteorologists a more bullish confidence in predicting what traditionally has been a forecaster’s greatest nightmare.
“I’m not sure I would have written that forecast five to eight years ago,” said National Hurricane Center senior hurricane specialist Dan Brown during a discussion last week at the Governor’s Hurricane Conference in West Palm Beach, Florida.
Brown was the forecaster on Ida’s first advisory when it was just a breezy circle of 35 mph winds about 115 miles south-southwest of Jamaica.
The 2021 rapid-intensification errors in the Atlantic and Pacific basins were reduced by 40% over a baseline average tallied between 2015 and 2017, according to a recent report by the Hurricane Forecast Improvement Program.
Although hurricane season officially begins June 1, regular forecasts are issued beginning May 15. That change was made in 2021 after six consecutive years of early tropical cyclones. It also coincides with the start date of the Pacific hurricane season. Tropical Storm Ana formed May 22 last year, racking up the seventh consecutive year for premature storms in the Atlantic.
An area of low pressure stalled off the mid-atlantic was teasing last week that it could muster subtropical storm strength – a status that would give it the name Alex. As of Thursday, it was still just a swirl of wet weather headed toward the coast. Accuweather meteorologists are also looking at a spot in the western Caribbean for something to potentially form late this month. The second name on the 2022 hurricane list is Bonnie.
“Wind shear is forecast to be relatively low in this zone past the middle of May and, from a climatological standpoint, the Caribbean to the southern Gulf of Mexico is a prime area to watch for tropical development into June,” said Accuweather lead longrange meteorologist Paul Pastelok.
Into the early 1990s, hurricane intensity models were based on climatology – what previous storms did when in a similar place at a similar time. Then models started incorporating pieces of real-time information to make predictions for a specific hurricane. Increasingly refined information from satellites, ocean buoys, weather balloons, ships at sea, hurricane hunters and dropsondes (a reconnaissance device) is fed to the models, which are seeing more slices of the atmosphere at higher resolutions.