Despite being landlocked, Colorado State University is home to some of the nation’s foremost experts on hurricanes and hurricane season activity. Each year experts and meteorologists around the country turn to CSU’s hurricane activity forecasts for estimates on activity in the upcoming hurricane season.
CSU recently released their updated numbers for the 2021 Atlantic hurricane season on June 3, 2021. They expect another “above average” year in the Atlantic hurricane basin.
The current CSU forecast for the 2021 Atlantic hurricane season estimates there will be:
The average Atlantic hurricane season, based on analysis of 1991 through 2020, includes:
The 2020 Atlantic hurricane season had:
Last year was a monstrous hurricane season, but Florida was thankfully spared the brunt of major hurricane activity. Compared to the average Atlantic hurricane season based on data from 1981 through 2020, last years season had:
Essentially, the 2020 Atlantic hurricane season had roughly double the number of named storm days, hurricane days and major hurricanes compared to a normal season from the past 40 years. It had well over double the normal number of named storms and major hurricanes.
If CSU’s current estimates for the 2021 Atlantic hurricane season holds true, this year should be about 25 to 30 percent calmer than the previous year.
However, that doesn’t mean Florida will have a less active year. In 2020, Florida got relatively lucky on the storm front. Hurricane Eta dropped a lot of rain on Florida but by the time it actually made landfall in the Florida Keys it only had 65 mph winds.
Hurricane Sally made landfall in Cutler Bay, Florida but by then had been downgraded to a tropical depression. However, even as a tropical storm it still caused roughly $7.3 billion of damage between Mobile, Alabama and Pensacola, Florida; and it spawned 16 tornadoes.
Hurricane Isaias paralleled our east coast back in early August 2020 but didn’t actually make landfall until it hit North Carolina.
Although 2020 was an active Atlantic hurricane season, Florida got relatively lucky on the hurricane front. Even if the 2021 hurricane season is less active, there’s no guarantee Florida will get through the Atlantic hurricane season unscathed.
This is a mixed bag for Florida. Back in December 2020 when the first estimates for 2021 were coming out, there was some uncertainty as to what the El Niño-Southern Oscillation (ENSO) was going to be doing in 2021. At the time, ENSO was in a La Niña phase.
How ENSO affects Florida’s hurricane season depends on the oscillation phase during the peak of the hurricane season. December 2020 forecasts predicted a weakening of La Niña to a neutral ENSO, which is thankfully what happened.
El Niño is ideal, as the above average Pacific surface temperatures actually means cooler Atlantic surface temperatures and a reduction in Florida hurricane season severity. The effect is reversed during La Niña, which would mean an increase in hurricane activity. That means neutral ENSO is better than La Niña, but not quite as good as an El Niño summer.
You can read more about the ENSO cycle in a few of our past blogs for more information. While we have no guarantee that we’ll stay in a neutral cycle, ENSO phases rarely switch straight from La Niña to El Niño right away, and the most recent La Niña just ended in March 2021.
The Atlantic Basin just refers to the part of the Atlantic where hurricanes form. Hurricanes that land in Florida and the Southeast United States are all Atlantic Basic hurricanes. These storms form in warm equatorial waters, often off the coast of West Africa, and move northeast and into the United States.
These storms can also sometimes form in the Gulf of Mexico down near central America and travel northeast to make landfall in Texas, Louisiana or Florida.
If a “tropical cyclone” starts in the Atlantic basin it’s known as a hurricane or a tropical storm. The only difference between a cyclone, typhoon and hurricane is where it forms. When these storms form in the Northeastern Pacific it’s called a typhoon. If the storm forms in the Northwestern Pacific or the Indian Ocean it’s called a cyclone.