A rare August with no tropical storms

Courtesy NOAA
Courtesy NOAA(Station)
Published: Aug. 31, 2022 at 7:16 AM EDT
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SARASOTA, Fla. (WWSB) - It’s only happened four times since 1929: No tropical storms have formed this August, during a year when the forecast looked very favorable for an active hurricane season.

August 2022 will likely be the fifth, in part because strong La Nina conditions are in place. In a La Nina, cold Pacific Ocean waters move to the coast of the Americas near the equator. La Ninas typically reduce the upper-level winds where hurricanes form, increasing the number of tropical storms.

Courtesy NOAA
Courtesy NOAA(Station)

This August is the first with zero tropical storms and a strong La Nina. The other years are:

  • 1929, strong El Nino year
  • 1941, El Nino year
  • 1961, Neutral, not El Nino or La Nina
  • 1997, Strong El Nino

We expect fewer tropical storms in El Nino years. Winds in the upper atmosphere are stronger over the Atlantic Basin. This pattern creates wind shear that can pull a potential storm apart before it has a chance to form. None of the zero-August-storm years occurred with La Nina conditions. Until now.

In 1961, we had neutral conditions. After a quiet August, September activity increased dramatically. Eleven of the 12 tropical storms that year occurred after Sept. 1, six of them in September. Three storms made landfall in the United States. Hurricane Carla was the strongest, hitting the Texas coast with 145 mph winds on Sept. 11, 1961.

Courtesy NOAA
Courtesy NOAA(Station)

Why such a quiet August in 2022?

We have the building blocks for tropical storms in place, warmer than average sea surface temperatures and a strong La Nina for the third year in a row. Forecasts were an active storm season just like 2021 and the record year 2020. What happened this year?

Dust from the Sahara Desert is one factor. Repeated episodes of Saharan dust have moved across the Atlantic, Caribbean and Gulf of Mexico this year. Normally these dust episodes taper off in August, but not this year. The dry air keeps tropical storms from developing.

We can also look at the Madden Julian Oscillation. That’s a big name that simply refers to an area of thunderstorms that circles the Earth near the equator. The placement of the MJO determines what areas have sinking air overhead. For much of the 2022 hurricane season, that area has been the Atlantic Basin. Sinking air keeps storm activity down, too.

Courtesy NOAA
Courtesy NOAA(Station)

What’s next for September?

All the ingredients are still in place for September: Warm sea surface temperatures, strong La Nina. What is likely to change in September is the Madden Julian Oscillation.

Computer models are in good agreement with it shifting to an orientation that will bring the rising air over the Atlantic Basin. That would be the game-changer for the 2022 hurricane season and lead to a couple of very active months for tropical storms. The American and European midrange computer models are already predicting possible storms in early September. We’ll know soon enough if all the pieces come together.

An interesting footnote to our third consecutive La Nina – It looks like it will stay with us into the winter. That typically gives us a dry and warm winter, just like the last two winters.