Atlantic hurricane season is ahead of schedule


Atlantic hurricane season is coming earlier than expected as the oceans warm, a new study has found. Big North Atlantic storms are forming earlier in the year than before, and forecasters say that means coastal communities need to be on alert earlier too.

Tropical storms that reach a certain strength are named by the World Meteorological Organization. And the first named storms to develop each year have come about five days earlier every decade since 1979, according to the study published today in the journal Communication Nature. Named storms that make landfall in the United States, meanwhile, have come about two days earlier every decade since 1900.

This means communities that frequently find themselves in the path of these storms may need to prepare for hurricane season earlier than in the past. And officials may want to rethink the schedule they’ve set for the Atlantic hurricane season, which officially began on June 1 every year since 1965.

“As a hurricane forecaster, in my late teens, I noticed that there was a very unusual preponderance of storms developing before the start of hurricane season,” says Ryan Truchelut, lead author of the new study. Truchelut is co-author of the paper and co-founder of the forecasting company WeatherTiger with his wife, physicist Erica Staehling.

The authors of the new study based their research on storm development on observational data from 1979 to 2020. They limited themselves to studying those four decades, because that’s roughly how long satellites have been around. to help forecasters see more storms developing. They felt that the inclusion of earlier years could have led to a biased assessment of seasonal trends over time.

In the past, it was difficult for researchers to work with such limited data to link warming temperatures to a longer hurricane season. But the last decade has been quite remarkable for forecasters. The seventh consecutive year that a named storm formed before June 1 was 2021.

Higher sea surface temperatures are likely the driving force behind this unusually early tropical storm activity, Truchelut and his co-authors found. These higher temperatures are strongly linked to climate change and hurricanes are gaining strength in warmer waters.

Temperatures in May are generally not warm enough to cause major hurricanes. But the public should still take precautions for previous storms, even if they are weaker, warns Truchelut. Heavy rain from these storms can pose a significant threat, even if the storm’s wind speed does not exceed the necessary threshold (111 miles per hour) to be considered a major hurricane.

The National Weather Service (NWS) is already considering whether to move the official first day of Atlantic hurricane season to May 15 from June 1. And while the date hasn’t officially changed, some hurricane forecasting efforts have already changed. Last year, the National Hurricane Center decided to start publishing tropical Atlantic weather forecasts on May 15. Those are routine forecast which usually don’t come out until June.

Also, “hurricane season doesn’t have a rigorous scientific definition,” Truchelut said. The edge. “It’s purely a social construct.” In 1935, the US Weather Bureau, the predecessor of the NWS, designated hurricane season for the Atlantic basin from June 15 to November 15. In 1965, the dates were moved from June 1 to November 30 to encompass 97% of storm activity in the region.

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