New data reveals hurricane seasons are getting busier

Tracking the Tropics

EAST PROVIDENCE, R.I. (WPRI) ─ Hurricane seasons are getting busier, and while that may not seem like a surprise, new data collected this year supports it.

Meteorologists and climatologists use 30 years worth of data to determine how the climate, or average weather, could be changing.

At the beginning of each decade, temperature, rainfall and hurricane data from the last 30 years are analyzed and compared to previous 30 year periods. For instance, they are now using data from 1991 to 2020 as a reference point, while last year we were using 1981 to 2010.

That data shows that hurricane averages have gone up significantly in recent decades.

“The largest increase has been this current one now,” Senior Research Associate at the University of Miami Brian McNoldy said. “The named storms and major hurricanes are up 19%, and hurricanes are up 12%.”

While the National Hurricane Center still needs to make the data official, during the period of 1991-2020, on average, there were 14.4 named storms per hurricane season.

Storms are given names when they reach tropical storm strength (winds greater than 39 mph). During the past three decades, a hurricane season averaged 7.2 hurricanes and 3.2 major hurricanes. A hurricane is considered major when the winds are at least 111mph.

These averages are up considerably from 1981-2010. During that time span, the average were 12 named storms, 6.4 hurricanes and 2.7 major hurricanes. The numbers have consistently been rising since the 1960s.

Why such a large jump in the numbers now? McNoldy said there are a few answers.

The 1980s were relatively quiet, tropics-wise. Yes, Southern New England was hit by Hurricane Gloria, but the overall number of storms and hurricanes was down. The 1980s are no longer in the data set being used.

“So we’re throwing out a bunch of inactive years and throwing in a bunch of active years,” McNoldy said.

With the latest chunk of data, three of the busiest years on record are included, 1995, 2005 and 2020, which certainly skew the numbers upward.

Just last year, Tropical Storm Isaias knocked out power to more than 100,000 National Grid customers in Rhode Island, part of a hurricane season so busy the list of names moved to the Greek alphabet.

Tree damage on Summit Avenue in Providence from Tropical Storm Isaias in August 2020, from Anita Bafoni

In addition, natural atmospheric and oceanic oscillations may play a role, but McNoldy said probably not a significant role.

In fact, for the past two decades, a process called the Atlantic Multidecadal Oscillation was believed to be a 60-80 year ocean water temperature cycle which impacted North American summers, Arctic sea ice and hurricane activity.

The person who coined that phrase, Michael Mann, recently said, upon further research, that it doesn’t exist.

Going back further in time, the tropical numbers were higher, especially in the time period of 1931 to 1960.

Southern New England was hit by two major hurricanes during that time, including the 1938 hurricane and Hurricane Carol.

The 1950s were a busy time for tropical weather everywhere, but in New England alone, Carol, Edna and even Donna in 1960 had large impacts in the region.

Still, there has not been such large jump in the numbers as there has been with the most recent data.

The remaining causes for the large jump are likely from humans.

The first is with technology. Improved technology, according to McNoldy has helped us find more tropical systems.

This GOES-16 GeoColor satellite image taken Friday, Sept. 18, 2020, at 12:20 p.m. EDT., and provided by NOAA, shows Hurricane Teddy, center, in the Atlantic, Tropical Depression 22, left, in the Gulf of Mexico, the remnants Paulette, top right, and Tropical Storm Wilfred, lower right. (NOAA via AP)

The GOES-16 satellite was launched into orbit in 2017 and provides the highest resolution from weather satellites scientists have ever had, and Hurricane Hunter aircrafts fly into tropical systems with great frequency with highly sophisticated weather instruments on board.

“We can see more happen at smaller scales. Things that we may have missed 30-50 years ago,” McNoldy said.

In addition, the oceans are warming, and that’s believed to be due to human activity, specifically the burning of fossil fuels. The added carbon dioxide, among other gases, acts similarly to how a greenhouse would act, keeping the heat in the atmosphere.

In this warming world, McNoldy said we might not see more named storms, and the upward trajectory of the number of storms may not continue.

In fact, he cautioned, in 2031 we could see the average go down.

“What we expect to happen is that of those storms that do form, they could skew on the more intense side.”

So that means more Category 3, 4 or 5 storms could be moving around the Atlantic Ocean in the coming decades.

In addition to the average number of hurricanes going up, hurricane season could begin earlier.

Dennis Feltgen of the National Hurricane Center said in the coming weeks, various organizations within the National Weather Service will meet to discuss the possibility of moving the start date to May 15. In recent years, storms have been developing in the Atlantic basin earlier than the June 1 start date.

Ultimately, according to Feltgen, the World Meteorological Organization makes the decision on the start date, but the National Hurricane Center will have a lot of say in the decision.

Hurricane season will start on June 1 this year. Any changes wouldn’t take place until at least next year.

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