The 2020 Atlantic Hurricane Season Isn't Off to as Busy a Start as It Seems

The 2020 Atlantic hurricane season, so far, is just one example why simply counting numbers of tropical storms and hurricanes doesn't tell the whole story.

Five tropical storms have already formed this season, through July 7.

Arthur and Bertha both formed in May, before the hurricane season "officially" began. It was only the sixth time since 1851, in which two named storms formed before June 1, according to Colorado State University tropical meteorologist Phil Klotzbach.

Cristobal and Edouard then became the earliest-in-season third and fifth named storms on record, according to Klotzbach.

So, we're on a record early-season pace for named storms, about 8 weeks ahead of an average season, according to the National Hurricane Center.

Short-Lived Storms

The large number of storms so far masks the fact these storms were all short-lived.

Bertha became a tropical storm on May 27, then moved ashore one hour later near Charleston, South Carolina.

Dolly gained its name as a tropical storm on June 23, then became a remnant North Atlantic low less than 24 hours later. Edouard suffered a similar fate less than two weeks later.

Meteorologists use a measure called the ACE index - short for Accumulated Cyclone Energy - to not only count named storms and hurricanes, but also factor in their intensity and how long they last. Long-lived, intense hurricanes have a high ACE index. Short-lived, weak tropical storms, a low ACE index.

Since these five tropical storms each didn't last long, it turns out the season's ACE index isn't that anomalous, compared to the meager average through July 7, according to data compiled by Klotzbach.

By this measure, 98% of an average hurricane season's activity is still left after July 7.

If you consider the hurricane season as a meal at your favorite restaurant - which I miss dearly due to the COVID-19 pandemic - we've ordered our food, we're sipping on our drinks, but haven't had any appetizers, yet.

Active Season Ahead

Seasonal forecasts continue to call for a hyperactive Atlantic hurricane season in 2020.

The latest outlook released Tuesday by Colorado State University forecasts 20 named storms, nine of which are expected to become hurricanes, and four of those hurricanes becoming major hurricanes – Category 3 or higher (115-plus-mph winds) on the Saffir-Simpson Hurricane Wind Scale.

This forecast is well above the 30-year (1981-2010) average of 13 named storms, seven hurricanes and three major hurricanes. It also includes the five named storms that have already formed this season through Edouard, so they expect another 15 named storms to form through the end of the hurricane season.

In other words, if hurricane season started today and we didn't already have five named storms, we would still have an above average hurricane season if the forecast pans out.

CSU's latest outlook is in agreement with outlooks released earlier by NOAA and The Weather Company, an IBM Business.

There are a number of factors in play for what appears to be an active season ahead.

First, a vast stretch of the tropical and subtropical Atlantic Ocean is warmer than average. That warm water isn't just skin deep. The Caribbean Sea and some adjacent areas already have impressive heat content contained below the surface, according to an analysis from the University of Miami. This reservoir of warm water is jet fuel for tropical storms and hurricanes.

Klotzbach also says the lack of an El Niño and a robust west African monsoon are also favoring an active season, priming the atmosphere by diminishing hostile shearing winds and bumping up the intensity of African easterly waves, the seedlings of most Atlantic Basin tropical storms and hurricanes.

Recent Cautionary Tales on Counting Storms, Hurricanes

While a greater number of named storms and hurricanes increases the odds of a landfall, there is no strong correlation between the number of storms or hurricanes and U.S. landfalls in any given season.

For example, the 2010 Atlantic season tied for the second most hurricanes - 12 - and third most named storms - 19 - of any season since 1851.

Hurricane Earl made an unnerving tease of the East Coast, brushing the Outer Banks of North Carolina before recurving away. Hurricane Alex made landfall in northeast Mexico, but did bring some flooding rain into Deep South Texas.

So, the season was very active, but the U.S. mainland impact was relatively low, as winds steering each storm or hurricane acted to keep them largely away.

We've also seen seemingly inactive seasons deliver the one big landfall.

The 1992 hurricane season produced only seven storms. However, one of those was Hurricane Andrew, which devastated South Florida as one of only four hurricanes to landfall in the U.S. at Category 5 intensity, easily the nation's costliest hurricane, at the time.

1983 was even quieter than 1992.

Only four named storms - yes, one less named storm than we've seen so far in the 2020 season - developed that entire season, the least of any Atlantic hurricane season since 1930.

But one of those four was Alicia.

This Category 3 hurricane pummeled the Houston metro area with high winds that shattered glass in the city's skyscrapers, claimed 21 lives and was, itself, a billion-dollar disaster.

A hurricane season can deliver many storms but have little impact, or deliver few storms, but one or more slamming into the U.S. with major impact.

That's why residents in the hurricane zone should prepare each year no matter what the seasonal forecast is.

A Recent Lucky Streak Ended With a Flurry of Landfalls

The U.S. averages one to two hurricane landfalls each season, according to NOAA's Hurricane Research Division statistics.

In 2019, there were two U.S. hurricane landfalls – Barry in Louisiana and Dorian in North Carolina.

(MORE: Why 2019's Hurricane Dorian Wasn't Retired by the World Meteorological Organization)

In 2018, four named storms impacted the U.S. coastline, most notably hurricanes Florence and Michael within a month of each other.

In 2017, seven named storms impacted the U.S. coast, including Puerto Rico, most notably hurricanes Harvey, Irma and Maria, which battered Texas, Florida and Puerto Rico, respectively.

Prior to that, the U.S. was on a bit of a lucky streak.

The 10-year running total of U.S. hurricane landfalls from 2006 through 2015 was seven, according to Alex Lamers, a meteorologist at the National Weather Service. This was a record low for any 10-year period dating to 1850, and considerably lower than the average of 17 per 10-year period in that same span.

None of the U.S. landfalls from 2006 through 2015 were from major hurricanes.

So it's impossible to know for certain if one or more U.S. hurricane strikes will occur this season. Even a weak tropical storm hitting the U.S. can cause major impacts, particularly if it moves slowly and triggers flooding rainfall.

(MORE: How Fast or Slow a Hurricane Moves Can Be As Important As Its Intensity)

While you should prepare for hurricane season every year, it is critically important to do so this year.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.