The 2020 hurricane season is off to a quick start, with five tropical storms in the books as of Wednesday. Two formed before the official start of the season, which is June 1. All of this early development could be a sign of busy times ahead in the Atlantic basin.
Right now, sea surface temperatures (SSTs) in the Gulf of Mexico, western Atlantic, and subtropical Atlantic are warmer than normal, ranging from the lower 80s to the lower 90s — prime fuel for tropical cyclone formation.
Experts with Colorado State University’s (CSU) Tropical Meteorology Project said that, quite often, exceptionally high June temperatures in this region have been associated with more active Atlantic hurricane seasons.
They are also expecting weak La Niña conditions during the remainder of the summer, extending into the fall. La Niña typically reduces wind shear over the Atlantic. Wind shear — increasing wind speed with altitude and/or change in wind direction with altitude — can shred tropical systems, keeping them from developing into destructive tropical storms or major hurricanes. But with less shear, the odds for intense cyclones could increase.
This is the 37th year for CSU’s Atlantic hurricane season outlook. In its latest outlook, issued Tuesday, the team predicted that 15 additional named storms will form, for a total of 20, and that nine of those will become hurricanes (sustained winds of at least 74 mph). This is compared to a forecast of 16 total named storms in the team’s previous outlooks from April and June; the number of forecast hurricanes increased from eight to nine from April to June but remains at nine in the July outlook.
From 1981 through 2010, the average number of named storms in an Atlantic season was 12. Six became hurricanes, and three became major hurricanes.
The amount of projected Accumulated Cyclone Energy (ACE) has increased since the first two outlooks. ACE is a measure of a named storm’s potential for wind and storm surge destruction, based on wind speed and how long the system remains a named storm (tropical storm or hurricane). CSU expects Atlantic basin ACE in 2020 to be approximately 150% of long-term averages.
For carriers and their drivers preparing for a busy hurricane season, what matters most is how many storms make landfall and where they hit. With this season getting off to an early start, and a high chance of a busy season, the time to prepare is now.
The CSU team anticipates the development of four major hurricanes — those Category 3 or higher. This is from the team’s Juy outlook:
“We anticipate an above-normal probability for major hurricanes making landfall along the continental United States coastline and in the Caribbean.”
CSU pegs the landfall probability at around 135% of the long-period average.
The 2020 Atlantic season has already been remarkable and record-setting. Four tropical storms developed before July.
When Cristobal formed on June 2 in the southern Gulf of Mexico, it marked the earliest date that the third named storm developed. The previous record was held by Tropical Storm Colin in 2016, which formed on June 5. Also, after landfall, Cristobal’s remnants traveled all the way to Wisconsin. Before Cristobal, the remnants of only three other Atlantic tropical cyclones had tracked through Wisconsin or the adjacent Lake Michigan waters in more than 100 years of records.
Arthur and Bertha were the first two named Atlantic storms of 2020, and they both formed in May, prior to the official June 1 start of the season. Arthur formed well east of Florida on May 16, and Bertha developed near the South Carolina coast on May 27. Dating back to 1851, only four other times have two cyclones become tropical storms before May 27. That last happened in 2012, preceded by similar occurrences in 1951, 1908 and 1887, according Dr. Phil Klotzbach, a tropical scientist at CSU.
A low pressure system off the South Carolina coast could become the next tropical storm of the season. The National Hurricane Center (NHC) gives it an 80% chance of happening sometime over the next two to three days. The next name on the list is Fay.
A busy start to hurricane season doesn’t always guarantee conditions will remain that way.
“Historically, Atlantic tropical cyclone activity (as measured by Accumulated Cyclone Energy) through June 30th has had very little relationship with the remainder of the season’s hurricane activity,” said Klotzbach in a tweet on June 8.
However, for now, CSU is sticking with a forecast of a higher-than-normal number of Atlantic basin storms this year because of the early start combined with warm SSTs and La Niña.