The hurricane season is expected to be overactive

CSU calls for 17 named storms, 8 hurricanes and 4 major hurricanes (Category 3 or higher). Each of these figures is above the typical seasonal average of 12 named storms, 6 hurricanes, and 3 major hurricanes.

However, according to Ken Graham, director of the National Hurricane Center (NHC), seasonal averages are being updated.

“We will be entering those new averages into the season. In fact, we will be releasing that information in the coming weeks,” said Graham.

CSU is one of many academic institutions, government agencies and private forecasting companies that release seasonal projections.

While the official forecast from the National Oceanic and Atmospheric Administration (NOAA) won’t come until the end of May, there is already a strong consensus that the Atlantic is heading for another active season.

Factors that increase hurricane activity

There is significant heat in much of the eastern Atlantic, where the ocean’s surface temperature is 1-3 degrees Celsius above normal in early April.

“The main reasons we’re going above average are the low probability of a major El Niño event and the relative warmth in the tropical (Atlantic), but especially in the subtropical eastern Atlantic,” said Phil Klotzbach, a research scientist at CSU. .

Sea surface temperatures are one of the ingredients needed to fuel hurricanes, so it makes sense that there is a correlation between those temperatures and an active season.

Another big factor is El Niño, or lack thereof. When El Niño is present, it reduces Atlantic hurricane activity due to increased vertical wind shear – changes in wind speed and direction that prevent hurricanes from forming.

Most dynamic and statistical models currently indicate a low probability of El Niño developing between August and October.
“The current probability of El Niño from NOAA is quite low for August-October (10%),” said Klotzbach.

Average conditions or even La Niña conditions create a more favorable climate for tropical storm development. While we’re coming out of an active La Niña pattern, it’s not quite over yet, according to NOAA.

At this point, the calming effect of El Niño on the Atlantic hurricane season does not seem likely before 2021.

Hurricane season changes are coming

The 2020 Atlantic hurricane season ended with a total of 30 storms mentioned – the most in any year ever. People along the coastline from Texas to Maine were hit by at least one named storm that season. But the post-season brought some significant changes, including the retirement of three individual storm names, as well as the full list of backup names.
The World Meteorological Organization hurricane committee held its annual meeting last month to discuss recent hurricane seasons and update operational plans.
Never again will the Greek alphabet be used to refer to tropical storms

Before 2021, when the hurricane season had used up all the names on the predetermined alphabetical list, the next plan of action was to use the Greek alphabet.

“The Greek alphabet will no longer be used in the future as it distracts from communication of danger and storm warnings and may be confusing,” the WMO announced in March.

It was decided to use a separate list of names as a backup.

The Greek alphabet is replaced by an additional list of names using the same rules as the Atlantic hurricane season name list – a list of names AZ, but excluding the letters Q, U, X, Y, and Z – for if and when the first list with names is exhausted.

This makes it easier to withdraw and replace the additional list of names when needed.

Preparation for the hurricane begins now

Climatically, about 30% of all Atlantic hurricanes make landfall in the US. However, it is not necessary for all 17 forecasted storms in the US to make landfall to become an impactful season.

“It doesn’t matter if there are 30 storms or one… if it hits you, it’s a busy season,” says Graham.

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The National Hurricane Center (NHC) is already starting preparations for this year’s season. This year, the center will be launching their products from the Atlantic outlook from May 15 instead of June 1 to better serve the communities affected by early season tropical systems.

Seven of the past 10 years, tropical systems have formed prior to the official start of the hurricane season, which is June 1.

Out of season, the NHC has also improved its storm surge modeling.

“We have a number of new storm surge models that we are very excited about,” says Graham. “I think it will improve our ability to release that information for storm surge evacuations, even sooner than ever.”

This is very important because Graham points out that storm surge is the deadliest part of tropical systems in the past. In addition, storm surge barrier forecasts are often the main driver for coastal evacuation plans.

“The best part, in some cases where we’re really sure, we’re going from 48 hours to get that information out, what we’re doing now, we’re going to expand that to 60 hours,” Graham said. “That’s a big deal for decision makers to help them make those really tough decisions about whether or not to evacuate.”

The NHC’s official hurricane forecast will be released in May and “Looks like we’re going back to average to above average,” said Graham.