Record slow hurricane season reaches new milestone

The current record-latest first hurricane formation is September 11. This year has not had any hurricanes yet, and there is nothing on the horizon.  The September 11 date has been met twice: 2002 and 2013. There is a slight nuance to this, however. Prior to the reliable satellite era which began about 50 years ago, some storms and portions of storm lifetimes were certainly missed.

With that in mind, there are two years in the historical records that had zero known hurricanes the entire season: 1907 and 1914. In the satellite era, the fewest number of hurricanes in a season is two, and that happened in 1982 and 2013.

Another metric we commonly look at is the Accumulated Cyclone Energy, or ACE. Rather than a simple count of storms, it is an integrated quantity that accounts for overall storm intensity and duration. For reference, an average season has about 122 ACE units (the units are 10⁻⁴ kt²) and the climatological average by this date is 60.

The ACE this year is at just 4.4, which is about 7% of average for the date. The last time a season had less ACE than this year was 1941 and a handful of years before that. However, those were all prior to the satellite era.  In the satellite era, this is the slowest start to a hurricane season on record.

The reason for this extremely quiet season is clear: the developing very strong El Niño.  The relationship between El Niño, La Niña, and Atlantic hurricane activity has been well-known for quite some time: El Niño tends to suppress activity and La Niña tends to enhance activity. The developing El Niño is "moderate" as of now, and is forecast to become "very strong" (likely the strongest on record) by later this Fall and into Winter.

Here's a look at ACE values through September 11 during El Niños during the satellite era. For comparison to 2026, I am using the June-July-August RONI value and counting only El Niños of moderate or higher strength (at least 1.0°C):

YEAR      RONI        ACE

1972        +1.1°C        32.2

1987        +1.1°C        17.7

1997        +1.5°C        34.4

2015        +1.3°C        26.6

2026        +1.4°C         4.4

Among its peers, activity across the Atlantic is clearly minimal this year.

We will probably still see lingering impacts of this El Niño on the 2027 Atlantic hurricane season...

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Tropical Depression 5 forms, Dolly dissipates

Since my previous post last Thursday, the tropical Atlantic has been fairly quiet.  Tropical Storm Dolly dissipated into an open wave on Friday morning, just one day after it formed. There's a very slim chance that it redevelops this weekend... more on that at the end. Elsewhere, a disturbance in the northwestern Gulf of Mexico organized into Tropical Depression 5 on Monday afternoon. If it reaches tropical storm intensity, the next name is Edouard.

At 5pm Eastern, TD5 is located just off the central Louisiana coast and is forecast to track northwest toward the Houston area on Tuesday as it slowly intensifies. 

Even if it does briefly reach tropical storm intensity on Tuesday, it has little time before landfall, so flooding rain will be the primary threat. Fortunately, the depression is very small, so impacts such as storm surge and heavy rain are also going to be fairly limited in scope.

The remnants of Tropical Storm Dolly are near the northern coast of Hispaniola and barely discernible. The odds of regeneration have decreased drastically in the past day, but the disturbance will travel toward the Bahamas and then Florida the rest of the week, bringing heavy rain with it.

Looking at where the season stands relative to climatology as we wrap up August, the Accumulated Cyclone Energy is 10% of average. In terms of storm counts, there have been 4 named storms, 0 hurricanes, and 0 major hurricanes. The average by now is 6, 2, and 1.  By any measure, this is an incredibly slow start to a season, and with a strong El Niño developing, Atlantic activity should remain suppressed for the remainder of the season. However, "suppressed" doesn't mean zero... just less than average. We are in the heart of the season and need to remain vigilant. 

In terms of ACE, the hurricane seasons since 1950 that had a slower start than 2026 were 2022, 1988, 1984, 1977, and 1967. 2022 and 1988 were during a La Niña, 1984 was fairly neutral but headed into La Niña. 1977 was a weak El Niño, and 1967 was neutral. So 2026 is the only one among these that is a strong El Niño.

If you're curious if there has ever been a season without any hurricanes, the answer is yes, at least that we know of. In the historical record which extends back to 1851, the only years with no hurricanes were 1914 and 1907.  Inspecting their ENSO phases, 1914 was a strong El Niño and 1907 was neutral.

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Tropical Storm Dolly forms in eastern Atlantic

The easterly wave I mentioned in Tuesday's post (Invest 96L) has been upgraded to Tropical Storm Dolly... the fourth named storm of the season.  Zooming in on the storm with some enhanced satellite imagery, we can see the mostly-exposed surface circulation and the thunderstorm activity displaced to the south of the center... and indication of some dry air and northerly wind shear.

The forecast from the National Hurricane Center as of 11am Eastern maintains it as a tropical storm for the next three days then dissipates.  Model guidance supports this with few exceptions, so the chance of this being a serious threat to the Leeward Islands and eastern Greater Antilles this weekend is very slim.

Here's where looking at ensembles is useful... to explore the spread of potential outcomes in the coming week+. Among the American GFS ensemble, the European ECMWF ensemble, and the Google DeepMind ensemble, you'd be hard-pressed to find any support for this to survive the next few days. Even the 1000-member DeepMind ensemble has zero members surviving much beyond the Leeward Islands. So the NHC forecast comes with a lot of confidence.

As I mentioned in the previous post, the name Dolly has been in circulation in the modern naming scheme since 1996 (it replaced Diana which was retired after the 1990 season). So, this is the 6th Dolly: 1996, 2002, 2008, 2014, 2020, 2026.  It's hard to ignore the connection with Dolly Parton's recent passing this year, but my connection to that list is seeing the real Dolly in concert in August 2008 (the 3rd tropical Dolly).

The Accumulated Cyclone Energy (ACE) is at about 12% of average for the date, and the forecasts don't show Dolly contributing too much to the tally. However, just because it's a slow season, we are entering the heart of it and even a single strong hurricane making landfall somewhere can make it a really bad season for that area.

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