La Niña Ending

[GordMay]

El Niño has a little brother, Atlantic Niño, who lives just across the South American continent, in the equatorial Atlantic Ocean.
Like El Niño, Atlantic Niño is characterized by warmer-than-average sea surface temperatures in the eastern equatorial basin, and weaker-than-average trade winds, throughout the east-central equatorial Atlantic.

Atlantic Niño, in contrast to El Niño, tends to peak in summer when ENSO is usually inactive, is usually shorter in duration, is overall much weaker than ENSO, and has more modest and local climate impacts.
For example, Atlantic Niño often disrupts the West African summer monsoon, leading to reduced rainfall in the Sahel region, and is linked to increased frequency of flooding in northeastern South America and the West African sub-Sahel countries bordering the Gulf of Guinea.

The atmosphere-ocean feedback responsible for the onset of Atlantic Niño is believed to be similar to that of El Niño, a process known as Bjerknes feedback (BF). Recent studies have shown a weakening of the Atlantic Niño variability in the past decades. The changes in eastern equatorial Atlantic SST variability have been attributed to the combined effect of a weakening of the Bjerknes feedback, and increased latent heat flux damping, and to a basin-wide warming, related to climate change.

The Atlantic Niño is just one member of a big extended family that covers much of the tropical and subtropical oceans.
Just like El Niño, Atlantic Niño has a sister, Atlantic Niña, that brings cooler-than-average equatorial Atlantic conditions and the opposite climate impacts as her brother. There are many other siblings , cousins, and distant relatives spanning the Pacific, Atlantic, and Indian Oceans, who share a feature in common: ocean surface temperature anomalies, along eastern boundaries, linked to changes in the upwelling of cooler water from below.

The underlying Bjerknes feedback mechanism consists of three components:
a) a weakening of the equatorial trades (westerly wind anomalies) in the western basin deepens the thermocline in the east;
b) the deepened thermocline reduces upwelling efficiency and warms sea-surface temperature (SST) in the east;
c) warm SSTs further weaken the equatorial trades. Various studies have suggested that a similar feedback mechanism operates in the equatorial Atlantic.

The latent heat flux (Fl) is the exchange of energy between the sea surface and the atmosphere, that occurs when water is evaporated from, or condenses onto, the sea surface.

There are four more relatives in the Atlantic Ocean, Benguela Niño/Niña along the coast of Angola and Namibia, and Dakar Niño/Niña along the east coast of West Africa.
There are four more in the Pacific, California Niño/Niña and Chile Niño/Niña along the California and Chilean coasts, respectively.
In the Indian Ocean, only two have been found so far, Ningaloo Niño/Niña off the west coast of Australia.

[Protondecay123]

Originally Posted by GordMay

Yes Cyclone “FREDDY” was an exceptional storm.
“FREDDY” (Feb 6 - Mar 13/23) generated an ACE of 84.7.
The next highest ACE, of the season, was “DARIAN” (Dec 18 - Dec 31/22), at 42.5.

The highest ever ACE previously ESTIMATED for a single storm in the Eastern or Central Pacific was Hurricane “Fico” in 1978, which generated an ACE of 62.8.

The next two closest Eastern Pacific tropical storms were Hurricane “John” in 1994, with an ACE of 54.0, and Hurricane “Kevin” in 1991, with an ACE of 52.1.
The seasonal record holder, for the Eastern Pacific Ocean hurricane season is 2018, with a total ACE of 318. The second highest ACE, of 295, was recorded in 1992, while the 3rd place is held by the 2015 Eastern/Central Pacific season, with the ACE of 287.

The highest ever ACE index ESTIMATED for a single storm, in the Atlantic basin, is 73.6 for the (4 week) San Ciriaco hurricane in 1899.

The highest ever ACE index CALCULATED for a single storm, in the North Atlantic Basin, was Hurricane Ivan in 2004, with a generated ACE of 70.4. The next two closest North Atlantic tropical storms were Hurricane Irma in 2017, with an ACE of 64.9, and Hurricane Isabel in 2003, with an ACE of 63.3.
And, many of those well-above-average years happened during the La Nina years. During the last 20 years, 2020, 2017, 2010, 2008, 2005, etc. were all during La Nina, or Neutral ENSO years.


The minimum and maximum values of Global ACE per year are respectively 416.2 and 1145.0.
The average value of the Global ACE per year is 730.5.
The contribution of Global ACE from the Eastern and Western Pacific is approximately 56% of the total ACE. The contribution of ACE from the Atlantic Ocean is approximately 13% of the total ACE.

Tropical Weather Theory
Learn what causes hurricanes or typhoons, how dangerous they are, and why they are one of the most destructive formations on Earth.
➥ https://learnweather.com/category/tropical-cyclone/

Great info there Gord. Thanks. The Reuters article i referred to stated that Typhoon Ioke in 2006 was number 2 for estimated ACE at 85. However I couldn’t confirm that with a Google search on my phone. Cheers!

[GordMay]

Originally Posted by Protondecay123

... The Reuters article i referred to stated that Typhoon Ioke in 2006 was number 2 for estimated ACE at 85. However I couldn’t confirm that with a Google search on my phone. Cheers!

Indeed, you're correct.
Super-Typhoon 'Ioke" formed in the Central Pacific, was the record holder for ACE, from a single storm, until "Freddy".


Evidently, “Ioke” was the first Category 5 hurricane to develop in the Central Pacific, since record keeping began in the early 1960s, and it is the most powerful storm to pass through the region since hurricanes Emilia and Gilma, both in July 1994.
Super Typhoon Ioke crossed the International Date Line on August 27, which by convention meant the tropical cyclone was then called a typhoon, instead of a hurricane.

From NOAA’s “Monthly Tropical Cyclones Report for February 2023, published online March 2023":
“... Hurricane/Typhoon Ioke (2006) is (was) the current record holder for ACE from a single storm with about 85 × 104 kt2. Freddy has currently (had) produced about 83 × 104 kt2 and may approach (eventually surpassed) Ioke's record ...”
➥ https://www.ncei.noaa.gov/access/mon...yclones/202302

And from Philip Klotzbach
Meteorologist at CSU specializing in Atlantic basin seasonal hurricane forecasts.
➥ https://twitter.com/philklotzbach

Mar 10
Cyclone #Freddy has now produced 17 #hurricane days (e.g., max sustained winds >=64 kt). That's the most hurricane days by a single hurricane/#typhoon/cyclone globally since Fico (1978-eastern North Pacific).

Mar 9
Latest NOAA ENSO forecast gives a 61% chance of #ElNino for the peak of the Atlantic #hurricane season (August-October). El Nino typically reduces Atlantic hurricane activity via increases in vertical wind shear. Too much shear tears apart hurricanes.

Mar 7
These statistics are based off of Joint Typhoon Warning Center data and will differ slightly from data based off of Regional Specialized Meteorology Centers (RSMC) advisories. In the case of Freddy, that data is from RSMC La Reunion.

Mar 7
#Freddy has now generated ~72 ACE, putting it in 2nd place for most ACE by an individual tropical cyclone since 1980. #Hurricane/#Typhoon Ioke (2006) holds the record with ~85 ACE.