The below forecast is based on current and projected ENSO conditions across the equatorial Pacific, very warm Atlantic and ocean/atmosphere model projections.
First of all let’s see what’s considered normal.
| Number | Named systems | Hurricanes | Major Hurricanes |
|---|---|---|---|
| 1 | Jun 20 | Aug 11 | Sep 1 |
| 2 | Jul 17 | Aug 26 | Sep 19 |
| 3 | Aug 3 | Sep 7 | Oct 28 |
| 4 | Aug 15 | Sep 16 | – |
| 5 | Aug 22 | Sep 28 | – |
| 6 | Aug 29 | Oct 15 | – |
| 7 | Sep 3 | Nov 15 | – |
| 8 | Sep 9 | – | – |
| 9 | Sep 16 | – | – |
| 10 | Sep 22 | – | – |
| 11 | Oct 2 | – | – |
| 12 | Oct 11 | – | – |
| 13 | Oct 25 | – | – |
| 14 | Nov 19 | – | – |
Credit: NOAA
CSU: North Atlantic Ocean Historical Tropical Cyclone Statistics
List of Atlantic hurricane records
| Most storms in a year | ||||
|---|---|---|---|---|
| Year | Tropical storms | Hurricanes | ||
| Hurricanes | Major | |||
| 2020 | 30 * | 14 | 7 | |
| 2005 | 28 * | 15 | 7 | |
| 2021 | 21 * | 7 | 4 | |
| 1933 | 20 | 11 | 6 | |
| 2023 | 20 * | 7 | 3 | |
| 1887 | 19 | 11 | 2 | |
| 1995 | 19 | 11 | 5 | |
| 2010 | 19 | 12 | 5 | |
| 2011 | 19 | 7 | 4 | |
| 2012 | 19 | 10 | 2 | |
| * Includes at least one subtropical storm Source: [7] |
||||
| Fewest storms in a year | ||||
|---|---|---|---|---|
| Year | Tropical storms | Hurricanes | ||
| Hurricanes | Major | |||
| 1914 | 1 | 0 | 0 | |
| 1930 | 3 | 2 | 2 | |
| 1857 | 4 | 3 | 0 | |
| 1868 | 4 | 3 | 0 | |
| 1883 | 4 | 3 | 2 | |
| 1884 | 4 | 4 | 1 | |
| 1890 | 4 | 2 | 1 | |
| 1917 | 4 | 2 | 2 | |
| 1925 | 4 | 2 | 0 | |
| 1983 | 4 | 3 | 1 | |
Despite being an El Nino year, 2023 Atlantic hurricane season ranks 4th for most-named storms in a year.
As of April 18, both Pacific and Atlantic sea surface temperature anomaly profiles look favourable for above normal tropical cyclone activity within the Atlantic in 2024…
As can be seen in the below global sea surface temperature anomaly chart, we have a developing cool pool in the far east tropical Pacific up against the South America coast. This is the beginnings of La Nina.
Now look east over to the Atlantic. Note how warm the tropical and sub tropical Atlantic is with two areas of patchy cool to the north.
Current SST’s as of April 18, 2024
In short, El Nino’s increase shear over the Atlantic with stronger upper level westerly winds, La Nina provides less shear and a more favourable environment for tropical cyclones within the Atlantic.
From NWS Jackson
How do El Niño and La Niña affect the Atlantic hurricane season?
The change in winds with height is referred to as vertical wind shear. Hurricane formation requires that winds be fairly uniform throughout the atmosphere. In other words, hurricanes cannot form if the vertical wind shear is too high.
El Niño produces stronger westerly wind at upper levels of the atmosphere across the tropical Atlantic than in normal non-El Niño seasons. This increases the total vertical wind shear, basically shearing the tops from developing storms before a healthy circulation can form. El Niño events generally suppress Atlantic hurricane activity so fewer hurricanes than normal form in the Atlantic during August to October, the peak of Atlantic hurricane season.
During La Niña, westerly winds high in the atmosphere weaken. This results in an expanded area of low vertical wind shear, allowing more Atlantic hurricanes to develop during La Niña events. La Niña increases the number of hurricanes that develop and allows stronger hurricanes to form.
The chances for the continental U.S. and the Caribbean Islands to experience a hurricane increase substantially during La Niña and decrease during El Niño.
El Niño and La Niña also influence where Atlantic hurricanes form. During La Niña, more hurricanes form in the deep Tropics from weather disturbances that originate over North Africa. These systems have a much greater likelihood of becoming major hurricanes, and of eventually reaching the U.S. and the Caribbean Islands.
The incidence of hurricanes is higher during the neutral phase (when neither El Niño nor La Niña are in effect) than during El Niño. Although hurricanes occur more often during La Niña episodes, significant tropical weather events have occurred during the neutral phase. For example, the record shattering 2005 hurricane season that included Katrina and Rita occurred during the neutral phase. Hurricane Andrew, the most destructive United States hurricane of record, made landfall along the Gulf coast during a neutral phase of the El Niño/Southern Oscillation in 1992.
- ALL HURRICANES (CATEGORIES 1-5)
Credit: NWS Jackson
- MAJOR HURRICANES (CATEGORIES 3-5)
Credit: NWS Jackson
What is La Nina? Unusually cold waters within the central and eastern tropical Pacific caused by strengthening of the easterly trade winds across the Pacific which force cold subsurface waters to rise to the surface.
Last year saw an unusually active Atlantic despite the presence of El Nino (increases shear over the MDR or main development region) of the Atlantic. Yes, there was less activity within the Caribbean and Gulf of Mexico (due to El Nino induced shear) but there was many cyclones further east and north due to exceptionally warm waters.
Credit: NOAA
Strongest of the 2023 season was Hurricane Lee but most destructive was Hurricane Idalia which peaked at landfall on Florida’s Big Bend.
La Nina’s tend to see reduced shear within the Caribbean and Gulf of Mexico and so I suspect we shall observe more systems further west in 2024 compared to 2023.
Both NMME and CFSv2 below show a continued cooling of the equatorial Pacific from South America westwards in the coming months indicative of La Nina.
CFSv2 SST projections from June-August
Credit: Tropical Tidbits
August-October
Credit: Tropical Tidbits
NMME SST projection for June-August.
Credit: Tropical Tidbits
August-October
Credit: Tropical Tidbits
Both CFSv2 and NMME models support increased activity with higher than normal precipitation within the western MDR of the Atlantic, Caribbean extending into the Gulf of Mexico.
June-August
Credit: Tropical Tidbits
August-October (NOTE ABOVE NORM PRECIP EXTENDS EAST INTO PEAK SEASON)
Credit: Tropical Tidbits
NMME Precip anomaly
June-August
Credit: Tropical Tidbits
August-October
Credit: Tropical Tidbits
Here’s a look at the CFSv2 projection for upward vs downward motion (brown is sinking air, green is rising air)
June-August (NOTE WIDESPREAD SINKING OVER PACIFIC, WIDESPREAD RISING ATLANTIC, AFRICA)
Credit: Tropical Tidbits
August-October
Credit: Tropical Tidbits
The above charts support atmospheric favourability with upward motion extending from Arabian Sea/Indian Ocean basin westward across equatorial Africa. Rising air here suggests a robust African monsoon and genesis region over the Ethiopian Highland region, the birth place of tropical waves. As well as an active African easterly jet which carries these waves westwards across the continent and out into the Atlantic.
The Forecast
TOTAL STORMS: 23-26 HURRICANES: 13-16 MAJOR: 7
The above predicted numbers are based on the developing La Nina in the Pacific with less shear in the upper levels of the Atlantic.
The SST profile of the Atlantic with cool over warm supports rising air within the MDR while a slightly stronger Bermuda high (sinking) may be present over the cooler waters to the north especially as the season enters August.
The African wave train is likely to be energetic after what could be dusty start to the 2024 season. Developing La Nina’s have been known to spread large amounts of Saharan dust across the Atlantic June and July which suppresses activity some. If this is the case, I expect this to die down as we head into August and September.
The 2024 season is expected to turn busy through August and September extending into early October. Of particular concern is the Caribbean and Gulf of Mexico which may have a lot of activity late August to mid-October when ocean heat content peaks and depth of 28C waters are deepest (enhanced by the loop current).
I suspect the majors (cat 3+) which develop could focus on the area just ENE of the Leewards, through the Caribbean, up through the Gulf towards Texas or north of the islands towards Florida.
The area stretching from Houston to Miami is particularly vulnerable this year and there may be two to four Cat 3 or greater threats to this area. Strength and exact position of the subtropical mid atlantic ridge (Bermuda-Azores high) which be critical is determining track and therefore intensity of systems roaming to western Atlantic basin.
From the Carolinas to New York, New England as well as Canadian Maritimes, 2 or 3 systems could threaten from upper end tropical storm to cat 1 hurricane.
From Mexico’s Yucatan down through Belize, Honduras and Nicaragua, the main threat likely comes late season, late October into November where 1 or 2 majors may threaten.
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