Here is part
two of the 2024 Atlantic hurricane outlook. This is an extension of my analysis from my 2024 Hurricane
Outlook Part One. I will take you through the reasons I think this is going to
be a very busy season.
The 2024 hurricane season is getting closer. The Hurricane Season starts on June 1’s and will end on November 30th. The 2024 Hurricane season should be quite different as we transition from El Nino into A la-Nina.
We still
have slightly above average SST in the equatorial Pacific. But these are much
cooler than they were a few months ago. We also have very warm SST in the
Northwestern Pacific.
Both of
these will play a big role in this year’s hurricane season.
In the
Atlantic SST anomalies across the Main Development Region (MDR) (the area
between the Lesser Antilles and the West Coast of Africa) are well above
average. The SST in the Caribbean and Gulf of Mexico (GOM) aren’t quite as
warm, but they are still above average. As we approach the heart of the
hurricane season, these Atlantic Basin SST will become even warmer.
Average
water temperatures since January in the Atlantic’s Main Development Region are
2 °F above last year, crushing previous highs by
almost 0.6 °F.
Another
thing we see in the Atlantic is cooler SST in the North Atlantic north of the
MDR. This is another indicator of an active season. As this temperature
contrast helps supply lift that the tropical waves can use to make it easier
for convection to develop in the MDR that could lead to Tropical Cyclone
development.
The ENSO is
a climate pattern that involves changing water temperatures in the Central and
Eastern equatorial Pacific. There are three statuses of the ENSO: La Nina,
neutral and El Nino.
Last year we
were in a strong El Nino with SST anomalies peaked in November-December last
year.
The primary
metric used by NOAA to gage the strength of an ENSO event is the
three-month-average temperature of the central tropical Pacific Ocean,
specifically in the Nino-3.4 region.
The
temperature anomaly—the difference from the long-term average, where long-term
is currently 1991–2020—in this region is called the Oceanic Nino Index (ONI).
We use a three-month average because ENSO is a seasonal phenomenon, meaning it
persists for at least several months.
The
threshold is further broken down into Weak (with a 0.5 to 0.9 SST anomaly),
Moderate (1.0 to 1.4), Strong (1.5 to 1.9) and Very Strong (≥ 2.0) events.
While we
don’t have official strength definitions, but, unofficially, an ONI anomaly of
1.5 °C or warmer is considered a strong El Nino. Last year the ONI peaked at
2.0 °C which would indicate a very strong El Nino.
Since
November-December last year, SST have dropped. Some areas in the equatorial
Pacific are already showing up cooler, as upwelling is bringing cooler water to
the surface. We’re quickly heading toward neutral. We’re most likely going to
become neutral sometime next month or in May. After that we should quickly move
into La Nina. The chances are growing for a La Nina to develop by summer and
hurricane season 2024.
The colder
subsurface water temperatures are just beneath the surface. Looking back at the
equatorial Pacific Nino regions, we can see region 1+2 off the South American
Coast is already showing much cooler SST.
Typically,
during La Nina hurricane seasons, the Atlantic Basin sees a more active season
due to less wind shear and trade winds and more instability.
During a La
Nina year that follows a strong El Nino like the one that is happening in 2024,
the tracks of tropical cyclones tend to be more active in the Caribbean and GOM.
The El Nino
events in the record (starting in 1950) with the largest Oceanic Nino Index
values are 1972–73 (2.1 °C), 1982–83 (2.2 °C), 1997–98 (2.4 °C), and 2015–16 (2.6 °C). 1987-1988 El Nino reached (1.7 °C). 2009-2010
(1.5 °C) These seasons were all followed by a La Nina.
Possible
Analogues…
La Nina
seasons following a strong El Nino
1973, 1983,1988,1995,1998,
2010 and 2016
Saharan air
layer (SAL) could be an inhibiting factor, especially during the first part of
the season. As I’ve said in the past, the SAL is a layer of hot dry that can
contain Saharan dust, blown off of Africa and out over the Atlantic.
SAL creates
atmospheric parameters that suppress tropical cyclone formation and
intensification. Last season featured less than average SAL over the Atlantic. If
that is again the case this year; it would increase the odds for an active
season.
The
Bermuda/Azores High (BAH) is a large area of high pressure that develops over
the subtropical Atlantic Ocean. It exerts a lot of influence on the track of
tropical systems.
The location
and strength of the BAH will also be important. As this will determine how far west the TC can
track. If the BAH is weak and farther east TCs will have a greater chance to
curve north up into the Atlantic. On the other hand, if the BAH is strong
farther west, there will be a greater opportunity of the TCs to make in into
the western Atlantic along with the Caribbean and GOM.
AccuWeather is calling for 20-25 named storms, with 8 to 12 becoming hurricanes, 4 to 7 of those becoming major hurricanes (Category 3 or above with at least winds of at least 111 mph). They are predicting 4 to 6 U.S. landfalling TCs. They say the seasonal Accumulated Cyclone Energy (ACE) will be 175-225.
Colorado State University (CSI) is calling for 23 named storms, 11 becoming hurricanes, 5 of those becoming major hurricanes.
WeatherBELL Analytics
says the season will have 25-30 named storms, with 14 to 16 becoming hurricanes.
Of these they are calling for 6 to 8 major hurricanes, with a seasonal ACE of 200
to 240.
Tropical
Storm Risk (TSR) calls for 20 named storms, 9 of these becoming hurricanes and
4 of these to become major hurricanes, with a seasonal ACE of 160.
All of these
have one thing in common; they are all calling for a very active and possibly
explosive hurricane season.
Based on the
SST temperature profiles, I think 2024 should be similar to seasons like 2020, 2017,
2011, 2010, 2008, 2005 and 1995.
While there
is no guarantee that an active season results in several U.S. landfalling TCs.
It does increase the odds.
The data
shows that the risk for hurricanes making landfall, are almost double when the
Atlantic is warm vs when it is cool. The data also shows the risk for
landfalling hurricanes is almost two and a half times greater during La Nina
seasons vs El Nino seasons.
We also have
those well above average SST in the Northeast Pacific. This favors a pattern that
could be very similar to what we had in 2005, 2007 and 2020. Those years saw several
U.S. Tropical Cyclone landfalls.
With the
super warm water in the Atlantic there is a greater risk for TCs to rapidly
strengthen. When you add in the increased risk for landfalling systems, the
idea of rapid intensification is something to worry about.
In part one,
I said the eastern Gulf Coast, Florida and the Carolinas are at an above
average risk for direct impacts. With a slightly less risk for the Texas Coast,
Middle Atlantic and New England seeing possible landfall TC risk. That still seems to be true. The Caribbean is
also going to be at a heightened risk.
The U.S. will likely see multiple landfalling tropical cyclones.
I will be
releasing part three in May.
