Over the
last several months, I’ve been posting quite a bit about the developing El
Nino. So, I wanted to touch back on it.
It’s been a while
since I explained the El Nino-Southern Oscillation (ENSO). So, I will start out
with that.
El Nino and
La Nina are both a part of a broader natural climate phenomenon called the El
Nino-Southern Oscillation cycle. El Nino is characterized by warmer than
average SST waters in the central and eastern equatorial Pacific, La Nina is
the opposite when the SST are cooler than average in the central and eastern
equatorial Pacific. Both phases cause changes in global weather patterns. as
the trade winds weaken or strengthen allowing warmer or cooler water to
transition back to that side of the ocean.
Each one of these ENSO phases can manifest with different strengths. A weak El Nino is when SSTS in region 3.4 are 0.5° C. to 1° C above average, A moderate El Nino is when SSTS are 1° C to 1.5° C above average. The El Nino is considered strong when the SSTs are 1.5° C to 1.9 °C above average. A very strong El Nino is in place when sea surface temperatures are 2° C. above average or higher. The opposite is true when it's a La Nina with the temperatures running below average. ENSO neutral is when the SSTs in region 3.4 are running between -0.5° C. to +0.5 ° C.
The La Nina
we had earlier this Spring has come to an end. Temperatures in the east-Central
Pacific Ocean are around average according the National Oceanic and Atmospheric
Administration. This means we’re in ENSO neutral conditions, meaning we’re not
in La Nina or El Nino. However, we are transitioning quickly to an El Nino, and
it could be a particularly strong one.
Current
conditions.
Global SST
Anomalies
Image
curtesy of NOAA Coral Reef Watch
Pacific
Image
curtesy of NOAA Coral Reef Watch
Image
curtesy of Tropical Tidbits
Image
curtesy of Tropical Tidbits
Atlantic
Image
curtesy of Tropical Tidbits
Sea surface
temperatures in the Atlantic remain near or slightly above average. These SST
are going to continue to warm, which will provide fuel for storms, setting the
stage for a battle between unfavorable wind conditions caused by El Nino and
the warmer ocean waters that strengthen brewing storms. We saw idea this play
out a couple of years ago
SST anomalies
changes over the last 7 days.
Image
curtesy of NOAA Coral Reef Watch
Subsurface
temperature anomalies
The subsurface water temperatures are warming quickly and are rising to the surface.
What the
models are showing
International Research Institute (IRI) ENSO Predictions Plume
The ECMWF anomaly
plume for Nino 3.4
The graph
above shows ECMWF model projections for sea surface temperature anomalies in
the central equatorial Pacific, a key area scientists monitor for ENSO
conditions. Each red line represents a different model’s forecast, charting how
high the temperature will rise above average over time.
The Probabilistic
ENSO outlook
Image curtesy of Climate Prediction Center / NCEP
The ENSO
strength probabilities
Here is a
look at NOAA’s strength-threshold table, which tracks the probability of the
index crossing +1.0° C, +1.5° C, and the +2.0° C delimiter where we head into super
El Nino territory. Some of the forecast ensemble members are in the
moderate-to-strong range. But some push into +2.0°C. But this is showing that as of late May 2026:
a super El Niño is certainly, but it is not the only outcome the model’s
supports.
Image
curtesy of Climate Prediction Center / NCEP
The reason
for the rapid rise toward a strong El Nino on the models, is the strong winds
blowing west to east which are pushing warm water eastward.
Nino regions
Nino regions
are specific areas in the tropical Pacific Ocean used to monitor sea surface
temperature anomalies that indicate El Nino or La Nina events.
The Nino 3.4
anomalies may be thought of as representing the average equatorial SSTs across
the Pacific from about the dateline to the South American coast. This is the region NOAA uses and tracks to
determine the state of the ENSO
Nino region 1+2
Nino Region
3
Nino Region
3.4
Nino Region
4
Images
curtesy of Tropical Tidbits
Looking at
the regions we can see they are all in El Nino territory
How
likely is this to happen?
Right now,
all the models and observations are pointing toward the idea of a very strong
El Nino developing this year. The idea that the models are all in agreement
that a strong El Nino is likely, does lend confidence to those making the call
for a strong El Nino. But it’s important to point out that models have gotten
it wrong before. We’re in the period that is called the “spring predictability barrier”
So we have to be at least a little skeptical of what the models are hinting at.
But with the observations also pointing in the same direction; the idea of a
moderate to strong El Nino later is year is a good one. I’m even seeing several
post and news articles discussing major winter impacts of this will have. But
the truth is, we simply don’t know for sure. There is also something called the
Autumn Predictability Barrier, due to the fact models are not always close to
be right. So, how strong it will be does
remain to be seen. But with everything pointing and coalescing around the
possibility for of a quick transition to at least a moderate El Nino, we should
prepare for the possibility.
So, for now,
my advice is to ignore the hype. Very strong El Nino’s don’t always lead to
bigger weather and climate impacts. Stronger events just make it more likely
that certain impacts might happen. When we measure the strength of the El Nino, we’re only
talking about the ocean temperatures in the eastern Pacific. But this figure is
not very well correlated with exact heat and rain effects. Because it only
captures ocean changes and doesn’t really manifest the atmospheric changes from
El Nino which is the true influence the weather systems that impact places like
the Northeast. In the end it doesn’t really matter that much for our weather if the index goes over
2°C mark becoming very strong. What matters much more is whether an actual El
Nino is present or not, and right now that is looking very likely.
The
impacts of a strong El Nino
During the
summer, El Nino brings about a shift in the path of the jet stream
Historically,
El Nino doesn't have a strong summer correlation signal for the climate over
most of the U.S. But the correlation becomes much stronger and clearer during
the winter. The truth is stronger events don’t always lead to bigger weather
and climate impacts. Stronger events just make it more likely that certain
impacts might happen.
Possible impacts here during this summer
During El
Nino more times than not, we see a dip in the northern Jet Stream and the
southern subtropical jet becomes much stronger and active.
During the
summer El Nino historically means a large part of the U.S., ends up seeing
cooler-than-average summers instead of warmer than average summers.
For us here
in the Northeast, El Nino summers are often characterized by higher amounts of
humidity. This is because the atmosphere is more active, we tend to see more
tropical air masses push into the region. This leads to the likelihood of more
heavy rain events and afternoon thunderstorms rather than long-term dry
spells. But this isn’t always the case.
During the
hurricane season
When the
Pacific warms, it has a big influence on the jet stream, this shift in the jet
stream often makes the eastern into central Pacific much more active and open
for development. But that shift in the jet stream ends up creating downdrafts,
sinking air and stronger wind shear in parts of the Atlantic Basin. This tends
to make conditions more hostile for hurricane development over the Atlantic
basin.
So, what
does that mean for the upcoming hurricane season in 2026? That really remains to
be seen.
But just
because it’s going to be an El Nino doesn’t mean there won’t be hurricanes.
Like I’m calling for in my Outlook, this season is looking to be average to
slightly above average to me. There can be and have been and major devastating
hurricanes, can and do occur in El Nino years. One of the strongest El Nino’s
on record, resulted in Hurricane Bob in 1991 He hit the eastern tip of Long
Island, Rhode Island, hit Massachusetts and then swirled into Maine in August
of 1991 as a Category 2 storm. Bob was the last hurricane to make landfall in
New England. So, we can’t say it couldn’t happen this season.
Here is the link to my most recent thoughts for the hurricane season.
Possible impact for the upcoming winter
The above graphic shows El Nino often leads to milder winters due to a northward shift of the polar jet stream, reducing cold Arctic air intrusions
The northern
US typically sees milder winters due to a northward shift of the polar jet
stream. But that doesn’t mean the entire winter pattern is consistently mild.
There can be cold air outbreaks. If the timing and the storm track corporate
there can be snowstorms.
The Southern
Sub Tropical Jet is normally strong and very active. For the Northeast, that
can mean an increase in nor'easter type winter storms and increased wintertime
precipitation, (rain, mix and snowfall). While a nor'easter can dump heavy snow
for the Middle Atlantic and Northeast it doesn’t guarantee the Northeast will
end up with above average snowfall. But many El Ninos have seen above average
snowfall. In fact, averaging all the El Nino winters, areas along the Coast
typically sees roughly 6 inches more snow than is considered average.
The data is
a bit less murky when it comes to lake effect snow.
As most of
y’all know the Great Lakes play a major role in winter weather this is
especially true for lake effect snow … which occurs when cold air moves over
the relatively warmer waters of the lakes
The last few
winters here on the Tug Hill have been very active lake effect seasons, where
it was buried. While there have been similar lake effect snow winters; it’s
more of an exception than a rule. Many times, during moderate to strong El Nino
events, winters in the lower Great Lakes snow belts tend to be warmer and drier
than average. That combination can lead to reduced snowfall.
Is the
strongest El Nino since the record levels last seen in 1877-1878 possible?
The short
answer is yes. But the long answer is much more complicated.
When trying
to forecast an El Nino, especially this year, problems can arise if we expect
El Nino to be the only factor dictating our weather.
Besides the
normal teleconnection interaction around the globe, we also had the recent Hunga
Tonga-Hunga Ha’apai volcano that erupted on Jan. 15, 2022, that blasted an
enormous plume of water vapor into Earth’s stratosphere. The volcanic event caused
the polar vortex to become disrupted quite a bit this past winter. The same
atmospheric disruption is also going to have at least some implications; for
the El Nino and atmospheric interaction that's going to occur over the summer
into the fall. Currently we see the atmospheric interaction with the developing
El Nino lagging. With the global SST
pattern, the way it is; and the stratosphere behaving as it is. It's a Good
indication that this year’s likely El Nino will be a different animal than
we've seen in the past and could cause surprises that many people aren't
anticipating. For example,
The most
recent El Nino, in 2023 into 2024, was one of the five strongest on record and
it played a role in the record global temperatures we saw in 2024. But in spite
of that, the 2024 hurricane season was extremely active and destructive,
featuring 18 named storms, 11 hurricanes, 5 major hurricanes. The reason for this was the near to and record
warm SST in the Atlantic Basin and how it overrode the El Nino effects. The
hurricane season of 2025 was during a La Nina and in spite of that the 2025
hurricane season wasn’t clear cut as far as activity. 2025 Atlantic hurricane
season featured 13 named storms, 5 hurricanes, and 4 major hurricanes,
including three Category 5 storms. As far as named storms it was slightly below
average, with the number of hurricanes and the number that became major is average.
So clearly what is going on with the ENSO is becoming less of a factor over the
last few years.
In a few of
my post on El Nino. I’ve talked about the fact that the global SST anomalies
are very warm. With out that stark temperature contrast between the Pacific and
Atlantic. This El Nino would have to technically be much warmer than past El
Ninos have been. So, with that being the
case. These years El Nino would have to be at least +2.5° C to even obtain the global
impact of what’s considered a super El Nino, that is much warmer than the
current threshold of +2.0° C. So, unless this event makes it to 3.0° C it might
only act like a moderate El Nino as far as global impact is concerned.
I don’t
really know if an El Nino of that caliber is going to happen. Yes, I think
we’re going to get an El Nino, that very well could become moderate to maybe a
strong one. But the idea of a true super El Nino might be very hard to achieve.
It’s not impossible, but the odds of getting there are high.
Above all we
have to remember every El Nino is different.
That’s it, I
hope you found this informative and a fun read. Let me know what you think!
