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May 8, 2025 (updated early-month)
Alert Status:
Not Active
(definitions)
ENSO-neutral is favored through the Northern Hemisphere summer 2025 (74% chance
during June-August), with chances exceeding 50% through August-October 2025
DIAGNOSTIC DISCUSSION:
In April 2025, ENSO-neutral continued, with near-average sea surface temperatures
(SSTs) covering most of the equatorial Pacific Ocean. All of the latest weekly
Niño index values were near zero, ranging from -0.2°C to +0.1°C. Subsurface
temperatures were mostly near average in the central and eastern Pacific Ocean,
with above-average subsurface temperatures remaining at depth in the western Pacific.
For the month, low-level and upper-level winds were near average across the equatorial
Pacific. Convection remained suppressed near and west of the Date Line and was
enhanced near Indonesia. Collectively, the coupled ocean-atmosphere system was ENSO-neutral.
Last month, the
IRI
and North American multi-model ansemble
anticipate ENSO-neutral to continue through the Northern Hemisphere summer and
early autumn 2025. The forecast team also favors ENSO-neutral, especially through
the summer, with chances nearing 50% during the autumn. The uncertainty increases
at longer time horizons, with a 46% chance of ENSO-neutral and a 41% chance of La
Niña during November 2025 - January 2026 (chances of El Niño are under
15%).
... Read more at the
NOAA's Diagnostic Discussion,
CPC ENSO Update
, and
CPC's Official Probabilistic ENSO Forecast
sites,
all updated at the same time in the early-month.
** Note: IRI's Monthly Ouick Look updates twice
per month and presents the latest update between the (I) early-month CPC official Probabilistic
Forecast (shown in this section) and (II) mid-month IRI Model-Based Probabilistic Forecast
(shown in the following two sections).
(The update of the CPC ENSO diagnostics discussion and forecast is scheduled
for the second Thursday of each month.)
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April 21, 2025 (updated mid-month)
During the forecast period, neither El Niño nor La Niña shows
a strong preference, with the probabilities for both phases gradually
increasing and then stabilizing in the upper 20% range.
As of mid-April 2025, the equatorial Pacific is in an ENSO-neutral state.
This shift is marked by sea surface temperatures in the Niño 3.4 region
that are now closer to average, with anomalies at 0.10°C for Mar, 2025.
The IRI ENSO
plume forecast
indicates a high probability (96%) of ENSO-neutral conditions for April to
June 2025. These neutral conditions are expected to continue through August
to October 2025, with probabilities staying above 50%. For later forecast
seasons, ENSO-neutral conditions remain the most likely outcome, though
probabilities decrease to the 40% range.
... Read more at the
IRI Technical ENSO Update,
IRI Model-Based Probabilistic ENSO Forecast
,
IRI ENSO Predictions Plume
, and
IRI Forecast Probability Distribution Based on the IRI ENSO Prediction
Plume
sites, all updated at the same time in the mid-month.
** Note: IRI's Monthly Ouick Look updates twice
per month and presents the latest update between the (I) early-month CPC official Probabilistic
Forecast (shown in this section) and (II) mid-month IRI Model-Based Probabilistic Forecast
(shown in the following two sections).
(The update of the IRI ENSO forecast is scheduled for the 19th of each month. If the 19th falls on a weekend or holiday, it is released on the closest business day.)
April 21, 2025 (updated mid-month)
|
... Read more
here, where
any specific model can be interactively examined, along with other detailed information.
(The update of the IRI ENSO forecast is scheduled for the 19th of each month. If the 19th falls on a weekend or holiday, it is released on the closest business day.)
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Ocean Niño Index (ONI) - NOAA's primary indicator for monitoring ENSO:
Journal Article: A Relative Sea Surface Temperature Index for Classifying ENSO Events
NOAA CPC's El Niño - Southern Oscillation (ENSO) resources webpage
El Niño Regions:
El Niño and La Niña events tend to develop during the period Apr-Jun and they
The spring predictability barrier: Forecasts made at some times of the year generally have higher skill than forecasts made at other times of the year -- namely, they are better when made between June and December than when they are made between February and May. This is a well-known challenge for forecaster and it can impact statistical models more than dynamical models.
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