|
January 9, 2025 (updated early-month)
Alert Status:
La Niña Advisory
(definitions)
La Niña conditions are present and are expected to persist through February-April
2025 (59% chance), with a transition to ENSO-neutral likely during March-May 2025
(60% chance).
DIAGNOSTIC DISCUSSION:
La Niña conditions emerged in December 2024 and were reflected in
below-average sea surface temperatures (SSTs) across the
central and east-central equatorial Pacific Ocean.
The latest weekly indices were -0.7°C in Niño-3.4 and -0.6°C
in Niño-4, with values close to zero in Niño-1+2 and Niño-3.
Subsurface cooling in the equatorial Pacific Ocean strengthened significantly,
with below-average temperatures dominating the central and eastern equatorial
Pacific Ocean.
Low-level wind anomalies were easterly over the western and central Pacific, while
upper-level wind anomalies were westerly over the central and eastern Pacific.
Convection was suppressed over the Date Line and was enhanced over Indonesia. The
traditional and equatorial Southern Oscillation indices were positive. Collectively,
the coupled ocean-atmosphere system indicated La Niña conditions.
The dynamical models in the IRI
plume
continue to predict a weak La Niña during the winter seasons, as indicated
by the Niño-3.4 index values less than -0.5°C. The North American Multi-Model
Ensemble (NMME) predicts slightly cooler SST anomalies with La Niña persisting
through February-April 2025. The forecast team favors the NMME guidance, predicting
weak La Niña conditions through the early spring before transitioning to
ENSO-neutral. Weak La Niña conditions are less likely to result in conventional
winter/spring impacts, though predictable signals can still influence the forecast
guidance (e.g., CPC's seasonal outlooks).
... 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.)
|
December 19, 2024 (updated mid-month)
As of mid-December 2024, ENSO-neutral conditions persist in the equatorial Pacific,
and both oceanic and atmospheric indicators remain in an ENSO-neutral state. The
IRI ENSO prediction
plume
forecasts slightly higher chances (59%) for ENSO-neutral conditions for
Dec-Feb, 2025, with a continuation of ENSO-neutral conditions from Jan-Mar, 2025
to Jul-Sep, 2025. For Aug-Oct 2025, no specific ENSO category emerges as favored.
In summary, ENSO-neutral conditions are expected to persist through the boreal
winter, spring, and summer of 2025.
DISCUSSION:
According to the most recent official
CPC
ENSO Outlook (issued on December 12, 2024), the La Niña onset is
forecasted in Nov-Jan 2024, with 59% chances; however, the objective IRI
model-based ENSO outlook forecasts indicate the continuation of ENSO-neutral
conditions for Dec-Feb, 2025. Thus, there is a notable difference between
the probability numbers in the early-month CPC Outlook and mid-month IRI
ENSO forecast. Going further forward, the CPC ENSO Outlook predicts a clear
preference for La Niña during the winter of 2025, followed by a return
to ENSO-neutral (61% chance in Mar-May) state during boreal spring of 2025.
In contrast, the objective IRI ENSO forecasts show a continuation of
ENSO-neutral conditions during the forecast period.
... 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.)
December 19, 2024 (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.)
|
Ocean Niño Index (ONI):
Journal Article: A Relative Sea Surface Temperature Index for Classifying ENSO Events in a Changing Climate>
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.
The content posted on this web page solely represents the opinions of the authors and does not constitute a statement of policy, decision, or position on behalf of NOAA or the US Government.
The appearance of external links on this World Wide Web site does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site.
