NOAA Updates its ENSO Alert on February 8, 2024 – The El Nino Advisory Continues. The La Nina Watch Begins – Timing of the Transition is Uncertain

February 9, 2024Posted inweatherNo Comments

On the second Thursday of every month, NOAA (really their Climate Prediction Center CPC) issues its analysis of the status of ENSO. This includes determining the Alert System Status.  NOAA again describes their conclusion as “ENSO Alert System Status: El Nino Advisory La Nino Watch”

The timing of the transition is not very clear which will impact the reliability of the Seasonal Outlook to be issued next Thursday.

We have included an interesting animation from and a link to an ENSO Blog article by Tom Liberto

 

CLIMATE PREDICTION CENTER ENSO DISCUSSION

The second paragraph is what is important:

“The most recent IRI plume indicates a transition to ENSO-neutral during spring 2024, with La Niña potentially developing during summer 2024.  Even though forecasts made through the spring season tend to be less reliable, there is a historical tendency for La Niña to follow strong El Niño events.  The forecast team is in agreement with the latest model guidance, with some uncertainty around the timing of transitions to ENSO-neutral and, following that, La Niña.  Even as the current El Niño weakens, impacts on the United States could persist through April 2024 (see CPC seasonal outlooks for probabilities of temperature and precipitation).  In summary, a transition from El Niño to ENSO-neutral is likely by April-June 2024 (79% chance), with increasing odds of La Niña developing in June-August 2024 (55% chance).”

Below is the middle paragraph from the discussion last month.

“The most recent IRI plume indicates El Niño will gradually weaken and then transition to ENSO-neutral during spring 2024 .  Some state-of the-art dynamical climate models suggest a transition to ENSO-neutral as soon as March-May 2024.  The forecast team, however, delays this timing and strongly favors a transition to ENSO-neutral in April-June 2024.  There are also increasing odds of La Niña in the seasons following a shift to ENSO-neutral.  It is typical for El Niño to peak in December/early January, but despite weakening, its impacts on the United States could last through April (see CPC seasonal outlooks for probabilities of temperature and precipitation).  In summary, El Niño is expected to continue for the next several seasons, with ENSO-neutral favored during April-June 2024 (73% chance).”

We now provide additional details.  The level of uncertainty with respect to how this El Nino will play out has increased a bit.

CPC Probability Distribution

Here are the new forecast probabilities. The probabilities are for three-month periods e.g. JFM stands for January/February/March.

Here is the current release of the probabilities:

This chart shows the forecasted progression of the evolution of ENSO from the current El Nino State to Neutral and by the summer to La Nina.  This kind of  bar chart is not very good at showing uncertainty.

Here is the forecast from last month.

The analysis this month and last month are different.  This month the probability of El Nino in MAM is much more than was expected last month.  That is important.