NOAA Updates its ENSO Alert on November 14, 2024 – We Remain in ENSO Neutral or do We?– Published November 15, 2024

November 15, 2024Posted inUncategorizedNo Comments

“Synopsis:   “In summary, La Niña is most likely to emerge in October-December 2024 (57% chance) and is expected to persist through January-March 2025).”

So we are really in ENSO Neutral but NOAA may not want to admit their forecast was wrong so they present it as waiting for La Nina. It is correct that we are in La Nina Watch but it is also correct that we currently remain in ENSO Neutral.

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 now describes their conclusion as “ENSO Alert System Status: La Nino Watch”

The exact timing of the transition is now perhaps more clear which should increase the reliability of the Seasonal Outlook to be issued next Thursday.

We have included an ENSO Blog article by Emily  Becker. It raises the question which I have raised before. With Global Warming, are we measuring the phases of ENSO correctly? This is a very important question. We will discuss this graphic which is provided by Emily Becker.

CLIMATE PREDICTION CENTER ENSO DISCUSSION (LINK)

The second paragraph is what is important:

The IRI plume predicts a weak and short duration La Niña, as indicated by the Niño-3.4 index values less than -0.5°C. The latest North American Multi-Model Ensemble (NMME) forecasts are cooler than the IRI plume and predict a weak La Niña.  Due to this guidance and La Niña-like atmospheric circulation anomalies over the tropics, the team still favors the onset of La Niña, but it is likely to remain weak and have a shorter duration than other historical episodes.  A weak La Niña would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance (e.g., CPC’s seasonal outlooks).  In summary, La Niña is most likely to emerge in October-December 2024 (57% chance) and is expected to persist through January-March 2025).

Below is the middle paragraph from the discussion last month.

“The IRI plume predicts a weak and a short duration La Niña, as indicated by the Niño-3.4 index values less than -0.5°C. The latest North American Multi-Model Ensemble (NMME) forecasts were warmer this month, but still predict a weak La Niña.  As a result of the warmer predictions and the recent weakening of equatorial trade winds, the team still favors a weak event, but has lowered the chances of La Niña.  A weaker La Niña implies that it would be less likely to result in conventional winter impacts, though predictable signals could still influence the forecast guidance (e.g., CPC’s seasonal outlooks).  In summary, La Niña is favored to emerge in September-November (60% chance) and is expected to persist through January-March 2025).”

We now provide additional details.

CPC Probability Distribution

Here are the new forecast probabilities. The probabilities are for three-month periods e.g. ASO  stands for August/September/October.

Here is the forecast from last month.

The analysis this month and last month are a bit different with again the transition to La Nina being slightly slower than thought last month. Also, the probabilities of a La Nina are lower than estimated last month. This seems to be a trend. The chart is clearer than the discussion in the summary report above.  The La Nina is a bit slower to arrive. I am not sure that we will actually have a La Nina.  However, one should read the Emily Becker article, which is discussed later in this article.

Some will need to click on “Read More” to read the rest of this article.

NOAA Updates its ENSO Alert on August 8, 2024 – We Remain in ENSO Neutral – Published August 9, 2024

August 9, 2024Posted inweatherNo Comments

“Synopsis:  ENSO-neutral is expected to continue for the next several months, with La Niña favored to emerge during September-November (66% chance) and persist through the Northern Hemisphere winter 2024-25 (74% chance during November-January).”  

So we are really in ENSO Neutral but NOAA may not want to admit their forecast was wrong so they present it as waiting for La Nina. It is correct that we are in La Nina Watch but it is also correct that we currently remain in ENSO Neutral.

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 now describes their conclusion as “ENSO Alert System Status: La Nino Watch”

The exact timing of the transition is now less clear which should decrease the reliability of the Seasonal Outlook to be issued next Thursday.

We have included an ENSO Blog article by Tom Di  Liberto.

 >

CLIMATE PREDICTION CENTER ENSO DISCUSSION (LINK)

The second paragraph is what is important:

“The IRI plume indicates that Niño-3.4 is most likely to be below La Niña thresholds for four overlapping seasons, from September-November 2024 through December 2024 – February 2025.  Based on updated guidance and recent observations, the forecast team predicts nearly equal chances for ENSO-neutral and La Niña in August-October 2024, with higher odds for La Niña in September-November. Although the rate of SST cooling has been slower than previously anticipated, below-average subsurface temperatures and low-level easterly wind anomalies remain conducive to La Niña development in the coming months.  In summary, ENSO-neutral is expected to continue for the next several months, with La Niña favored to emerge during September-November (66% chance) and persist through the Northern Hemisphere winter 2024-25 (74% chance during November-January).”

Below is the middle paragraph from the discussion last month.

“Compared to the previous month, the most recent IRI plume delayed the emergence of La Niña to September-November 2024, with La Niña then persisting through the Northern Hemisphere winter.  The forecast team is also favoring a delayed development of La Niña this month, but is anticipating the transition to occur earlier (August-October).  This is, in part, supported by the continuation of below-average subsurface ocean temperatures and near-term forecasts suggesting a resurgence of easterly wind anomalies in July.  In summary, ENSO-neutral is expected to continue for the next several months, with La Niña favored to emerge during August-October (70% chance) and persist into the Northern Hemisphere winter 2024-25 (79% chance during November-January).”

We now provide additional details.

CPC Probability Distribution

Here are the new forecast probabilities. The probabilities are for three-month periods e.g. JAS stands for July/August/September.

Here is the forecast from last month.

The analysis this month and last month are a bit different with again the transition to La Nina being slower than thought last month. This seems to be a trend. The chart is clearer than the discussion in the summary report above.  The La Nina is slower to arrive and is projected to last perhaps one month less than previously forecast. I am not sure that we will actually have a La Nina.

Some will need to click on “Read More” to read the rest of this article.

NOAA Updates its ENSO Alert on August 10, 2023 – The El Nino Advisory Continues. In a Week, NOAA Will Tell Us How this Impacts U.S. Weather

August 11, 2023Posted inClimate, weatherNo 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”

There is not much doubt that we have an El Nino. How long it lasts and its strength remains to be seen.

CLIMATE PREDICTION CENTER ENSO DISCUSSION

The second paragraph is what is important:

“The most recent IRI plume indicates El Niño will persist through the Northern Hemisphere winter 2023-24.  Given recent developments, forecasters are more confident in a “strong” El Niño event, with roughly 2 in 3 odds of an event reaching or exceeding 1.5°C for the November-January seasonal average in Niño-3.4.  Note that a strong El Niño does not necessarily equate to strong El Niño impacts locally, with the odds of related climate anomalies often lower than the chances of El Niño itself (e.g., CPC’s seasonal outlooks).  In summary, El Niño is anticipated to continue through the Northern Hemisphere winter (with greater than 95% chance through December 2023 -February 2024.”

We now provide additional detail but I am keeping this article shorter than usual because nothing much has changed since last month.

CPC Probability Distribution

Here are the new forecast probabilities. This information in the past has been released twice a month and the first release is based on a survey of Meteorologists, the second is based on model results. The probabilities are for three-month periods e.g. JAS stands for July/August/September. The first forecast is used to develop the Seasonal Outlook which will be issued next Thursday so that is what I am focusing on.

Here is the current release of the probabilities:

You can clearly see The forecast does not extend beyond MAM 2024 and one does see a slight tail-off in the probabilities for El Nino conditions in the Eastern Pacific after the winter season.

NOAA Updates it’s ENSO Outlook on December 8, 2022

December 9, 2022Posted inweatherNo Comments

Updated at 3:45 p.m. December 9, 2022 to complete certain edits that were not completed at the time this article was published. They add a little more clarity to the discussion.

On the second Thursday of every month, NOAA issues its analysis of the status of ENSO. This includes determining the Alert System Status. Although the current status remains the same i.e.  La Nina Advisory, the forecast has again been adjusted slightly from the prior month. There is some disagreement on when this La Nina will end with the best guess being perhaps March. But some meteorological agencies believe it could be sooner than that.

But I have actually seen only a few signs of it starting to happen. But all the meteorologists agree that it will.  Could they all be wrong? Probably not.

Will this La Nina transition quickly to the El Nino phase? That would be unusual but some of the models suggest this will happen.