BOM Archives - EconCurrents

NOAA Updates its ENSO Alert on July 13, 2023 – El Nino is here and 90% Likely to Last through Winter with a 20% Chance of a MegaNino

By Sig Silber July 15, 2023weatherNo Comments

On the second Thursday of every month, NOAA issues its analysis of the status of ENSO. This includes determining the Alert System Status. NOAA again describes their Report as “ENSO Alert System Status: El Nino Watch”

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

From the NOAA Analysis:

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. Forecasters favor continued growth of El Niño through the fall, peaking this winter with moderate-to-strong intensity (81% chance of November-January Niño-3.4 ≥1.0C). An event that becomes “historically strong” (seasonally averaged Niño-3.4 ≥ 2.0C), rivaling the winters of 1997-98 or 2015-16, has an approximately 1 in 5 chance. In summary, there is a greater than 90% chance that El Niño will continue through the Northern Hemisphere winter.

We now provide additional detail.

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. JJA stands for June/July/August. The first forecast 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 FMA 2024 but one does see a slight tail-off in the probabilities for El Nino conditions in the Eastern Pacific after the winter season.

NOAA Updates its ENSO Alert on May 11, 2023 – El Nino now 90% Likely

By Sig Silber May 12, 2023weatherNo Comments

Lightly Edited at 9:39 p.m. Saturday, May 12, 2023 to add some details that I was too exhausted to sort out when I published early this morning.

There is not much doubt that we will have an El Nino.

From the NOAA Analysis:

The combination of a forecasted third westerly wind event in mid-late May, and high levels of above-average oceanic heat content, means that a potentially significant El Niño is on the horizon. While at least a weak El Niño is likely, the range of possibilities at the end of the year (November-January) include a 80% chance of at least a moderate El Niño (Niño-3.4 greater than or equal to 1.0°C) to a ~55% chance of a strong El Niño (Niño-3.4 greater than or equal to 1.5°C). It is still possible the tropical atmosphere does not couple with the ocean, and El Niño fails to materialize (5-10% chance).

NOAA Updates it’s November 2022 ENSO Outlook

By Sig Silber November 14, 2022weatherNo Comments

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 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.

NOAA Updates its ENSO Analysis on September 8, 2022 – La Nina will probably end soon.

By Sig Silber September 11, 2022weatherNo Comments

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 been adjusted slightly from last month. The IRI analysis suggests it could be slightly later than it appeared last month. Also, the probability that it will extend into the winter is much higher. So what I anticipated as being a three-peat looks to be a reality. But in theory, things could change.

Nevertheless, that is what both NOAA and I think will happen. But it could happen a bit earlier or a bit later.

I provided a small sample of model runs by a number of different meteorological agencies that is presented by the Australian Bureau of Meteorology (BOM) and they suggest that maybe we will be in ENSO Neutral in January or February rather than March as NOAA seems to be thinking. NOAA is placing more weight on the statistical rather than dynamic models but statistics requires data and there have not been a lot of similar situations but what data there is suggests March is more likely than January or February. But perhaps this La Nina will continue beyond March. Maybe it will continue for a fourth year.

NOAA Updates the Status of ENSO February 10, 2022

By Sig Silber February 11, 2022weatherNo Comments

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 been adjusted somewhat from last month. The forecast calls for the La Nina to continue to fade. The timing is shown in the NOAA discussion and the IRI probability analysis. The Australian Meteorological Service thinks this will happen sooner and I agree. I present some information that suggests that NOAA has the timing wrong and that the transition to ENSO Neutral will occur fairly soon.

The impact of the NOAA forecast for the transition from La Nina to ENSO Neutral will show up next Thursday when NOAA issues its Seasonal Outlook. The NOAA ENSO Status Update provides an advance indication of how the forecast might change. To repeat, I expect the demise of La Nina to occur somewhat sooner than predicted by NOAA. It is not a significant difference. There is a lag between the ENSO state and the impact on U.S. weather. Thus the exact date when a fading La Nina meets the criteria for ENSO Neutral may not be very important in terms of the actual impact on Spring and Summer weather including the North American Monsoon (NAM). We will learn what NOAA thinks next Thursday.