ENSO Updates (2007 thru 2023)

[euro6208]

This season's tune will be alot different once el nino is declared...

[cycloneye]

This season's tune will be alot different once el nino is declared...

What season you are eluding to?

[euro6208]

This season's tune will be alot different once el nino is declared...

What season you are eluding to?

Mainly the different basins in the Northern Hemisphere...

Active Pacific, Quiet Atlantic...

[xtyphooncyclonex]

This season's tune will be alot different once el nino is declared...

What season you are eluding to?

Mainly the different basins in the Northern Hemisphere...

Active Pacific, Quiet Atlantic...

Pacific Bias, then.

[Yellow Evan]

They should IMO pull the trigger, but I won't be surprised if they don't and just pull it when we get 5 ONI months of El Nino.

[cycloneye]

El Nino is declared

EL NIÑO/SOUTHERN OSCILLATION (ENSO)
DIAGNOSTIC DISCUSSION
issued by
CLIMATE PREDICTION CENTER/NCEP/NWS
and the International Research Institute for Climate and Society
5 March 2015


ENSO Alert System Status: El Niño Advisory



Synopsis: There is an approximately 50-60% chance that El Niño conditions will continue through Northern Hemisphere summer 2015.

During February 2015, El Niño conditions were observed as the above-average sea surface temperatures (SST) across the western and central equatorial Pacific (Fig. 1) became weakly coupled to the tropical atmosphere. The latest weekly Niño indices were +0.6oC in the Niño-3.4 region and +1.2oC in the Niño-4 region, and near zero in the Niño-3 and Niño-1+2 regions (Fig. 2). Subsurface temperature anomalies increased (Fig. 3) associated with a downwelling oceanic Kelvin wave, which was reflected in positive subsurface anomalies across most of the Pacific (Fig. 4). Consistent with weak coupling, the frequency and strength of low-level westerly wind anomalies increased over the equatorial Pacific during the last month and a half (Fig. 5). At upper-levels, anomalous easterly winds persisted across the east-central Pacific. Also, the equatorial Southern Oscillation Index (EQSOI) remained negative for two consecutive months. Convection was enhanced over the western equatorial Pacific and near average around the Date Line (Fig. 6). Overall, these features are consistent with borderline, weak El Niño conditions.

Compared to last month, several more models indicate El Niño (3-month values of the Niño-3.4 index equal to or greater than 0.5oC) will continue throughout 2015 (Fig. 7). This is supported by the recent increase in subsurface temperatures and near-term model predictions of the continuation of low-level westerly wind anomalies across parts of the equatorial Pacific. However, model forecast skill tends to be lower during the Northern Hemisphere spring, which contributes to progressively lower probabilities of El Niño through the year. In summary, there is an approximately 50-60% chance that El Niño conditions will continue through Northern Hemisphere summer 2015 (click CPC/IRI consensus forecast for the chance of each outcome).

Due to the expected weak strength, widespread or significant global impacts are not anticipated. However, certain impacts often associated with El Niño may appear in some locations during the Northern Hemisphere spring 2015.

http://www.cpc.noaa.gov/products/analys ... odisc.html

[Yellow Evan]

They should IMO pull the trigger, but I won't be surprised if they don't and just pull it when we get 5 ONI months of El Nino.

I jinked it lol. Just when I posted this.

I'm proud of this El Nino. After all it went through and how everyone thought we won't get one, we got one.

[xtyphooncyclonex]

OMG YES!!! AFTER 6 YEARS of waiting...

[euro6208]

No surprise there...

even cycloneye is trigger happy

[xtyphooncyclonex]

Probably the earliest declaration since 1997, when it was declared April.

[Yellow Evan]

Probably the earliest declaration since 1997, when it was declared April.

March comes before April, so I guess it'd be the earlier (or latest in a sense since this evens started in 2014).

[cycloneye]

Here is more info from IRI.

During January through February 2015 the SST just met the thresholds for weak Niño conditions. Lately some of the atmospheric variables began indicating an El Niño pattern a little more than they had been before January. The consensus of ENSO prediction models indicate warm neutral to borderline El Niño conditions during the February-April season in progress, continuing into northern spring 2015, with some suggestion of strengthening El Niño toward mid-2015.

http://iri.columbia.edu/our-expertise/c ... o/current/

[Ntxw]

This declaration counts for 2014-2015 which will have begun in September of 2014 per ONI officially. I don't think this is surprising that they declared it and I even get in a sense from their wording they didn't want to declare but have to given the ONI will be so. But it does appear a multi-year (unbroken) El Nino may happen if we continue this in 2015-2016. The last one was in 1986-1987 and 1987-1988

[cycloneye]

The CPC blog discussion will be interesting to read later today where they tip about all the details of the declaration.

[cycloneye]

Humor on social media.

[WeatherGuesser]

OMG YES!!! AFTER 6 YEARS of waiting...

Why waiting? You say that as if it means something good.

[Yellow Evan]

This declaration counts for 2014-2015 which will have begun in September of 2014 per ONI officially. I don't think this is surprising that they declared it and I even get in a sense from their wording they didn't want to declare but have to given the ONI will be so. But it does appear a multi-year (unbroken) El Nino may happen if we continue this in 2015-2016. The last one was in 1986-1987 and 1987-1988

I think there is a decent chance it last through the summer. The sub-surface is still warming, which should provide this event fuel.

[cycloneye]

This declaration counts for 2014-2015 which will have begun in September of 2014 per ONI officially. I don't think this is surprising that they declared it and I even get in a sense from their wording they didn't want to declare but have to given the ONI will be so. But it does appear a multi-year (unbroken) El Nino may happen if we continue this in 2015-2016. The last one was in 1986-1987 and 1987-1988

I think there is a decent chance it last through the summer. The sub-surface is still warming, which should provide this event fuel.

Warm pool remains solid as of March 5.

[cycloneye]

Interesting CPC blog discussion about all the details on why they pulled the trigger towards the declaration of El Nino and looking ahead.

What tipped us over the line?

What’s different this month? For starters, it’s the second month in a row with a negative value for the Equatorial Southern Oscillation Index (EQSOI, -0.5 for February), one indicator of a weakened Walker Circulation. Also, the pattern of below-average rainfall in the central Pacific, which was very inconsistent with El Niño, recently transitioned to near-average rainfall (as indicated by outgoing longwave radiation). The increased rainfall we were seeing in the western equatorial Pacific continued.

Late January and February saw a couple of westerly wind bursts over the central tropical Pacific, and the forecast for the first two weeks of March suggests these winds will continue. When the winds in this region turn more westerly, they can encourage movement of warmer surface waters eastward and either trigger or strengthen downwelling Kelvin waves, leading to warmer SST anomalies in the central and eastern parts of the tropical Pacific.

Also, over the last month, we saw an increase in sub-surface heat content and the growth of a moderate downwelling Kelvin wave. This suggests that there is likely to be a continuing source of warmer-than-average ocean temperatures for the next couple of months, potentially encouraging the continuation of the weak atmospheric coupling.

On the other hand—showing that we are still very close to the borderline—the Tahiti - Darwin SOI, another indicator of ENSO (though farther off the equator compared to the EQSOI), was +0.2 for February. Also, the “near average” rainfall in the central Pacific combined with above-average rainfall in the western Pacific is not a strong indication of El Niño conditions. As we’ve discussed before, a strong signal would be above-average rainfall in the central and eastern Pacific, and below-average rainfall to the west.

Going forward, we will need to continue to monitor whether pressure and rainfall across the equatorial Pacific remain consistent with El Niño conditions.



What’s to come?

The CPC/IRI consensus forecast calls for an approximately 50-60% chance that El Niño conditions will continue through the spring. In the ocean-atmosphere coupling indicative of El Niño, warmer waters lead to atmospheric changes, and those atmospheric changes in turn help maintain the warmer water. So, it’s possible that even the weak coupling we’re seeing now will support the continuation of the positive SST anomalies. As I mentioned above, the recent westerly wind anomalies and the downwelling Kelvin wave will also help to keep the SSTs above average for the next few months.

Dynamical climate models are mostly forecasting a slow increase in the Niño3.4-region SST anomalies throughout 2015. Springtime is a difficult time of year for forecasting, as models traditionally have some difficulty seeing beyond the so-called “spring barrier,” and so the CPC/IRI consensus forecast probabilities decrease somewhat going into the summer, as forecast confidence decreases. That said, probabilities remain at or above 50% that El Niño conditions will continue through the fall.

After twelve months of El Niño Watches, we are issuing an El Niño Advisory. However, what it really represents is an incremental crossing of the borderline. If we follow the “Is it El Niño Conditions” flowchart, the warmer SST conditions, our anticipation that they will continue for the next several seasons, and signs of weak atmospheric coupling over the past month, mean we arrive at “yes!” From an impacts perspective, this is not particularly momentous, as El Niño impacts are weak in the spring and summer. Still, after months of hovering under the threshold, we can now say that El Nino conditions have arrived.

http://www.climate.gov/news-features/bl ... 3%B1o-here

[wxman57]

Average SSTs in the Nino 3.4 region have been .5C or greater above normal since September. To declare an El Nino, the 3-month average values must be .5C or greater for 5 consecutive cycles. So far, we have SON, OND, NDJ, DJF, which is 4 cycles of 3-month averages at or above .5C compared to normal. Jan-Feb-March needs to average .5C above average or more to be official. Given the current value of +.6C, that appears likely.