ENSO Updates (2007 thru 2023)

[cycloneye]

Notice the dip to La Nina threshold once again in the CFS long range forecast,after it is at Neutral thru the Summer.



ECMWF as well has the long range not going up from Neutral in the Summer,and hints the same as CFS.

[cycloneye]

There are more signs that La Nina has reached it's peak,and now is slowly fading.The question is,how fast La Nina weakens and turns Neutral.Here is the SOI (Southern Occilation Index) that is still very high in positive territory,but compared to the first days of the year,when it was at 26+,it has trended slowly down.

On January 3



On Febuary 12

[cycloneye]

Here are graphics from January 12 to Febuary 12 that show well how La Nina has faded in that period.In fact,the Eastern Equatorial Pacific has warmed faster than the other areas to the west.

January 12



Febuary 12

[Migle]

So, let's say the La Nina starts rapidly fading and we go to Neutral before the start of the summer. Is there a chance we could go to El Nino by October?

[cycloneye]

Climate Prediction Center 2/14/11 update

La Nina continues to weaken and at this update,is up to -1.2C from -1.7C that was two weeks ago.

Two Weeks Ago Update

Niño 4= -1.3ºC
Niño 3.4= -1.7ºC
Niño 3= -1.4ºC
Niño1+2= 0.0ºC


This Week Update

Niño 4= -1.2ºC
Niño 3.4= -1.2ºC
Niño 3= -0.8ºC
Niño1+2= +0.2ºC

http://www.cpc.ncep.noaa.gov/products/a ... ts-web.pdf

[Macrocane]

So, let's say the La Nina starts rapidly fading and we go to Neutral before the start of the summer. Is there a chance we could go to El Nino by October?

I don't think so, that would be a rare occurance, in the last 60 years there has been only one ocassion that had El Niño then La Niña and then El Niño again, that was in 1963-1964-1965. I think that we could see a weak La Niña or Neutral conditions by the time of the hurricane season.

[cycloneye]

Here is Dr Jeff Masters discussion of what is going on with ENSO and what may occur in the comming months.

Posted by: JeffMasters, 4:03 PM GMT en Febuary 15, 2011
A significant shift is occurring in the Equatorial waters of the Eastern Pacific off the coast of South America, where the tell-tale signs of the end to the current La Niña event are beginning to show up. A borderline moderate/strong La Niña event has been underway since last summer, with sea surface temperatures (SSTs) about 1.5°C below average over a wide stretch of the Equatorial Pacific. These cool SSTs have altered the course of the jet stream and have had major impacts on the global atmosphere. The La Niña has been partially responsible for some of the extreme flooding events in recent months, such as the floods in Australia, Sri Lanka, and Colombia. La Niña is also largely to blame for the expanding drought over the southern states of the U.S. But in the last few weeks, SSTs in the Equatorial Pacific have undergone a modest warm-up, and these temperatures are now about 1.2°C below average. A region of above-average warmth has appeared immediately adjacent to the coast of South America--often a harbinger of the end to a La Niña event. An animation of SSTs since late November shows this developing warm tongue nicely. Springtime is the most common time for a La Niña event to end; since 1950, half of all La Niñas ended in March, April, or May. The weakness displayed by the current La Niña event has prompted NOAA's Climate Predictions Center to give a 50% chance that La Niña will be gone by June. If La Niña does rapidly wane, this should help reduce the chances for a continuation of the period of high-impact floods and droughts that have the affected the world in recent months.



What does this mean for hurricane season?

As many of you know, the phase of the El Niño/La Niña is critical for determining how active the Atlantic hurricane season is. La Niña or neutral conditions promote very active Atlantic hurricane seasons, while El Niños sharply reduce Atlantic hurricane activity, by increasing wind shear. Will the probable demise of La Niña this spring allow an El Niño to take its place by this fall? Well, don't get your hopes up. Since 1950, NOAA's Climate Prediction Center records that there have been sixteen La Niña events during February (26% of all years.) In half of those years, La Niña was still active during the August - September - October peak of Atlantic hurricane season, six (38%) transitioned to neutral conditions, and only two (12%) made it all the way to El Niño. So historically, the odds do not favor a transition to El Niño by hurricane season. The latest set of computer model forecasts of El Niño/La Niña (Figure 2) also reflect this. Only two of the sixteen models predict El Niño conditions by hurricane season.

[cycloneye]

Australian 2/16/11 Update

They are on the same page as Climate Prediction Center and that is ,La Nina weakens towards Neutral ENSO by the Summer.Also,they hint that La Nina may reform by the fall.

La Niña event now passed its peak
Issued on Wednesday 16 February 2011 | Product Code IDCKGEWWOO

The La Niña event which has dominated the Australian climate for the past nine months is showing signs of weakening. Pacific Ocean temperatures, most notably below the surface, have warmed, while atmospheric indicators such as the Southern Oscillation Index (SOI), trade winds and cloud patterns have eased from their respective peaks in early January.

These observations are consistent with both the life cycle of past La Niña events and long-range climate models, which show the Pacific gradually warming during the southern autumn of 2011. All available climate models suggest further weakening of the La Niña is likely through autumn, with most indicating a return to neutral conditions by winter 2011. However, there remains some risk that the event may reform after autumn.

http://www.bom.gov.au/climate/enso/

[cycloneye]

ENSO Models Febuary Update

Compared to January,the number of models going to Neutral and then up to El Nino has increased somewhat.But,the majority of them stay in Neutral status thru the Summer and fall.

January



Febuary



Uploaded by imageshack.us

http://iri.columbia.edu/climate/ENSO/cu ... table.html

Current Conditions
As of mid-February 2011, SSTs indicate moderate strength La Niña conditions in the central and eastern equatorial Pacific. For January the SST anomaly in the NINO3.4 region was -1.65 C, indicative of moderate to strong La Niña conditions, and for the November-January season the anomaly was -1.62 C. Currently the IRI's definition of El Niño conditions rests on an index of SST anomalies, averaged over the NINO3.4 region (5S-5N; 170W-120W), exceeding the warmest 25%-ile of the historical distribution, and similarly for La Niña relative to the 25%-ile coldest conditions in the historical distribution. The NINO3.4 anomaly necessary to qualify as La Niña or El Niño conditions for the Feb-Mar-Apr and the Mar-Apr-May seasons are approximately (-0.45C, 0.40) and (-0.40, 0.40), respectively.


Expected Conditions
The most recent weekly SST anomaly in the NINO3.4 region is -1.2 C, indicating moderate La Niña conditions in the tropical Pacific; this is slightly weaker than the -1.65 C level observed in January. What is the outlook for the ENSO status going forward? February is a time of the year during which the observed ENSO state is often beginning to move toward weaker anomaly values, particularly if an ENSO episode has been occurring. One might ask whether the current La Niña condition should therefore be expected to weaken, and if so, at what rate. In the current case, negative subsurface sea temperature anomalies have continued to occupy the central and eastern equatorial Pacific, but have been pushed farther east and have weakened somewhat in the last one month as the event has also been starting to weaken at the sea surface. Sea temperature anomalies below the surface often portend SST anomalies to be expected in the following few months, as they are subject to the climatological upwelling in the eastern part of the basin. Current low-level wind anomalies still indicate enhanced trades in the western and west-central tropical Pacific, but somewhat more weakly than up to one month ago. The traditional and equatorial SOI indices remain well above their average, indicating that the atmospheric component of the event is still quite robust. The SOI and the enhanced trade winds imply above-average upwelling activity in the eastern tropical Pacific, at least for the very near term, and suggest that the still negative subsurface sea temperature anomalies will likely continue to find their way to the surface during the coming month or two. The continued surfacing of below-average subsurface waters implies a likelihood for short-term continuation of the currently moderate La Niña conditions, although the SST anomaly may continue to weaken as the sub-surface negative heat content weakens against a backdrop of the seasonal cycle of ENSO that suggests a decline in strength at this time of year. Above-average subsurface waters are strengthening in the western tropical Pacific, and have been edging eastward during the last few months. As they continue to expand eastward they may begin to displace the still large volume of below-average water to their east over the course of the coming four months. Whether this positive heat content will eventually surface and induce El Niño conditions later this year is very uncertain, as will be discussed below.

Presently, the models and observations taken together indicate probabilities of approximately 94% for maintaining La Niña conditions, near 6% for returning to ENSO-neutral conditions, and nearly 0% for developing El Niño conditions during the Feb-Apr 2011 season in progress. Probabilities for La Niña decrease to 74% for Mar-May, and to 49% for Apr-Jun. In late northern spring the probabilities for La Niña decline to 34% for May-Jul and to 26% for Jun-Aug and for the following several seasons. Beginning with May-Jul, neutral ENSO conditions are seen as being the most likely, with 50% probability.


The above assessment was made in part on the basis of an examination of the current predictions of ENSO prediction models as well as the observed conditions. For purposes of this discussion, El Niño SST conditions are defined as SSTs in the NINO3.4 region being in the warmest 25% of their climatological distribution for the 3-month period in question over the 1950-present timeframe. The corresponding cutoff in terms of degrees C of SST anomaly varies seasonally, being close to 0.40 degrees C in boreal late-spring to early-summer season and as high as 0.75 degrees C in late boreal autumn. La Niña conditions are defined as NINO3.4 region SSTs being in the coolest 25% of the climatological distribution. Neutral conditions occupy the remaining 50% of the distribution. These definitions were developed such that the most commonly accepted El Niño and La Niña episodes are reproduced.

The models show nearly unanimous agreement regarding the continuation of La Niña conditions for the Feb-Apr season, but vary somewhat in their predicted rate of weakening negative anomalies between Feb-Apr and the forthcoming seasons. Many of the statistical and dynamical models call for the event to decline to neutral sometime between the Mar-May season and the May-Jul season. For the Mar-May season, 83% of the models still indicate at least weak La Niña conditions, and 17% show neutral conditions. By May-Jul, only 35% still show La Niña conditions, 48% neutral, and 17% weak El Niño conditions. At lead times of 4 or more months into the future, statistical and dynamical models that incorporate information about the ocean's observed subsurface thermal structure generally exhibit higher predictive skill than those that do not. Among models that do use subsurface temperature information, 7 of 16 (44%) predict ENSO-neutral SSTs for the Jun-Aug seasons, 5 of 16 (31%) predict La Niña conditions, and 4 of 16 (25%) predict El Niño conditions. (Note 1). (Note that La Niña conditions for Jun-Aug require a NINO3.4 SST anomaly of -0.50 or stronger, and El Niño conditions require 0.45 or stronger.) Caution is advised in interpreting the distribution of model predictions as the actual probabilities. At longer leads, the skill of the models degrades, and skill uncertainty must be convolved with the uncertainties from initial conditions and differing model physics, leading to more climatological probabilities in the long-lead ENSO Outlook than might be suggested by the suite of models. Furthermore, the expected skill of one model versus another has not been established using uniform validation procedures, which may cause a difference in the true probability distribution from that taken verbatim from the raw model predictions.

[Ntxw]

I'm no expert on ENSO predictions or anything, but it seems the La Nina is fading out about as quickly as it came in last year. Truly amazing...I wonder if the warming in the 1-2 regions (though slight atm) has any precursors of things to come.

[cycloneye]

I'm no expert on ENSO predictions or anything, but it seems the La Nina is fading out about as quickly as it came in last year. Truly amazing...I wonder if the warming in the 1-2 regions (though slight atm) has any precursors of things to come.

The likely outcome for the summer is Neutral ENSO,based on the trends and the ENSO Models ,but you never know if it warms faster than forecasted and El Nino surprises all of the experts and all of us who follow this on a daily,weekly or monthly basis.

[MGC]

The chance of a near 2 degree C SST swing by the heart of the Atlantic hurricane season in remote IMO....that being said, I am going to use neutral conditions in my upcoming 2011 Atlantic hurricane WAG.....MGC

[Ntxw]

Look at how quickly the 1+2 regions have spiked. Now question is will this be only temporary or is this a harbinger of things? Last year there was a Nino spike in spring right after it cooled before the Nina took control, so one can ever be sure. Neutral does seem best bet according to model trends, but sometimes you just gotta use your eyes .



Uploaded with ImageShack.us



Uploaded with ImageShack.us

[cycloneye]

Below are the tao anomalie graphics ten days apart,and they show that despite the pushback by the warm waters in the extreme Eastern Pacific,La Nina is mantaining it's grip,if anything,is a little bit cooler at Nino 3 and 3.4 areas.

[Ntxw]

Analogs I found that would be nice to compare is 99-00, 07-08 Ninas which both featured Neutral/Weak Ninas the following winters followed by >=Moderate Ninos 2nd winter after.

[South Texas Storms]

Analogs I found that would be nice to compare is 99-00, 07-08 Ninas which both featured Neutral/Weak Ninas the following winters followed by >=Moderate Ninos 2nd winter after.

So you are saying we could possibly be seeing an el nino event not next winter but the winter after (winter 2012-2013)?

[cycloneye]

Climate Prediction Center 2/28/11 Weekly Update

No big changes in this update as La Nina holds on.

14th of Febuary Update

Niño 4= -1.2ºC
Niño 3.4= -1.2ºC
Niño 3= -0.8ºC
Niño1+2= +0.2ºC


This Week's Update

Niño 4= -1.0ºC
Niño 3.4= -1.2ºC
Niño 3= -0.7ºC
Niño1+2= +0.3ºC


http://www.cpc.ncep.noaa.gov/products/a ... ts-web.pdf

[KWT]

I suspect neutral is looking by far the best call right now, which combined with probably above average temps in the Atlantic which likely means another above average season coming up.

[cycloneye]

Update at 3/2/11 by the Australians

No surprises here.

ENSO Wrap-Up Update

La Niña continues to weaken in the tropical Pacific
Issued on Wednesday 2 March 2011 | Product Code IDCKGEWWOO

The La Niña event in the Pacific Ocean continues to weaken after reaching peak intensity in early January. Pacific Ocean temperatures along the equator, particularly those below the surface, have warmed over the past month. This warming has markedly reduced the strength and volume of the cool water that has been present during the previous nine months. Current observations in the Pacific Ocean are consistent with the breakdown phase of La Niña events. In some contrast, atmospheric indicators of the La Niña, including trade winds, cloudiness and the Southern Oscillation Index (SOI) remain strong, with the February value of the SOI being highest on record for that month. These atmospheric indicators may be expected to weaken over the coming month as the ocean surface warms.

All available climate models suggest further weakening of the La Niña is likely through the southern hemisphere autumn, with a return to neutral conditions by winter 2011. The risk that the event may reform after autumn has reduced.

During La Niña events, tropical cyclone numbers are typically higher than normal during the November to April period, with February and March the peak. The influence of La Niña on Australian rainfall and temperature typically peaks during winter to mid-summer, and then weakens during the following autumn.

The influence of the Indian Ocean Dipole (IOD) on Australian rainfall is limited during the months from December through to April.

[cycloneye]

Climate Prediction Center 3/7/11 Weekly Update

Nino 3.4 cooled slightly from last week's update.

Last Week's Update

Niño 4= -1.0ºC
Niño 3.4= -1.2ºC
Niño 3= -0.7ºC
Niño1+2= +0.3ºC


This Week's Update

Niño 4= -1.0ºC
Niño 3.4= -1.3ºC
Niño 3= -0.8ºC
Niño1+2= -0.5ºC


http://www.cpc.ncep.noaa.gov/products/a ... ts-web.pdf