ENSO Updates (2007 thru 2023)

[Ed Mahmoud]

Maybe not, but the speed of the demise of the cold phase means an El Niño could develop more quickly than expected.



1997 was supposed to be neutral during hurricane season.

[cycloneye]

Lets not forget that Neutral ENSO has seen active seasons and U.S Landfalls,the last one 2005.I am not saying that 2008 will be like 2005 but in a general way,seasons with Neutral conditions are active.

[boca]

I wonder if someone could bring uppast seasons of La Nina's transtioning into El Nino's within a years time span. I always thought that it takes a couple of years for the conditions to change.

[RL3AO]

Looks like a repeat of 1999 almost. A pretty strong La Nina in Dec-Jan-Feb (-1.5 in 1999 and 2008) weakens fairly quickly to -0.8 by Mar-Apr-May. It re-strengthened to a moderate La Nina by the peak of the 1999 season.

So is this why Bastardi is using 1999 as an analog season?

[RL3AO]

I wonder if someone could bring uppast seasons of La Nina's transtioning into El Nino's within a years time span. I always thought that it takes a couple of years for the conditions to change.

1976 went from -1.6 in Dec-Jan-Feb to +0.8 in Sep-Oct-Nov. Nothing like 1998 which went from +2.3 to -1.5 in the same calendar year.

[tolakram]

We saw the curve, I posted it somewhere, where the line was heading up at a sharp angle and all the models insisted on taking a right turn and continuing la nina for a while.

Some of these model plots are still obviously wrong. Look at the actual line vs projected.







Hard to imagine that we won't be in a mild el nino event soon, but what do I know.

[cycloneye]

Its easy to see how the cool waters haved faded in the past 3 months by looking at this graphic.

[littlevince]

Has anyone noticed this ?

La Nina and Pacific Decadal Oscillation Cool the Pacific

A cool-water anomaly known as La Niña occupied the tropical Pacific Ocean throughout 2007 and early 2008. In April 2008, scientists at NASA’s Jet Propulsion Laboratory announced that while the La Niña was weakening, the Pacific Decadal Oscillation—a larger-scale, slower-cycling ocean pattern—had shifted to its cool phase.




...
Unlike El Niño and La Niña, which may occur every 3 to 7 years and last from 6 to 18 months, the PDO can remain in the same phase for 20 to 30 years. The shift in the PDO can have significant implications for global climate, affecting Pacific and Atlantic hurricane activity, droughts and flooding around the Pacific basin, the productivity of marine ecosystems, and global land temperature patterns. “This multi-year Pacific Decadal Oscillation ‘cool’ trend can intensify La Niña or diminish El Niño impacts around the Pacific basin,” said Bill Patzert, an oceanographer and climatologist at NASA's Jet Propulsion Laboratory, Pasadena, Calif. “The persistence of this large-scale pattern [in 2008] tells us there is much more than an isolated La Niña occurring in the Pacific Ocean.”
...

Source: NASA

[Cyclone1]

It seems to me, and maybe I'm wrong, but neutral years tend to have more TC's while La Nina years tend to carry stronger ones.

Personally, I don't put too much weight into ENSO for forecasting the number of storms, because in many ways it's really about the luck of the draw. 1988 and 1989 was a strong La Nina. Both of those years, tropical wise are quite infamous, with Gilbert and Hugo, but nothing else outstanding occured. 2005 was a neutral year coming out of and going into an El Nino, and it had more storms than 88 and 89 combined including 4 category 5's. (That's why I call 05 an absolute fluke season.) So it seems that while ENSO does have a noticable effect, it's more about localized conditions for each individual storm that determine the season.

Maybe I just stated the obvious, but right now I have nothing better to do.

[Derek Ortt]

2005 was largely la nina at the end of the season. I do not believe that the cool waters lasted at the threshold for a long enough period of time to qualify as a la nina (and 2004 may not have lasted long enough to qualify as el nino... but both seaosns lasted long enough to significantly affect late season TC activity in those two seasons)

[KWT]

Despite the surface temps of the sea rising over the previous 2 months the atmosphere still seems to be in a la nina mode with the GLAAM still low and the easterly trades still going strong for now.

[Ptarmigan]

It seems to me, and maybe I'm wrong, but neutral years tend to have more TC's while La Nina years tend to carry stronger ones.

Personally, I don't put too much weight into ENSO for forecasting the number of storms, because in many ways it's really about the luck of the draw. 1988 and 1989 was a strong La Nina. Both of those years, tropical wise are quite infamous, with Gilbert and Hugo, but nothing else outstanding occured. 2005 was a neutral year coming out of and going into an El Nino, and it had more storms than 88 and 89 combined including 4 category 5's. (That's why I call 05 an absolute fluke season.) So it seems that while ENSO does have a noticable effect, it's more about localized conditions for each individual storm that determine the season.

Maybe I just stated the obvious, but right now I have nothing better to do.

Some Neutral seasons were very active, like 2005, 1995, and 1933. Tell the truth, I think 1933 had more storms than 2005. I always point out that Arctic Oscillation, NAO, AMO, QBO, PDO, PNA, and Aleutian Low plays a role too. I even think Sahel region plays a role since tropical waves originate from that area. A wetter Sahel means more tropical waves. Also, monsoon plays a role too. As for 2005, it was Neutral to weak La Nina.

[Ptarmigan]

2005 was largely la nina at the end of the season. I do not believe that the cool waters lasted at the threshold for a long enough period of time to qualify as a la nina (and 2004 may not have lasted long enough to qualify as el nino... but both seaosns lasted long enough to significantly affect late season TC activity in those two seasons)

Most storms in 2004 formed between August and September. It did have a late start and end.

[KWT]

Interesting I agree with Derek the atmosphere did seem to respond in a El nino way in the autumn of 2004, hence why everything seemed to shut off shop after September. If we had a weak la nina forming we'd have seen another 1969 type season with regards to number of tropical storms at least IMO.

[cycloneye]

La Niña pattern fades; Pacific now generally neutral

Pacific climate patterns are now generally neutral. The 2007/08 La Niña event continued to fade during the past two weeks, with the majority of indicators returning to near-normal levels. Only the western to central Pacific displays any features typical of a La Niña event, with cooler than normal ocean temperatures, enhanced Trade Winds and reduced cloud amounts.

Elsewhere, ocean surface and sub-surface temperatures continued to warm, and as a result, are no longer at levels typical of a La Niña event. Furthermore, the Trade Winds across the eastern half of the Pacific are close-to or weaker than average, and the SOI has continued to retreat from the strong positive values seen earlier in the year and is now in the neutral range. The decline in La Niña has seen below average rainfall return to large parts of eastern and northern Australia during March and April.

Computer model predictions show Pacific temperatures gradually increasing over the next two seasons, but remaining near-average. The models indicate a low chance of either a stronger warming to El Niño levels or a re-intensification of La Niña conditions during 2008.


BoM Latest Update of ENSO



More confirmation to what the update of the ENSO models said yesterday about La Nina gone.Next week Climate Prediction Center will release their May update.Lets see if they are on the same page as the ENSO models and BoM (Aussies) or are alone.

[cycloneye]

The warm anomalies in the Eastern Pacific continue to expand westward.

[cycloneye]

Synopsis: A transition from La Niña to ENSO-neutral conditions is possible during June- July 2008.

La Niña continued to weaken during April 2008, as reflected by changes in sea surface temperatures (SSTs) across the equatorial Pacific Ocean. Negative SST anomalies in the central and east-central equatorial Pacific have weakened, while positive SST anomalies are confined to parts of the eastern equatorial Pacific (Fig. 1). The latest weekly SSTs in the westernmost Niño-4 and Niño-3.4 regions are between 0.6°C and 0.8°C below average, while departures in the easternmost Niño-3 and Niño-1+2 regions are 0°C and -0.3°C respectively (Fig. 2).

Positive subsurface ocean temperatures at thermocline depth have continued to increase in central and east-central equatorial Pacific (Fig. 3). While this increase has resulted in positive heat content anomalies (average temperatures in the upper 300m of the ocean; Fig 4), a shallow layer of negative anomalies in the central Pacific continues to persist between the surface and 100m. Despite these changes, SSTs remain sufficiently cool to maintain the persistent atmospheric anomalies associated with La Niña. Enhanced low-level easterly winds and upper-level westerly winds continued across the central equatorial Pacific, convection remained suppressed throughout the central equatorial Pacific, and enhanced convection covered the far western Pacific. Collectively, these atmospheric and oceanic conditions indicate an ongoing La Niña.

A majority of the recent dynamical and statistical SST forecasts for the Niño 3.4 region indicate La Niña will persist through May-June-July 2008 (Fig. 5). Thereafter, there is considerable spread in the forecasts, with the majority reflecting ENSO-neutral conditions (-0.5 to 0.5 in the Niño-3.4 region) during the second half of the year. However, the spread of the models spans the possibility of a return to La Niña or even an El Niño by the end of 2008. Based on current atmospheric and oceanic conditions and recent trends, a transition from La Niña to ENSO-neutral conditions is possible during June- July 2008.



Climate Prediction Center May Update



Thry are less bullish than what BoM (Aussies) is predicting and that is Neutral conditions now.Instead Climate Prediction Center in its May update says that Neutral ENSO is "possible" in the Equatorial Pacific by July.

[tolakram]

El Nino by fall, I predict all the models are horribly wrong.

[Ed Mahmoud]

El Nino by fall, I predict all the models are horribly wrong.

1997 all over again!

[cycloneye]

Here is the SOI graphic:



Still is above the 0.00 line but falling slowly.