Australians Update of ENSO=High chance of el nino

[cycloneye]

CURRENT STATUS as at 6th April 2005:
Next update expected by 20th April 2005 (two weeks after this update).

Summary - Some Indicators Ease, but Conditions Remain Delicately Balanced.

After strong signals were observed in a number of El Niño indicators during February, March brought a general easing of conditions in the tropical Pacific atmosphere and, to a lesser extent, ocean surface temperatures. The change in the atmosphere was highlighted by a rapid rise in the Southern Oscillation Index to near zero (+3 on April 4), suggesting the strong negative February value (the lowest value since February 1983) may have been related in part to strong Tropical Cyclone activity in the South Pacific rather than an extreme background climate state (El Niño events are normally associated with sustained large negative values). Likewise, Trade Winds returned to near normal late in the month. Central equatorial Pacific Ocean surface temperatures cooled briefly, but have again warmed (to around +0.5°C above normal) as warm sub surface waters reached the surface. Likewise temperatures below the surface of the equatorial Pacific remain abnormally warm (> 4°C above normal). The subsurface temperatures are seen as critical to any further developments and hence are being monitored closely.

Despite the moderating of some indicators, the chance of a basin-wide El Niño occurring later this year remains higher than normal. Currently the tropical Pacific Ocean surface around the dateline remains warmer than average, subsurface waters in the central and eastern Pacific are warm, and the potential for a weakening or reversal of the Trade Winds over the coming weeks is real as it is likely that strong convection will move into the Pacific region from the west. As the southern hemisphere autumn is the critical time for El Niño development, any further changes in the tropical Pacific ocean temperatures or atmosphere will be monitored closely.

Historical data and the latest information indicate that:
The subsurface warmth in the central Pacific is progressively shifting east, and should reach South America later this month. This movement is called a "Kelvin wave". The current Kelvin Wave is the strongest observed for the past 2 years.
Surface temperatures in the eastern to central Pacific are likely to rise further in response to the arrival of the Kelvin wave.
The recent westerly wind burst and its associated strong subsurface warming have not been included in the initial conditions of several international computer models. The Bureau of Meteorology's POAMA model has included these, and it has listed the chance of Pacific ocean warming above El Niño thresholds during the late southern winter and spring 2004 to above 50%, which is around double the long-term average for this time of year.

There remains uncertainty about:

Model skill - March to June is known as the "predictability" barrier and model skill is at its lowest predicting across this span of months.
The intensity and duration of the surface warming in the eastern to central Pacific in response to the Kelvin wave, and whether this warming will force the atmosphere (i.e., lower the SOI/increase high cloud) or remain for long enough to be enhanced by any further Kelvin Waves.
The strength and impact of follow-up westerly wind bursts during autumn - the chances of an El Niño event occurring this year will be raised significantly if there are significant westerly wind bursts (which may trigger further Kelvin Waves) in the next few months.

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


My Take=However they dont go that far to indicate 100% that el nino will develop.SOI has risen in the last couple of weeks and the Aussies see some uncertaintys.In other words it is not a stone that El Nino will develop however if more Kelvin Waves like the present one move eastward then there will be a very high chance of El Nino to be around by Summer and Fall.

[Matt-hurricanewatcher]

If so El nino are a dime a dozen


Also when are we going to have another big one?

[cycloneye]

Now let's see what the American side says about ENSO when tommorow they will issue the April Update.Let's see if NOAA talks the same language as the Aussies and take into account that Kelvin Wave.At link below is the March Update from NOAA.

http://www.cpc.ncep.noaa.gov/products/a ... _advisory/

[vbhoutex]

If it happens as the Aussie's allude it could it still sounds like it will be too late to affect our season very much, unless I am reading their timing incorrectly. Will definitely be interested to see what the US comes out with. If indeed it does develop or begin to develop I may have to lower my season numbers.

[cycloneye]

If it happens as the Aussie's allude it could it still sounds like it will be too late to affect our season very much, unless I am reading their timing incorrectly. Will definitely be interested to see what the US comes out with. If indeed it does develop or begin to develop I may have to lower my season numbers.

Yes David the timing is very important about this to see how much impact if an El Nino comes the peak of the season will have.

[weatherwindow]

in an earlier post...i had asked the board wheter or not the typical evolution of a warm episode, ie, the warming of el nino areas 3 and 4 and the subsequent warming of areas 1 and 2, was necessary condition prior to a phase change to a cool episode....it was not replied to. can anyone shed some light on this?...if the aussie scenario verifies, areas 1 and 2 may finally warm to "complete"the warm episode. it seemed strange to me that, despite reasonable warming in the central pacific since last summer, the eastern pacific remained cool....didnt resemble any previous warm episode that i was familiar with......rich

[HurricaneBill]

If so El nino are a dime a dozen


Also when are we going to have another big one?

I read somewhere the next big El Nino is expected between 2010-2013. I don't know if this is true or not.

[cycloneye]

In 2002 there was an el Nino (moderate) and el Nino 1-2 area was not warmer than el Nino 3-4.To have a true moderate to strong El Nino it has to be over +4 Celsius in all the areas,el Nino 1-2 west of Southamerica,el Nino 3 in the eastcentral pacific and el Nino 4 area west of 150w.For Pacific SST, an anomaly in the range of 1.5 to 3.5 degrees Celsius would be considered characteristic of an El Niño; the warmer and more widespread the water, the stronger the El Niño.

Is that what you wanted to know about.?

[weatherwindow]

luis.....thanks for the info. ...just one more question....is the warming normally sequential ie, 4-3-2-1?......or is it more random?,.......rich

[MWatkins]

luis.....thanks for the info. ...just one more question....is the warming normally sequential ie, 4-3-2-1?......or is it more random?,.......rich

Hey Rich,

For what it's worth...I believe each event is different. For example, in the 1997 event the trades reversed from east to west and the warming really started in the east then spread back to the west over time.

I believe the 1983 event was similar. I'd have to go back and look at the others...but I believe each event has it's own identity.

MW

[Matt-hurricanewatcher]

IF El nino comes pocking its head out again. It better be a huge one like biggest of the last 500 years. If not I don't went Mr.EL NINO!!!