El Nino/La Nina Update
“Region 3.4 holding in weak El Nino range”
The SST anomaly value for region 3.4 held steady at 0.7C this past week and indicates we remain in a weak El Nino which has been ongoing since June. Although, I do not show the data here, the latest update shows that all 4 ENSO regions are in a range from 0.7C to 0.9C above normal and this indicates we have a basin-wide weak El Nino event ongoing. For those wondering what the ENSO regions are, here is a link http://www.cpc.noaa.gov/products/analysis_monitoring/ensostuff/nino_regions.shtml
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Week Ending |
Region 3.4 departure from normal |
|
6/3/2009 |
0.3 |
|
6/10/2009 |
0.5 |
|
6/17/2009 |
0.7 |
|
6/24/2009 |
0.9 |
|
7/1/2009 |
0.9 |
|
7/8/2009 |
0.8 |
|
7/15/2009 |
0.9 |
|
7/22/2009 |
0.9 |
|
7/29/2009 |
0.8 |
|
8/5/2009 |
0.8 |
|
8/12/2009 |
0.7 |
|
8/19/2009 |
0.7 |
The subsurface has warmed a bit over the last week as you can see from the two images below. The warm pool has strengthened in the eastern sections and expanded a bit in the central sections of the equatorial Pacific. This adds support to the assertion that this El Nino event is not going to fall apart anytime soon. The trade winds are remaining light we are seeing stronger westerly anomalies showing up just east of the dateline, this could be a sign that a more typical El Nino trade wind configuration is beginning to set up. The SOI has been negative the last 6 days and is around -5 for a 30 day average. All this means that we are in a weak El Nino and that this El Nino will likely last into the cool season.
August 16th Subsurface Temperatures August 22nd Subsurface Temperatures
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I have attached below the latest model forecasts for region 3.4. The thing to take from this graphic is that most of the models strengthen our El Nino into a moderate event peaking in the Fall, in the 1.2 to 1.4 range, and then slowly weaken it through the winter. So a good El Nino analog for the coming fall and winter would be one that became weak in the summer, peaked in a moderate phase in the fall, and then weakened but maintained an El Nino status through the winter. Some years that come to mind that fit this bill are 2006-07 (although this event is stronger than that one), perhaps 2002-03 (it peaked in the strong range in November, perhaps stronger than what this event will do), 1965-66 (although it was also a bit stronger than this event may end up being), and 1963-64.
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Again, if you have questions about ENSO phase please ask questions or check out this link which explains the process further http://www.cdc.noaa.gov/enso/
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