HIGHLIGHT: The seasonal mean NINO3.4 anomaly was -0.35 for JJA2011, slightly colder than MJJ. Last winter’s La Nina had weakened to the point of the present state being neutral but appears to become colder again.

The CA method, acting on global JJA2011 seasonal means as latest input, has all of its members on the cold side of neutral. La Nina conditions, but weaker and in 10 out 12 members only, are expected by CA to return for the later part of 2011, with a slight increase in coolness towards the end of the year. Thus there could a weak return of La Nina next winter. Some members crawl hesitantly into positive territory by summer 2012. Only one member goes for an El Nino in 2012.

Weights have changed only modestly. There are eight years with high +ve weight!, and nine high -ve weight. OCN flavor is much reduced compared to a few years ago, with more +ve weight given to older years than ever before and a high –ve weight to 2003. Also note, aside from interannual, the strong sign of interdecadal variation, with +ve in the 2000s and around 1970, and –ve around 1990 and early sixties.

Table 1. Inner products (IP; scaled such that the sum of absolute values is 100; not shown) and weights (Wgt multiplied by 100.) of each of the years to construct an analogue to the sequence of 12 consecutive overlapping 3-month periods defined as the base (currently the 12 overlapping seasons string JAS2010 thru JJA2011). Years in the table are labeled by the year of the middle month of the most recent predictor season. Weights for 1956 and 2010 are less (by 50%) because only half the members use these years ("early" members use 1956, "late" members 2010). Data currently thru Aug 2011.

Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Weigt
1956	xx	3	1966	xx	-7	1976	xx	10	1986	xx	-16	1996	xx	5	2006	xx	9
1957	xx	-2	1967	xx	3	1977	xx	-3	1987	xx	-8	1997	xx	-1	2007	xx	3
1958	xx	-10	1968	xx	-12	1978	xx	-2	1988	xx	-3	1998	xx	-6	2008	xx	11
1959	xx	-9	1969	xx	7	1979	xx	7	1989	xx	6	1999	xx	3	2009	xx	8
1960	xx	-14	1970	xx	5	1980	xx	2	1990	xx	2	2000	xx	13	2010	xx	16
1961	xx	-1	1971	xx	8	1981	xx	-3	1991	xx	0	2001	xx	-3	2011	xx	NA
1962	xx	13	1972	xx	4	1982	xx	2	1992	xx	-13	2002	xx	3		xx	Xx
1963	xx	11	1973	xx	-4	1983	xx	3	1993	xx	-5	2003	xx	-17		xx	Xx
1964	xx	2	1974	xx	10	1984	xx	-10	1994	xx	-11	2004	xx	-7		xx	Xx
1965	xx	-8	1975	xx	2	1985	xx	-6	1995	xx	-11	2005	xx	11		xx	Xx

Weights are high +ve (>+0.10) for 2010,2008,2005,2000,1976,1974,1963,1962.

Weights are high -ve (< - 0.10) for 2003,1995,1994,1992,1986,1984,1968,1960,1958.

Ens ave Nino34 anomaly forecasts, for leads -3, -2, -1, 0 etc: in plain numbers (ensemble mean):

-0.35	-0.36	-0.4	-0.48	-0.53	-0.58	-0.61	-0.56	-0.49	-0.41	-0.3	-0.19	-0.15	-0.12	-0.1	-0.02	0.08	0.15	0.2	0.17	0.09
	JAS11		SON		NDJ		JFM		MAM		MJJ		JAS		SON12		NDJ		JFM13
One month ago: -0.31	-0.31	-0.29	-0.26	-0.28	-0.33	-0.38	-0.42	-0.4	-0.37	-0.32	-0.22	-0.14	-0.12	-0.1	-0.04	0.06	0.17	0.25	0.3	0.26
MJJ11		JAS11		SON11		NDJ		JFM		MAM		MJJ		JAS12		SON		NDJ		JFM13

Two months ago:

-0.5	-0.48	-0.38	-0.29	-0.28	-0.31	-0.38	-0.43	-0.47	-0.44	-0.41	-0.33	-0.24	-0.15	-0.07	0.02	0.09	0.19	0.28	0.34	0.38
	MJJ11		JAS		SON		NDJ		JFM12		MAM		MJJ12		JAS		SON		NDJ	2013

Three months ago:

-0.74	-0.69	-0.51	-0.23	-0.16	-0.15	-0.19	-0.27	-0.31	-0.36	-0.35	-0.34	-0.32	-0.32	-0.25	-0.18	-0.07	-0.02	0.01	0.01	0.03
MAM		MJJ11		JAS		SON		NDJ		JFM12		MAM		MJJ		JAS		SON12		NDJ

Four months ago:

-1.02	-0.97	-0.74	-0.45	-0.33	-0.25	-0.26	-0.33	-0.45	-0.48	-0.47	-0.4	-0.34	-0.26	-0.25	-0.18	-0.13	-0.01	0.06	0.11	0.12
	MAM11		MJJ		JAS		SON		NDJ		JFM		MAM12		MJJ		JAS		SON

Anomalies relative to 1981-2010 climo, as of the May 2011 release. Older forecasts (previous to May 2011 release) are relative to 71-2000