HIGHLIGHT: The seasonal mean NINO3.4 anomaly was -1.54 for NDJ2010/11, essentially unchanged from OND. La Nina has been “peaking” for several months and is borderline strong.

The CA method, acting on global NDJ2010 seasonal means as latest input forecasts the 3 mo running mean anomaly for Nino34, has 100% of its members in or above strong La Nina territory thru JFM. La Nina conditions, weaker, are expected by CA for the indefinite future. This is a change from just 2 months ago when a change into positive territory was predicted for summer 2011.

Weights have developed more than usual from last month. There are nine years with high +ve weight!, and five high -ve weight. OCN flavor is present: many +ve weights in recent years, but continuing high +ve weights for around 1970 also point to interdecadal variation. Still, the high –ve weights are older than the high +ve weights.

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 DJF2009/10 thru NDJ2010/11). Years in the table are labeled by the year of the middle month of the most recent predictor season. Weights for 1956 and 2009 are less (by 50%) because only half the members use these years ("early" members use 1956, "late" members 2009). Data currently thru Jan 2011. Expect changes next month when one full year is added.

Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Weigt
1956	xx	-3	1966	xx	4	1976	xx	-12	1986	xx	-16	1996	xx	14	2006	xx	12
1957	xx	-3	1967	xx	-6	1977	xx	8	1987	xx	-1	1997	xx	1	2007	xx	20
1958	xx	-3	1968	xx	-2	1978	xx	-1	1988	xx	13	1998	xx	9	2008	xx	8
1959	xx	-5	1969	xx	12	1979	xx	-1	1989	xx	-3	1999	xx	12	2009	xx	7
1960	xx	-4	1970	xx	18	1980	xx	6	1990	xx	6	2000	xx	-13	2010	xx	NA
1961	xx	1	1971	xx	-3	1981	xx	3	1991	xx	-5	2001	xx	7		xx	Xx
1962	xx	4	1972	xx	-2	1982	xx	-8	1992	xx	-4	2002	xx	2		xx	Xx
1963	xx	2	1973	xx	17	1983	xx	-2	1993	xx	-8	2003	xx	1		xx	Xx
1964	xx	-7	1974	xx	-2	1984	xx	-15	1994	xx	-4	2004	xx	1		xx	Xx
1965	xx	-11	1975	xx	10	1985	xx	-6	1995	xx	6	2005	xx	-4		xx	Xx

Weights are high +ve (>+0.10) for 2007, 2006,1999,1996,1988,1975,1973,1970,1969. Weights are high -ve (< - 0.10) for 2000,1986,1984,1976,1965.

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

-1.54	-1.62	-1.66	-1.39	-1.07	-0.83	-0.67	-0.6	-0.57	-0.59	-0.62	-0.69	-0.68	-0.5	-0.36	-0.21	-0.02	0.08	0.17	0.2	0.27
NDJ		JFM		MAM11		MJJ		JAS		SON		NDJ		JFM12		MAM		MJJ		JAS
One month ago: -1.54	-1.67	-1.86	-1.88	-1.47	-1.07	-0.78	-0.54	-0.38	-0.24	-0.19	-0.14	-0.16	-0.07	-0.07	-0.06	-0.02	0.11	0.23	0.33	0.36
	NDJ		JFM11		MAM		MJJ		JAS		SON11		NDJ		JFM12		MAM		MJJ

Two months ago:

-1.58	-1.67	-1.91	-2.12	-1.91	-1.42	-0.94	-0.55	-0.23	0	0.2	0.32	0.45	0.56	0.61	0.56	0.5	0.41	0.39	0.38	0.38
SON10		NDJ		JFM11		MAM		MJJ		JAS		SON11		NDJ		DJF12		FMA		AMJ12

Three months ago

-1.44	-1.51	-1.75	-2.09	-2.06	-1.79	-1.26	-0.75	-0.34	-0.04	0.17	0.34	0.48	0.62	0.7	0.73	0.67	0.56	0.45	0.43	0.44
	SON		NDJ		JFM11		MAM		MJJ		JAS11		SON		NDJ		JFM12		MAM

Four months ago

-1.17	-1.25	-1.49	-1.88	-2.03	-1.98	-1.71	-1.19	-0.7	-0.3	-0.03	0.14	0.27	0.38	0.51	0.59	0.6	0.54	0.43	0.37	0.38
JAS		SON		NDJ		JFM11		MAM		MJJ		JAS		SON11		NDJ		JFM12		MAM

Anomalies relative to 1971-2000 climo.