HIGHLIGHT: The seasonal mean NINO3.4 anomaly was -1.54 for OND2010, unchanged from SON. La Nina may be peaking around now and is borderline strong.

The CA method, acting on global OND2010 seasonal means as latest input forecasts the 3 mo running mean anomaly for Nino34, has 100% of its members in strong La Nina territory for the rest of the winter and hovering near –1.9C at the peak in DJF, making it a strong La Nina. La Nina condition are expected by CA thru MJJ2011, followed by weak +ve anomalies later on, but not above +0.5!.

Weights have developed more than usual from last month. CA has corrected itself away from the extreme forecast now that December is not coming in at -2.0C or so, but only -1.5, as have been the last 4 months. It is hard to find the peak in the 2010 La Nina. CA projects it to happen later than usual, like DJF to JFM. There are eight years with high +ve weight!, and four high -ve weight. OCN flavor is present: many +ve weights in recent years, but high +ve weights for around 1970 also point to interdecadal variation. 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 NDJ2009/10 thru OND2010). 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 Dec 2010.

Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Weigt
1956	xx	0	1966	xx	3	1976	xx	-8	1986	xx	-16	1996	xx	12	2006	xx	7
1957	xx	-6	1967	xx	-9	1977	xx	6	1987	xx	2	1997	xx	-3	2007	xx	19
1958	xx	-7	1968	xx	-4	1978	xx	2	1988	xx	9	1998	xx	10	2008	xx	13
1959	xx	-7	1969	xx	11	1979	xx	-1	1989	xx	3	1999	xx	9	2009	xx	5
1960	xx	-1	1970	xx	13	1980	xx	8	1990	xx	2	2000	xx	-8	2010	xx	NA
1961	xx	-2	1971	xx	-4	1981	xx	2	1991	xx	-5	2001	xx	3		xx	Xx
1962	xx	6	1972	xx	-3	1982	xx	-10	1992	xx	-3	2002	xx	9		xx	Xx
1963	xx	1	1973	xx	13	1983	xx	-1	1993	xx	-4	2003	xx	5		xx	Xx
1964	xx	-4	1974	xx	-2	1984	xx	-14	1994	xx	-9	2004	xx	0		xx	Xx
1965	xx	-11	1975	xx	11	1985	xx	-4	1995	xx	5	2005	xx	2		xx	Xx

Weights are high +ve (>+0.10) for 2008, 2007,1998,1996,1975,1973,1970,1969. Weights are high -ve (< - 0.10) for 1986,1984,1982,1965.

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

-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

One month 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

Two 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

Three 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

Four months ago:

-0.83	-0.89	-1.14	-1.53	-1.79	-1.96	-1.94	-1.7	-1.22	-0.76	-0.38	-0.14	0.01	0.14	0.24	0.35	0.39	0.37	0.3	0.2	0.18
	JAS		SON		NDJ		JFM11		MAM		MJJ		JAS		SON11		NDJ		JFM12

Anomalies relative to 1971-2000 climo.