HIGHLIGHT: Normals will change to 1981-2010, starting next month.

The seasonal mean NINO3.4 anomaly was -1.25 for JFM2011, down from DJF (-1.50). La Nina appears to weaken, not unusual for the season of course.

The CA method, acting on global JFM2011 seasonal means as latest input, has 100% of its members in La Nina territory thru AMJ. La Nina conditions, but weaker and some members not making -.5, are expected by CA for rest of 2011. Thus there could a weak La Nina next winter. Some members crawl into positive territory by early spring 2012.

Weights have changed because a) one month ago the matrix size has increased by one, from 53 to 54, and this resets the weights given co-linearity among years, and b) weights (if conserved) have moved into the next year. There are eleven years with high +ve weight!, and seven high -ve weight. OCN flavor is present: many +ve weights in recent years, but continuing high +ve weights for around 1970-74 also point to interdecadal variation. Still, the high –ve weights are generally 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 FMA2010 thru JFM2011). 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 Mar 2011. Note changes because one full year of data was added as of last month.

Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Wgt	Year	IP	Weigt
1956	xx	2	1966	xx	-13	1976	xx	7	1986	xx	-8	1996	xx	14	2006	xx	1
1957	xx	-9	1967	xx	-1	1977	xx	-12	1987	xx	-12	1997	xx	10	2007	xx	1
1958	xx	-4	1968	xx	-7	1978	xx	4	1988	xx	-2	1998	xx	-3	2008	xx	18
1959	xx	-1	1969	xx	4	1979	xx	0	1989	xx	10	1999	xx	3	2009	xx	11
1960	xx	-11	1970	xx	10	1980	xx	-2	1990	xx	-6	2000	xx	11	2010	xx	0
1961	xx	-4	1971	xx	12	1981	xx	4	1991	xx	4	2001	xx	-10	2011	xx	NA
1962	xx	5	1972	xx	-5	1982	xx	1	1992	xx	-6	2002	xx	13		xx	Xx
1963	xx	9	1973	xx	1	1983	xx	2	1993	xx	-9	2003	xx	-5		xx	Xx
1964	xx	-1	1974	xx	20	1984	xx	-1	1994	xx	-13	2004	xx	2		xx	Xx
1965	xx	-7	1975	xx	-7	1985	xx	-10	1995	xx	-7	2005	xx	5		xx	Xx

Weights are high +ve (>+0.10) for 2010,2009,2008, 2002, 2000,1997,1996,1989,1974,1971,1970. Weights are high -ve (< - 0.10) for 2001,1994,1987,1985,1977,1966,1960.

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

-1.26	-1.23	-1.01	-0.64	-0.49	-0.41	-0.36	-0.38	-0.43	-0.54	-0.54	-0.49	-0.36	-0.18	-0.06	-0.02	0.03	0.06	0.18	0.25	0.32
JFM11		MAM			MJJ		JAS		SON11		NDJ		JFM12		MAM		MJJ		JAS

One month ago:

-1.46	-1.49	-1.33	-0.99	-0.78	-0.69	-0.67	-0.65	-0.66	-0.71	-0.79	-0.77	-0.67	-0.47	-0.27	-0.05	0.03	0.09	0.08	0.15	0.2
	JFM11		MAM		MJJ		JAS		SON11		NDJ		JFM12		MAM		MJJ		JAS12

Two months ago:

-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
Three months 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

Four 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

Anomalies relative to 1971-2000 climo. Will be 1981-2010 next month!!!