HIGHLIGHT:  The seasonal mean NINO3.4 anomaly was -0.50 for AMJ2011, down from MAM.  La Nina has weakened to the point of the present state being neutral, not unusual for the season of course.

The CA method, acting on global AMJ2011 seasonal means as latest input, has most of its members on the cold side of neutral.  La Nina conditions, but weaker and only in a few members, are expected by CA for rest 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 into positive territory by early spring 2012. Spread is high and peculiar with some members that go warmest first and end coldest (and vice versa), see graphic sst1.gif

Weights have changed only modestly. There are nine years with high +ve weight!, and eight high -ve weight. OCN flavor is much reduced, with more +ve weight given to older years than ever before and a high –ve weight to 2004. Also note the string of negative weights for 1985 to 1995, a strong sign of interdecadal variation.

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 MJJ2010 thru AMJ2011). 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 June 2011.

Year

IP

Wgt

Year

IP

Wgt

Year

IP

Wgt

Year

IP

Wgt

Year

IP

Wgt

Year

IP

Weigt

1956

xx

0

1966

xx

-8

1976

xx

 11

1986

xx

-10

1996

xx

13

2006

xx

 11

1957

xx

-4

1967

xx

 2

1977

xx

-7

1987

xx

-10

1997

xx

 3

2007

xx

-2

1958

xx

-5

1968

xx

-10

1978

xx

 4

1988

xx

-8

1998

xx

-6

2008

xx

15

1959

xx

-6

1969

xx

 8

1979

xx

 4

1989

xx

 3

1999

xx

 3

2009

xx

  9

1960

xx

-16

1970

xx

 6

1980

xx

 1

1990

xx

 0

2000

xx

11

2010

xx

12

1961

xx

-4

1971

xx

 6

1981

xx

 6

1991

xx

-4

2001

xx

-7

2011

xx

NA

1962

xx

 12

1972

xx

 1

1982

xx

 2

1992

xx

-14

2002

xx

 3

xx

Xx

1963

xx

 13

1973

xx

-5

1983

xx

 3

1993

xx

-8

2003

xx

-9

xx

Xx

1964

xx

-8

1974

xx

16

1984

xx

-2

1994

xx

-15

2004

xx

-10

xx

Xx

1965

xx

-10

1975

xx

 3

1985

xx

-5

1995

xx

-7

2005

xx

 5

xx

Xx

 

Weights are high +ve (>+0.10) for 2010,2008,2006,2000,1996,1976,1974,1963,1962. Weights are high -ve (< - 0.10) for 2004,1994,1992,1987,1986,1968,1966,1960.

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

-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

One month 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

Two 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

Three months ago:

-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

Four months 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

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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