HIGHLIGHT: The seasonal mean NINO3.4 anomaly was positive at 0.62 C for DJF2014/15, almost unchanged from NDJ, and the fourth running 3-month mean > = 0.5C.
The CA method, acting on global DJF2014/15 seasonal means as latest input, but using a string of global SST going back one year, has all of its members staying positive until JJA 2015. By that time most members will have fallen below 0.5C. The ensemble mean has already peaked at about 0.75 in NDJ2014/15. So much for a very weak warm event in winter 2014/15 in terms of Nino34 SST. CA-SST is rather non-committal about what might happen later in 2015, but if anything slightly +ve. A few members go >= 0.50 later in the year. No members indicate La Nina.
Weights were stable from last month. There are 6 (6) large +ve (-ve) weights in excess of abs(0.10). Four years in the 1956-1965 decade have unusually high weights (like 1959 +0.16 and 1965 -0.19) – this old decade has only recently become so important in constructing the analogue. Moreover, 1958, 1959 and 1960 are ALL strongly positive, so in addition to interannual, the interdecadal plays a big role here.
Announcement: As of this month the covariance matrix has been upped by one. This could lead, potentially, to rather big changes to weights assigned to individual years. But that did not happen. If weights were unchanged they moved forward into the next year, given conventions etc.
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 JFM2014 thru DJF2015). Years in the table are labeled by the year of the middle month of the most recent predictor season. Weights for 1956 and 2014 are less (by 50%) because only half the members use these years ("early" members use 1956, "late" members 2014). Data currently thru Feb 2015. This month the year 2014 has, for the first time, a weight in this table.
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Weigt |
1956 |
xx |
-7 |
1966 |
xx |
-11 |
1976 |
Xx |
-2 |
1986 |
xx |
4 |
1996 |
xx |
5 |
2006 |
xx |
8 |
1957 |
xx |
-6 |
1967 |
xx |
-4 |
1977 |
Xx |
7 |
1987 |
xx |
7 |
1997 |
xx |
5 |
2007 |
xx |
-5 |
1958 |
xx |
15 |
1968 |
xx |
4 |
1978 |
Xx |
4 |
1988 |
xx |
-12 |
1998 |
xx |
-4 |
2008 |
xx |
4 |
1959 |
xx |
16 |
1969 |
xx |
-8 |
1979 |
Xx |
-8 |
1989 |
xx |
-10 |
1999 |
xx |
-6 |
2009 |
xx |
-3 |
1960 |
xx |
14 |
1970 |
xx |
-3 |
1980 |
Xx |
6 |
1990 |
xx |
-2 |
2000 |
xx |
-15 |
2010 |
xx |
10 |
1961 |
xx |
-4 |
1971 |
xx |
1 |
1981 |
Xx |
1 |
1991 |
xx |
5 |
2001 |
xx |
1 |
2011 |
xx |
4 |
1962 |
xx |
3 |
1972 |
xx |
-14 |
1982 |
Xx |
-5 |
1992 |
xx |
0 |
2002 |
xx |
1 |
2012 |
xx |
13 |
1963 |
xx |
3 |
1973 |
xx |
1 |
1983 |
xx |
-2 |
1993 |
xx |
2 |
2003 |
xx |
9 |
2013 |
xx |
8 |
1964 |
xx |
-6 |
1974 |
xx |
-1 |
1984 |
Xx |
3 |
1994 |
xx |
6 |
2004 |
xx |
3 |
2014 |
xx |
13 |
1965 |
xx |
-17 |
1975 |
xx |
8 |
1985 |
Xx |
-8 |
1995 |
xx |
0 |
2005 |
xx |
0 |
2015 |
xx |
NA |
Weights are high +ve (>+0.10) for 2014,2012,2010,1960,1959,1958
Weights are high -ve (< - 0.10) for 2000,1989,1988,1972,1966,1965
Ens ave Nino34 anomaly forecasts, for leads -3, -2, -1, 0 etc: in plain numbers (ensemble mean):
0.62 |
0.58 |
0.46 |
0.35 |
0.33 |
0.34 |
0.3 |
0.2 |
0.18 |
0.26 |
0.35 |
0.35 |
0.25 |
0.27 |
0.25 |
0.25 |
0.24 |
0.19 |
0.17 |
0.24 |
0.27 |
JFM15 |
MAM |
MJJ |
JAS |
SON15 |
NDJ |
JFM16 |
MAM |
MJJ |
JAS |
One month ago:
0.76 |
0.72 |
0.59 |
0.34 |
0.28 |
0.23 |
0.22 |
0.19 |
0.12 |
0.09 |
0.14 |
0.19 |
0.17 |
0.05 |
-0.04 |
0 |
0.08 |
0.12 |
0.12 |
0.11 |
0.18 |
NDJ |
JFM15 |
MAM |
MJJ |
JAS |
SON15 |
NDJ |
JFM16 |
MAM |
MJJ |
JAS |
Two months ago:
0.75 |
0.77 |
0.68 |
0.5 |
0.32 |
0.25 |
0.19 |
0.19 |
0.17 |
0.15 |
0.13 |
0.21 |
0.25 |
0.14 |
-0.01 |
-0.06 |
0.01 |
0.11 |
0.14 |
0.11 |
0.05 |
NDJ |
JFM15 |
MAM |
MJJ |
JAS |
SON15 |
NDJ |
JFM16 |
MAM |
MJJ |
Three months ago
0.6 |
0.66 |
0.78 |
0.76 |
0.63 |
0.46 |
0.38 |
0.29 |
0.25 |
0.17 |
0.17 |
0.18 |
0.25 |
0.25 |
0.19 |
0.07 |
0.02 |
0.09 |
0.16 |
0.12 |
-0.02 |
SON |
NDJ |
JFM15 |
MAM |
MJJ |
JAS |
SON15 |
NDJ |
JFM16 |
MAM |
MJJ |
Four months ago:
0.35 |
0.41 |
0.63 |
0.92 |
0.88 |
0.8 |
0.65 |
0.58 |
0.45 |
0.35 |
0.19 |
0.14 |
0.13 |
0.21 |
0.31 |
0.29 |
0.2 |
0.14 |
0.19 |
0.25 |
0.2 |
SON |
NDJ |
JFM15 |
MAM |
MJJ |
JAS |
SON15 |
NDJ |
JFM16 |
MAM |
Anomalies relative to 1981-2010 climo.