HIGHLIGHT: The seasonal mean NINO3.4 anomaly was positive at 0.96 C for AMJ2015, up from MAM. Impressive numbers for a low variance season.
The CA method, acting on global AMJ2015 seasonal means as latest input, but using a string of global SST going back one year, has all of its members, staying >0.5 from now until AMJ2016. By NDJ 2015 12 out of 12 members are >1.0, with 11 out 12 members >1.5 and six members above +2.0C. By NDJ2015 the ensemble mean is near 2.0. Another large warm up from last month’s forecast. A strong forecast by any standard. Then a significant cool down in 2016.
Weights were very stable from last month, although the subtle changes caused another 0.5C warm up in the forecast. There are 6 (6) large +ve (-ve) weights in excess of abs(0.10). So negative analogues play a big role in shaping the forecast, but less so than a month ago. Five years in the 1957-1966 decade have unusually high weights (like 1959 +0.17 and 1965 -0.20) – this old decade has only recently become so important in constructing the analogue. Moreover, 1964-1966 are all strongly -ve, so in addition to interannual, the interdecadal plays a big role here. Noteworthy is also the high weight for 2014. The last year is used in only 6 of the 12 construction so 0.18 is doubly impressive. In the 6 constructions 2014 was used in, the weight was an unheard of 0.36. The forecast should thus be considered with a warning, namely that the warm event currently shaping up has a chance evolving the same way as last year (and disappoint some). Of the historically strong warm event years (57, 72, 82, 97) the weights are 0.08, -0.06, 0.00 and 0.10 respectively, therefore, as of now the situation has not yet evolved into a classical or canonical warm event.
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 MJJ2014 thru AMJ2015). 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 June 2015.
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Weigt |
1956 |
xx |
-6 |
1966 |
xx |
-10 |
1976 |
Xx |
-1 |
1986 |
xx |
6 |
1996 |
xx |
-4 |
2006 |
xx |
-2 |
1957 |
xx |
8 |
1967 |
xx |
-3 |
1977 |
Xx |
-1 |
1987 |
xx |
-1 |
1997 |
xx |
10 |
2007 |
xx |
-13 |
1958 |
xx |
12 |
1968 |
xx |
1 |
1978 |
Xx |
0 |
1988 |
xx |
-16 |
1998 |
xx |
7 |
2008 |
xx |
3 |
1959 |
xx |
17 |
1969 |
xx |
4 |
1979 |
Xx |
-8 |
1989 |
xx |
-1 |
1999 |
xx |
-5 |
2009 |
xx |
13 |
1960 |
xx |
3 |
1970 |
xx |
-2 |
1980 |
Xx |
4 |
1990 |
xx |
-4 |
2000 |
xx |
-11 |
2010 |
xx |
-2 |
1961 |
xx |
-5 |
1971 |
xx |
-6 |
1981 |
Xx |
4 |
1991 |
xx |
13 |
2001 |
xx |
-4 |
2011 |
xx |
5 |
1962 |
xx |
-3 |
1972 |
xx |
3 |
1982 |
Xx |
0 |
1992 |
xx |
6 |
2002 |
xx |
5 |
2012 |
xx |
-1 |
1963 |
xx |
2 |
1973 |
xx |
0 |
1983 |
xx |
-5 |
1993 |
xx |
1 |
2003 |
xx |
7 |
2013 |
xx |
3 |
1964 |
xx |
-13 |
1974 |
xx |
2 |
1984 |
Xx |
-9 |
1994 |
xx |
9 |
2004 |
xx |
-1 |
2014 |
xx |
18 |
1965 |
xx |
-20 |
1975 |
xx |
1 |
1985 |
Xx |
-1 |
1995 |
xx |
-2 |
2005 |
xx |
-4 |
2015 |
xx |
NA |
Weights are high +ve (>+0.10) for 2014, 2009,1997,1991,1959,1958
Weights are high -ve (< - 0.10) for 2007,2000,1988,1966,1965,1964
Ens ave Nino34 anomaly forecasts, for leads -3, -2, -1, 0 etc: in plain numbers (ensemble mean):
0.96 |
0.95 |
0.94 |
0.93 |
1.12 |
1.47 |
1.88 |
2.05 |
1.97 |
1.7 |
1.36 |
1.04 |
0.64 |
0.1 |
-0.28 |
-0.39 |
-0.43 |
-0.45 |
-0.5 |
-0.48 |
-0.43 |
MJJ |
JAS |
SON2015 |
NDJ |
JFM2016 |
MAM |
MJJ |
JAS |
SON |
NDJ |
One month ago:
0.73 |
0.72 |
0.75 |
0.71 |
0.65 |
0.75 |
1.01 |
1.34 |
1.47 |
1.4 |
1.19 |
0.95 |
0.74 |
0.31 |
-0.03 |
-0.32 |
-0.38 |
-0.42 |
-0.5 |
-0.58 |
-0.57 |
MAM15 |
MJJ |
JAS |
SON15 |
NDJ |
JFM16 |
MAM |
MJJ |
JAS |
SON16 |
NDJ |
Two months ago:
0.6 |
0.57 |
0.57 |
0.59 |
0.53 |
0.44 |
0.5 |
0.71 |
0.96 |
1.05 |
0.98 |
0.83 |
0.7 |
0.56 |
0.33 |
0.11 |
-0.05 |
-0.02 |
-0.03 |
-0.06 |
-0.08 |
MAM |
MJJ |
JAS15 |
SON |
NDJ |
JFM16 |
MAM |
MJJ |
JAS |
SON |
Three months ago:
0.57 |
0.51 |
0.42 |
0.34 |
0.36 |
0.32 |
0.22 |
0.24 |
0.38 |
0.56 |
0.61 |
0.57 |
0.5 |
0.49 |
0.43 |
0.29 |
0.14 |
0.06 |
0.14 |
0.17 |
0.17 |
JFM15 |
MAM |
MJJ |
JAS |
SON |
NDJ |
JFM16 |
MAM |
MJJ |
JAS |
SON |
Four months ago:
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 |
Anomalies relative to 1981-2010 climo.