HIGHLIGHT: The seasonal mean NINO3.4 anomaly was positive at 0.60 C for FMA2015, almost unchanged from JFM.
The CA method, acting on global FMA2015 seasonal means as latest input, but using a string of global SST going back one year, has most of its members, staying >0.5 from now until the end of 2015. By SON 2015 11 out of 12 of the members are >0.50, with 8 out 12 members peaking >1.0 and one member is above 1.5. By NDJ the ensemble mean is above 1.0. A large warm up from last month’s forecast.
Weights were stable from last month, but changed some. There are 3 (6) large +ve (-ve) weights in excess of abs(0.10). So negative analogues play a big role in shaping the forecast. This is unusual. Five years in the 1957-1966 decade have unusually high weights (like 1959 +0.17 and 1965 -0.29) – this old decade has only recently become so important in constructing the analogue. Moreover, 1958, 1959 and 1960 are ALL strongly positive and 1964-1967 all strongly -ve, so in addition to interannual, the interdecadal plays a big role here. Noteworthy is also the high weight for 2014. 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 0.35. 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 stay weak). None of the historically strong warm event (57, 72, 82, 97) have a high +ve weight, also strange.
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 MAM2014 thru FMA2015). 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 Apr 2015.
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Wgt |
Year |
IP |
Weigt |
1956 |
xx |
-6 |
1966 |
xx |
-14 |
1976 |
Xx |
-1 |
1986 |
xx |
6 |
1996 |
xx |
5 |
2006 |
xx |
-1 |
1957 |
xx |
2 |
1967 |
xx |
-6 |
1977 |
Xx |
2 |
1987 |
xx |
-6 |
1997 |
xx |
8 |
2007 |
xx |
-4 |
1958 |
xx |
12 |
1968 |
xx |
0 |
1978 |
Xx |
6 |
1988 |
xx |
-13 |
1998 |
xx |
-3 |
2008 |
xx |
-3 |
1959 |
xx |
17 |
1969 |
xx |
-7 |
1979 |
Xx |
-12 |
1989 |
xx |
-3 |
1999 |
xx |
-5 |
2009 |
xx |
4 |
1960 |
xx |
5 |
1970 |
xx |
-1 |
1980 |
Xx |
9 |
1990 |
xx |
-1 |
2000 |
xx |
-18 |
2010 |
xx |
2 |
1961 |
xx |
-2 |
1971 |
xx |
-3 |
1981 |
Xx |
-1 |
1991 |
xx |
5 |
2001 |
xx |
-8 |
2011 |
xx |
1 |
1962 |
xx |
1 |
1972 |
xx |
0 |
1982 |
Xx |
-1 |
1992 |
xx |
8 |
2002 |
xx |
3 |
2012 |
xx |
9 |
1963 |
xx |
6 |
1973 |
xx |
4 |
1983 |
xx |
-3 |
1993 |
xx |
0 |
2003 |
xx |
15 |
2013 |
xx |
0 |
1964 |
xx |
-10 |
1974 |
xx |
1 |
1984 |
Xx |
1 |
1994 |
xx |
8 |
2004 |
xx |
-1 |
2014 |
xx |
18 |
1965 |
xx |
-20 |
1975 |
xx |
2 |
1985 |
Xx |
-5 |
1995 |
xx |
7 |
2005 |
xx |
4 |
2015 |
xx |
NA |
Weights are high +ve (>+0.10) for 2014, 1959,1958
Weights are high -ve (< - 0.10) for 2000,1988,1979,1966,1965,1964
Ens ave Nino34 anomaly forecasts, for leads -3, -2, -1, 0 etc: in plain numbers (ensemble mean):
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 |
One month 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 |
Two 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 |
Three months 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 |
Four 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 |
Anomalies relative to 1981-2010 climo.