Come per l'AMO...
Si avvicinano il 1998 (), 1983 e il 1969, ma mai a questi livelli.
E questo segue il mese di aprile, con il secondo valore più alto dall'inizio serie

Codice:
  1948         2010
 1948    -0.17   -0.18    0.26   -0.03   -0.46   -0.20   -1.60   -2.42   -1.81   -2.02   -1.78   -0.28
 1949    -0.13   -0.13   -0.29    0.53   -0.66   -0.60   -1.04   -2.09   -0.81   -1.77   -1.03   -0.32
 1950    -0.17   -0.30   -0.96   -1.93   -2.27   -2.23   -2.12   -2.62   -0.52   -2.14   -0.82   -0.32
 1951    -0.17   -0.30   -0.93   -0.70   -0.93   -0.56   -0.07    2.23    1.50    1.55    1.09    0.01
 1952    -0.07   -0.26   -0.31    0.35    0.24    0.85   -0.16    2.42    2.44    1.73    1.05   -0.05
 1953    -0.17   -0.12    0.57    1.58    0.09    0.48    0.25    1.56    1.30    0.47    1.21   -0.10
 1954    -0.13   -0.29   -0.77   -1.49   -1.29   -1.71   -1.74   -0.79   -0.70   -3.83   -1.95   -0.25
 1955    -0.17   -0.30   -0.87   -2.21   -1.76   -1.89   -1.96   -0.93   -0.65   -0.33    0.62   -0.32
 1956    -0.17   -0.30   -0.61   -1.43   -1.53   -2.49   -1.86   -1.50   -1.97   -1.05   -1.65   -0.23
 1957    -0.17   -0.26    0.12    0.19    0.64    1.35    1.63    2.42    3.15    2.64    1.60    0.34
 1958     0.12    0.19    1.82    1.54    2.42    5.75    2.94    3.55    2.82    1.76    1.18    0.17
 1959     0.19    0.38    0.98    0.83    0.16   -0.07    1.18   -0.48    1.19    0.21    0.23   -0.16
 1960    -0.16   -0.21   -0.63   -0.79    1.13    0.20    0.91    1.45    1.40    1.28    0.84   -0.01
 1961    -0.02    0.04   -0.39   -0.00   -0.25   -0.52   -0.91    0.34   -0.18   -0.39   -0.23   -0.32
 1962    -0.17   -0.19   -0.54   -1.54   -1.39   -0.26    0.92    2.50    1.44    1.47    1.15   -0.23
 1963    -0.17   -0.30   -0.09    0.42   -0.01    0.45   -0.27    2.49    2.04    1.78    1.92   -0.09
 1964    -0.08   -0.14    0.03   -0.45   -1.13   -0.85   -0.46   -1.09   -1.03   -1.43   -1.37   -0.32
 1965    -0.17   -0.30   -0.64    0.18    0.37   -1.63   -0.62   -1.12   -0.57    0.68    0.68    0.32
 1966     0.16    0.06    0.31    0.30   -0.86   -1.19   -0.22    0.44    0.76    0.45    1.14   -0.32
 1967    -0.17   -0.27   -0.78   -1.11   -1.47   -1.93   -1.98   -2.72   -1.34   -0.33   -0.23   -0.29
 1968    -0.17   -0.30   -0.96   -2.59   -2.47   -2.24   -0.93   -0.01    1.24    0.64    0.77   -0.14
 1969    -0.09   -0.01    2.04    2.09    4.28    4.30    4.67    1.95    2.49    1.30    2.01   -0.19
 1970    -0.17   -0.29   -0.73   -0.42   -1.11   -1.08   -1.25   -0.55   -0.24   -0.13   -0.22   -0.32
 1971    -0.17   -0.30   -0.96   -2.57   -2.32   -1.95   -1.54   -2.97   -3.97   -3.38   -1.90   -0.32
 1972    -0.13   -0.30   -0.57    0.33    0.17   -1.40   -0.64   -1.47   -1.21    1.55    0.87    0.63
 1973     0.14    0.05    1.03    0.20   -0.25   -1.07   -0.57   -1.11   -0.72   -1.92   -1.47   -0.29
 1974    -0.17   -0.30   -0.83   -0.78   -1.52   -1.70   -2.79   -3.16   -4.35   -3.61   -1.85   -0.17
 1975    -0.17   -0.30   -0.34   -0.22   -1.21   -1.21   -2.55   -3.60   -3.54   -3.14   -2.11   -0.32
 1976    -0.17   -0.30   -0.87   -1.11   -1.04   -1.76   -2.34   -2.23   -3.42    0.21    0.03   -0.25
 1977    -0.14   -0.16   -0.58   -1.16   -0.94   -1.62   -0.62   -1.98   -1.33   -0.66   -0.50    0.01
 1978    -0.16   -0.22   -0.63   -0.76   -1.03   -0.56   -1.31   -2.03   -2.55   -1.54   -1.31   -0.10
 1979    -0.17   -0.23   -0.73   -0.02   -0.52   -0.81   -0.56   -0.92   -1.81    0.41   -0.37   -0.21
 1980    -0.13   -0.18   -0.59   -0.13    0.95    1.21   -0.01    0.34    1.26    0.22    0.20   -0.16
 1981    -0.17   -0.30   -0.76   -1.21   -0.77   -0.80   -0.76   -0.47    0.83   -0.60    0.13   -0.14
 1982    -0.17   -0.14   -0.37    0.67    0.46   -0.14   -0.46   -1.99   -2.16   -2.27   -1.31    0.45
 1983     1.60    3.17    4.47    3.73    4.13    4.82    3.33    1.88    0.16    0.05   -0.08    0.27
 1984    -0.17   -0.30   -0.52   -0.04   -0.80   -2.62   -3.09   -4.25   -6.13   -5.28   -2.02   -0.32
 1985    -0.17   -0.30   -0.91   -2.40   -1.90   -1.59   -2.28   -2.76   -3.15   -2.93   -1.74   -0.25
 1986    -0.17   -0.30   -0.77   -1.79   -0.98   -1.99   -1.30   -2.28   -1.09   -1.99   -1.44    0.02
 1987    -0.03    0.18    1.76    2.44    2.70    3.12    3.98    5.14    5.41    4.18    3.48    0.70
 1988     0.31   -0.01    0.77   -0.04    0.15   -0.30   -0.39   -0.98   -1.86   -2.31   -1.69   -0.20
 1989    -0.17   -0.30   -0.91   -1.90   -1.29   -1.84   -1.33   -0.96   -2.10   -0.80   -0.50    0.03
 1990    -0.13   -0.12   -0.31    0.66    0.49    0.87    0.62    0.44    2.84    2.67    0.73    0.03
 1991    -0.03   -0.03    0.44    0.96    0.72    1.49    0.89   -0.46   -0.69   -1.36   -1.78   -0.29
 1992    -0.04    0.10    0.55    2.72    1.98    0.96    0.74   -1.30   -0.53    0.54   -0.42    0.08
 1993    -0.14    0.03    0.21    2.19    2.13    0.94    0.47   -0.42    0.19    0.56   -0.54    0.11
 1994    -0.13   -0.22   -0.26    0.54    0.22    0.94    0.94   -0.59    0.25    0.79   -0.29    0.27
 1995     0.04    0.08   -0.10    0.48    0.16    1.58    2.71    3.02    1.63    1.96    0.79   -0.03
 1996    -0.17   -0.25   -0.41   -0.51   -0.27   -0.23   -1.23   -2.14    0.88   -0.37   -1.63   -0.14
 1997    -0.17   -0.21    0.19    0.67    2.16    3.77    4.75    5.05    6.13    6.07    4.73    3.32
 1998     3.57    4.93    5.43    4.80    4.46    5.33    6.02    5.82    3.35    3.32    1.56   -0.04
 1999    -0.17   -0.23   -0.24   -0.50   -0.83    0.71   -0.08    3.09    1.45    0.21   -0.08   -0.21
 2000    -0.17   -0.30   -0.80   -0.04   -0.31   -1.11   -0.66    1.09    1.16    0.96    0.65    0.03
 2001    -0.17   -0.24   -0.44    0.12   -0.68    0.51    0.57    2.95    3.09    2.07    1.89   -0.01
 2002    -0.13   -0.14    0.06    0.81    0.47   -0.36    0.71    0.68    1.77    3.03    1.15    0.01
 2003    -0.03    0.02    1.21    0.46   -0.09    1.43    1.99    4.58    3.74    4.71    2.91    0.00
 2004    -0.14   -0.19   -0.34    0.63    0.31    1.14    2.18    4.44    3.67    3.16    2.70    0.07
 2005    -0.06   -0.22    0.36    1.40    3.11    4.42    5.84    4.90    4.40    2.45    1.48   -0.25
 2006    -0.17   -0.30   -0.52   -0.07    0.45    0.95    2.14    4.29    4.92    5.22    3.18    0.06
 2007    -0.04    0.00   -0.29    0.45    0.04    0.19    1.63    1.52    1.63    1.40    0.47   -0.16
 2008    -0.17   -0.28   -0.53    0.17   -0.31   -0.02    0.99    3.42    2.70    2.62    1.84   -0.30
 2009    -0.17   -0.30   -0.76   -0.11    0.25    1.85    3.79    4.09    3.77    4.87    3.17    0.79
 2010    -0.00    0.64    1.85    4.04    5.81
http://www.esrl.noaa.gov/psd/data/correlation/whwp.data