The NAO becomes more significant as we head from summer into autumn and obviously winter.
Over the past 12 months, the NAO has been predominantly positive and I believe this is strongly connected to the weak solar maximum of sunspot cycle 24. The positive NAO has laid to a warm Europe last summer, winter and even summer this year. We saw the peaking of sunspot cycle 24 back last February, this produced a warm, stormy winter for Western Europe and may have helped flip the long term warm AMO (Atlantic Multidecadal Oscillation) ‘briefly’ negative or cold.
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However, since the DOWNTURN of the solar cycle 24 maximum, we’re seeing a negative trend with the NAO which has only just begun late this summer.
What’s interesting however is that we saw a sharp drop during August which produced the coolest August in the UK in 21 years (since 1993) following a weak positive during spring and summer which brought about a warmer than normal June through July period. The question is why did we go from sustained positive to the lowest negative value since February 2010 so quickly? Is this a natural switch being flicked and nature’s way changing a long term pattern? Is this a sign of a negative trend for the upcoming winter as the solar cycle heads towards another minimum? What may this mean for the pattern ahead? These are all questions I am asking myself.
Here’s the data which goes back to 1950.
Monthly Teleconnection Index: North Atlantic Oscillation (NAO)
Indices are normalized using the 1981-2010 base period monthly means and standard deviations.
Values are set to -99.90 for calendar months when the pattern
is not normally a leading mode of variability.
The data is written in format(i4,3x,i2,1x,f6.2).
YEAR MONTH INDEX
1950 1 0.56
1950 2 0.01
1950 3 -0.78
1950 4 0.65
1950 5 -0.50
1950 6 0.25
1950 7 -1.23
1950 8 -0.19
1950 9 0.39
1950 10 1.43
1950 11 -1.46
1950 12 -1.03
1951 1 -0.42
1951 2 0.35
1951 3 -1.47
1951 4 -0.38
1951 5 -0.50
1951 6 -1.35
1951 7 1.39
1951 8 -0.41
1951 9 -1.18
1951 10 2.54
1951 11 -0.54
1951 12 1.13
1952 1 0.57
1952 2 -1.38
1952 3 -1.97
1952 4 0.95
1952 5 -0.99
1952 6 -0.10
1952 7 -0.06
1952 8 -0.49
1952 9 -0.38
1952 10 -0.28
1952 11 -1.32
1952 12 -0.49
1953 1 -0.12
1953 2 -1.00
1953 3 -0.45
1953 4 -1.96
1953 5 -0.56
1953 6 1.41
1953 7 0.43
1953 8 -1.04
1953 9 -0.19
1953 10 1.95
1953 11 0.96
1953 12 -0.52
1954 1 -0.08
1954 2 0.40
1954 3 -1.27
1954 4 1.31
1954 5 -0.03
1954 6 0.06
1954 7 -0.57
1954 8 -2.57
1954 9 -0.28
1954 10 1.16
1954 11 0.29
1954 12 0.55
1955 1 -2.65
1955 2 -1.71
1955 3 -0.96
1955 4 -0.60
1955 5 -0.26
1955 6 -0.80
1955 7 1.78
1955 8 1.25
1955 9 0.46
1955 10 -1.09
1955 11 -1.49
1955 12 0.07
1956 1 -0.76
1956 2 -1.71
1956 3 -0.46
1956 4 -1.30
1956 5 2.10
1956 6 0.41
1956 7 -0.72
1956 8 -1.89
1956 9 0.38
1956 10 1.47
1956 11 0.40
1956 12 0.00
1957 1 0.71
1957 2 -0.32
1957 3 -1.73
1957 4 0.39
1957 5 -0.68
1957 6 -0.42
1957 7 -1.16
1957 8 -0.83
1957 9 -1.47
1957 10 1.95
1957 11 0.63
1957 12 0.02
1958 1 -1.14
1958 2 -1.64
1958 3 -2.46
1958 4 0.26
1958 5 -0.17
1958 6 -1.08
1958 7 -1.69
1958 8 -2.13
1958 9 0.08
1958 10 0.68
1958 11 1.59
1958 12 -0.74
1959 1 -1.52
1959 2 0.33
1959 3 -0.56
1959 4 0.25
1959 5 0.41
1959 6 0.71
1959 7 0.77
1959 8 -0.05
1959 9 1.00
1959 10 1.48
1959 11 0.30
1959 12 0.32
1960 1 -2.01
1960 2 -2.59
1960 3 -0.93
1960 4 1.33
1960 5 0.47
1960 6 0.10
1960 7 0.38
1960 8 -1.93
1960 9 0.53
1960 10 -1.37
1960 11 -0.67
1960 12 -0.03
1961 1 -0.03
1961 2 0.07
1961 3 0.17
1961 4 -1.83
1961 5 -0.28
1961 6 1.17
1961 7 -0.36
1961 8 1.03
1961 9 1.36
1961 10 1.07
1961 11 -0.79
1961 12 -1.46
1962 1 0.20
1962 2 0.18
1962 3 -2.99
1962 4 0.93
1962 5 -0.04
1962 6 0.47
1962 7 -2.43
1962 8 0.05
1962 9 -0.21
1962 10 0.96
1962 11 -0.38
1962 12 -1.31
1963 1 -2.98
1963 2 -1.53
1963 3 -0.85
1963 4 -1.61
1963 5 2.05
1963 6 -0.13
1963 7 -0.74
1963 8 -0.95
1963 9 1.89
1963 10 1.53
1963 11 -1.47
1963 12 -1.87
1964 1 -1.62
1964 2 -2.06
1964 3 -1.66
1964 4 0.25
1964 5 0.53
1964 6 1.61
1964 7 1.92
1964 8 -2.40
1964 9 0.34
1964 10 1.32
1964 11 -0.14
1964 12 -0.23
1965 1 -0.65
1965 2 -2.20
1965 3 -1.99
1965 4 0.64
1965 5 -0.52
1965 6 0.60
1965 7 0.35
1965 8 0.45
1965 9 0.51
1965 10 0.92
1965 11 -1.88
1965 12 1.18
1966 1 -2.54
1966 2 -2.02
1966 3 0.18
1966 4 -0.96
1966 5 0.25
1966 6 1.37
1966 7 0.35
1966 8 -2.39
1966 9 -0.29
1966 10 -0.23
1966 11 -0.18
1966 12 0.58
1967 1 -1.55
1967 2 -0.23
1967 3 1.18
1967 4 0.05
1967 5 -0.87
1967 6 1.72
1967 7 0.44
1967 8 1.73
1967 9 1.05
1967 10 0.59
1967 11 0.50
1967 12 -0.51
1968 1 -0.36
1968 2 -1.91
1968 3 0.02
1968 4 -1.32
1968 5 -1.58
1968 6 0.64
1968 7 -0.77
1968 8 -0.97
1968 9 -1.73
1968 10 -1.99
1968 11 -1.11
1968 12 -1.39
1969 1 -1.48
1969 2 -2.20
1969 3 -2.04
1969 4 1.52
1969 5 0.56
1969 6 0.86
1969 7 0.60
1969 8 -1.99
1969 9 2.17
1969 10 1.23
1969 11 -1.14
1969 12 -0.35
1970 1 -2.26
1970 2 0.28
1970 3 -1.41
1970 4 -1.56
1970 5 1.11
1970 6 1.87
1970 7 0.13
1970 8 0.00
1970 9 0.06
1970 10 -0.49
1970 11 -0.76
1970 12 -1.20
1971 1 -1.82
1971 2 -0.17
1971 3 -1.28
1971 4 -0.41
1971 5 0.51
1971 6 -1.28
1971 7 0.27
1971 8 1.87
1971 9 0.53
1971 10 1.14
1971 11 -0.34
1971 12 0.47
1972 1 -0.19
1972 2 -0.08
1972 3 0.35
1972 4 -0.38
1972 5 0.93
1972 6 1.19
1972 7 0.21
1972 8 1.57
1972 9 0.03
1972 10 1.70
1972 11 0.43
1972 12 0.09
1973 1 -0.46
1973 2 0.52
1973 3 -0.09
1973 4 -0.73
1973 5 -0.36
1973 6 0.70
1973 7 0.60
1973 8 -0.20
1973 9 -0.15
1973 10 -0.84
1973 11 -1.11
1973 12 0.21
1974 1 1.05
1974 2 -0.60
1974 3 -0.43
1974 4 0.41
1974 5 -0.17
1974 6 0.17
1974 7 -0.73
1974 8 -0.95
1974 9 0.95
1974 10 1.04
1974 11 -0.70
1974 12 1.30
1975 1 0.17
1975 2 -1.15
1975 3 -1.04
1975 4 -1.89
1975 5 -0.43
1975 6 -0.54
1975 7 1.57
1975 8 -0.46
1975 9 1.67
1975 10 -0.08
1975 11 0.30
1975 12 -0.09
1976 1 -0.80
1976 2 0.61
1976 3 0.38
1976 4 0.14
1976 5 0.94
1976 6 1.11
1976 7 -0.29
1976 8 2.34
1976 9 -1.11
1976 10 0.42
1976 11 0.04
1976 12 -1.57
1977 1 -1.72
1977 2 -1.00
1977 3 -1.25
1977 4 0.56
1977 5 -0.75
1977 6 -0.27
1977 7 -0.42
1977 8 -0.49
1977 9 0.51
1977 10 1.08
1977 11 -0.21
1977 12 -1.02
1978 1 0.26
1978 2 -2.94
1978 3 0.33
1978 4 -1.42
1978 5 1.05
1978 6 1.70
1978 7 -1.11
1978 8 0.70
1978 9 0.60
1978 10 2.61
1978 11 3.06
1978 12 -1.54
1979 1 -2.12
1979 2 -1.20
1979 3 0.41
1979 4 -2.01
1979 5 -0.90
1979 6 1.92
1979 7 0.86
1979 8 1.11
1979 9 1.13
1979 10 0.18
1979 11 0.42
1979 12 0.84
1980 1 -1.38
1980 2 -0.39
1980 3 -0.73
1980 4 1.26
1980 5 -1.34
1980 6 -0.07
1980 7 -0.39
1980 8 -3.01
1980 9 0.79
1980 10 -1.41
1980 11 -0.52
1980 12 0.63
1981 1 -0.08
1981 2 0.60
1981 3 -1.65
1981 4 0.25
1981 5 0.24
1981 6 -0.15
1981 7 0.08
1981 8 0.38
1981 9 -1.27
1981 10 -0.96
1981 11 -0.53
1981 12 -0.11
1982 1 -1.55
1982 2 0.86
1982 3 0.80
1982 4 -0.04
1982 5 -0.44
1982 6 -1.34
1982 7 1.18
1982 8 0.21
1982 9 1.86
1982 10 -0.29
1982 11 1.55
1982 12 1.56
1983 1 1.34
1983 2 -1.04
1983 3 0.59
1983 4 -1.07
1983 5 -0.01
1983 6 1.31
1983 7 1.22
1983 8 1.95
1983 9 -0.95
1983 10 1.22
1983 11 -1.16
1983 12 0.18
1984 1 1.42
1984 2 0.37
1984 3 -0.79
1984 4 -0.45
1984 5 0.55
1984 6 -0.12
1984 7 -0.04
1984 8 1.35
1984 9 0.31
1984 10 0.43
1984 11 -0.20
1984 12 -0.09
1985 1 -2.38
1985 2 -1.00
1985 3 -0.19
1985 4 0.20
1985 5 -0.40
1985 6 -0.50
1985 7 1.25
1985 8 -0.74
1985 9 -0.36
1985 10 1.49
1985 11 -0.84
1985 12 0.11
1986 1 0.78
1986 2 -1.58
1986 3 1.39
1986 4 -0.79
1986 5 0.84
1986 6 1.54
1986 7 0.15
1986 8 -1.53
1986 9 -0.95
1986 10 2.20
1986 11 2.27
1986 12 0.83
1987 1 -1.85
1987 2 -1.27
1987 3 -0.26
1987 4 2.03
1987 5 0.96
1987 6 -1.53
1987 7 0.55
1987 8 -1.19
1987 9 -1.04
1987 10 0.66
1987 11 0.06
1987 12 0.21
1988 1 0.68
1988 2 0.42
1988 3 -0.58
1988 4 -1.42
1988 5 0.64
1988 6 1.19
1988 7 -0.32
1988 8 -0.07
1988 9 -0.82
1988 10 -0.66
1988 11 -0.49
1988 12 0.48
1989 1 0.85
1989 2 1.82
1989 3 1.54
1989 4 0.16
1989 5 1.33
1989 6 0.03
1989 7 1.00
1989 8 -0.11
1989 9 2.15
1989 10 0.48
1989 11 0.03
1989 12 -1.15
1990 1 0.70
1990 2 1.16
1990 3 1.13
1990 4 2.03
1990 5 -1.37
1990 6 0.29
1990 7 0.56
1990 8 1.12
1990 9 1.18
1990 10 0.76
1990 11 -0.39
1990 12 0.11
1991 1 0.49
1991 2 0.74
1991 3 -0.61
1991 4 0.17
1991 5 0.12
1991 6 -0.52
1991 7 -0.46
1991 8 1.46
1991 9 0.61
1991 10 0.30
1991 11 0.37
1991 12 0.34
1992 1 -0.66
1992 2 0.77
1992 3 0.51
1992 4 1.88
1992 5 2.49
1992 6 0.51
1992 7 0.19
1992 8 0.97
1992 9 -0.28
1992 10 -1.40
1992 11 1.12
1992 12 0.35
1993 1 1.35
1993 2 0.12
1993 3 0.30
1993 4 0.91
1993 5 -0.67
1993 6 -0.29
1993 7 -3.14
1993 8 0.03
1993 9 -0.41
1993 10 -0.26
1993 11 2.56
1993 12 1.36
1994 1 0.70
1994 2 0.08
1994 3 0.92
1994 4 1.10
1994 5 -0.48
1994 6 1.84
1994 7 1.34
1994 8 0.36
1994 9 -1.14
1994 10 -0.54
1994 11 0.54
1994 12 1.78
1995 1 0.57
1995 2 0.85
1995 3 0.91
1995 4 -1.07
1995 5 -1.33
1995 6 0.44
1995 7 -0.19
1995 8 0.76
1995 9 0.45
1995 10 0.72
1995 11 -1.59
1995 12 -1.64
1996 1 -0.65
1996 2 -0.52
1996 3 -0.66
1996 4 -0.33
1996 5 -0.93
1996 6 0.87
1996 7 0.70
1996 8 1.19
1996 9 -0.69
1996 10 0.15
1996 11 -0.72
1996 12 -1.40
1997 1 -1.08
1997 2 1.48
1997 3 1.13
1997 4 -1.25
1997 5 -0.21
1997 6 -1.17
1997 7 0.37
1997 8 0.94
1997 9 0.74
1997 10 -1.34
1997 11 -1.08
1997 12 -0.98
1998 1 -0.05
1998 2 -0.57
1998 3 0.51
1998 4 -0.88
1998 5 -1.17
1998 6 -2.44
1998 7 -0.45
1998 8 -0.15
1998 9 -1.80
1998 10 0.20
1998 11 -0.43
1998 12 0.72
1999 1 0.39
1999 2 -0.11
1999 3 -0.16
1999 4 -1.18
1999 5 0.90
1999 6 1.44
1999 7 -0.87
1999 8 0.38
1999 9 0.50
1999 10 0.73
1999 11 0.55
1999 12 1.40
2000 1 0.19
2000 2 1.48
2000 3 0.40
2000 4 -0.18
2000 5 1.52
2000 6 0.28
2000 7 -1.00
2000 8 -0.50
2000 9 -0.06
2000 10 1.51
2000 11 -1.10
2000 12 -0.63
2001 1 -0.22
2001 2 0.07
2001 3 -1.73
2001 4 -0.15
2001 5 0.03
2001 6 0.11
2001 7 -0.22
2001 8 -0.22
2001 9 -0.49
2001 10 0.25
2001 11 0.53
2001 12 -0.86
2002 1 0.00
2002 2 0.80
2002 3 0.32
2002 4 1.14
2002 5 -0.15
2002 6 0.69
2002 7 0.65
2002 8 0.36
2002 9 -0.54
2002 10 -1.97
2002 11 -0.32
2002 12 -0.96
2003 1 -0.32
2003 2 0.26
2003 3 -0.07
2003 4 -0.34
2003 5 0.06
2003 6 0.24
2003 7 0.16
2003 8 -0.22
2003 9 0.16
2003 10 -0.86
2003 11 0.77
2003 12 0.50
2004 1 -0.85
2004 2 -0.60
2004 3 0.67
2004 4 1.11
2004 5 0.23
2004 6 -0.59
2004 7 1.16
2004 8 -0.74
2004 9 0.52
2004 10 -0.69
2004 11 0.63
2004 12 1.03
2005 1 1.26
2005 2 -0.51
2005 3 -2.32
2005 4 -0.47
2005 5 -1.11
2005 6 0.26
2005 7 -0.48
2005 8 0.35
2005 9 0.76
2005 10 -0.55
2005 11 -0.46
2005 12 -0.50
2006 1 0.97
2006 2 -1.02
2006 3 -1.75
2006 4 1.20
2006 5 -1.01
2006 6 1.15
2006 7 0.93
2006 8 -2.35
2006 9 -1.43
2006 10 -1.92
2006 11 0.33
2006 12 1.15
2007 1 -0.25
2007 2 -0.98
2007 3 1.11
2007 4 0.04
2007 5 0.66
2007 6 -1.01
2007 7 -0.55
2007 8 -0.31
2007 9 0.85
2007 10 1.00
2007 11 0.48
2007 12 0.23
2008 1 0.53
2008 2 0.38
2008 3 -0.32
2008 4 -1.31
2008 5 -1.55
2008 6 -1.09
2008 7 -1.24
2008 8 -1.62
2008 9 1.14
2008 10 0.47
2008 11 -0.47
2008 12 -0.35
2009 1 -0.52
2009 2 -0.38
2009 3 0.19
2009 4 -0.36
2009 5 1.61
2009 6 -0.91
2009 7 -2.11
2009 8 -0.37
2009 9 1.62
2009 10 -0.61
2009 11 -0.16
2009 12 -1.88
2010 1 -1.80
2010 2 -2.69
2010 3 -1.33
2010 4 -0.93
2010 5 -1.33
2010 6 -0.52
2010 7 -0.39
2010 8 -1.69
2010 9 -0.62
2010 10 -0.50
2010 11 -1.84
2010 12 -1.80
2011 1 -1.53
2011 2 0.35
2011 3 0.24
2011 4 2.55
2011 5 -0.01
2011 6 -0.98
2011 7 -1.48
2011 8 -1.85
2011 9 0.67
2011 10 0.94
2011 11 1.30
2011 12 2.25
2012 1 0.86
2012 2 0.03
2012 3 0.93
2012 4 0.37
2012 5 -0.79
2012 6 -2.25
2012 7 -1.29
2012 8 -1.39
2012 9 -0.43
2012 10 -1.73
2012 11 -0.74
2012 12 0.07
2013 1 -0.11
2013 2 -0.96
2013 3 -2.09
2013 4 0.60
2013 5 0.58
2013 6 0.83
2013 7 0.70
2013 8 1.12
2013 9 0.38
2013 10 -0.88
2013 11 0.81
2013 12 0.79
2014 1 -0.17
2014 2 1.07
2014 3 0.44
2014 4 0.19
2014 5 -0.80
2014 6 -0.67
2014 7 0.21
2014 8 -2.28
When looking back to last month, the NAO tanked to a value of -2.28. The last time it dropped that negative was Feb 201o, it got close during June 2012 which followed one of our coldest spring’s in recent times with the coldest March in 50 years.
The question is, is there a connection between the sudden NAO drop last month following the persistent positive and the upcoming winter? I’m trying to find it but in all honestly I don’t see anything.
However, there is a beautiful connection between solar and NAO when looking at seasonal means for the Dec-Feb period. Note the all out peaking of positive with the NAO when the solar cycle peaked around 1990. The trend has been downward ever since as each solar cycle becomes weaker and weaker.
Look at the close correlation with solar.
There’s a lag between solar maximum and warming of the Atlantic as you can see in the chart below. Notice that the AMO has been warm since the mid-90s, AFTER the big solar maximum around 1990s. There was a sharp downturn which followed, bringing about a return of both negative NAO and cold winters to both sides of the Atlantic. Do we have the same coming this winter?
Although the AMO was cold during the cold era of the late 60s and 70s, the current warm AMO cycle DOES favour more North Atlantic/Greenland blocking. 2009-10 was a warm AMO but the solar cycle was about as weak has it’s been in the last 100 years which meant a strong negative NAO and major cold for US and UK/Europe.
This winter is a tough call because we won’t be in a solar minimum like we saw back in 09-10, however, there have been fierce winters on the backside of ‘weak solar max’s’.
From what I can see, there’s a trend towards negative NAO this winter and that trend started with a sudden drop in August. That dip to -2 may be the switch flick to a new trend which last’s till the solar cycle bottom’s out and begins the climb towards sunspot cycle 25.
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