"Philip Eden" philipATweatherHYPHENukDOTcom wrote in message
...
For those who like to view Britain's weather through the flawed
prism of the NAO index, that index during March was negative,
very very negative, more negative even than any calendar month
since Feb 1986.
And yet there was much mobility over the Atlantic Ocean and
western Europe south of latitude 50 degN, and this mobility
penetrated across the whole of the British Isles during the second
week of March and again from the 24th onwards, resulting in an
outstandingly wet month in many parts of the UK ... exactly
what one is supposed to get with a -ve NAOi month, right?
snip
The NAO index is useful *if* you know how to use it. There is a misconception
that a negative NAO always means a blocked pattern - it doesn't . That can be
seen clearly in the mathematics as a negative NAO can arise from a shallower
than normal Icelandic low and a less intense Azores high. Even a high over
Iceland all month can still mean lows/fronts crossing the UK but further south
than normal. The NAO is really only useful for climatologists and possibly for
seasonal prediction not for the prediction of individual months and weeks. It is
an atmospheric mode of variability ie part of the spectrum that causes
variability in the atmospheric flow over the North Atlantic, to understand it
properly one needs to go into wave theory, which is involved. Once again we see
people dabbling in and using something they don't properly understand (I don't
mean you BTW Philip). And you can't understand it properly without many
weeks/months of training in mathematics and meteorology.
Will.
--
" You cannot count your life a success unless you can find one person who says
that they are happier because you were born "
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