Philip Eden wrote:
"Robin Nicholson" wrote:

But I am still hoping that someone might conjure up a few figures for
Bad Augusts Good Julys ref the thread head so I have just tweaked the
subject to hopefully get a response!

The conventional view that warm, dry, sunny Julys tend to be followed
by warm, dry, sunny Augusts is certainly supported by events, at least
during the last 60 years.

Sometimes the summer culminates in a
spectacularly hot and sunny August, as in 1947 or 1995. Sometimes
July is the peak of the season and August, though still warm and dry,
is slightly less newsworthy, as in 1983 or 1989.

Without resorting to statistics, within that 60-year period I would
say that a more-or-less +-+ July was followed by a more-or-less
+-+ August in 1947, 49, 55, 59, 75, 76, 83, 84, 89, 90, 95, 97,
and 03. The only exceptions were 94 and 99, but neither of those
Augusts was thoroughly -+-.

The convention is to label the Atlantic oscillation plus or minus.

August 1994 began with a week of warm, occasionally thundery
weather, and the rest of the month was fairly average with
occasional warm days. August 1999 began with three very hot
days, it then was exceptionally wet for just over a week (remember
the cloudy solar eclipse?), then a fortnight of dry but often rather
cool weather. The first half of September 1999 was uncommonly
hot.

July 1994 had been particularly strange synoptically,
ending up with the biggest southerly component over the UK of
any July in the last 133 years. This month will also have a
substantial southerly component without challenging 1994.

Even before the mid-1940s, +-+ Julys were often followed by
+-+ Augusts, though probably not as frequently as since.

One of the biggest switches from +-+ July to -+- August in
the entire record occurred in 1941, so I've dug out the relevant
Monthly Weather Reports. The whole year was odd ... a cold
and snowy winter giving way to an exceptionally cold and
cloudy spring. June was anticyclonic, cool for two weeks
then very warm.

July's warmth was largely due to a long hot spell from 1st-12th
with isolated warm days thereafter. Some parts of the UK
had a rather wet month, and there was a shortage of sunshine
in the northern half of the country. Mean sea-level pressure
was actually slightly below normal over most of the British
Isles.

August was a markedly cyclonic/westerly month, with
a deep (for the season) low pressure area often found in the
northern North Sea or over southern Scandinavia. Eleven
major depressions crossed the British Isles during the course
of the month. The temperature, which had reached 34-35°C
during two separate spells in the first half of the summer,
failed to pass 22°C over most of the UK after 4th August.

September was simply perfect ... very anticyclonic, very
dry and pleasantly warm with only 1 or 2 hot days ... many
stations reported practically the same mean temperature for
both Aug and Sept.

FWIW, October was anticyclonic in the south, November
was a southerly month, and December anticyclonic/westerly.

Over the last few days, I've been looking at what the EarthObservatory
commentatoes have had to say about sea level air pressure oscillations.
Their PDF on the NAO featured this little comment:

"much like El Niño, the NAO varies in a rhythmic pattern from decade
to decade. Ever since the 1960s, the difference in pressure between the
Azores high and the Icelandic low has repeatedly grown on average for
three to five years and then has waned and decreased on average for
another three to five years.

Though the researchers have not had much luck in predicting the
anomaly's behavior, many believe that its multi-year variations may be
linked to currents in the sea or the formation of sea ice."

Looking at the Atlantic Charts these last few days has shown me that
there is very little difference in the the pressures considered highs
and lows. In fact the deep low slated for the middle of the week isn't
all that deep.

And no doubt it is going to find it's way past the UK and Norway and
end up in the Arctic like so many others have done so far this summer.

Anyone else think the same? (I wonder where Alistair MacDonald is
hiding this past few months. Reanalysing his position on glowballs no
doubt.)