On Sep 10, 7:50*am, Dawlish wrote:

The fine weather should last for a while too, as I've implied with my
similar forecast for 3 days time, but a change may be a-coming for 10
days time - the ECM is leading that possibility but the gfs has not
shown enough consistency yet; some runs having dallied with a
continuance of the anticyclonic weather whilst others have shown a
return to Atlantic weather over the last 48 hours. Another couple of
gfs runs showing windy and wet weather at T240 and I'd be convinced
this blocking pattern won't last to the end of the third week of
September.

This illustrates perfectly the difficulties of forecasting at 10 days
and the need for both gfs consistency and ECM agreement for me to be
able to forecast with any degree of accuracy at that distance.

After writing the above, yesterday, The 00z gfs and the runs last
night, have shown a continuance of the higher pressure out to T240, at
least for England. The 00z ECM shows an Atlantic low stalling. What do
you forecast?



Well the Meto is hedging its bets, but this forecast was issued at
lunch yesterday and, as usual in the morning, is a day out of date.

"UK Outlook for Tuesday 15 Sep 2009 to Thursday 24 Sep 2009:
Much of the country will remain dry through the middle of next week
and over next weekend, but with variable amounts of cloud. Some sunny
spells are likely, more especially in the southwest of England and
Southwest Wales at first. The far Northwest of Scotland could see a
little little rain at times, with also a small risk of showers
extending into far south and southeast of England. Temperatures in all
parts should be near normal, and feeling pleasant in sunshine.
**Southern and Central parts should start mainly dry and fine in the
longer outlook, but there is a low risk of it turning more unsettled
with time. The Northwest is expected to turn more unsettled with
occasional showers or rain.**"

Updated: 1201 on Thu 10 Sep 2009

That's also an interesting comment in the 6-15 day forecast because
that phrase gives an insight into the forecaster's thinking - more
likely to continue settled over England, but a chance of it not doing
so. It also reflects my thinking that an actual forecast would have
less than a 75% chance of being correct.

Therein lies the current problems of forecasting at 10 days. It really
is very difficult.

Still super weather for most. Cool nights and mornings and a
scintillating September day on the south coast yesterday. Hopefully
another one to come. 20C and sunshine is just marvellous weather and
the September light, especially on a morning is quite superb.