Here is a summary of the NWP output for 12z on Monday.
Issued 0540z, 24/11/06

The outlook is still unsettled but as December draws closer the long-term
outlook is less certain. GFS has been keen on a northerly plunge with rising
heights to the west, while ECM (and MetO) develop high pressure to the NE,
near Scandinavia. If GFS is right the unsettled conditions will continue for
some time, if MetO/ECM is correct then things will become increasingly
settled within a week. As ever, more runs are needed.

Analysis and evolution to T+120 via GFS
http://85.214.49.20/pics/Rtavn001.png
http://85.214.49.20/pics/avnpanel1.gif
A deep low lies to the NE of the UK with strong SW'lies and southerlies
across the British Isles. Tomorrow sees strong to gale force SSE'lies as low
pressure fills to the west of Ireland, followed by SW'lies and SSW'lies as
the low deepens on Sunday. By Monday a new low lies to the west, bringing
further strong southerlies.

T+120 synopsis
http://85.214.49.20/pics/Rtavn12015.png /
http://85.214.49.20/pics/Rtavn1201.png
http://85.214.49.20/pics/Rjma1201.jpg /
http://85.214.49.20/pics/Rukm1201.jpg
http://85.214.49.20/pics/Recm1201.jpg /
http://85.214.49.20/pics/Rngp1201.jpg
The jetstream chart shows a marked trough to the NW of the UK and a ridge to
the east. The jet covers the North Sea on a south/north alignment. At the
500hPa level there's an upper low near Iceland and a ridge to the east. The
UK lies between the two, with a SW'ly flow aloft. MetO is similar, albeit
with a deeper low near Iceland. ECM also has a low near Iceland but the
upper ridge to the east is much less defined; indeed there's an upper low to
the NE of Scandinavia instead of a large ridge as with GFS and MetO. The
minor runs (JMA, GEM and NGP) all show a similar trough to the west and
ridge to the east setup.
At the surface GFS has a deep low to the SW of Iceland with strong SSW'lies
for the UK. MetO places the low further west, with a trough over the UK.
Behind the trough winds are SW'lies, ahead of the trough they're
southerlies. ECM shows SSW'lies for all, again with low pressure to the SW
of Iceland. JMA is very similar to the ECM in terms of the low's position
and GEM centres the low a little further south, with southerlies for the UK.
Finally NOGAPS has strong to gale force SSW'lies for the UK with the
Icelandic low closer to the UK.

Evolution to T+168
ECM shows the upper low near Iceland filling, only to be replaced with
another upper low further west. Meanwhile the weak upper ridge to the NE
build slowly over Scandinavia by day 7. At the surface winds are southerlies
for all on day 6 with a trough to the west. By day 7 the trough moves
(slowly) over the North Sea, with light WSW'lies for the UK in its wake.
The GFS shows the upper ridge to the NE declining and a new upper ridge
building over the UK by day 7. A shallow trough brings westerlies for all at
T+144, followed by SW'lies and SSW'lies on day 7 as pressure builds over
France.

Looking further afield
ECM shows a high over Finland on day 8, with a trough to the west of the UK
and light SE'lies as a result. The trough fills on day 9 as pressure builds
to the west and the high to the NE builds. Winds are SSE'lies or SE'lies for
most, with easterlies for SE England. By day 10 a ridge covers the UK,
leading to light winds for most. The exceptions are NW Scotland (which lies
under SW'lies) and SE England, which lies under easterlies.
GFS shows an upper ridge building to the west from days 8 to 10. On day 8 a
trough crosses the UK, with strong southerlies in advance and westerlies
following behind. Strong westerlies and NW'lies affect the UK on day 9 as
another trough moves eastwards, followed by NW'lies for all on day 10 with
low pressure filling to the NE.

Ensemble analysis
(http://expert.weatheronline.co.uk/da...ia/ensdia.html - last
night's 18z)
The ensembles still show a "sine wave" effect but a change is looming; by
the beginning of December a gradual cooling trend is evident (as was the
case with the previous few runs).