Thanks for making the changes Darren & I hope you can continue to afford the
time each day. This is without doubt the best daily analysis publicly
available and I can imagine lazy or late & hungover public servants in
Bracknell relying on this in a crisis !

Ross


"Darren Prescott" none@no,dns wrote in message
...
Here is a summary of the NWP output for 12z on Thursday.
Issued 0523z, 29/10/06

The models show a chilly but largely dry end to the working week with
temperatures slowly rising through the weekend as high pressure moves away
to the east. Nigh time frosts are likely to be widespread on Thursday into
Friday and Friday into Saturday.

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 weak ridge lies to the west of the UK. It will transfer quickly
eastwards
tomorrow, then low pressure to the NW will deepen significantly, bringing
a
windy Tuesday. The low then moves eastwards as high pressure builds to the
NW on Wednesday, introducing a change to much cooler conditions.

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.png /
http://85.214.49.20/pics/Rukm1201.png
http://85.214.49.20/pics/Recm1201.png /
http://85.214.49.20/pics/Rngp1201.png
The upper air charts show a strong jet over the Eastern Seaboard of the
States, followed by a longwave ridge over the UK. The jet then heads
southwards over western Scandinavia with a marked trough over Finland and
the Baltic states. The 500hPa chart reflects this, with a marked upper
ridge
centred over Ireland. Consistency between the runs is reasonable, although
the MetO, NGP and ECM runs keep the core of the ridge a few hundred miles
further west. The models differ over the Scandinavian trough, with MetO
showing a major feature while GFS and JMA show much higher heights, albeit
still below 528dam.

At the surface, the upper ridge translates into a high over or near the
UK.
GFS centres the high over southern Scotland with light winds for all,
whereas ECM brings a light easterly or SE'ly flow over much of the UK,
with
the centre over Scotland. MetO is notable in having the high centred to
the
NW, allowing northerlies to affect most areas. The other runs also show a
high over the UK and light winds as a result.

Evolution to T+168
ECM keeps the upper ridge over the UK, with a very slow movement
eastwards.
At the surface that translates to high pressure slowly declining and
moving
eastwards, with the UK settled out to T+168. By then SW'lies cover
Scotland,
southerlies affect Northern Ireland and England and Wales lie under
easterlies. GFS is much more progressive, with the upper ridge flattening
and moving eastwards. As such, the surface high moves swiftly eastwards,
to
be over central Europe by day 7. By then southerlies and SW'lies cover the
UK, with some mild air being advected northwards. The MetO T+144 was
unavailable at the time of writing but would probably show the high moving
SE'wards over the UK.

Looking further afield
ECM out to 10 days takes the surface high eastwards, with the jet roaring
away to the north of the UK. As a result temperatures slowly rise in a
southerly flow and the majority of England and Wales at least stays dry.
The GFS, meanwhile, shows a zonal flow developing with SW'lies on days 8
and
9 and NW'lies on day 10 as a weak ridge builds to the west. By then a
strong
jet covers the North Atlantic and it passes straight over the UK - there's
very little amplitude to the waves, reflecting the zonal surface charts.
Again, as with ECM, increasingly mild conditions are likely as time goes
by.

Ensemble analysis (http://85.214.49.20/wz/pics/MT8_London_ens.png - last
night's 18z)
The GFS ensembles show a remarkable drop in temperatures aloft for the
start
of the month, with a 13-degree drop in the course of a day likely. After a
couple of cool days the runs show good agreement on a rise back above the
mean by the 5th, although at the surface an inversion is quite likely.
Beyond that it stays largely dry for London with mild winds from a
southerly
quarter.