Here is a summary of the latest NWP output for noon (GMT) on Saturday.
Issued 0433z, 25/05/10.

The models show the jetstream crossing the UK during the weekend. All areas
will be at risk of rain on Saturday but later on Sunday and into Monday the
risk will transfer northwards as pressure builds to the south and SW.
Temperatures will gradually increase, perhaps becoming warm or very warm
again in the south by Monday.

ECMWF: http://www.wzkarten.de/pics/Recm1201.gif
SW'lies cover the UK, with a trough to the west and a ridge to the SE. On
day 6 a trough covers Scotland, with SE'lies there and WSW'lies elsewhere.
There are further WSW'lies on day 7, with a trough over Scotland.

MetO: http://www.wzkarten.de/pics/Rukm1201.gif
A ridge covers the UK, bringing light winds for all. On day 6 there's little
change, with a ridge persisting.

GFS: http://www.wzkarten.de/pics/Rtavn1201.png
The UK lies under SW'lies with a low over northern Scotland. A col covers
the UK on day 6, with light winds. Day 7 sees a weak ridge with further
light winds.

GEM: http://www.wzkarten.de/pics/Rgem1201.gif
The Canadian run shows SSW'lies with a trough to the NW and a low to the
west.

JMA: http://www.wzkarten.de/pics/Rjma1201.gif
JMA shows a large ridge to the west and NW'lies over the UK as a result.