FAX - as before, LP to the SW so rain continuing there, and bringing fronts N-wards across Britain from the south - a slight difference is that HP to the north is weaker so winds are more S-ly and fronts move takes a bit longer further north. Then on Tue 10th the LP moves a little N-wards and stretches a trough over N England, so fronts move E-wards for S England and the E-lies are back for Scotland.
GFS Op - takes an extra day i.e. Wed before the trough moves in. Then by Fri 13th this trough has transformed into a defined LP 975mb centred N Ireland and drawing in cold air from Scandinavia for all of Britain but esp the north. This LP circulates around the eastern side of the N Sea until Tue 17th drawing down rather cold N-lies, gale force Sat14th. A brief rise of pressure then another LP from the Atlantic passes across Britain 970mb N England Thu 19th entraining more cold air before finally HP and mild weather arrive from the SW Sun 22nd.
ECM - never really develops the cold weather; on Fri 13th the LP is already moving off SE-wards, the last of the cold air touching the SE Sun 15th as a ridge of HP moves up from the SW for the rest of Britain, even S-ly gales on Tue 17th. Later that week ECM converges with GFS as an LP moves in from the NW Thu 19th, but again fails to entrain cold air and fizzles out into a weak SW-ly.
AIFS - London, maxima about 8C now and around Tue 17th, down to 3C Fridays 13th and 20th. Rain in the milder periods, else drier. Edinburgh, much as London, perhaps a degree or two colder.
GEFS - in the S, mean temp and most ens members a little above norm to Fri 13th, then mostly a few degrees below norm to Tue 17th (but control and some runs 10+C below). After 17th mean is near norm but not meaningful as such a wide spread of ens members. Dry around Mon 9th. else rain in most ens members, often heavy if SW. In the N, similar, but cold spell has better agreement with good chance of snow at that time.
War is God's way of teaching Americans geography - Ambrose Bierce
Chichester 12m asl