The models have been for some time playing with a switch from zonal to meridional to occur about a week from now, but with major difficulties in predicting where and how strong the associated northerly plunge will be (and the southerly uprise but for some reason that seems to excite less interest). So this morning's version, with GFS and ECM taking different views:
WX summary: week 1 as yesterday with cold air moving in steadily from the NE; but this area of cold shrinks a little in week 2 while becoming colder. But also in week 2 there is evidence of a northerly with intense cold over S Norway and a patch with the 0C isotherm in E France & S Germany not connected to the E, and even a small spot of 0C over Scotland. All this is new since yesterday. The rian/snow pattern has altered too - from N Atlantic and separately the W Med week 1, to week 2 where the W coast of Europe, the Baltic and the Alps/Italy are affected.
Jet: currently mostly W-ly to N of Scotland. looping N Sun 14th, back to a W-ly for a few days, then from Thu 18th looping S a little to the E of UK so that the S-ly flow on the trailing side of the loop runs down across the UK for a week before the loop breaks up
GFS op: W/SW-lies between LP to the N and HP to the S to Sat 13th before the HP intensifies 1035mb covering UK Tue 16th then retreating to Greenland with N-ly plunge and eventually LP 990mb N Sea Sun 21st with cold pool across the Low Countries. Reload Tue 23rd, 985 mb Cornwall with cold pool over UK, filling and moving SE while HP edges in from the W weakening but not displacing the N-ly.
GEFS: mean temp declines slowly and steadily from mild now to a little below Thu 25th. Op & control take a dive to 8 or 10C below from Wed 18th along with some other runs but there is a group which remains mild so cold plunge not nailed on yet. A very small amount of ran from Thu 18th, dry until then (a worry for water supplies, this should be the recharge season). More variation in temps further north but overall similar.
ECM: makes more of LP off W Scotland Fri 12th which moves SE and keeps pressure slack over UK rather than high until it travels on to France Sun 14th. HP then re-establishes over UK but not so intense as GFS Tue 16th. The HP centre then retreats SW to Biscay not to Greenland Fri 19th (end of run) and suggests that any cold plunge will be from the NW and only affect Shetland
War does not determine who is right, only who is left - Bertrand Russell
Chichester 12m asl