We do seem to have a rough blend of GFS and ECM's Monday output for this mornings runs from both of those models, which produces enough of a Med. trough to bring a mid-latitude block to the UK, but not so much as to bring much of an easterly flow within the next 10 days, let alone a properly cold one.
GFSP has the HP a little further south with slack conditions for the UK.
A critical period looks to be around day 6 when we have this sort of setup from GFSP, ECM and GFS:
The Arctic High has linked with the block to our east, and this would lead to a strong high around the Svalbard area if the Atlantic didn't go blasting through and breaking the link.
Unfortunately for those seeking a notable outbreak of cold and/or snowy conditions as soon as possible, all three of the models have that shortwave low doing the damage.
ECM proceeds in much the same way as it has done for the past four runs, shifting a deep trough to Scandi/Siberia and hinting at low heights dropping south in the Atlantic, with a ridge building north from the UK in an attempt to split the polar vortex. It could work out nicely, but the day 10 chart is a rather messy affair with lots of shortwaves flying around, and it would perhaps take several bites of the apple to get a desirable outcome.
GFS and GFSP are extremely keen on throwing the polar vortex lobe over Canada/Greenland to Scandinavia, this being consistent across their respective 00z and 06z op runs.
GFSP does this more quickly than GFS, but GFS has a more extreme end result. Both of the charts below could really do with higher heights in the Arctic. GFSP appers to be lacking in polar high pressure, but by the end of the run a 1045mb high is approaching the pole and there's also a ridge across Canada, so promising for the outlook going forward. You can sort of see what I mean on the GFS 06z chart that I've posted:
That's GFSP on the left and GFS on the right. The former is actually marginal for snow, becoming more favourable by day 16. The latter is cold enough for snow nationwide, though we would be waiting for that shortwave over Iceland to deliver the real goods.
Overall, then, the polar vortex really does look to be getting a move on not long into December, but how fast it does so and where exactly it goes remains inconclusive in the model output.
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T-Max: 30.2°C 9th Sep (...!) | T-Min: -7.1°C 22nd & 23rd Jan | Wettest Day: 25.9mm 2nd Nov | Ice Days: 1 (2nd Dec -1.3°C in freezing fog)
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