Models are increasingly pointing to the likely development of a very windy and cold period this weekend. Friday will see the gradual ramping up of a west to northwest wind in the 30-50 mph range but it will remain mild enough to prevent snow except perhaps on summits.
By Saturday, the parent low in the region near the Faeroes deepens further and colder air gradually works into the circulation as winds increase further to about 40-60 mph from the west-northwest. The snow line could come down in elevation especially across Donegal, Mayo and other parts of the north and west, to about 300m.
Then by Sunday further development takes place with the low transferring a deep centre southeast across Scotland into the North Sea. This will lead to severe gales in many parts of Ireland and Britain, and it will be cold enough for mixed wintry showers (at sea level, temps will be 3-5 C, at 300m near freezing) of hail and snow -- there could be some heavy snow amounts in northwest facing coastal regions similar to last December's Greenland express although it won't be quite as sustained or intense. As usual in these situations, the effects will be less dramatic towards the east and south but anyone planning to travel to the UK might want to consider the possibility of disruptions to road and air travel due to wind and local snowfalls. It looks particularly bad on the 18z GFS run for Yorkshire and East Anglia with a hurricane force storm in the North Sea. Winds over Ireland are likely to peak at around 50-70 mph given the model run and reasonable subjective tweaking of the output based on second-order factors (such as research energy peaks and sea surface temperatures).
This outlook may be revised rather substantially depending on the output of the more reliable 00z model runs. However, it has been "in the works" for several days and fits the developing global circulation which is seeing widespread intensification of zonal flow combined with an expanding arctic circulation of unusual intensity for this stage of the season.
This trend looks likely to reload around the 10th to 12th when more severe gales may develop at the full moon, with associated storm surge potential (just as a long-distance heads up).