Brilliant discussion today by lots of posters! Too much scepticism by some I feel but I don't blame anyone for being sceptical about models predicting easterlies! Many don't come off! This partic easterly has been predicted for Thur/Fri for several days now and the deep cold air has been brought forward to Wed now: this bringing forward of the cold is quite characteristic of easterlies as the models successfully manage to balance the easterly energy from the Atlnatic and the westerly energy on the southern flank of the Scandi high. These models really are amazing applications of IT and we should all respect this despite the flaws!
Two other points I would like to make:
1) Aberdeen GFS ensembles now bullish on -10 C T850s for two to three days Thurs to Sat: similar t850s just before Xmas 2010 albeit a different synoptic pattern resulted in several days of heavy snow in Edinburgh and throughout central Scotland including 7 inches in Glasgow. We shouldn't under-estimate the intensity of Lake-effect snow with T850s of -10 C.
2) The ECM 12Z op is poor relative to the other output: it doesn't bring in as much cold air as UKMO and GFS which perhaps explains why the weekend blows away the cold. A big cold block is hard to shift and even when there are processes to erode the block, it takes time. While I cannot discount ECM, my recollections are that UKMO handles these Scandi-highs the best!
Exciting times I think. The easterly is not looking very dry now but there are disturbances in the easterly flow!