Apologies for my lack of posts this week; I've had a nasty cold and haven't felt sufficiently clear-headed until today to attempt anything beyond a brief comment. If all goes well, I'm intending to post my next 'lesson' on Monday, which will be on the Norwegian Model of cyclogenesis - formation of fronts within a low pressure system.
As for the computer models, it seems that there will be a warm-up from later today (in the west and north-west), spreading east during tomorrow, accompanied by a fair bit of rain. It won't last for long in the east or in the central UK, though, as, by Tuesday, the weakened fronts will be retrogressing (moving against the usual zonal flow - in other words east to west rather than west to east), which will reintroduce chillier but largely dry weather, with variable cloud amounts and moderate overnight frosts. JohnnyO and others in the north-west of the UK may well stay wetter and milder, though, as the anticyclone that has brought us the cold spell seems likely to position itself over the south and east of the country next week, allowing weak fronts to head up the western fringes from the south-west, before they roll over the top of the high and drift away to the east.
Beyond next weekend, there's a significant degree of uncertainty. Until this morning, mild south-westerlies or a slack area of high pressure over the UK seemed the most probable eventualities; however, there is now a tentative signal for a possibility of something colder from the north, given that the Atlantic is very quiet at present, with a weak polar front jet resulting from a flabby polar vortex. What's causing the uincertainty is that the only sizeable 'lobe' of the vortex is heading from west to east to our north over the next few days, shifting from the central parts of Canada to Siberia. Short-medium range deterministic models always struggle with the effects of such pattern changes on small areas of the northern hemisphere in the mid-high latitudes, and this case seems to be no exception.
