The latest offering from the GFS model predicts a rather cold northwesterly airstream on Christmas Day, a bright looking day with wintry shower especially across northwestern areas. This brief cold snap may well be the last in a series of cold north or northwesterly incursions that you can trace back to the end of October (fig 1).
As so often happens between Christmas and New Year, the weather drastically changes in mood, and this year doesn’t fail to disappoint in this regard, as it turns progressively milder on Boxing Day, and by the start of 2018 its super mild across the British Isles and the bulk of Europe, if this chart for January 1st is to be believed (fig 2).
The GFS solution does contradict the latest extended outlook from the Met Office though, which suggests that in the final days of December “Temperatures will be near to or below average and snow is likely, at times”, they go on to imply that things might turn more settled and anticyclonic as we go into January 2018 (fig 3). As always, it will be interesting to see what transpires in a couple of weeks time.
Just a week ago the Met Office were saying in their extended outlook that the weather looked blocked into the New Year, just a week later they’ve changed their mind – well these are the days of climate change – it looks likely that the current regime of blocking and occasional northerly outbreaks of the last few weeks, will give way to a spell of more zonal, milder and windier weather before Christmas, although they do say that the New Year could see things turning quieter and more settled (fig 1).
The bullet list below is a quick look at the LWT for 12 UTC each day from the latest GFS model run, and things do seem to be turning milder and progressively more cyclonic well before Christmas.
12 Dec – W
13 Dec – W
14 Dec – CW
15 Dec – NW (last of the cold northerly outbreaks)
Curious choice of words in the extended outlook for Christmas and the New Year from the Met Office in this mornings forecast, I don’t think I’ve ever heard the word ‘benign’ used in a weather forecast before, but I suppose it does beat ‘changeable’.
The Met Office have now completed a 180° about-face regarding the second half of the December turning mild, and now admit that the weather over the British Isles for the next 30 days looks blocked well into the New Year (fig 1). If you remember they were postulating that mobility would return by the 15th of December, and that the rest of December would be basically wet, mild and zonal. I never believed December would pan out as they forecast in their 3 month winter outlook for contingency planners, so that suits me just fine. Don’t ask me why I thought that, I have no scientific reasoning to support it, I just knew that more often or not their extended outlooks and seasonal forecast are completely wrong. I did say that this Winter could end up being the equivalent of their ‘barbecue’ summer and I still believe that. Now all that we have to worry about is if this is just the start of a 1-5-5 or a 1-1-1 Winter!
I’ve recently found that one of the best ‘barometers’ (pardon the pun) off finding out the output from the Met Office NWP model is the 6-30 day extended outlook they update each day on their main forecast page of their website. This might seem really obvious to most, but for me it’s nothing short of a revelation on the inner thinking of the medium range forecasters just down the road in Exeter. The only reason that is so, is because of the paucity of NWP that the Met Office issue. Compare the PPVO89 fax chart that you can find with the barrage of graphical output that you can find on the internet from the GFS, ECMWF, ARPEGE, ICON, HIRLAM and sundry other NWP models, the quality of the graphics from sites such as WXCHARTS.eu far exceeds anything being produced on the old BBC graphics or by the Met Office’s new using Visual Cortex systems, anyway I’m rambling.
The latest Outlook issued early this morning is now no longer talking about a switch to milder weather from the middle of December that successive forecasts of the last week or so have been forecasting would happen (fig 2). This was probably because they were still trying to support the solution proffered in the three-month contingency forecast they issued on the 24th of November, which is already starting to look a little shaky. Basically what the medium range forecaster is saying is that the switch to a mild weather pattern that they had been expecting to happen in mid-December had disappeared, and that the UK could remain in a battle ground, with colder weather to the north and east, and milder weather to the south and west. It’s all still pretty bland and unspecific as it often is, but they’ve left nothing out of the extended outlook (bar the kitchen sink) in an effort to cover any eventuality that might crop up in the run up to Christmas.
The Met Office have said in their latest 3-month outlook, that the period between November and the end of January 2018 is likely to be mild and wet on the whole (fig 1 & 2). As usual, they’ve covered just about every other possible contingency with phrases such as:
When the MJO is in this phase it favours more blocked weather types…
…an increased chance of high pressure and a shift to cooler conditions in early November. (really cooler in November?)
…although some show more likelihood of high-pressure patterns over the North Atlantic implying a greater likelihood of northerly or north-westerly winds.
…there are also indications that blocking high-pressure patterns, possibly linked to the current MJO event, will
influence the UK during parts of the month (November).
…the risk of colder-than-normal conditions remain a significant possibility
…favouring weather patterns associated with colder-than-normal-weather
The best of luck to any contingency planner out there trying to make any sense of that.
Here’s are the forecast temperature and precipitation summaries from the Met Office for Summer 2017. They can be shortened still further – warmer than average with near average rainfall. It’s theusual bland mix of probabilities, that can only make sense to the contingency planners amongst us. You know what I think about the values of the three-month outlook in this format, so I won’t go on about it again. At least there’s no mention of what the barbecue index for this summer is likely to be.