BBC monthly outlook
Summary
A wet & windy late October. Cold snaps in November
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Saturday 31 October – Sunday 8 November
A transition from wet & windy to drier & calmer.
A barrage of active Atlantic fronts and deep low pressure systems will continue to dictate our weather through this weekend and into Monday. The remnants of ex-Hurricane Zeta and the associated extra warmth and moisture from the tropical Atlantic will help to fuel the intensity of some of the low pressure systems, leading to copious heavy rainfall in the west and frequent strong winds.
Saturday will be a windy day for us all, with the prospect of gales over western areas, with gusts over 60mph in exposed areas, locally around 70mph along the west Wales coast and some of the hills and headlands of western Britain and Ireland. A broad band of heavy rain will sweep eastwards over all parts, but sunnier skies will come into south-western parts of the UK in the afternoon, leading to a drier interlude.
More wet and very windy weather on Sunday and Monday too, with the heaviest rainfall focused again over western parts, and strong winds from the south-west. Sunday night into Monday will see widespread wind gusts over 45mph, even inland over southern England.
A change to a colder and more showery weather pattern on Tuesday, with brisk winds from the north-west. But then a dramatic change to calmer, drier and sunnier weather from Wednesday and Thursday onwards, as high pressure builds. Cold nights with some local frost and dense fog patches, but milder and still quite sunny weather towards next weekend, as southerly winds freshen.
Monday 9 November – Monday 16 November
High pressure overhead. A quieter side to Autumn.
Extensive ridges of high pressure are expected to remain influential across most of the UK, with a continuation of a drier and calmer than average weather pattern for November, especially in the south.
The days are short and the nights are long in November, with the sun increasingly low in the sky, especially in the early to mid-mornings and again by mid-afternoon.
With a lack of mild air flowing across the UK from the Atlantic, it can get pretty chilly under the high pressure ridges, especially at night. Frost is likely where skies are clear for a few hours overnight. Patchy fog is likely to form too, some rather dense. The weather will be pleasant at times, with some late autumn sunshine breaking through. Other days, blankets of cloud will spread in from the North Sea and sit across the UK all day, leading to overcast and rather dull and dank conditions.
Over northern Scotland, a stronger westerly wind flow could still be close enough to bring in some fronts and windier and wetter weather.
However, these conditions will tend to fade with time, as high pressure extends further north and west during the second half of the week.
Tuesday 17 November – Sunday 29 November
A greater chance of some cold air from the north.
In some of our recent updates, we have been mentioning the prospect of some cold northerly plunges occurring as we head deeper into autumn. With a La Nina event ongoing in the Pacific (a vast area of cooler than normal sea surface temperatures over the central and eastern tropical Pacific ocean), then the UK can often see an increase in the frequency of northerly winds in late autumn and early winter.
But the latest forecast computer models are very opposed with regards to how the second half of the month will play out and this reduces the confidence in the forecast. In this situation we have to look for trends in the individual models over their last few updates. We also have to bear mind how skilful they tend to be at predicting certain weather patterns correctly, based on their past performance.
Our preference remains for there to be more extensive high pressure than we have seen for a few weeks over the north Atlantic and up across Iceland and Greenland. This help to steer Atlantic low pressure systems southwards over Scandinavia and eastern Europe, while pulling down colder air from the Arctic towards the UK. This increases the likelihood for some frosty nights, cold day and the potential for wintry showers.
However, we also don't think that there will be a solid 2 weeks of cold weather either. We saw this during the second half of November 2010, which led into the remarkably cold and snowy December of that year.
This November, we think the cold weather will come down from the north in several pulses. Brief interludes of milder and quite unsettled weather are expected between them, but sustained periods of unusually mild weather seem unlikely.
Further ahead
The second half of November is still very uncertain, with some conflicting signals in today's guidance. The update next week will assess whether there are more definitive indications of how the late November patterns will evolve.
https://www.bbc.co.uk/weather/outlook