BBC monthly outlook
Monday 23 October—Sunday 29 October
A brief warm spell in the south, perhaps?
The working week will begin on a rather cloudy note for most parts as an Atlantic weather front slowly moves from west to east, bringing outbreaks of rain. Through Monday afternoon clearer skies will push in from the west, bringing a bright end to the day for all with lighter winds than of late.
Through Tuesday and Wednesday, a distinct north/south split in weather conditions is anticipated to develop across the UK. A conveyor of warm and moist Atlantic air will spread into the southern half of the UK from the southwest in the form of a waving weather front. The exact form and position of this front is posing a significant problem for forecasters at present. However, at the time of writing the general consensus is that the wettest weather will be across parts of southwest England and Wales, with southeast England and East Anglia remaining largely cloudy with occasional spells of rain. Further north, skies will often be brighter, but frequent showers and blustery winds will likely affect Northern Ireland and Scotland at times.
Through Thursday, an uncertain jet stream developments out in the mid-Atlantic which will have the affect of backing winds to southerlies. The resulting warm southerly winds will likely push the aforementioned waving weather front north into Northern Ireland and Scotland, bringing rain to these areas. There will be warmer, humid and generally cloudy conditions across the southern half of the UK. Should cloud break in the south though, we could register temperatures into the low 20s in one or two spots.
Through Friday and into next weekend, it currently looks as if any warm spell in the south will be relatively short-lived. This is due to a developing jet stream, this time to the north of the UK, pushing the same weather front all the way south and east again, opening the door to some fresh north to northwesterly winds and showers for the weekend. Showers will be most frequent in the northwest.
Monday 30 October—Sunday 5 November
Settling down? Not for Long!
At time of writing, the latest computer forecasting models suggest that the last few days of October will likely end on a showery note as an area of low pressure to the east of the UK influences our weather. Such a weather set up will also likely result in a reasonably brisk north to northwesterly wind, giving distinctly average temperatures, and perhaps a cool feel at times. At the same time, the majority of models hold a ridge of high pressure just to the west of the UK. There is a small chance that this ridge of high pressure may just drift eastwards closer to or in fact over the UK, which would allow for a brief spell of dry and bright weather by day, but also with accompanying chilly nights and patchy overnight frost and fog.
Regardless of whether the ridge brings a brief drier spell, eventually, as we move into the first full week of November, the majority of model output hints on the resumption of a theme of westerly winds. Further Atlantic weather fronts are expected to sweep in from the west to bring unsettled weather to all parts of the UK at times.
Monday 6 November—Sunday 19 November
Becoming drier and chillier into November?
There is always a significant degree of uncertainty in longer term weather forecasts, and this week's attempts are no exception. That said, our models are giving a weak indication that as we head into mid-November, the Atlantic jet stream will weaken slightly and begin to meander further north and south. Such positioning of the jet will likely mean that pressure will tend to be higher than average near or over the UK. An high pressure in the vicinity of the UK during November often results in drier than average conditions, with chilly nights that often yield frost and fog. So, as we head into mid-November, at time of writing, the feeling is that we could be in for a spell of bright and dry days, with a few chilly nights.
A natural phenomena which we can observe across the other side of the world is lending weight to the forecast described. The Madden Julian Oscillation (or MJO) is a climate system that, broadly speaking, occurs in a cycle across the Indian Ocean and Pacific Ocean. Identifying patterns in rainfall across this area of the globe can give forecasters insight into how weather conditions will likely pan out nearer to our shores in a few weeks' time. Analysis of the current phase of the MJO would suggest a build of pressure near the UK by mid-November, which ties in nicely with computer model predictions. We will of course keep you updated as to how the forecast develops here at the BBC Weather Centre.
Next week
Will there be any sign of really cold weather for the end of November in the next edition of the monthly outlook? Stay in touch with the BBC Weather Centre to find out the details.
http://www.bbc.co.uk/weather/2635167#outlook