BBC Monthly weather forecast updated today:
http://www.bbc.co.uk/weather/2635167#outlook Monthly Outlook
Summary
A new year, a new weather set up?
The final week of the old year closed on an exceptionally wet and mild note. Unfortunately, a series of heavy rainfall events through December brought extensive flooding across the north and west. Met Office statistics show that December 2015 was the wettest December on record for Scotland and Wales, with parts of Northern Ireland and northern England also beating December rainfall records. December 2015 was also exceptionally mild, smashing the previous December record set in 1934.
A warmer atmosphere carries a greater amount of moisture, and prevailing mild southwesterly winds through December brought the devastating rainfall. But why were conditions so mild?
El Nino is a meteorological phenomenon whereby every few years part of the Pacific Ocean becomes warmer than normal. An El Nino often results in a mild and wet start to the UK winter. It is difficult for climatologists to directly link any one particular weather event to natural cycles of atmospheric variability such as El Nino, and longer term effects such as global warming, but historical data and computer models suggest that such factors increase the likelihood of a persistent Atlantic southwesterly jet stream, such as that which has brought so much mild and moist air to our shores through December.
So what about 2016? Can we expect any change in the weather?. Well, the good news is that an anticyclone has developed over Russia, resulting in a block of cold air over eastern Europe and Scandinavia. This cold high has re-orientated the jet stream and steered it south of the UK. We can therefore expect further wet and windy conditions. However, the crucial difference between December and January is likely to be that because of the jet streams more southerly track, the warm tropical air that brought so much rain will likely be replaced by less mild air. The cooler air will hold less moisture, so the impact of these storms will probably be less severe.
Monday 4 January—Sunday 10 January
Wet and windy again ... but not as extreme.
A large area of low pressure will dominate the UK weather during the early part of this week. Most places will see plenty of showers through Monday and Tuesday, with strong winds for the far southwest and far northeast. Prolonged rainfall that occurred through weekend across eastern Scotland and northeast England is likely to continue for a time, leading to the threat of some localised flooding issues across some northeast parts of the UK. Any precipitation could turn wintry over the high ground of northern Scotland and perhaps Northern Ireland for a time.
By midweek, a transient ridge of high pressure will edge in from the west, resulting in a chilly start on Wednesday morning, particularly across Northern Ireland, western Scotland, northwest England and Wales where frost is likely. Wednesday is likely to be the driest day for many part of the UK, although further showers are possible.
Through Thursday, another Atlantic weather system will push through most places form the west, potentially bringing a brief spell of transient sleet snow to the hills of northern England, Northern Ireland and Scotland.
Into the weekend, further spells of wet and windy weather are anticipated.
Temperatures will be nearer to average compared to the recent mild weather, with coldest weather always more likely to the north.
Monday 11 January—Sunday 17 January
No real sign of any significant change
The remainder of the first half of January will stay wet and windy for much of the time as Atlantic weather systems continue to spill in from the west. The windiest conditions will most likely be across western and particularly southwestern areas. Most of the rain is expected to fall across western areas, with the best chance of drier interludes to the east. There will be some brief incursions of colder air from the north in between weather systems, during which clearer and drier conditions are anticipated. These brief colder spells may well increase the chance of some snowfall to high ground across central and northern parts of the UK.
Monday 18 January—Sunday 31 January
A chance of a lengthier dry spell ... for some
As we move into the second part of January, some of the tools we use for medium range forecasting are suggesting the possibility of some drier conditions for eastern areas of the UK for a time. That said, even these drier interludes look likely to be interrupted now and then by the wet and windy spells that will persist in western areas throughout the period. Toward the end of January, most of the computer models hint at a return to wet and windy conditions for all parts of the UK. Temperatures look likely to be near or slightly above average through the second half of January, with the coldest air again confined chiefly to the north.
Next week
Next week's issue will cover the early part of February. With two of the three winter months having passed without a lengthy cold spell, we'll try to find out if there is any weather more akin to a typical winter on its way.
Monthly forecasting
The weather beyond about a week ahead stretches even the most experienced weather forecaster. Complex numerical weather forecast models from the Met Office and the European Centre for Medium-Range Weather Forecasts (ECMWF) are run many times for the month (and season) ahead to build up a picture of the likelihood of different weather types affecting the UK.
Next update at 10:00, Monday 11 January
Home Location - Kellands Lane, Okehampton, Devon (200m ASL)
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Sean Moon
Magical Moon
www.magical-moon.com