Winter proper may pounce upon us next week
December, the first month of winter, has delivered us storm after storm, leading to what has been the windiest month that the UK has seen since January 1993.
Not only have recent weeks been dominated by wind and rain, it has also been milder than average, with any colder interludes brief and not giving much in the way of snow.
However, that could be about to change, as the weather computer models are showing signs of a switch in the weather pattern into next week, with something more akin to winter a distinct possibility.
Whilst the detail is still subject to change, I thought I would take a look at what may happen and the reasons for it.
Jet stream changes
During the recent stormy spell of weather, the jet stream was extremely active – roaring across the Atlantic as fast as 230mph, five miles up in the atmosphere.
This was not only spawning vicious storms, but also catapulting them towards the UK as the jet stream acts as an atmospheric superhighway.
In the coming days, the jet stream is not only going to slow down a bit, but also meander quite far south towards Iberia and the Mediterranean.
This will cause low pressure systems to move to these areas instead of here and open the door to high pressure building across the UK and Scandinavia – allowing cold air to gradually move eastwards.
Battle of the air masses
Early next week, the UK could well find itself in the middle of a battleground between cold air to the east and mild air to the west.
The uncertainty at the moment lies in whether the cold or warm air will win. Today, the weather models are slightly in favour of the cold air winning, although this is still subject to change.
Will there be any snow?
Initially, rain may be more of a headache than snow. Whenever warm and cold air collides, weather fronts form, producing cloud and rain.
The concern for Sunday into Monday is that as the cold and warm air battle it out, a band of rain could become slow-moving, which would not be good news given that the ground is still saturated and river levels high – bringing a flood risk.
If the cold air does win the battle, the rain could start to turn to snow later on Monday, as the cold air starts to dig in from the east.
Temperatures are also likely to take a tumble, with widespread frosts at night and highs of 2-6C during the day by Tuesday.
So, there could well be a taste of winter proper next week, but again, it has to be stressed that there is still uncertainty with the detail.
Jet stream image: Wetterzentrale