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For the first time this winter, after a relentless spell of westerly winds, many areas are expected to see a general change to colder conditions as we head through the weekend and into next week.

As the colder air becomes established it will be competing with milder air from the Atlantic. Where the two meet, snow is likely, with western areas most at risk.

Here in Yorkshire there is a risk of some patchy snow later in the weekend and into monday mainly in western areas - although it is unlikely to be heavy. At the same time wintry showers may affect coastal areas.

But the exact location of this battle between cold air from the east and milder air from the west is still a source of uncertainty, and getting the detail right will cause problems.

Much of the country will then have a period of quiet, settled & cold weather as we head through next week, with sharp overnight frosts developing.

After that, the outlook remains a major headache for forecasters, as it has for some time. In fact I can't remember the last time there has been so much disagreement between the major forecasting models.

As I've explained before, each computer model runs many times, and each time the initial starting conditions of the atmosphere are changed by a very small amount, in order to see what happens.

An example of this can be seen below, from the American GFS model, from midnight.

It clearly shows that after a few days, when all the model runs are in broad agreement, each separate run of the model thereafter yields different results - with some solutions showing a 15 Celsius difference in temperature at 5000ft.

The latest information gathered so far today shows a shift away from the milder south-westerly scenario described above - but such run to run changes have been common this week and until there's more consistency it's impossible with any degree of confidence to determine which scenario will ultimately win.

That said, a cold early February is the more likely scenario.

Finally, since my blog has featured articles in the past about the merits of different private forecasting companies before, and how some newspapers often use their long range forecasts for front page headlines, I thought you might be interested in about Positive Weather Solutions which appeared in the Guardian yesterday.

Follow me on twitter @Hudsonweather.

The Northern Lights, or Aurora Borealis, featured prominently across the skies of Northern Britain last night. The fabulous photograph below, taken at the Tan Hill Inn in North Yorkshire, is courtesy of North news and pictures.

These atoms, having absorbed the energy from the collision, become excited; they then emit this energy which is seen by us as different coloured lights.

It's exactly the same process when a neon light glows when charged with electricity.

A pale green is the most common Northern Light, caused by the charged particles colliding with oxygen atoms.

Normally, most charged particles are directed no further south than 20 degrees from the North (or South) Pole, but during high solar activity, or a 'solar storm', auroras can be seen much further south.

It's not the first time we've seen Northern Lights recently, and it's all part and parcel of the general increase in solar activity in the last few months. This follows a prolonged period of very low solar activity in the last few years.

Experts believe there is a chance to see the Northern Lights again tonight by looking towards the northern horizon. Skies will be clear for much of the night, too.

As we head into the second half of winter, there's still no real indication of a change in the weather pattern that has so dominated the UK since winter began on 1st December.

Despite one or two short lived cold snaps, which brought some snow mainly to the hills of Northern Britain, many parts of the UK still haven't had any measurable snow at all.

So far it's been the turn of traditional meteorology, and the powerful supercomputers which produce most of our forecasts, which has given the best guidance this winter.

The European Centre for Medium Range Forecasting (ECMWF) - which produces arguably the most reliable short to medium range output up to 10 days ahead, offered a clear signal in October, that averaged over the 3 months of winter, temperatures would be close to average. And so far it's been spot on.

This was published at the time of tabloid headlines of another cold and snowy winter, based on several private weather companies who use at least in part solar considerations in formulating their forecasts.

The ECMWF forecast was largely ignored - after all who's interested in a headline which suggested winter would be average?

Climatology also offered some good advice, in that after three successive cold winters, the record books indicate having four cold winters in a row would be unusual for the UK - a point which I made on this blog in Autumn of last year.

So how are the next few weeks likely to pan out?

Our weather will continue to be unsettled through the rest of January, and still dominated by westerly winds.

Cold snaps are likely, as air is pulled in from a more northerly point at times, which would lead to some snow, particularly over northern hills - but as we've found so far this winter it's unlikely to be long lasting and crucially many populated areas other than in Scotland are likely to escape.

Further ahead, climate records give us an indication of what might lie in store in February.

They suggest that we could see a change to a colder, more anticyclonic 'blocking' type of weather, following such a long run of westerly winds.

Computer models have been hinting that a general change is possible, from the point of view that only slight changes in the initial atmospheric conditions have led to huge variations in what the computer expects our weather to be like 10 days ahead.

But if we do see the jet stream weaken and alter course which would lead to a change in our weather, it's just as likely to be uneventful as it is to be one where widespread heavy snow occurs. And that's unlikely to grab the headlines.

The Global temperature in December, according to the UAH satellite measure, showed little change from the previous month with an anomaly of +0.127C above the running 30 year mean, shown on the graph below.

For 2011 as a whole, the UAH global temperature was 0.149C above the 30 year running mean (or approximately 0.402C above the standard 1961-1990 mean).

This is considerably cooler than 2010's near record anomaly of 0.414C above the 30 year running mean - but it's still the 9th warmest on satellite record.

And that's despite the fact that global temperatures have been depressed by colder water in equatorial regions of the Pacific associated with la Nina, both during the early stages of the year, and again in the last few months.

Met Office figures released later this month are expected to show that 2011 was the 11th warmest globally in 150 years of temperature records.

UPDATE

High Bradfield, 1000ft high in the Pennines to the west of Sheffield recorded a gust of 93mph, very similar to that recorded in the powerful lee wave storm that affected Sheffield in February 1962. Other gusts in our area were in the range 60-75mph.

ENDS

The Met Office have again warned of severe gales into this evening and overnight across much of Eastern England from the Pennines to the coast, and the Scottish Borders to the Wash. Gusts could reach 70mph in more exposed areas.

This comes hot off the heels of yesterday's storm, more powerful than the one we suffered in early December, which can be seen on the NOAA satellite image below.

On 28th December winds again reached close to 100mph in parts of Scotland, so yesterday's even more powerful storm was the third in quick succession.

Wind speeds across some parts of the UK were quite exceptional, with 102 mph recorded at Edinburgh Blackford Hill.

And at Malin Head in Northern Ireland, not only did gusts reach 105 mph, but a new record mean speed of 78 mph was observed - Hurricane force 12 on the Beaufort scale.

Although our weather is normally dominated by westerly winds in winter, they have been unusually persistent and strong through December and into January. The jet stream, which is responsible, has been a very powerful feature, but it is positioned where it should be at this time of the year.

Because of the position and strength of jet stream, according to Philip Eden writing in the Sunday Telegraph, December was the second most 'westerly' in 139 years of records.

Interestingly it could be that after the last few years when the jet stream has at times been disrupted and pushed further south than normal, possibly because of an unusually weak solar cycle, that this is the beginning of a more 'normal' weather pattern becoming established through 2012.

On the subject of the recent spectacular failings of long range forecasts issued by several private weather companies, today's article on that subject by George Monbiot of the Guardian is well worth a read,

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