Reporting the wintry weather
Autumn 2009 started on a mild note and many of us may have been thinking that winter might just let us off the hook.
However, with winter officially starting in less than a week's time we are looking at the weather turning wintry too.
Throughout October and November the UK was under the influence of warm air with subtropical origins, this kept temperatures above average and brought notable amounts of rainfall.
In contrast and since the weekend we've seen a shift in the source of our air; from a warm southern ocean to a cold eastern continent.
Thanks to the dominance of high pressure we'll be bringing in air that's travelled from the bitter plains of Russia, delivering a biting wind and temperatures that struggle to get above freezing.
So it's going to be cold, is it going to feel cold?
How we interpret temperatures varies according to a number of factors, chiefly the humidity of the air and strength of the wind. These combine to produce a phenomenon widely termed "wind chill" and provide a scale by which we can measure what the temperature "feels like".
The brisk and dry easterly wind this week will make the temperatures feel quite different. For example an east coast day time maximum of 2C may actually feel like -2C once the wind chill effect has been accounted for.
When these values are significant we'll be doing our best to highlight them in our broadcasts so keep your eyes peeled.
Meteorologists often talk about broad areas of air with common characteristics.
Air masses as they are collectively known move large regions of air with similar temperatures and humidities about the globe. They receive their attributes according to whether they form over warm or cold land or oceans.
We've been working on a way to illustrate this technical piece of data as a clear and representative graphic. We think this new graphic does a good job of showing why it's going to get colder or warmer because it shows where our air is coming from.
By showing the movement of the mass of cold air, represented by shades of blue, we can describe one of the mechanisms influencing temperature and get an insight into the incredible forces at work within the atmosphere (we'll be trialling this on Weatherview over the coming weeks).
And it doesn't stop there, the movement of the blue colours also reveals another property of the cold air; its potential to produce snow.
So what about the white stuff? Well some areas are certainly in for a light covering over the next few days but the regional details are particularly important; many western parts of the country are likely to be wondering what all the fuss is about.
To keep abreast of the latest forecast for your region the BBC Weather website provides local video forecasts as well as a detailed five day outlook.
If you're interested in anything a little further away (a white Christmas or wet New Year maybe?) the Monthly Outlook gives our best guess of the next four weeks and how conditions are likely to vary.
We hope the additions to our winter forecasting armoury will give you a better idea of why the weather is varying and also help to keep you better prepared.
Of course, you'll still need to look out for the specific details of rain, wind, frost, fog and temperature, all of which can combine to provide hazardous winter conditions.
Jumpers at the ready.
Richard Chapman is editorial manager of BBC Weather.