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Issued: 0900 GMT Monday 17th January 2005
Forecaster: Simon Keeling

Winter is set to return to the UK and Ireland during the next 24-48 hours as Arctic air floods across the countries. The Weatheronline Weather Centre is currently watching temperatures falling across all areas, it's 11C in Liverpool, but at Stornoway temperatures are already near 3C and it's sleeting.

And it's that cold air which is set to invade all places during Monday and Tuesday. Coming from a northwesterly direction, the air is relatively moist and this is going to bring snow. There could be blizzards across Scotland, Ireland and northern England, with snow showers throughout Wales and the Midlands. A covering of snow for many areas.

As a trough moves east on Tuesday there is a risk of further, more persistent snow, before milder air rushes in from the Atlantic, temporarily, on Wednesday,.

Meteorologists like to look at the temperature of the air away from the effects of surface heating. One of the most useful charts for this is the 850 millibar temperature (basically the temperature at about 5000ft). Today this chart clearly shows the cold air moving in.

If you have a look at these maps here and then click on "loop" you can see how temperatures across England and Wales are generally above freezing, although already they are down to -5C in western Scotland. As the loop runs watch the cold air streaming across the whole of the UK and Ireland, before things start to warm up slightly by Tuesday afternoon. Remember though, this is the temperature at 5000ft NOT at the surface!

You can also watch the rain turn to snow and then back again by visiting our Type of Precipitation maps. The triangular symbols indicate showers, black for rain, blue crosses for snow.

Our thoughts are also now turning to the weather this weekend. High pressure is indicated to build to the west of Ireland thus weekend. As this happens winds will turn back to the north, reintroducing colder weather.