Rare bursts of 'thundersnow' could strike the UK within hours thanks to a mix of wintry and stormy conditions.
Unsettled weather will begin to sweep across the country on Tuesday, with the Met Office forecasting showers in the south and snow in many northern areas.
Yellow warnings for snow and ice applied by the agency will cover an area stretching from Manchester up to the Shetland Islands, meaning some disruption is possible.
Weather radar maps from WXCharts meanwhile showed large fronts of often torrential rain arriving from the Atlantic in several waves over the next few days, with this also expected to fall as snow in places.
This combination - brought on in part by the after-effects of Storm Elliott in North America on the jet stream - has prompted the possibility of thundersnow being witnessed in the British Isles yet again this month.
The rare phenomenon occurs when thunderstorms are whipped up in wintry conditions, and was last reported in Aberdeenshire on December 8.
If thundersnow occurs at night, the lightning appears brighter as the light reflects off the snowflakes, according to the Met Office.
Over in Ireland, the country's official meteorological agency Met Eireann has pinpointed December 29 as the most likely date for thundersnow, forecasting that showers will be "falling as sleet and snow on hills and with thunder at times".
The Met Office, meanwhile, expects the disruption of the jet stream by Storm Elliott to have a clear - if relatively mild - effect on our weather in the run-up to the New Year.
Deputy Chief meteorologist David Oliver said: "The jet stream will help to develop low-pressure systems which are likely to affect the UK between Christmas and New Year.
"These will bring some wet and windy weather at times and the chance of some snow in the north of the UK, as is often the case at this time of year."
UK weather forecast:
Snow in the north today, otherwise unsettled and often mild.
Today:
Milder, wetter, windier weather moving northeastwards. Some heavy rain across western hills but snow more likely for parts of the north, especially hills in northern Scotland. Drier in west later.
Tonight:
Rain clearing east but probably lingering in the far north. Elsewhere, a lot of dry weather developing but rain in the south later. A patchy frost in the north.
Wednesday:
Rain returning north through the day, heaviest over hills in the southwest. Showers following later, locally heavy. Windy with coastal gales in the south. Mild away from the north.
Outlook for Thursday to Saturday:
Unsettled with blustery showers Thursday, heaviest/most widespread in the north and west. After a dry start Friday, further wet and windy weather will cross all areas, clearing to showers Saturday.
