"Rain will extend eastwards to all parts on Monday night, turning to sleet and snow, with snow depositions likely over the midlands, north and east".
It applies from Monday at 6pm to Tuesday at 6am and warns of "falls of snow from Monday evening, with accumulations totalling up to 3cm possible in some areas, leading to treacherous road conditions by Tuesday morning".
So we should probably expect that national weather warning to be extended beyond Tuesday before too long.
Mr Snell said the working week would start on a "bitterly cold" note, with people across the United Kingdom waking up to temperatures between 0C and -2C (32-28.4F), dropping to -7C in sheltered parts of Scotland and spots most prone to the cold in the Midlands and Wales.
That's expected to spread across the rest of England, Wales, Scotland and Northern Ireland on Monday and into Tuesday and Wednesday.
Temperatures could plunge into the minuses in the capital and as low as -10 in parts of Scotland.
The forecast for the south east is for scattered wintry showers tonight, with icy surfaces expected, and brisk easterly winds persisting on the Kent coast.
After a bout of dismal and damp conditions today, the weekend will end on a frosty note while the spell of rain, sleet and snow moves in across the UK. Maximum temperature 4 °C. Dry, often sunny on Wednesday, but remaining cold with overnight frosts.