The yellow alert has been issued for snow between 3am and 3pm in all but the coastal fringes of the county.
The spell of snow is expected to extend across parts of Scotland and the northern half of England.
A separate amber warning is in force for parts of northern England. Some roads and railways will be affected leading to longer journey times by road, bus and train services. Some delays to air travel are also expected.
The chief forecaster said: "A band of rain, heavy at times, is expected to move eastwards over the UK on Friday. With cold air in place, a spell of snow will develop on its leading edge. Above around 100 metres, 2-5cm is possible quite widely and above 250 metres, accumulations of 10-15cm are possible. At low levels, snow will be more variable with 0-3cm possible. The warning has been updated to include the Central Lowlands as well as the north Midlands."
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A Met Office yellow warning means severe weather is possible over the next few days and could affect you. You should plan ahead thinking about possible travel delays, or the disruption of your day-to-day activities. The Met Office is monitoring the developing weather situation and yellow means keep an eye on the latest forecast and be aware that the weather may change or worsen, leading to disruption of your plans in the next few days.