National Rail says it expects snow and ice across the UK will impact the rail network throughout the morning.

The six Met Office yellow warnings cover all of Northern Ireland, most of Wales, north and west Scotland, and the east coast, central and southern England.

Right now, trains between Llandudno and Blaenau Ffestiniog have been suspended and replaced with buses on the Transport for Wales network.

They explain how snow and ice can affect the railways:

• Snow built up on the tracks can block points (the equipment that allows trains to move between tracks)
• Ice can coat the overhead power cables, preventing trains from drawing the power they need to run and leaving them stranded
• Icicles on tunnels, bridges and other structures can also damage trains and overhead power cables
• Where snow lies deeper than 30cm, trains can’t run safely unless they have been fitted with snow ploughs

It’s a chaotic start to the morning on the Tube.

• London Overground: Severe delays Sydenham to West Croydon while we fix a points failure at Selhurst
• District line: Severe delays due to an earlier points failure at Plaistow
• Hammersmith & City line:  Severe delays due to an earlier track fault at Plaistow
• Metropolitan line: Severe delays Moor Park to Harrow-on-the-Hill, southbound only, due to an earlier points failure at Northwood
• Piccadilly line: Severe delays Hammersmith to Uxbridge while we fix a points failure at Northfields
• Jubilee line: Minor delays due to a shortage of trains