NETWORK RAIL has deployed frontline teams in north west England, western Scotland and Wales as Storm Jonas approaches across the Atlantic.
The weather system has dumped almost record levels of snow in a number of American states, but it is expected to bring winds and rain, rather than snow, when it makes landfall here.
Even so, flooding is likely in areas which are still saturated after the heavy rain of the past few weeks, and with high winds forecast when the storm arrives, speed restrictions are likely in North Wales on the line from Chester to Holyhead.
Network Rail said: "We are preparing for the worst while of course hoping for the best. With a lot of rain expected to fall on already-saturated areas, flooding is likely. And in some places repairs are still taking place following damage from the last storms.
"As you'd expect, we're drafting in additional frontline staff to tackle any potential problems that may arise. Our advice to train passengers is check before you travel on nationalrail.co.uk, so you know what to expect."
Meanwhile, the West Coast Main Line remains closed at Lamington viaduct near Lockerbie while Network Rail continues to repair previous storm damage, while teams are also at work repairing various embankments in Cumbria and Lancashire. In Wales, the Conwy Valley line remains closed after floods over Christmas. Record rainfall caused damage at more than 100 places on the line between Llandudno Junction and Blaenau Ffestiniog. Network Rail hopes to re-open the route by the end of February.