Motorists travelling on the Glenshane Pass on Tuesday and Wednesday should do so with extra care and apprehension.
At the time of publishing, the pass was open, traffic was moving smoothly but drivers were being advised to stay vigilant.
The Met Office has upgraded a yellow status weather warning for snow and ice to amber. This means the likelihood of disruption arising from the snow is much greater.
"Snow showers will be heavy and frequent through the rest of Tuesday, gradually easing off during the early hours of Wednesday, with a further slow improvement expected through Wednesday daytime, as showers become less heavy and less frequent," reads the amber weather warning on the Met Office website.
"Some high ground is likely to see 15-25 cm building up, especially above 200-300 metres. At low levels throughout the warning area, 5-10 cm will be more typical. Showers will be accompanied by hail and lightning at times, while strong winds bring the potential for temporary blizzard conditions and drifting of lying snow, mainly over high ground."
The warning is valid between 3:00pm on Tuesday and 8:00am on Wednesday.