Dunedin's Northern Motorway and the Haast Pass now have dedicated MetService snow warning systems.
The roads, both subject to extreme weather, have been added to the organisation's road snowfall warning system, which is available on its website.
New Zealand Transport Agency Otago Southland journey manager Graeme Hall said that meant more specific forecasts for the roads.
For the Northern Motorway for instance, the MetService would predict how much snow was expected on the Leith Saddle.
The new forecasts, which would be on the organisation's website and be disseminated through media, were the latest additions to a service that included the Lindis Pass Rd, Rimutaka Hill Rd, Milford Rd, Arthurs Pass and Lewis Pass.
Warnings were issued when there was a likelihood of snow settling on one or more of the roads.
The lead time for those warnings was usually between 48 and 24 hours.
The probability of snow was predicted by the MetService's specialist weather services team, made up of its most experienced meteorologists using atmospheric models, observational data and snow forecasting techniques developed in-house.
Mr Hall said the system would provide road users with greater guidance and certainty in planning their journey when severe winter weather was looming.
It would also help address road user requests for better and more detailed road disruption warnings during snow and ice events.
