A low-lying west of the South Island is expected to move slowly east over central New Zealand later today.

An associated trough is expected to pass over the lower North Island and upper South Island, as the low progresses slowly eastward.

This trough is expected to bring further heavy rain and isolated thunderstorms at times to Taranaki and the upper South Island. This watch is for the possibility that accumulations could approach warning amounts about Mt Taranaki, the Richmond Ranges, and the Northwest Nelson Ranges.

However, the heaviest falls are likely to be confined to isolated places in thunderstorms and not covering a broad enough area to warrant a full warning.

The rain expected to ease from northern parts of the South Island this evening and Taranaki tonight.

People in the affected areas are advised to stay up to date with latest forecasts in the unlikely event that a full warning is required.