The ridge of high pressure that brought mostly settled weather the past weekend is now set to move to the east of the country early this week. However, it then stalls to the east for much of this week and allows a warm northerly flow to spread on to the country. A frontal system within this northerly flow then becomes slow-moving over the west of the South Island and MetService Orange Heavy Rain Warnings have been issued.

MetService Meteorologist David Miller explains, “This front will bring significant accumulations of rain to northern and western parts of the South Island, with rain developing there overnight Monday into Tuesday. During this time, up to 500mm, and perhaps even higher amounts in places may be recorded, with the largest amounts expected in the ranges. Significant impacts can be expected, such as slips, flooding and rapidly rising rivers and streams.”

“This event is exceptional not just in its accumulation amounts, but also its prolonged nature, with heavy rain expected to continue in these areas right up until Thursday evening.”

MetService Severe Weather Meteorologists will be in close contact with regional council hydrologists and Civil Defence during this event and will collaborate to decide whether this Rain Warning will be upgraded to a Red Warning. Red Warnings are reserved for only the most extreme weather events and requires immediate action to protect people, animals, and property from the impact of the weather.

The North Island does not miss out on the severe weather either. During the second half of the week, the front is expected to move eastwards onto the North Island and heavy rain is likely in many parts of the island. Elevated areas such as Mount Taranaki, the Tararua Range and Central Plateau mountains are especially at risk of seeing impacts from heavy rain. Additionally, strong northeasterlies ahead of the front could affect exposed parts of the North Island.

A Strong Wind Watch and Heavy Rain Watch have already been issued for Northland, and further areas could be added in the coming days.

On a slightly more positive note, the frosty temperatures observed last week will be a distant memory, with temperatures expected to be warmer than average this week.

Looking ahead to this weekend, models are indicating that another front may bring yet more heavy rain to western parts of the South Island. This will be closely monitored by MetService meteorologists throughout the week.

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