Rural Monthly Outlook:

Issued 13 June 2018

Potential for further rain for the eastern North Island next week

This is a special issue of the MetService Rural Outlook, following on from the recent heavy rain on the east coast of the North Island. The Government has declared a 'medium scale adverse event' around Tolaga Bay, Gisborne.

The Stats associated with the 12 June subtropical low

Pressures dipped to 988hPa at White Island, very close to the low centre as it peaked in the Bay of Plenty. Peak wind gusts recorded were 169 kilometre/hr at White Island, 105 kilometre/hr at Whakatane, and 100 kilometre/hr at New Plymouth.

Since noon Monday, 120-250mm of rain was recorded in the Gisborne Ranges, with patchy 80-250mm of rain observed in the Hawkes Bay Ranges. Coastal locations in both Gisborne and Hawkes Bay recorded much lower totals. For example, Tolaga Bay recorded 43 mm over the last 48 hours, and Gisborne City 62mm. Wairoa observed 72 mm of rain, while Napier saw 48 mm during the same period. Pahiatua recorded 50mm, and Dannevirke 39 mm. Parts of the Wairarapa also saw significant totals of more than 150mm. For example, Ngawi clocked up 173mm, Kaitoke 164 mm, while Masterton came in at 45 mm.

The next fortnight

Quieter weather is forecast for the next 48 hours. Northwesterlies spread across New Zealand from Friday, bringing showery weather to western areas, but a welcome drier run for the eastern North Island. It is likely that another broad (complex) low pressure area forms over the Tasman Sea later this weekend (17 June),and moves towards the North Island early next week. The effect of this low is to produce cold southeasterly winds across the east of the South Island at the start of next week, followed by a dry ridge of high pressure there for the remainder of next week. The low is likely to bring showers or rain across much of the North Island to begin the working week.

However, it is the potential for further southeasterlies and the risk of another deep subtropical low for the eastern North Island that we need to keep a close eye on. If this plays out around the middle of next week, expect further rainfall for the eastern North Island. Some of the models we monitor have a very wet signal for eastern areas, especially Northland and Gisborne. However, other models keep the subtropical low and most of its associated rainfall well offshore, away from the country.

If you live along the east coast of the North Island, anywhere between Northland and Hawkes Bay, it will be important to keep up with the MetService forecast and severe weather information next week (

Bottom Line

Next week looks very dry for the time of year in the west and south of the South Island. Closer to normal weekly rainfall totals are predicted for both the east of the South Island, and the west of the North Island, with a wet start to the week, but a dry finish. Eastern areas of the North Island signal wetter than usual, but there is currently a large spread in the forecast rain amounts because of the uncertainty around another subtropical Low.