Torrential rain reminiscent of Cyclone Gabrielle

The “atmospheric river” which pumped sub-tropical torrents over the district over the past couple of days. Image supplied

Torrential rain like Cyclone Gabrielle fell across the district in the past two days, causing widespread surface flooding and rivers to rise to warning levels.

The  downpour on Sunday night overloaded the capabilities of the city’s sewerage system, and the district council had to open the emergency valves and release sewage into the Tūranganui River at the Gladstone Road bridge.

The Medical Officer of Health, river users and others who  might be affected were notified, and signs posted at swimming and recreation sites.

The council advises no swimming, taking of shellfish from rivers or beaches for at least five days after the sewer valves are closed and the warnings removed.

The region would seem to have escaped without serious damage despite the deluge.

The Waipaoa River rose to the five-metre level just before midday yesterday and Gisborne District Council issued a flood warning.

Inland near Te Karaka, the Waikohu River rose from two metres to eight metres by midday.

The top end of the district and the Raukumara Range from East Cape down to Tolaga Bay had falls totalling several hundred millimetres over the period up to 10am yesterday morning.

The steep enclosed valleys around Mount Hikurangi saw the biggest falls, with the top end of Tapuaeroa Valley getting over 400mm, Raukumara Station over 344mm, Pakihiroa Station 257mm and Waikura Valley 218mm.

Further south, the north-facing hill country had anywhere from 100 to 160mm while around Gisborne city, totals averaged 60 to 100mm.

As of yesterday morning, an Orange Heavy Rain Warning was still in place, with more heavy rain expected as far south as Wairoa and Napier. The forecast to 11pm last night was for a further 70 to 100mm near the Coast and 100 to 150mm inland.

The severity of the rain was the result of a slow-moving front dragging down an “atmospheric river” from the sub-tropics, which MetService says will move away to the east by tomorrow.

Slips yesterday afternoon caused road closures on State Highway 35, Opotiki to East Cape at Omaio (no detour available); and just west of Opotiki on SH2 (detour available).

Waka Kotahi reported no other closures on the Coast and in other places such as  Waioeka which received over 280mm of rainfall by 3pm on Sunday.

With the soil resaturated, land movement will be a risk around the district, where there are still 28 repair projects from Cyclone Gabrielle, including eight total road closures from major landslides and bridges knocked out.

MetService says while the rain will clear away by tomorrow, the weather will remain unsettled, but the good news is that no serious weather event is expected for this region in the immediate future.