Heavy rain warning for Saturday issued by MetService

A heavy rain watch at yellow level for Saturday was upgraded at 8.25pm Friday to an orange-level warning for Tairāwhiti north of Gisborne city until 5pm Saturday. 

The Met Service had said periods of heavy rain may approach warning criteria but there was a “low chance” of upgrading to a warning. 

In the upgraded warning - for the 14 hours from 3am to 5pm Saturday - it said to expect 70 to 90mm of rain, especially north of Tolaga Bay.

Peak rates of 10 to 15mm/h were expected from late Saturday morning.

MetService said there was minimal chance of upgrading to a red warning.

The rain is coming from a deep subtropical low brushing past the North Island. 

Tairāwhiti Civil Defence has been monitoring the situation. 

The development of the low was likely to be classed an “explosive cyclogenesis”, known colloquially as a “weather bomb”. 

“It’s when a low develops very quickly, often associated with intense weather near it,” the MetService said, adding that it looked to be remaining well offshore and should pass quickly, with a brief reprieve on Sunday before a new weather system brought showers to the North Island and parts of the South Island. 

Ahead of the approaching weather system, work to keep the Wairoa River mouth clear was given the go-ahead by Hawke’s Bay Regional Council on Tuesday. 

MetService said likely impacts of the rain were that streams and rivers may rise rapidly. Surface flooding, slips and difficult driving conditions were possible.

Residents were advised to clear drains and gutters to prepare for heavy rain, avoid low-lying areas and drive cautiously.

The update at 8.20am Saturday is:

Heavy Rain Warning - Orange
Area: Tairāwhiti/Gisborne north of Gisborne City
Period: 9 hours from 8:00am Sat 20 Jul to 5:00pm Sat 20 Jul
Forecast: Expect 40 to 70 mm of rain on top of what has already fallen, with the largest amounts likely north of Tolaga Bay. Peak rates of 10 to 15 mm/h.
Minimal chance of upgrading to a Red Warning.