NZ Historic Weather Events Catalogue
July 1998 New Zealand Flooding ( 1998-07-01 )
Heavy rain fell in Waikato, Bay of Plenty, Wellington, Marlborough, Tasman-Nelson and the West Coast, bringing flooding and slips to some places. Te Kuiti recorded rainfall with a return period of over 100 years.
New Zealand
Multi Hazard
Duration: 2 days - From the 1st to the 2nd of July.
On the 1st, a deep, complex depression developed in the northern Tasman Sea. A strong northerly flow developed ahead of this depression, dragging moist, humid air towards New Zealand. On the 2nd, an associated cold front crossed the North Island. A very strong, moist northerly flow ahead of the front was responsible for the heavy rain in northern districts, and the wind flow was at the ideal angle of onshore flow into the Bay of Plenty region. A cold southerly change followed the depression as it passed to the east, and this brought the period of heavy rain to Wellington that day.
Flooding
On the 1st and 2nd, a northerly storm moved across the North Island, bringing floods to a number of districts.
Heavy Rain
High rainfall occurred throughout Coromandel, Bay of Plenty, Tongariro, Taupo, Buller, Golden Bay, Marlborough and Nelson on the 1st.
Some places received over 200 mm (20.0 cm) of rain.
Heavy rain was initially in the northerly overnight on the 1st/2nd and then in a more serious southerly in late morning on the 2nd.
North Island
Multi Hazard
at
North Island
A blocking anticyclone to the north-east of the North Island and a low pressure area to the west. Surface airflow was predominantly from the north-west. A combination of abundant moisture and high winds on northern slopes resulted in orographical enhancement producing widespread precipitation throughout Waikato and the Central North Island.
South Island
Heavy Rain
at
South Island
The northerly rain storm's initial impact occurred in the South Island's West Coast, Nelson and Marlborough.
Waikato
Flooding
at
Waikato
A sequence of storm events over the catchments of Lake Taupo and the middle reaches of the Waikato River led to extensive and prolonged flooding downstream of Hamilton.
The July 1998 events were extreme, with return periods of inflows to the Waikato between Taupo and Karapiro between 15-80 years.
The Mangakino and Waipapa catchments on the western side of the river experienced record floods, nearly twice as large as any recorded in the previous 35 years.
Return periods between 2-10 years were common for the Waikato tributary area (between Lake Taupo and Karapiro).
Return periods for the Rangitaiki and Tongariro catchments were as high as 20 years.
The events occurred in winter, meaning enhanced catchment wetness and potentially greater runoff, and intense rainfall was very localised.
Heavy Rain
at
Te Kuiti
The Te Kuiti gauge recorded a three-day rainfall with a return period of 33 years.
The Te Kuiti gauge recorded a seven-day rainfall with a return period of 100 years. >>100 years at 14 days)
The Te Kuiti gauge recorded a 14-day rainfall with a return period of more than 100 years.
Wellington
Multi Hazard
at
Wellington
Both State Highways out of Wellington were affected by slips and floods on the 1st.
Flooding
Sewerage problems occurred in Wellington on the 1st.
Marlborough
Multi Hazard
at
Marlborough
The worst affects were in rural areas of Nelson and Marlborough Sounds. Flooding and slips affected properties.
Rivers ran high, and flooding and slips affected roads.
Tasman-Nelson
Flooding
at
Tasman-Nelson
Sewerage problems occurred in Nelson on the 1st.
Multi Hazard
The worst affects were in rural areas of Nelson and Marlborough Sounds. Flooding and slips affected properties.
Rivers ran high, and flooding and slips affected roads.
West Coast
Multi Hazard
at
West Coast
Flooding and slips affected properties.
Rivers ran high, and flooding and slips affected roads.
Heavy Rain
at
Ahaura River
Ahaura recorded daily totals for seven days prior to the event of: 70 mm, 68 mm, 0 mm, 0 mm, 0 mm, 23 mm, and 20 mm.
Ahaura recorded a maximum intensity of 7 mm (0.7 cm) - the highest one hour rainfall intensity recorded in the 48 hours prior to event peak.
Flooding
The Ahaura River at the Gorge recorded a peak level of 4.254 m on the 1st (Return Period approximately two years).
Flooding
at
Dobson
The Grey River at Dobson recorded a peak level of 5.441 m on the 1st (Return Period approximately two years).
Heavy Rain
at
Moana
Moana recorded daily totals for seven days prior to the event of: 80 mm, 33 mm, 0 mm, 0 mm, 1 mm, 33 mm, and 33 mm.
Moana recorded a maximum intensity of 7 mm (0.7 cm) - the highest one hour rainfall intensity recorded in the 48 hours prior to event peak.
Heavy Rain
at
Waipuna
Waipuna recorded daily totals for seven days prior to the event of: 56 mm, 59 mm, 0 mm, 0 mm, 0 mm, 21 mm, and 12 mm.
Waipuna recorded a maximum intensity of 8 mm (0.8 cm) - the highest one hour rainfall intensity recorded in the 48 hours prior to event peak.
Flooding
The Grey River at Waipuna recorded a peak level of 4.053 m on the 1st (Return Period less than two years).
References
- Henderson, R.; Thompson, S. Waikato Tributary floods of July 1998.
- Major weather events in New Zealand, Floods and Rainfall, Floods to 30 Sep 2005.
- Major weather events in New Zealand, Floods and High Rainfall, Floods to 31st July 2006.
- Major weather events in New Zealand, Floods and High Rainfall to 31st May 2006.
- www.metservice, notable weather events.govt.nz.
- Southland Regional Council (CD).
July 1998 New Zealand Flooding ( 1998-07-01 )
Heavy rain fell in Waikato, Bay of Plenty, Wellington, Marlborough, Tasman-Nelson and the West Coast, bringing flooding and slips to some places. Te Kuiti recorded rainfall with a return period of over 100 years.
New Zealand
Multi Hazard
Duration: 2 days - From the 1st to the 2nd of July.
On the 1st, a deep, complex depression developed in the northern Tasman Sea. A strong northerly flow developed ahead of this depression, dragging moist, humid air towards New Zealand. On the 2nd, an associated cold front crossed the North Island. A very strong, moist northerly flow ahead of the front was responsible for the heavy rain in northern districts, and the wind flow was at the ideal angle of onshore flow into the Bay of Plenty region. A cold southerly change followed the depression as it passed to the east, and this brought the period of heavy rain to Wellington that day.
Flooding
On the 1st and 2nd, a northerly storm moved across the North Island, bringing floods to a number of districts.
Heavy Rain
High rainfall occurred throughout Coromandel, Bay of Plenty, Tongariro, Taupo, Buller, Golden Bay, Marlborough and Nelson on the 1st.
Some places received over 200 mm (20.0 cm) of rain.
Heavy rain was initially in the northerly overnight on the 1st/2nd and then in a more serious southerly in late morning on the 2nd.
North Island
Multi Hazard
at
North Island
A blocking anticyclone to the north-east of the North Island and a low pressure area to the west. Surface airflow was predominantly from the north-west. A combination of abundant moisture and high winds on northern slopes resulted in orographical enhancement producing widespread precipitation throughout Waikato and the Central North Island.
South Island
Heavy Rain
at
South Island
The northerly rain storm's initial impact occurred in the South Island's West Coast, Nelson and Marlborough.
Waikato
Flooding
at
Waikato
A sequence of storm events over the catchments of Lake Taupo and the middle reaches of the Waikato River led to extensive and prolonged flooding downstream of Hamilton.
The July 1998 events were extreme, with return periods of inflows to the Waikato between Taupo and Karapiro between 15-80 years.
The Mangakino and Waipapa catchments on the western side of the river experienced record floods, nearly twice as large as any recorded in the previous 35 years.
Return periods between 2-10 years were common for the Waikato tributary area (between Lake Taupo and Karapiro).
Return periods for the Rangitaiki and Tongariro catchments were as high as 20 years.
The events occurred in winter, meaning enhanced catchment wetness and potentially greater runoff, and intense rainfall was very localised.
Heavy Rain
at
Te Kuiti
The Te Kuiti gauge recorded a three-day rainfall with a return period of 33 years.
The Te Kuiti gauge recorded a seven-day rainfall with a return period of 100 years. >>100 years at 14 days)
The Te Kuiti gauge recorded a 14-day rainfall with a return period of more than 100 years.
Wellington
Multi Hazard
at
Wellington
Both State Highways out of Wellington were affected by slips and floods on the 1st.
Flooding
Sewerage problems occurred in Wellington on the 1st.
Marlborough
Multi Hazard
at
Marlborough
The worst affects were in rural areas of Nelson and Marlborough Sounds. Flooding and slips affected properties.
Rivers ran high, and flooding and slips affected roads.
Tasman-Nelson
Flooding
at
Tasman-Nelson
Sewerage problems occurred in Nelson on the 1st.
Multi Hazard
The worst affects were in rural areas of Nelson and Marlborough Sounds. Flooding and slips affected properties.
Rivers ran high, and flooding and slips affected roads.
West Coast
Multi Hazard
at
West Coast
Flooding and slips affected properties.
Rivers ran high, and flooding and slips affected roads.
Heavy Rain
at
Ahaura River
Ahaura recorded daily totals for seven days prior to the event of: 70 mm, 68 mm, 0 mm, 0 mm, 0 mm, 23 mm, and 20 mm.
Ahaura recorded a maximum intensity of 7 mm (0.7 cm) - the highest one hour rainfall intensity recorded in the 48 hours prior to event peak.
Flooding
The Ahaura River at the Gorge recorded a peak level of 4.254 m on the 1st (Return Period approximately two years).
Flooding
at
Dobson
The Grey River at Dobson recorded a peak level of 5.441 m on the 1st (Return Period approximately two years).
Heavy Rain
at
Moana
Moana recorded daily totals for seven days prior to the event of: 80 mm, 33 mm, 0 mm, 0 mm, 1 mm, 33 mm, and 33 mm.
Moana recorded a maximum intensity of 7 mm (0.7 cm) - the highest one hour rainfall intensity recorded in the 48 hours prior to event peak.
Heavy Rain
at
Waipuna
Waipuna recorded daily totals for seven days prior to the event of: 56 mm, 59 mm, 0 mm, 0 mm, 0 mm, 21 mm, and 12 mm.
Waipuna recorded a maximum intensity of 8 mm (0.8 cm) - the highest one hour rainfall intensity recorded in the 48 hours prior to event peak.
Flooding
The Grey River at Waipuna recorded a peak level of 4.053 m on the 1st (Return Period less than two years).
References
- Henderson, R.; Thompson, S. Waikato Tributary floods of July 1998.
- Major weather events in New Zealand, Floods and Rainfall, Floods to 30 Sep 2005.
- Major weather events in New Zealand, Floods and High Rainfall, Floods to 31st July 2006.
- Major weather events in New Zealand, Floods and High Rainfall to 31st May 2006.
- www.metservice, notable weather events.govt.nz.
- Southland Regional Council (CD).