Significant heavy rain is forecast to hit the west of the South Island mid-week, bringing possible flooding and slips, and possibly a rare Red weather warning.
MetService Meteorologist Angus Hinds today described it as a significant event - "even by West Coast standards. We're talking huge amounts of rainfall through the second half of this week... it is going to be all on for the western South Island."
The active front, preceded by a moist and strong northerly flow, was forecast to move northeast over the South Island from Wednesday to Friday, bringing significant heavy rain to the West Coast, thunderstorms, and possibly severe gales about Fiordland and inland parts of Otago and Canterbury.
The heaviest rain is expected in Westland - of up to half a metre. In the 38 hours from 5am on Wednesday until 7pm on Thursday, 400mm to 550mm of rain was set to accumulate about the ranges, and 150mm to 300mm near the coast. Peak rates of 30mm/h to 45mm/h about the ranges, with thunderstorms possible.
‘‘Orange Heavy Rain Warnings are now in force for Westland and Buller. There is a possibility that the warning for Westland may be upgraded to a Red Warning closer to the time," a MetService spokesman said.
‘‘In addition, Heavy Rain Watches are now in force for Fiordland, the headwaters of Otago and Canterbury lakes and rivers, and also the northwest part of Tasman.’’
In Buller, 250mm to 350mm of rain was forecast about the ranges, and 150mm to 200mm near the coast in the 36 hours from 1pm on Wednesday until 1am on Friday. Peak rates of 20mm/h to 35mm/h about the ranges, with thunderstorms possible.
The weather event was expected to affect the headwaters of Otago lakes and rivers from 5am on Wednesday until 5am on Thursday, and Fiordland from 1pm on Wednesday until 10am on Thursday. Warnings for these areas may be issued closer to the time.
The spokesman said the heavy rain could cause streams and rivers to rise rapidly.
‘‘Localised flooding and slips are likely, and driving conditions may be hazardous during the event.’’
Residents and trampers were urged to keep up to date with the latest MetService warnings and watches.
Severe gales
MetService advised there may be severe northerly gales about Fiordland on Wednesday, and about inland parts of Otago and Canterbury from Wednesday to Friday.
Also, there is low confidence of severe north to northeast gales about Westland, Buller and western Tasman on Wednesday and Thursday.
- additional reporting ODT Online
