A front is expected to cross the South Island on Wednesday and Thursday,with heavy rain in the west.
The heaviest falls are expected about Fiordland and the ranges of Westland, where 150 to 250mm could accumulate over a 24 hour period. Spillover rain is also forecast for the headwaters of the Canterbury and Otago lakes and rivers, and 80 to 120mm could accumulate within 10 to 15km of the divide in 15 to 18 hours.
The remainder of Westland and Buller, and also the Tararua Range could see rain accumulations reaching warnings amounts. People are advised that streams and rivers are likely to rise rapidly, and surface flooding and slips are possible.
In addition, northwest gales are expected to become severe in eastern areas from Southland to Marlborough ahead of the front, with gusts of 130 km/h in exposed places. Northwest gales across Wellington and Wairarapa could also rise to severe gales. However, about the Canterbury High Country and foothills, damaging gusts of 140 km/h are possible.
Winds of this strength have the potential to damage trees, powerlines and unsecured structures, as well as making driving hazardous, especially for high-sided vehicles and motorcycles. People should also be aware that these conditions can elevate the fire risk.
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