Here we have Uesi's expected route to NZ. The strings show each member of the latest ECMWF ensemble forecast, where the model is run up to 50 times with slightly different initial conditions to see how those small changes might affect the outcome. https://t.co/RTPA5t4MlM ^RK pic.twitter.com/s5NDB2MzzI
A severe weather outlook has been issued by MetService detailing significant heavy rain and severe east and northeast gales for the Southern Alps, West Coast, Otago and Southland for Sunday and Monday.
Another update is expected this morning.
WeatherWatch said much of the storm will likely stay at sea and only part of it will hit the South Island on Sunday - but it will be enough to dump 150mm of rain in 24 hours on the West Coast and bring waves of up to eight metres.
"Storm surge and large waves have the possibility to cause coastal erosion and possibly cause some coastal flooding, especially around rivers in New Zealand later on Sunday and into Monday," Weather Watch said.
But while it is set to miss the North Island, WeatherWatch said the "leftovers" might bring some welcome downpours to the drought regions.
"Showers, by definition, are off and on and hit and miss - so not everyone will be lucky enough to get some rain. But in New Zealand some of our droughts get fixed this way, by repetitive afternoon downpours rather than a low bringing rain."
Niwa's Valentine's Day forecast.
WeatherWatch said the downpours will be inland for the most part, but may drift to some coastal areas later.
"They will mostly form through Waikato and Northland and towards Gisborne and Hawke's Bay with next Tuesday, Wednesday and Thursday perhaps the best opportunities."
Plenty of high cloud over the North Island thanks to ex-cyclone #Uesi. It may help drop daytime highs by a degree or two in some places.#NewZealand#Weather