Warning: Strong wind advisory in force for all areas

Situation: A strong southwest flow over New Zealand weakens on Saturday as a narrow ridge moves onto the country from the Tasman Sea. A trough crosses the South Island on Sunday and the North Island on Monday, followed by another ridge.

Forecast: For Manukau and Waitemata Harbours: Thursday: Southwest 25 knots gusting 35 knots. Sea rough. Fair visibility in showers, poor at times in heavier showers this afternoon. Friday: Southwest 25 knots gusting 35 knots easing to 20 knots gusting 30 knots in the morning, then rising to 25 knots gusting 35 knots knots in the afternoon. Rough sea becoming moderate in the morning, then becoming rough in the afternoon. Fair visibility in showers, poor at times in heavier showers during the afternoon. For the Hauraki Gulf and Bream Head to Cape Colville: Thursday: Southwest 25 knots gusting 40 knots. Sea rough. Fair visibility in showers, poor at times in heavier showers this afternoon. Friday: Southwest 25 knots gusting 35 knots. Sea rough. Fair visibility in showers, poor at times in heavier showers during the afternoon.

Outlook: Outlook until midnight Monday: Saturday: Southwest 25 knots, easing to 20 knots at night. Early showers, then mostly fine. Sunday: Southwest 15 knots, tending northwest 15 knots in the evening. Cloud increasing, few showers developing. Monday: A change southwest 25 knots. A few showers.

Swell: Swell forecast to midnight Monday: East Coast: Nil significant. West Coast: Southwest 4 metres, easing to 3 metres today, rising to 4 metres for a time on Saturday, easing to 2 metres on Sunday.

High tide at Auckland
Time: 5:02pm Thursday 17 May 2012 - Height: 2.9m
Time: 5:20am Friday 18 May 2012 - Height: 2.9m
High tide at Onehunga
Time: 8:26pm Thursday 17 May 2012 - Height: 3.7m
Time: 8:42am Friday 18 May 2012 - Height: 3.7m