Severe Weather Outlook - Cold Snap Expected
Severe Weather Outlook
Issued: 1:43pm Thursday 11 August 2011, Valid from Saturday 13 August 2011 to Tuesday 16 August 2011
[Original and updates at Severe Weather Outlook and other Weather Warnings from MetService.com]
On Saturday, a southerly flow should become established over New Zealand.
On Sunday, a cold front should sweep northwards over the country, followed by a very cold southerly outbreak. Disturbances within the southerly flow are expected to continue to affect the country through to Tuesday, bringing showery conditions to most places, although the South Island West Coast should remain mostly fine. There is still a lot of uncertainty with this southerly flow, such as how much shower activity it will bring, and to what areas, and when, and exactly how cold it will be. However, snow could fall to very low levels, even sea level in some places. There is a moderate risk of heavy snow in the east and south of both islands, also the central North Island high country, as indicated on the chart. In Gisborne and Hawkes Bay, including the Tararua District, the flow may be too southwesterly for much snow, and the risk of heavy snow in these areas is asessed as only low at this stage. However, there is also a low risk of heavy snow about Nelson, Wanganui, and Taranaki.
There is also a low risk that southerly winds will reach severe gale force during this period about the South Island east coast from Banks Peninsula to Cape Campbell, and also about Wellington and southern Wairarapa.
Low confidence: a 20% likelihood (or 1 chance in 5) that the event will actually happen.
Moderate confidence: a 40% likelihood (or 2 chances in 5) that the event will actually happen.
High confidence: a 60% likelihood (or 3 chances in 5) that the event will actually happen.