Two contrasting weather systems affect New Zealand this week
The cold southerlies which affected southern and eastern parts of the North Island last weekend eased on Monday as the
low pressure system moved well east of Aotearoa. MetService meteorologist Andy Best commented “The upper half of the
North Island had to contend with unsettled weather during Monday and Tuesday as a complex trough moved over the area.”
He went on to say, “Wednesday saw the arrival of a welcome ridge of high pressure which spread from the Tasman Sea
across the whole of the country, and brought fine conditions with lots of Spring sunshine.” The only downside to the
ridge was that clear nighttime skies brought chilly overnight temperatures, with frosts, low cloud and fogs for many
inland areas.
MetService meteorologists are currently focusing on a couple of major weather systems which are expected to bring severe
weather conditions across the country during the next few days. The first being a low with associated fronts which
approaches the South Island today, and moves across the island during Monday and early Tuesday. Ahead of this feature
are strong northwesterly winds affecting the lower half of the South Island as well as heavy rain forecast for parts of
Fiordland and Westland. The system tracks southeast on Monday bringing very cold air over lower parts of the South
Island. A heavy snow watch and road snow warnings are in force for regions and roads in the southern half of the South
Island.
The second weather feature is a subtropical low expected to move southwards over the waters east of the North Island
during Tuesday and Wednesday. There is currently computer model uncertainty about the track of this low, therefore we
have a low risk that rainfall accumulations could approach warning amounts about Northland, Auckland, Coromandel
Peninsula, Bay of Plenty and northern parts of Gisborne from Tuesday to Wednesday. The image below shows the expected
accumulated rainfall from early today (Sunday) up until midnight Tuesday.