Prof Jim Salinger, climate scientist and visiting professor at Stanford University, noted to the SMC:
“It looks like tropical cyclone Evan, after strafing Fiji, will head for northern New Zealand and affect it as an ex tropical cyclone with possibly high winds and rain.
“The US Navy’s Joint Typhoon Warning Center has ex TC Evan located about 800 km directly north of Auckland and heading almost due south, with sustained winds in it’s centre of 110 km/hr by 6 pm Friday 21 December, which puts it in striking distance of northern New Zealand.
“By 1 am on Sunday 23 December the American GFS weather forecasting model has the cyclone 500 km due north of Auckland, affecting Northland and drifting slowly south.
“By midday Monday 24 December the ECMWF (usually the most accurate forecasting model)has it in a similar position with strong south easterlies and rain affecting Northland. This model then moves Evan west and weakens it.
“For New Zealand, in the neutral ENSO conditions we are currently experiencing increases the risk of experiencing an ex-tropical cyclone. There is just over a 4 out of 5 chance of an ex-tropical cyclone passing within 500 km of the country sometime between November and May, with the highest risk districts being Northland and Gisborne.
“By the time such systems reach New Zealand they are no longer classified as tropical cyclones, but can still cause strong winds and heavy rainfall. The most common months for ex-tropical cyclones to affect New Zealand are January to March. South Pacific tropical cyclones are grouped into classes ranging from 1 to 5, with 5 being the most dangerous. In an average season, four are likely to reach class 4 with mean wind speeds of at least 64 knots or 118 km/h, and one to two, class 5, with mean speeds in excess of 90 knots or 167 km/h.”
For more and updated information check the MetService website.
The MetService Severe Weather Outlook currently notes:
A low of tropical origin may be approaching the north of the country late on Friday which may bring strong winds and rain to Northland, Auckland and the Coromandel Peninsula. At present it looks more likely that warnings will not be required before midnight Friday although they may be needed in the weekend.