A small but intense low – predicted position at midnight Thursday.  Image / MetService

A storm in the northern Tasman Sea has strengthened today and now has the same wind speed as a category 1 Tropical Cyclone says WeatherWatch.co.nz.

The storm isn’t very large in size but is described as a “vigorous depression” in a severe weather watch issued this afternoon by state forecaster MetService.

WeatherWatch.co.nz head weather analyst Philip Duncan says it’s been tough to work out the path of this particular storm but weather models and forecasters are starting to agree now.  “This low is especially hard to track due to a large high to the east of the country.  If the high strengthens just a little the low may hardly affect northern New Zealand if the high weakens then the heaviest rain may well indeed move over Northland and Coromandel”.

“It’s now becoming clear that heavy rain will affect northern and western extremities in both islands with blustery winds north of Waikato and south of Dunedin”.

Mr Duncan says Anzac dawn ceremonies across the country may be affected by the low which is likely to continue deepening for another 24 hours.   The wet spots are likely to be Northland, Taranaki, Nelson, the West Coast and Southland.  

Strong winds are likely to affect Auckland and northern New Zealand and Southland.  No frosts are expected anywhere unlike previous years. 

He says as the day progresses rain may spread to many regions.

“Hopefully the rain will hold off in most populated places until after dawn services” says Duncan.  “The data suggests this will be the case in most places but we’ll have a much clearer idea on Thursday afternoon”.

MetService has updated their severe weather outlook for northern New Zealand with “moderate” confidence heavy rain will affect places north of Whangarei and across the Coromandel Peninsula also the entire northern and western coastline of the South Island.   Latest data provided by the government forecaster shows the low in the Tasman has sustained winds of 65km/h – gale force is 62km/h.  

The central air pressure is 996hPa which is likely to drop in to the 980s.  Duncan says a low of that depth situated near northern New Zealand is always worth monitoring.

He says despite the low having such strong winds it can’t be classed as a tropical cyclone as it’s not in the tropics.