If you’re wanting a clear prediction for Saturday in northern New Zealand – good luck. A rapidly deepening low pressure system will cross Auckland and northern NZ over Saturday and the speed that it will form and deepen means it is very tricky to precisely lock in places potentially exposed to severe weather…or the exact timing of peak rain and wind.

Our Best Thinking:
Because the low is yet to truly form we need to rely far more on computer models than normal (a bit like landing a plane with instruments when you can’t see the runway).

From the modelling WeatherWatch.co.nz trusts most we can see pockets (localised areas) of severe weather on Saturday north of Taupo and south of the Far North.  Generally speaking this low is at the lower end of the severe scale – but its location, rapid deepening and fast movement means it is certainly ‘one to watch’.

RAIN:
A band of rain around the low will move in to the upper North Island on Saturday (north of Taupo).  Between 6am and 12noon some falls may be heavy enough to cause localised surface and flash flooding around Auckland, Waikato, Northland and Coromandel Peninsula – but the heaviest rain will not be widespread.  WeatherWatch.co.nz’s confidence of this remains around Low to Moderate.  Conditions ease into the afternoon as southerlies blow through and the low tracks east.

GALES:
The deeper the low gets, the stronger the winds will be.  It will still be deepening as it crosses northern NZ on Saturday.  Like the rain, we see potentially damaging wind gusts (at the lower end) in isolated pockets and exposed parts of northern NZ north of Taupo.  However there is plenty of calm in the mix too – the centre of the low is calm, as is much of the weather before it.  These lows are short and sharp – and the most widespread winds may come in the southerly change afterwards on Saturday PM and Sunday.

MORE CLARITY
We strongly urge people to look at both the RAIN and WIND maps at WeatherWatch.co.nz for Saturday. With the rain, areas in red/purple/orange indicate the heaviest falls.  With the wind, areas in red/purple/orange indicate the strongest winds: www.weatherwatch.co.nz/maps

This low is at the lower end of the severe scale – but it’s location (over our most populated regions) and the fact it is going to deepen rapidly means it is one to watch. Hopefully it will just be an excuse for a lazy Saturday sleep in!

COLD BLAST:
While this low is upper North Island focused, there is a cold change in the tail of it all.  Colder air will move up the South Island on Saturday and get even colder on Sunday.  Some snow is possible to low levels and the air will be cold – but conditions looks set to improve later into Monday and Tuesday as another high slowly comes in from the west.

Please also check Government forecaster MetService for any warnings and severe weather outlooks.

– WeatherWatch.co.nz