The saturated, wetter than average, eastern side of the South Island may be in for even more rain next week as two other very large lows cross over New Zealand. These big low pressure systems, like the one we saw this week, will have great ‘reach’, tapping into moisture-rich sub-tropical air further north of NZ and pulling it down to places not normally so exposed to set in rain, like the eastern South Island.

While totals continue to vary greatly next week, due to the volatile set up of these two large lows, the general picture is becoming clear: Otago and Canterbury are shaping up to have a much wetter than average November with more wet weather coming.

But just how much is coming and where specifically? That is yet to be locked in because some of the heaviest downpours may be a bit hit and miss (with lighter drizzle falls elsewhere). We’ll provide more details this weekend or Monday about where the heaviest rain will be next week. There will be very large dry areas too, so that needs to be factored in. The hills and ranges of both islands then also play a part at blocking rain clouds – or – enhancing them.

At this stage nothing is jumping out as being overly alarming, but the set up next week is absolutely worth monitoring due to recent heavy rain and flooding. There is also *some* heavy rain potential later next week, but due to the very large size of these incoming lows the precise area/tracking of this heavy rain could move quite a lot – including which island it may even affect the most, so we need more time to lock in. In the meantime, please use the 10 day rain maps in our MAPS tab to get a better understanding of the set up.

AVOID CONFLATING THUNDERSTORMS WITH “NORMAL RAIN”.
Among the rain bands next week we also have another feature to factor in – afternoon downpours and thunderstorms. These may significantly add to the overall rain totals for NZ in the coming week. Afternoon downpours will be far more isolated but could triple the predicted rainfall totals in that local area. This may also contribute extra water to rivers in places that haven’t had any rain. These downpours are most likely well inland over/near the main ranges and highlands of both islands. 

DRY SPELLS IN THE MIX
NZ does NOT have a full week of rain coming, despite what some forecasters or weather icons may suggest. Instead we have a high risk of daily downpours which will shift around quite a bit. Next week will see some large areas of dry and sun too, but these two large lows will produce areas of rain (possibly heavy) which means it will be a busy week next week tracking all these various moving parts.

– ABOVE: This coming Monday shows rain coming into Otago again, once again a long journey from the sub-tropics but still brings with it extra moisture.

– BELOW: Long range possible set up next Friday (8 days from now) shows another low bringing more rain down the eastern side of NZ. This is not locked in yet, nor is it known how heavy or long lasting this rain might be.
– Maps by MetOcean

COMPARED TO NORMAL WHAT IS COMING? Rainfall map compared to normal for the next 7 days. Blue = wetter than average, White = normal rainfall for late November, Red = Drier than usual.  Big thanks to the US GOVERNMENT for this helpful data.

– WeatherWatch.co.nz