New Zealand is dealing with a rare set up of high pressure that is not only bringing days if not weeks of warmer than average weather to the country but is also producing inland downpours that are significantly drenching central areas, especially the North Island.
This rain map below covers expected rainfall in and around New Zealand for the next 10 days. Red colouring means little to no rain, or just 5% of average in dark red (basically dry for 10 days). Areas with white shading have average rainfall while those with blue are likely to see more rain than average.
The high over the New Zealand area is big and strong (and wider than Australia!) and that’s why there’s zero rain at sea…but over land, with the daytime heat showers developing some inland areas are getting a drenching. WeatherWatch.co.nz says yesterday it’s likely that around the Central North Island the downpours this week will give some localised areas more than a months worth of rain.
The warmer than average November weather is currently producing conditions across New Zealand more similar to the middle of summer.
As you can see (below) it’s a very different story in eastern and southern Australia which is much wetter than usual. They have more wet weather coming in for the start of Summer and the first two weeks of December.
There is a chance that their large areas of low pressure will drift over the Tasman Sea in 10 to 14 days time and replace our high pressure as we head into the middle of December, but it’s too far out to lock in just yet. For now, NZ is a mix of very dry with daytime deluges over land, which will become more North Island focused as we head into this weekend.
– Images / GFS, US Government
– By head forecaster Philip Duncan, WeatherWatch.co.nz
on 28/11/2017 9:25am
Where are the heat showers getting all of their moisture from? Is there a lot of moisture trapped under the high?
on 28/11/2017 10:09am
Generally speaking yes, there is surface moisture coming down from further north. So that combined with good surface heating, surface converging winds then a relatively cold upper atmosphere then thunderstorms can form. If the upper air was warmer then nothing may happen. It all has to come together generally speaking, has happened many times in the past and will continue to happen into the future 🙂