Storm Watch - 24th September 2013

Over the last few days a subtropical low has formed over the seas to the north of the country. It is now starting to make its presence felt over the North Island.  In this blog post we will keep you updated with what’s going on around the country and how the weather is changing.

Maths, Physics and Meteorology

When recruiting and training people to become meteorologists, MetService requires that trainees hold a university science degree in maths and physics. Why maths and physics?

First and foremost, meteorology is a science, and we need people in our National Forecast Centre who are capable of applying the scientific thinking that they’ve developed at university to understand the state of the atmosphere.

Let’s look at specific examples of why maths and physics are important to meteorology.


The physics of fog

More comprehensive mountain forecasts aid safety in the outdoors

From Wednesday 31 July, you'll see a new format for the Mountain forecasts that MetService produces under its commercial contract with the Department of Conservation.

While the current mountain forecasts for various National Parks are short and to the point, they rely to an extent on the user being able to "join the dots". One of the main aims of the new format is to be as clear as possible about those weather conditions influencing safety in the outdoors.

Each mountain forecast will contain:

The Shortest Day

June 21st is the Northern Solstice and marks the shortest day here in the Southern Hemisphere.  On the 21st the sunrise is around 7:48am and sunset 5:00pm in Wellington, giving just over 9 hours of potential sunshine for the capital.

The timing of sunrise and sunset varies from location to location, sunrise in Gisborne being almost an hour earlier than in Invercargill.  You can find the sunrise and sunset times for the next ten days on the forecast pages at, just underneath the towns and cities forecasts.

Napoleon’s Winter

What would New Zealand’s history be like without the First and Second World Wars? Blame the terrible Russian winter and Napoleon’s folly according to historian Adam Zamoyski in his riveting book 1812 Napoleon’s Fatal March on Moscow. The losses suffered in the invasion, particularly to his cavalry, ensured Napoleon’s downfall the following summer. That led to an aggressive Germany unified under a militaristic Prussia while in Russia, the Tsar came to believe he was God’s instrument on Earth.

A Look Back at Summer

The story of summer 2012/13 was rain, or rather the lack of it. Drought was declared for the North of the country on the 27th February, shortly followed by the rest of the North Island and parts of the South Island.

A new dish

A new satellite receiver ("dish"), for improved reception of data from polar-orbiting weather satellites, was installed at MetService in early February.


Polar-orbiting weather satellites yield rich information about the atmosphere, valuable for New Zealand weather forecasting.

Benefits of faster access to more data, and sharper identification tools, include:

Why it's been so dry

For about the last month, anticyclones have dominated the New Zealand area. Many places have had little or no rainfall since early February.

The map below shows the average mean sea level pressure over the New Zealand area over the last month or so. There's no doubt about the pressure being high and not changing very much. Because this map shows averaged pressures, we don't see the few troughs that have passed across the New Zealand area in the last 28 or so days.