Want to understand NZ weather? Here is how

MetService meteorologist Lewis Ferris gives us a breakdown on how to get the most from MetService.com along with his top tips on how to be weather savvy ahead of an outdoor adventure.

Where on the MetService website should you be looking for important weather information?
What tips do you have for a rookie? 

If you are planning on exploring one of New Zealand’s beautiful national parks then your first stop for weather information should be MetService’s National Parks forecast page. This is the easiest place to find a weather forecast five days in advance as a team of meteorologists with mountain forecasting expertise prepare the wording for the forecasts to complement the computer-generated data for spot locations in the relevant national park.   

If you’re venturing into the mountains outside of the national parks, checking the Brief Mountain Forecast further down the page is recommended. This forecast provides a general indication of expected weather conditions for major North Island and South Island mountain areas above 800 metres, giving special emphasis to hazardous weather.  

But if you’re not heading into the mountains then you should be covered by our rural forecasts where days 1-6 are written by our qualified meteorologists, and further out is computer generated. 

How far in advance can you rely on a forecast?

The most recent forecast is generally going to be the best forecast. If the forecast changes from dry to wet, then it’s best to follow the most recent advice.

When planning you should check the forecasts every day during the lead up. If it’s a relatively straightforward weather situation then the forecast will tend to remain similar in the leadup. If the forecasts are changing considerably then this is a good sign that the situation is complex and there’s plenty of uncertainty in the weather models. 

From your expert opinion, what advice do you have for people wanting to understand the weather more in-depth? Do you have any tips to best navigate the MetService website?

If you’re about to head into the outdoors, then checking our Severe Weather Forecasts is strongly advised. 

These forecasts denote the areas which are likely to see severe weather in the next couple days while the Severe Weather Outlook gives a breakdown of at-risk areas six days out. 

Thunderstorms can occur anywhere in New Zealand and at any time of year, be sure to check the Thunderstorm Outlook page that shows at-risk areas over the next two days.

The ‘Maps & Radar’ part of the website contains a lot of useful information. At first you will land on the Radar page which is great for looking at real-time observed rainfall around the country. Due to the mountainous nature of New Zealand, there is a few blind spots to be wary of. Check the key for approximate intensities. 

The ‘3 day’ and ‘5 day Rain Forecast’ pages show model data that our meteorologists use when crafting the text for the forecasts. These pages are worth studying as it gives you a better understanding on where the weather is coming from which will help you apply local knowledge.   

The black wind barbs show the wind speed in knots which you can multiply by two for the approximate kmph speed (tip: taking a look at the key will tell you about the rain colour scheme). 

Moving along the tabs near the top of the page from ‘Rain’ to ‘Surface Pressure’ is where you will find the synoptic maps which show isobars, fronts and troughs. These maps give an even deeper look as to what is causing the weather. Closely spaced isobars mean more wind and the presence of fronts and/or troughs will tend to denote an area of adverse weather. 

Moving along one more tab and you will see the satellite imagery which is useful for checking how New Zealand looks from 36,000km in space. 

The ‘Visible’ imagery is only available while the sun is up but the ‘Infrared’ imagery is available 24 hours a day.

What weather patterns will keen adventurists need to look out for this summer? 

This summer is looking to establish well as a La Niña event. In a nutshell this opens us up to receiving more warm, humid air from the north which could be accompanied by intense low-pressure systems. While on a seasonal view the South Island might run warmer and dryer than usual it always pays to check the forecast because cold southerly outbreaks are still possible any time of year. Thunderstorms can also be very prevalent during the summertime when the atmospheric conditions are right, a fine morning might turn into a downpour come afternoon!

Check the forecast, make a plan, get out there and enjoy it!