What goes into predicting the weather for Christmas day?

By Francesca Emms
Photography by Isabella Austin

Featured in Capital #69
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Lewis Ferris works for MetService (not MetLink) and he’s a meteorologist (not a meteoricist), so he can’t tell you what time the bus is coming, and he doesn’t study meteors. Lewis did a Bachelor of Science (Physics) at Otago University, and then moved to Wellington to do a Master of Meteorology at Victoria University. Now he’s a Communications Meteorologist, working at the top of the Botanic Gardens. “We undeniably have the best office view in Wellington. Fantastic location aside – I get to work with a group of talented people who care about providing a weather service that helps keep people safe and prepare for the impacts of the weather. We help people make informed decisions; gumboots or jandals, bike or bus, camping or motel?” Lewis says the time he got to chat with John Campbell live on TV was pretty cool.  “But it wasn’t nearly as nerve-wracking as doing a weather forecast for a friend’s wedding day.”

As someone who enjoys bike riding, Lewis finds having a good understanding of the weather is a bonus – it helps with planning. “I’m trying to do more bikepacking trips this summer. After riding bmx almost my entire life, I have bought a bike with suspension so I will be riding a lot more trails soon.” Photography is his “chosen creative pursuit and if it’s ever foggy in Wellington chances are I’m out there with a bag full of cameras and too much film.” He says he spends a lot of time “and money” at photography business Splendid.  If he’s not on his bike or behind the camera, you might spot Lewis at a gig. His favourite local bands include Mystery Waitress, ONONO (Cap #50), and Mermaidens (Cap #12). “Being able to see these bands live is a selling point for me.”

Predicting the weather for Christmas Day is pretty much the same as any other day, he says. “Ten days out, the models give us a first calculation as to what may happen. Then six days out, our ‘extended range’ forecaster will analyse the available information and have a first attempt at pinning down the details.” He explains that New Zealand’s location surrounded by sea in lower latitudes (the Roaring 40s) means our weather changes rapidly, so at this time there’s a large spread of possible outcomes. “As the big day gets closer, we home in on details as the computer-generated weather models come in line.” MetService meteorologists will still be poring over the data on Christmas Eve, overnight, and into Christmas Day. “I’ve got 20°C, blue skies and a light northerly for Wellington on my wish-list but all three is a big ask.”


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