James Renwick: Victoria University professor on whether the forecasting technology could have better predicted Wellington rainfall

Assurance MetService gave the most notice possible before yesterday's flash flooding in Wellington.

The record breaking 77-millilitre an hour deluge inundated the Capital from about 4am.

Wellington, Wairarapa and Hawke's Bay south of Tutira still sit under an Orange heavy rain warning until later tonight.

A slip's burst a wastewater pipe in Vogeltown - forcing a household to evacuate.

Victoria University professor James Renwick says MetService uses the best forecasting technology.

He says it's a bit like earthquakes, which are unpredictable, but can be detected as they happen.

LISTEN ABOVE

See omnystudio.com/listener for privacy information.

Episode Transcript

Speaker 1 (00:00):
James Rennick, Professor of Climate Science as a Victoria University.

Speaker 2 (00:03):
Is with us.

Speaker 1 (00:03):
Hi, James, settle this for US, James, are there these
supercomputers that can do it or not?

Speaker 2 (00:11):
There are supercomputers and some of them are in New Zealand.
Both of those stories are correct. You know, met Service
use the best technology Earth Sites New Zealand do as well,
and it's all one organization very soon. So that's good news.
But yeah, it's a question of really observations of data
and how it's used. So it may be there are

(00:34):
companies in the US that can do a little bit better.
But ultimately, for these very localized rainfall, extreme rainfall events
where one thunderstorm delivers a huge amount of rain to
one street in the city, you come up against the
sort of chaos in the weather. You can never be
super precise because we can never observe the weather in
enough detail to be able to predict this at that

(00:57):
level of detail. So met Service do a great job
with the technology we have, which is world leading, but
I think the person from met Service is right, You're
never going to be able to get these forecasts perfect
at the scale that we need them for these really
extreme events.

Speaker 1 (01:12):
Okay, So James, can I just this is this is
the This is happening with more frequency because of climate change,
isn't it?

Speaker 2 (01:20):
Yes? It is?

Speaker 1 (01:21):
Okay. So then if this is happening with more frequency
because of climate change, as in this will happen more
and more to us and we cannot forecast it, then
is the only way that we deal with this to
have triggers, much more sophisticated triggers, so that when it's happening,
we get a really quick, quick bit of intel to say, hey,
something's happening.

Speaker 2 (01:40):
Yeah, there's room to improve in that sense. Met service
forecasting agencies working with civil defense and regional councils to
get word out to people more quickly is definitely a
way forward. And I should say, you know, the forecast
can improve. I'm not trying to say we're doing the
best we possibly can. Now you can always have a

(02:00):
fast compared with a more high resolution model that produces
more detail at local scale. So there are improvements that
can be made in that sense in terms of the
computer hardware and so on. But yeah, the messages, the
communication I think is at least is important. So getting
the word out in a way that people can use
it in good times.

Speaker 1 (02:23):
Like though, I mean, let's say, let's let's take the
example of Ireland Bay and Wellington. Like all of us,
people are asleep, it's three in the morning. All of
a sudden, there is just a huge amount of water.
How do you in the space of I don't know,
you know, but the metsivice picks it up and an
hour later it's happening, and then an hour later it's
in people's houses. How do you get that information to
people in a way that keeps them safe.

Speaker 2 (02:43):
Yeah, that's the question, isn't it. And sometimes it's just
not possible. It happens so quickly, and it's a little
bit like an earthquake. You know, you can't predict when
the earth earthquakes are going to happen, and you know,
the science New Zealand can detect them happening and let
people know, but they're happening by that stage. And it's
a little bit like that. With there's really extreme rainfall events.

(03:04):
You might be able to have half an hour's warning,
but if it's three in the morning, well that's not
much use because everyone's asleep.

Speaker 1 (03:09):
And by the time wake things on our phone.

Speaker 2 (03:14):
Yes, that's true, and that can be used, but it's yeah,
I mean, if the timing's really awkward, like it's the
middle of the night, such as it was over the
weekend in Wellington, it's still pretty hard and that's just
the reality. Sometimes these events happen very very quickly.

Speaker 1 (03:28):
Yeah true that Hey, thank you. James has always loved
chatting to you. James Rennard, Professor of Climate Sciences at
Victoria University. It's twenty away from six. For more from
Heather Duplessy Allen Drive, listen live to news talks.

Speaker 2 (03:40):
It'd be from four pm weekdays, or follow the podcast
on iHeartRadio.