NZ Weather Forum

Looks like some more substantial rain coming up for western regions from Wednesday.
Could turn Red

Looks like an impressive wet period for the NI from 10th thru the weekend.

I use MetVUW and it's been consistent for a few runs now.

Someone tell me the rain forecasts are wrong here, because honestly it looks like the East Coast is going to have a biblical amount of rain. But I might be doom scrolling.

MS model is spitting out 50mm in 12 hours from.6pm tomorrow, thats got to be worthy if a Watch, surely?

Razor wrote: ↑Tue 08/02/2022 20:19 MS model is spitting out 50mm in 12 hours from.6pm tomorrow, thats got to be worthy if a Watch, surely?

You would think so. They’ve issued watches for much less in the past.

MS charts are increasing totals for North and mid-Canterbury for tomorrow morning, but they're still going for low confidence of heavy rain.

I see a chance of severe thunderstorms put out by MS for the lower central North Island today - Whanganui, Bulls, Palmy area.

Skies turning darker shades of grey near Amberley. Looks a little ominous but still no watch from MS so likely just a pretty soggy but undramatic night this side.

Chris W wrote: ↑Wed 09/02/2022 14:37 Skies turning darker shades of grey near Amberley. Looks a little ominous but still no watch from MS so likely just a pretty soggy but undramatic night this side.

The MS computer generated models flummox me- if they don't want to stand by its output and put a watch/ warning up then whats the point in them publicising the data in the website to start with?

I've had so many colleagues say to me today "I see the met service says 50 mils plus tonight". in a 12 hour period if thats not a warnable amount for Christchurch then I'll be damned.

<rant over>

Razor wrote: ↑Wed 09/02/2022 14:53

Chris W wrote: ↑Wed 09/02/2022 14:37 Skies turning darker shades of grey near Amberley. Looks a little ominous but still no watch from MS so likely just a pretty soggy but undramatic night this side.

The MS computer generated models flummox me- if they don't want to stand by its output and put a watch/ warning up then whats the point in them publicising the data in the website to start with?

I've had so many colleagues say to me today "I see the met service says 50 mils plus tonight". in a 12 hour period if thats not a warnable amount for Christchurch then I'll be damned.

<rant over>

Totally agree. That amount of rain in that space of time over the plains will cause plenty of issues. As I said yesterday, they’ve issued watches and warnings for much less.

Warning sent out by the council via The Press but still nothing from Metservice:

https://www.stuff.co.nz/national/weathe ... -peninsula

Bradley wrote: ↑Wed 09/02/2022 15:08 Warning sent out by the council via The Press but still nothing from Metservice:

https://www.stuff.co.nz/national/weathe ... -peninsula

Interesting. I wonder who advised them to send the alert? You would think if it was MS that they would have issued their own watch/warning.

MS's Warning/Watch criteria is 'greater than 50mm within 6 hours or 100mm within 24 hours'...

https://www.metservice.com/warnings/sev ... g-criteria


Also, the hourly model forecast data is rarely accurate and should be viewed as a trend only...

MetService wrote:The hourly model data shown can differ from the written forecast and icons, which are produced by MetService meteorologists and take into account model data along with many other data sources. If they differ significantly, please use the text forecasts.

darcyplumb wrote: ↑Wed 09/02/2022 15:16

Bradley wrote: ↑Wed 09/02/2022 15:08 Warning sent out by the council via The Press but still nothing from Metservice:

https://www.stuff.co.nz/national/weathe ... -peninsula

Interesting. I wonder who advised them to send the alert? You would think if it was MS that they would have issued their own watch/warning.

Probably CWU

Razor wrote: ↑Wed 09/02/2022 15:44

darcyplumb wrote: ↑Wed 09/02/2022 15:16

Interesting. I wonder who advised them to send the alert? You would think if it was MS that they would have issued their own watch/warning.

Probably CWU

Ah yes - i forgot about them.

Nev wrote: ↑Wed 09/02/2022 15:20 MS's Warning/Watch criteria is 'greater than 50mm within 6 hours or 100mm within 24 hours'...

https://www.metservice.com/warnings/sev ... g-criteria


Also, the hourly model forecast data is rarely accurate and should be viewed as a trend only...

MetService wrote:The hourly model data shown can differ from the written forecast and icons, which are produced by MetService meteorologists and take into account model data along with many other data sources. If they differ significantly, please use the text forecasts.

This isn't an attempt to troll the MS- it just appeals to the scientist in me that they so often have "model" amounts that end up bearing no resemblance to the forecasts.

That being said, doing the math on the page as at 1545hrs as the event comments here, their modelling gives ChCh 67mm for the event, with 51.8mm of it falling in the 6 hours overnight from 2300hrs to 0500hrs. No that would either a necessitate a warning... or a change to the model just a handful of hours out, To say its rarely accurate and trend only...is just unscientific and verging on "now"casting if a warning does indeed emerge so late. Surely worthy of a Watch? ChCh has a much lower threshold for problems as others have said before me

Lets see what plays out....

Agree with all of the above re MS wording, warnings, now casting etc. On a side note, it pains me what CWU has become.

Also the radar is starting to fill in very nicely from the north.... I can see 60mm from now until 8am tomorrow.

And another local council pulls the flood warning trigger... Kaiapoi ain't exactly alpine. Interested to hear who's advice they are taking

Razor wrote: ↑Wed 09/02/2022 19:00 And another local council pulls the flood warning trigger... Kaiapoi ain't exactly alpine. Interested to hear who's advice they are taking

Knowing how CWU is run.. I'd almost guarantee is them.

Razor wrote: ↑Wed 09/02/2022 19:00 And another local council pulls the flood warning trigger... Kaiapoi ain't exactly alpine. Interested to hear who's advice they are taking

Some strong wording in there especially around the use of the pumps and the system capacity. As you mentioned, I’m also intrigued about where they are getting their info from.

darcyplumb wrote: ↑Wed 09/02/2022 19:14

Razor wrote: ↑Wed 09/02/2022 19:00 And another local council pulls the flood warning trigger... Kaiapoi ain't exactly alpine. Interested to hear who's advice they are taking

Some strong wording in there especially around the use of the pumps and the system capacity. As you mentioned, I’m also intrigued about where they are getting their info from.

They have a direct line to Met Service.

TonyT wrote: ↑Wed 09/02/2022 19:16

darcyplumb wrote: ↑Wed 09/02/2022 19:14

Some strong wording in there especially around the use of the pumps and the system capacity. As you mentioned, I’m also intrigued about where they are getting their info from.

They have a direct line to Met Service.

Interesting. A few of us are scratching our heads as to why there’s no watches or warnings from MS but there are now two local councils who are planning for flooding. Is this purely based on their strict watch/warning issuance criteria?

I will attempt to somewhat diffuse this semi deliberate fuse I have lit by observing 30-40mm in short order is enough to cause the odd issue in CCC and WDC.

And MS have dialed back "the model" to 40-50mm

darcyplumb wrote: ↑Wed 09/02/2022 19:21
Interesting. A few of us are scratching our heads as to why there’s no watches or warnings from MS but there are now two local councils who are planning for flooding. Is this purely based on their strict watch/warning issuance criteria?

I would assume so. Complain to your local MP.

TonyT wrote: ↑Wed 09/02/2022 19:34

darcyplumb wrote: ↑Wed 09/02/2022 19:21
Interesting. A few of us are scratching our heads as to why there’s no watches or warnings from MS but there are now two local councils who are planning for flooding. Is this purely based on their strict watch/warning issuance criteria?

I would assume so. Complain to your local MP.

haha good one!