NZ Weather Forum

More hail here now. I also see some cells sparking occasionally off the west coast from Auckland.

Canterbury Weather Updates just posted the following:

Rain rain and more.

Prepare for flooding with 120-140mm total by tomorrow for Canterbury plains. Rivers are starting to rise and surface flooding in alot of places.

Heavy Snow is falling and will continue above 1000m.

The big concern is flooding from this event.

I'm not entirely sure where they are referring to with those kind of numbers - north Canterbury maybe??

Article in Grey Star tonight about a waterspout or tornado somewhere between Seven Mile and Nine Mile on the Coast Road at lunchtime Sunday .I am at Seven Mile (Runanga ).It certainly was pretty wild at noon yesterday .No damage being reported other than upturned garden furniture

Nice thunderstorm moving past just to the south of here. May just clip us here in New Lynn/Titirangi.

Yes, Cb out to SW with a few rumbles. Lightning seen as well.

Bradley wrote: ↑Mon 18/09/2017 14:53 Canterbury Weather Updates just posted the following:

Rain rain and more.

Prepare for flooding with 120-140mm total by tomorrow for Canterbury plains. Rivers are starting to rise and surface flooding in alot of places.

Heavy Snow is falling and will continue above 1000m.

The big concern is flooding from this event.

I'm not entirely sure where they are referring to with those kind of numbers - north Canterbury maybe??

I think thats from canterbury snow watch group, either way I also struggle to crunch those totals even inland into the high country. Possibly pushing 90-100mm for the north canterbury high country and kaikoura of more concern, where further slips and repair work on SH1 are very likely.

Its certainly your typical wrapping in low strong S-SE winds driving the rain against the foothills and remaining mostly dry on the eastern plains, apart from heavy rain overnight and some good bursts around mid afternoon with large west coast drops.
Id say with Christchurch in the shelter mode a maximum top of 15-20mm until midday tomorrow, which in many respects will be welcome as weve had our fair share of flooding this year as it is.

Thunderstorm with heavy (but quite small) hail went right over here. Impressive

Hurunui District Council advising of developing flooding situation around Hanmer Springs

Just over 40mm now, very wild and windy outside with steady rain.

Going by ECAN website some big numbers hit. Townsend station in the Lees Valley the highest with 170mm for the event

Edit to add link... several other sites met the 100-150mm as well
https://www.ecan.govt.nz/data/rainfall-data/

Very much an inland event, 170mm is a lot, picked up 50mm here in total

Cleared out to be a lovely day up here. Could become unstable south of here though.

Briefly off topic. I've just had to rub my eyes on watching the rapid intensification of Hurricane Maria. Absolutely bombing viewtopic.php?f=9&t=5718

Richard wrote: ↑Tue 19/09/2017 07:20 , picked up 50mm here in total

Same here Richard.
Thought I heard thunder before but it was probably just one of those MT hopper trucks going down the road. Possibly the only sound of thunder you likely to get in these parts or near to it

Dew points were too low to get any decent convection today..... All potential convection mixed out pritty quickly.

I see, yet, another cluster of thunderstorms in the Tasman Sea heading towards Auckland

There is a 500mb trough crossing the upper North Island late Thursday/early Friday with the chance of thunder. Something to keep an eye on.

Tornado Tim wrote: ↑Tue 19/09/2017 21:14 Dew points were too low to get any decent convection today..... All potential convection mixed out pritty quickly.

GFS never indicated there would be anything. Not sure what Metservice were seeing in their models.

jamie wrote: ↑Wed 20/09/2017 10:15

Tornado Tim wrote: ↑Tue 19/09/2017 21:14 Dew points were too low to get any decent convection today..... All potential convection mixed out pritty quickly.

GFS never indicated there would be anything. Not sure what Metservice were seeing in their models.

The upper trough was still there but there was no low level moisture feed.

Interesting rainfall recordings about northern North Canterbury, i had 50mm while a farmer 2k's away near the Hurunui pub had 97mm, Greta Valley 127mm while 10k's east out at the beach of Motunau 61mm.

Richard wrote: ↑Wed 20/09/2017 17:39 Interesting rainfall recordings about northern North Canterbury, i had 50mm while a farmer 2k's away near the Hurunui pub had 97mm, Greta Valley 127mm while 10k's east out at the beach of Motunau 61mm.

32mm in Amberley

Antarctic temp anomaly continues to drop..... at the end of June, a similar temperature event occurred which leaked around July 17th to the mid latitudes. NZ had a cold core moisture rich gyre on July 20th. Interesting to keep a watch on this one.

Some fairly heavy showers coming thru here at present

Interesting. More wetter here than Levels today.
Shows you that rainfall totals can verify around South Canterbury.

Rainfall this week Rangiora, 35mm Monday, 2mm Tuesday, 13mm Thursday and 5mm today so far so a continuation of the very wet year here.

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Yes starting to get wet here now too, though ive seen it a lot wetter, 62mm since 18th