NZ Weather Forum

Looks like some major rain on the cars starting this evening for Westland and Buller.
Some models pointing at 700mm for some parts with gales also. That amount of rain would make it interesting for certain eastern rivers I would say, as well as the obvious slips and flooding about Westland and the Main Divide.
Also worth noting that the 3 day maps on Metservice this morning look nasty!
Thoughts?

Perhaps retitle to heavy rain for western areas and North Island, this system looks troubling for Golden Bay/Tasman also and possibly might be quite wet in the western/central North Island this weekend.

Chris W wrote: ↑Thu 15/07/2021 10:11 Perhaps retitle to heavy rain for western areas and North Island, this system looks troubling for Golden Bay/Tasman also and possibly might be quite wet in the western/central North Island this weekend.

Fair enough. Have updated now

Oh dear. MetService have urgently upgraded their warning to a RED WARNING. Using words such as isolated communities major flooding and slips and disruption to transport.

Too much warning text to copy but I'll just paste in the red warning, any further text at the link below:

https://www.metservice.com/warnings/home

Heavy Rain Warning

This rain is expected to cause dangerous river conditions and significant flooding. Slips and floodwaters are likely to disrupt travel, making some roads impassable and possibly isolating communities.

Area: Buller and Westland north of Fox Glacier
Valid: 33 hours from 9:00pm Thursday to 6:00am Saturday
Forecast: Expect 330 to 380mm of rain about the ranges, and 150 to 200mm about the coast. Peak rates of 20 to 30mm per hour expected from Friday afternoon. Thunderstorms possible tomorrow and early Saturday.
Changes: Upgraded to a Red Warning

Tropical fed water bomb developing on the 3pm microwave total precip water image over the Tasman.

I'd be shocked if SH73 manages to stay open during this event.

Looks a serious event this, and smack bang in the middle of the school hols

Over 200mm already up round Arthur's Pass.

https://www.ecan.govt.nz/home/flood-warning/

Concerns for many rivers but of most concern at the moment is the Ashburton River. Strong wording here from ECAN. Something to watch as the day progresses.

Dry Creek is rising up in Methven. Also warmed up during the day to 12 degrees with the north westerly.

Had a quick look at rainfall so far from the start (late 14th) until 6pm this evening and also looked at how the models are doing.

Cropp River 554mm
Tuke River 519mm
Mt Browning 478mm
Ivory River 451mm
Hokitika River 415mm (Colliers creek)
Haast River 336mm
Orikaka 333mm
Carrington 325mm
Arthurs Pass 293mm

From the 14th July 00z run, EC & GFS didn't have anywhere above 300mm until this 7pm this evening. Only 2 models had 450mm+ Access G and GEM.

Cropp River at Waterfall just cracked 600mm for the event. 448mm in the last 24 hours.

Thats some serious rain CT. not unprecedented for there. They do hold the NZ record at over 1000mm. But still am impressive system. Certainly more than i expected.

NIWA's Cropp River at Waterfall site, which is about 25 km inland and 975m asl, holds most of NZ's high rainfall records, including 758mm in 24 hrs and 1086mm in 48 hrs (the latter more recently in 2019).


https://niwa.co.nz/education-and-traini ... te/extreme

Cropp River at Waterfall has now cracked 750mm. Tuke River at Tuke hut is now catching it at 724mm. Couple others now over 600mm for the event.

Wind is ramping up quickly now. Gist to 74km so far. Might see 100km gust this arvo.


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The north branch of the Ashburton River has broken out again at Thompson’s Track and is flowing through farms.

Flood protection at the 2019 south branch breakout of the Rangitata River has been eroded significantly and is expected to breach this afternoon. ECAN on site.

Nice bit of wind on Wharite Peak near Palmy this morning

Cropp river at Waterfall cracks 800mm for the event. Westport feeling the wrath of a flooding river and high tide crossing paths.

Tuke river at Tuke hut cracks 1 metre for the thread, currently on 1019.5mm. Cropp river at Waterfall just on 900mm.

With not much left in the system, here were the top 5 totals for the end of the thread.

1025mm Tuke River at Tuke Hut
910mm Cropp River at Waterfall
784mm Styx river at Mt Browning
738mm Ivory River at Ripplerock
633mm Orikaka river at Plateau


Here were the main model extreme estimates on the last run before rain started on late 14th July.

802mm = Access G
776mm = Sth Korean
644mm = GEM
493mm = Icon
475mm = UK
452mm = GFS
349mm = EC

MetService on early 15 July said some places would push 350mm+. NIWA's high res model on 15 July went with a max of 499mm.

GFS wanting to bring a repeat performance next weekend, which is not what anyone wants to hear