Nth Island Thunderstorms - Aug 28 - Sep 01

jamie · Unread post by **jamie** » Tue 31/08/2021 04:58

Jeez just woken to see it is still stationary over the same spot. Would imagine major flooding issues.

This whole system wasn’t well picked by models but handled very poorly in terms of now casting by MetService.

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Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 05:37

43mm here in total and still raining
we had another burst of thunder and lightening at 10:30 last night

but huge totals in the Waitakere ranges (e.g 171mm re that weather station I linked above)
and more to come for them...its very stationary!
I see on the news last night Met Service said nothing jumped out at them re severe weather

David · Unread post by **David** » Tue 31/08/2021 05:46

Surprised to wake up to only 10mm since midnight here, thought some of that heavy stuff in the gulf would make its way down here.

9mm more and it will be the first month since February to reach average rainfall!

Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 05:57

careful what you wish for
still more feeder bands that could push a bit further south yet...a real battle is going on

Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 06:27

now a warning is issued

GraemeWi · Unread post by **GraemeWi** » Tue 31/08/2021 06:50

We are at 156mm for the event with 92mm since midnight

I checked a stream level this morning - Opanuku which runs through Henderson Valley - it passed its previous flood record from 2005 and there was extensive flooding back then

http://aklc.hydrotel.co.nz/hydrotel/cgi ... tchment=26

Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 06:53

the low center is now retreating N as the high muscles in
so the rain band is slowly moving north
so south Auckland area, Waiuku/ Pukekohe looks like they will not get much more heavy rain

Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 31/08/2021 07:05

40mm here so far since last night. Nice convergence working in off the gulf. MS feel asleep at the wheel last night.

Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 07:08

MS feel asleep at the wheel last night

YUP
everything here new and posted this needed to be warned yesterday afternoon

spwill · Unread post by **spwill** » Tue 31/08/2021 07:50

It would be good to have more information/photos on the large hail report last night, these events obviously tend to be very isolated.

Brassnz · Unread post by **Brassnz** » Tue 31/08/2021 07:55

43mm overnight here also.

Razor · Unread post by **Razor** » Tue 31/08/2021 07:56

Reading the stuff and NZ Herald articles, looks like a massive event for West Auckland. My old hood in years gone past. The dams will be full!

Hope everyone is ok up there, sounds nasty

Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 08:49

we have sunny patches here now
the low and front are being pushed back by the high
and its weakening slowly
so places that got it initially like Hellensville, are about to get it again
so the warning is too late, except it might help with insurance claims

some places got over 200mm
amazing

David · Unread post by **David** » Tue 31/08/2021 08:58

27mm for me, sun peeping out now. Seems I won't quite make it to average rain for the month after all

jamie · Unread post by **jamie** » Tue 31/08/2021 09:18

Where were MetService last night. I really hope they are scrutinised for the major failure.

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Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 31/08/2021 09:30

Unfortunately MS were lazy model gazing and not looking at winds obs, radar and satellites. I do my own forecasts, so I only look at MS and NIWA for entertainment purposes but I feel sorry for the folks in West and NW Auckland who weren't warned, even when a major convergence zone was developing on radar.

Nev · Unread post by **Nev** » Tue 31/08/2021 09:36

Some amazing MS 24 hour rainfall totals (mm) to 9am this morning (mostly overnight):
104 .. Whenuapai
89 ... Whangaparaoa
17 ... Auckland Aero

27mm here.

Nice MS 24 hour rainfall accumulation graphic to 6am this morning…

MetService Akld 24 hr rainfall accu. to 6am - Aug 31.jpg

NZstorm · Unread post by **NZstorm** » Tue 31/08/2021 09:41

spwill wrote: ↑Tue 31/08/2021 07:50 It would be good to have more information/photos on the large hail report last night, these events obviously tend to be very isolated.

localised ENHANCEMENT OF WIND SHEAR. nOT THAT UNUSUAL WHEN WE HAVE THE STRONG DYNAMICS as WE HAD LATER YESTERDAY.

Cyclone Tracy · Unread post by **Cyclone Tracy** » Tue 31/08/2021 09:46

Council gauges for historical records. Mangatangi Dam which needs water the most for Auckland only had 45mm.

Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 09:53

that confirms it then over 200 mm in places (Waitakere ranges) ..wow

GraemeWi · Unread post by **GraemeWi** » Tue 31/08/2021 09:58

We are now at 172mm for the event, it's cleared and brightened now.

NZstorm · Unread post by **NZstorm** » Tue 31/08/2021 10:00

Awhituobs wrote: ↑Tue 31/08/2021 09:53 that confirms it then over 200 mm in places (Waitakere ranges) ..wow

was quite persistent rain last night. I will provide a severe weather analysis. Would be interested to read others thoughts. Looks like about 70mm fell here in Grey Lynn.

Razor · Unread post by **Razor** » Tue 31/08/2021 10:06

Niwa reports Kumeu 208.9mm in the 24hrs to 9am- second highest recorded total in history there

Awhituobs · Unread post by **Awhituobs** » Tue 31/08/2021 10:39

Auckland Water storage has been given a good boost (up till midnight)
https://www.watercare.co.nz/Water-and-w ... dam-levels

I also see Northland has a warning, as the low and front drift north
good , Met Service are back on the ball

David · Unread post by **David** » Wed 01/09/2021 06:27

My station had it highest daily windrun in 7 years yesterday

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