Tasman low NI 15-17 Sept

Cyclone Tracy
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Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

Thought I would just create a thread for this developing Tasman low. Initial trough and warm front in the next 24 hours followed by an occluded front and -21C @500 hPa uppers. Several heavy rain watches and a warning now in place by MS.
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Last edited by Cyclone Tracy on Wed 15/09/2021 15:38, edited 1 time in total.
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Re: Tasman low NI 15-17 Sept

Unread post by harleyb »

Here's quite a remarkable satellite image from today. A real story of two halves.
2021-09-15_NI_cloud_SI_clear.jpeg
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Re: Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

Latest EC 00z has the low cutting off and now consolidating a circulation near Cape Reinga tomorrow. EC now upgrading to 50-60mm locally.
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Re: Tasman low NI 15-17 Sept

Unread post by Awhituobs »

certainly some good rain bands drifting and building towards the area from the NW currently :)
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Re: Tasman low NI 15-17 Sept

Unread post by jamie »

We have had drizzle and rain all day. I wasn’t following it in the models too closely but I wasn’t expecting it to be this far south today. Looks like tomorrow could be action packed.


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Re: Tasman low NI 15-17 Sept

Unread post by David »

Picked up 12mm overnight. Seems to be clearing already!
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Re: Tasman low NI 15-17 Sept

Unread post by Ash »

Looks like it could get very wet in Hawkes Bay.
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Re: Tasman low NI 15-17 Sept

Unread post by Awhituobs »

more showers rain showers moving down from the north, its not over :)
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Re: Tasman low NI 15-17 Sept

Unread post by David »

There was a really brief reversal in wind direction here earlier, kind of interesting
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Re: Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

David wrote: Thu 16/09/2021 08:30 There was a really brief reversal in wind direction here earlier, kind of interesting
Good pick up. I observed the same between 4am and 5:00am. There was a surface trough moving through Auckland during that time.
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Re: Tasman low NI 15-17 Sept

Unread post by ricky »

Same observed here in Grey Lynn, abrupt change around 3:20am, back to ENE by 3:40
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Re: Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

Had 20mm so far over the 2 days, 12mm overnight with light rain atm. Merging vortexes this afternoon in the Tasman NW of Auckland with a NW to NE convergence line developing, 14 to 15C dew points. Interesting afternoon and evening ahead.
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Re: Tasman low NI 15-17 Sept

Unread post by spwill »

I see the dewpoint behind the front at Whangarei is currently 17C, Whangarei got 38.8mm.
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Re: Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

Pressure now down to 997.9, 17c with a 16c DP and brightening sky.
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Re: Tasman low NI 15-17 Sept

Unread post by Nev »

37mm here so far today, nearly 20mm of which fell in the hour to about 10:30am... 8-o

I see MS have a Severe Thunderstorm Watch for Auckland and Waikato for this arvo and evening.
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Re: Tasman low NI 15-17 Sept

Unread post by David »

Really muggy 17C dewpoint now
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Re: Tasman low NI 15-17 Sept

Unread post by David »

Up to 19C here a little earlier and the dewpoint peaked at 18.2C - the highest dewpoint I've ever recorded for September (12 years)
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Re: Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

Latest water vapour image showing this Tasman specimen has a nice cold dry air and warm moist air convergence underway. The occluded frontal boundary will be wrapping around shortly.
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Re: Tasman low NI 15-17 Sept

Unread post by spwill »

A mostly fine warm afternoon so far, Cb convergence line visible out to the NE
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Re: Tasman low NI 15-17 Sept

Unread post by Awhituobs »

I can see nice CB tops way to my north and the rain radar shows an impressive line of very heavy rain
Last edited by Awhituobs on Thu 16/09/2021 17:28, edited 2 times in total.
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Re: Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

intermittent rainfall rates between 30 to 70mm/hr in the last 10 minutes.
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Re: Tasman low NI 15-17 Sept

Unread post by Peter »

Cyclone Tracy wrote: Thu 16/09/2021 16:44 intermittent rainfall rates between 30 to 70mm/hr in the last 10 minutes.
can see it looming across the harbour from Pt Chevalier
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Re: Tasman low NI 15-17 Sept

Unread post by Awhituobs »

I see Auckland area (warkworth) broke the september max temperature record today according to Niwa! (23.5c)
(it was a record for me to , 18.8C)
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Re: Tasman low NI 15-17 Sept

Unread post by Cyclone Tracy »

Up to 32mm for the day so far, light rain at the moment but the band is back-building a little to the north. Wind moving between NNE & NE locally with pressure now down to 994.8 hPa.

Centre of the low circulation looks to be moving towards the far North, currently at 992 hPa at Kaitaia Airport.
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Re: Tasman low NI 15-17 Sept

Unread post by David »

24.2mm here today. That's the highest daily total for me since February, funnily enough
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