Tasman low with embedded front & troughs Jan 17- 23

[Cyclone Tracy]

Thought it might be time to put a thread together for this one, as it plenty of rainfall potential for parts of the North and South Island. Current situation is a Tasman low with an upper polar injection has stalled over the Tasman due to a very strong high pressure ridge to the east of NZ. A moisture rich atmospheric river is squeezing down towards the upper north island from the tropics meaning a strong wet northerly flow is unfolding in the upcoming days. A secondary strong unstable northerly flow will enter into the North Island on Sunday from the same but decayed Tasman depression.

The Access R model and the MetService have upgraded the system in the last 12 hours. Plenty wind and rain warnings now in place over the next 48 hours.

[Chris W]

Some high temperatures for the eastern South Island tomorrow and Saturday with a moderate thunder risk for coastal Otago and Southland. Does look very wet again over on the coast and for the North Island.

[Cyclone Tracy]

Getting some reasonable north easterly wind gusts on the north shore in Auckland now. Clocking around mid 80's km/h facing the Hauraki gulf on North head with the hand held .

[jamie]

Unless rain is going to magically appear, I’m really struggling to see where the high rainfall totals are going to come from.....or am I missing something?

[NZstorm]

11mm in Auckland but the front is fairly weak. We will get precip for the rest of the day though.

[David]

Yes GFS showing only 25mm here. But even if that's all we get, it will be a nice watering for the garden.

[einzack]

Some large rainfall numbers in the Nelson region.
Totals for the 17th based on the Tasman.govt.nz website:

[Cyclone Tracy]

Some big numbers in the Nelson region Einzack, nice stats.

MetService sticking with their big numbers. Latest warnings still at 100mm+ across a wide area in the NI until tomorrow morning.

Here's my 2 cents worth on the 9.20am IR sat pic. Front has basically stalled and cloud tops are getting very cold north of the North Island.

[Cyclone Tracy]

Heaviest of the rain around the upper north island is off the east coast. Centre of the low in the Tasman has moved around 50 km west in the last 4 hours. It will be interesting now to see if the stalled front starts tracking westward with the low and drags the narrow rainband with it.

[David]

Bit of a fizzer here. Only 14mm so far.

[jamie]

This is exactly why I asked the question of where is this “heavy rain” going to come from. Still no sign of it.

[Cyclone Tracy]

Only 16mm so far here but it's starting to rain fairly steady at the moment. The low has tracked north west in the last few hours and is dragging the rain bands closer to east coast near of Auckland.

[Cyclone Tracy]

Gauge is now ticking over. 30mm

[jamie]

Pushing 20mm now.

I see the heavy rain now. It’s still north of the country but the tail is down to Auckland. Too bad it’s sitting to the east of the country. Had it stalled right on the country there would be some big rainfall total.

[NZstorm]

42mm here falling over a 30hr period. Rain was patchy but very welcome. 105mm for the month now.

Looks like more rain around on Monday, possibly heavy thundery.

[David]

Had 29mm rain here overnight, making 44mm total.

[Cyclone Tracy]

43mm so far here. With the low still tracking north west , the rain will get dragged with it. Round 2 on Monday has varied opinions across the models, it's been a very hard system to pick with this strong high pressure ridge blocking it.

[NZstorm]

Looking like the shortwave trough will move across the country Monday/Tuesday time frame with some precip/thunderstorm chances.

[Tornado Tim]

Heavy Shower with Low risk of a storm popping up in inland Waikato tomorrow afternoon with temps in the high 20's and sfc dps reaching around 20-21.

[Cyclone Tracy]

Trough very active this morning to the north, near -80c cloud tops in areas.

[NZstorm]

What I would like from this system is a nightime storm. That's possible overnight Monday.

[spwill]

keep a watch on Tuesday afternoon for thunderstorms across parts of the NI but as always have to wait and see how it looks on the day, small changes in the likes of the timing of the upper trough, position of the convergence all make a big difference.

[Tornado Tim]

Tropical DP's with N to NE'r making it Humid as.....
Currently 29 with 21.1 DP.....

[tgsnoopy]

26.3°C with a dewpoint of 21.6°C here according to my Kestrel. Don't think it's cooled much this afternoon. Honestly feel like I'm sweating worse here than I did in Darwin last month.

[Cyclone Tracy]

Some upgrades on the main models for large areas of the NI over the next 48 hours. GFS certainly lifting totals around Auckland. Maps until the end of Tuesday for run 2101 00z.