Subtropical low NI 31 May - 2 June

[Cyclone Tracy]

I think this might be worth a separate thread. A subtropical disturbance will move south towards the North Island on Saturday with a deepening surface low developing near the upper North Island on Sunday afternoon. Heavy rain and strong north easterlies will be in order for several areas, finer details to come in the next 24 hours. Current global modelling is ranging falls from 50 to 200mm across the upper NI and the Bay of Plenty.

MS have issued their first watch.

Heavy Rain Watch

Area: Northland, especially in eastern areas
Valid: 20 hours from 10:00am Sunday to 6:00am Monday
Forecast: Periods of heavy rain. Rainfall amounts may approach Warning criteria.

Area: Auckland north of the city, Great Barrier Island and Coromandel Peninsula
Valid: 22 hours from 3:00pm Sunday to 1:00pm Monday
Forecast: Periods of heavy rain. Rainfall amounts may approach Warning criteria. Note, rain should ease in Auckland late Monday morning, then Coromandel Peninsula early Monday afternoon.

[Cyclone Tracy]

Total Precipitable Water near 50mm at the top of the atmospheric river on Sunday evening. If the cut off low stalls this could become a water bomb around parts of the NI.

[NZstorm]

EU has a warm sector dewpoint 16C over us Monday which will be a nice temperature for the first day of winter. Max temp looks about 19C.

[David]

Projected rainfall only 20mm here now on GFS. Need a lot more then that for the dams.

[Cyclone Tracy]

EC and Icon's latest 18Z run locking onto widespread decent falls for the upper NI.

[David]

Metservices Whitianga Aero site showing 54mm from 11pm to midnight followed by 53mm from midnight to 1am. That's some intense localised rainfall!

[spwill]

Metservices Whitianga Aero site showing 54mm from 11pm to midnight followed by 53mm from midnight to 1am. That's some intense localised rainfall!

Whitianga with 172mm since yesterday.

[NZstorm]

An isolated severe thunderstorm north of Wellsford this morning dumped 65mm in an hour to 4am according to a PWS. Dp's 15C up there.

Looks like the deep instability clears away this morning with the rain system approaching.

Lightning chart for 4am this morning.

[Cyclone Tracy]

Very moisture rich atmospheric river on the 8am water vapour image above the eastern flank as the low undergoes cyclogenesis.

[Cyclone Tracy]

5mm to start things off here. Low is currently around 300km north of the tip moving south with heavy wrap around showers moving into parts of Northland and the Hibiscus coast. Several PWS's around Northland now over 50mm which is great for the drought. That PWS north of Wellsford is on about 90mm for the day now.

[David]

Just 4mm of very light rain here so far. Wind was a bit gusty this morning but is back to a light breeze now.

[Cyclone Tracy]

Active lightning and some decent plumes of moisture appearing above the occluded frontal boundary, chasing down the warm front on the 8pm water vapour image. Access G and the UK appear to be the most accurate models on the 00Z run for the centre of circulation at 8pm.

[David]

Just 11mm so far, this system has really under delivered on model projections

[Awhituobs]

we have had very little rain here as well so far, incredible really..been like a big hole in the rain over us
just 4mm
but I see a new big rain band heading our way

[NZstorm]

Persistent light rain since 3pm yesterday with 19mm recorded here. Grey Lynn weather station showing similar amount.

[spwill]

Easterly rain is more reliable for Nothland/ Coromandel. Dps come up today so hopefully that will mean some heavier precip here.

[jamie]

Not even 2mm here


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[Cyclone Tracy]

18mm so far here, light to moderate rain currently on south easterly flow. The low is currently circulating more than 200km further north east than models predicted 24 hours ago.

[Nev]

18.5mm here so far since yesterday arvo.
26mm at Whenuapai, 18mm at Whangaparaoa and just 8mm at Auckland Aero.

Cool graphic from MS showing rainfall accumulation over the 24 hrs to 7am this morn…

MetService NI Rain Accum. 24 hrs to 7am, Jun 01.jpg

[treetop]

still waiting in Tauranga .between 5 and 10 mm so far . No red on the radar either maybe less instabiliity with the cooler seas now. Hopefully some action as the low gets closer this evening [orographic convection windward of the Kaimais]

[jamie]

That graphic is rather incorrect. I’ve had 2mm and the pic is showing 60+ for a large area around me.


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[Awhituobs]

at least eastern NI is getting much needed rain

[spwill]

Dps come up today so hopefully that will mean some heavier precip here.

Looks like the better moisture will stay east of here.

[Cyclone Tracy]

Low's centre is now about 100km NE of Great Barrier Island, the south eastern flank is starting to push more precip east into the Gulf and the Coromandel peninsular.

[Awhituobs]

we might get some rain yet if those showers coming off the coromandel can keep it together and make it this far west