Heavy Rain, Squalls & possible Tornadoes upper N.I. - Jul 18

[NZstorm]

The will be a bit of a thunder risk for the west and north of the North island tomorrow but the top of Northland looks the best spot given thats where the best moisture will be.
Instability is weak but shear very high so any convection will be very squally. It would not surprise me to see a tornado report from the far north tomorrow.

[NZstorm]

Just looking at 18z run of gfs and squalls tomorrow could interesting. 60knots + possible given very strong 850mb flow.

[NZstorm]

Looking like a big wind punch coming into Northland and Auckland afternoon/evening with severe gales in exposed areas and gusts to 70knots.

There doesn't look to be much convective potential in the overnight models and the thunder risk looks minimal. But low topped convection could still produce some strong squalls.

I am posting under July weather as its a bit of a different topic to South Island snow which is being covered in the other thread.

[Manukau heads obs]

yes, the low has developed explosively alright!
I better batten down the hatches

[Nev]

Pretty wet and windy here this morn. Here's this morn's T-storm Outlook update for today…

MetService - Thunderstorm Outlook

Valid to: Midnight Saturday 18 Jul 2015
Issued at: 8:50am Saturday 18 Jul 2015

A front is forecast to move across northern and central New Zealand later this morning and afternoon, bringing a brief period of heavy rain and strong northwesterly winds to the area. Refer to the latest Severe Warning Warning and Watch for more details. There is a low to moderate risk of brief embedded thunderstorms in these areas with the passage of the front, as indicated on the chart. Any thunderstorms that eventuate are likely to produce localised heavy rain of 10 to 25mm per hour and possibly more in a few places, strong wind gusts of 90 to 110 km/h and there is a low risk of a small tornado near the coast.

A deep fast moving low and associated trough are then forecast to move across the North Island in the evening, bringing a further moderate risk of thunderstorms to western and northern areas. These thunderstorms are also likely to produce localised heavy rain and strong wind gusts of 90 to 110 km/h and there is a low risk of one or two SEVERE THUNDERSTORMS producing damaging wind gusts in excess of 110 km/h and possibly a small tornado.

There is a broader low risk of thunderstorms extending further east and south down to parts of Nelson and the Marlborough Sounds, as indicated on the chart.

No thunderstorms or significant convection expected elsewhere.

MetService T-storm Outlook map for July 8.png

[NZstorm]

I am not optimistic about thunder today but severe wind events a possibility.

The front crossing the north this morning has huge helicity values, if that can line up with any surface based instability, a tornado could occur. I see the risk as Northland and top of Coromandel.

[jamie]

There is a nice red band in the main front. Would that be squally?

[spwill]

Torrential rain through here just now

[David]

I see we have a severe weather warning now for northerly gales this evening. Certainly an indoors day...

[spwill]

A burst of strong wind now, that's the front passing here now

[NZstorm]

Interestingly I have recorded 30mm here this morning compared to Ricky's 15mm. We are about 1km apart.

Edit, error, my reading is 18mm for today.

[Nev]

Tiritiri gusting over 130 km/h and Whangaparaoa 117 km/h...

[David]

A burst of strong wind now, that's the front passing here now

Yes, just getting some strong N gusts here now following about 1 minute of torrential rain

[littleheaven]

We just had what might have been some kind of downburst in Glenfield. Rain was surging and extremely heavy, and then there was a huge wind gust that hit the house, shook the whole building and the rain was swirling upwards.

[ben g]

Just had a beauty squall come through Belmont/devonport with the change. Torrential rain with severe wind, visibility down to around 100-200 m for a few minutes. The Gutter on my garage blew off, taking with it my rain gauge :s Now the rains stopped for the first time since 7am.
Fire service scanner just beginning to go crazy. 4 roofs blown off, around akl, tree on house with people trapped.

[KiwiWeather]

"A tornado has hit a property in rural north Auckland, at Wellsford. Fire crews were heading to the scene"
http://www.stuff.co.nz/national/7034242 ... -kicks-off

[ben g]

We just had what might have been some kind of downburst in Glenfield. Rain was surging and extremely heavy, and then there was a huge wind gust that hit the house, shook the whole building and the rain was swirling upwards.

Yup I have to say the thought ran through my mind as it picked up,I actually moved away from the glass windows.

Reports of "tornado" with many houses damaged in Avondale.

I guess it was Just a strong squall line tho seeing how wide spread the damage\ action reports are.

[NZstorm]

I will check out the tornado report.

[littleheaven]

Yes, I've seen similar descriptions from Torbay to West Akl on Twitter. Was quite disconcerting to feel the walls and floor flexing. We're on poles at the front so we get quite a good wobble on when the wind gets up underneath.

[Nev]

Someone on WW Facebook said there was a tornado at North Shore Golf Course (Albany) and that they would post some photos...

[GraemeWi]

[Nev]

MS reported that there was a 172 km/h localised gust at Red Head (Island?) in the Bay of Islands.

[ben g]

Should keep RODALCO busy!

image.jpg

[NZstorm]

Been for a drive and seen broken tree branches but nothing major. Looks like squalls.

[cbm]

Got to love the technology we have now. I saw this coming, was able to text/warn family and grab the video camera ready to film. It put a part of the lawn have never seen flood before, go from no surface water to under 2-3cm of water in about 3 minutes.

1c91-14e9e75d800-14e9e7b51ac.RadarBOP.jpeg