General May Weather

[Avalanche]

Im still learning this stuff, but i looked at the Cape models before and didnt see anything to suggest severe Thunderstorms. Im still learning though, so i might be missing something. Can anyone else offer any guidance to why Metservice may think they might go to the severe spectrum for Wellington?

[Cyclone Tracy]

My 2 bobs worth on Wellington tonight.... Latest Access R model 18z run has sustained wind speeds around 120 to 130 km/h @850 hPa over Wellington from 9pm to midnight. Some of those winds will mix down to the surface and could be destructive. One of the MS criteria for a severe thunderstorm is 110 km/h + wind gusts which would be the main reason for the watch in Wellington IMO but lightning is also a chance with total totals above 50 around the same time.

There is also significant temperature differences from the sea surface to 500 hPa once the front goes through....45 to 50c degrees. It's going to be a very unstable south westerly flow tomorrow into the NI with those cold uppers. Could be a waterspout outbreak coming off the Tasman into the NI especially around Taranaki.

[NZstorm]

Im still learning this stuff, but i looked at the Cape models before and didnt see anything to suggest severe Thunderstorms. Im still learning though, so i might be missing something. Can anyone else offer any guidance to why Metservice may think they might go to the severe spectrum for Wellington?

just adding to what Cyclone Tracy wrote, todays thunderstorm set up is what is known has high shear, low CAPE set up. So you need to look at the wind fields to see the severe potential. The 850mb wind is a good place to start looking for severe potential. Also the strong wind fields can creat severe thunderstorm structures such as bow echoes or small supercells which produce severe winds such as the Waikanae storm in July 2011. viewtopic.php?t=4481

[NZ Thunderstorm Soc]

Just heard some thunder around the MT. Peel area.
I thought I would let you know.
Also: Nice recent capping of snow on Mt. Peel as well

[Avalanche]

Hey thanks guys, really appreciate the input, its not far away now, pretty gusty in Wellington now. I see Thunderstorms moving up the west coast of the South Island. Will be interesting to see if the Thunderstorms go severe over Wellington.

[Richard]

Heavy rain here at the moment but what unusual is it blowing NW as well, normally stops while it rains and starts up again when the shower passes.

Wonder if there will be spill over lightning like it did Sunday evening.

[NZ Thunderstorm Soc]

The 2 thunder sounds I heard, that was it and nothing else, sadly. Seems they are moving north and just leaving bleak weather down here. Sferics dying away which is a bit sad

[NZstorm]

Lightning seen to south from a cb near Port Waikato.

[spwill]

There have been Cbs visible south of Auckland this afternoon but dry here apart from some early showers, up to 19C. Front tonight will be interesting to watch as it comes north.

[Cyclone Tracy]

Cloud tops getting colder around the front. CG now spotted around Cook strait, Tasman bay.

It’s seems like there will be 5 systems to affect NZ in this SSW related sequence. System 2 coming through now and system 3 right behind it Thursday into Friday. System 4 seems as though it will be consumed by system 3 with a fujiwhara effect and push a deep SW to southerly over NZ during the weekend, with a deep cut off low east of NZ. System 5 will be able to balloon into SE Oz with the ridge moving east, possibly creating a cyclonic Tasman gyre, one to watch for NZ next week.

Overnight the polar jet was reaching 400 km/h south of Africa, throw in the ballooning Rossby wave over NZ and it’s not looking that Autumnal for the next week. At the moment the lower area of the stratospheric polar vortex is bulging out of shape with a lot of energy pushing down into the tropopause and polar jet south of Africa.

https://earth.nullschool.net/#2018/05/2 ... 21,-45.661

[BeaconHill]

Massive electrical storm over Wellington right now.

[NZ Thunderstorm Soc]

Massive electrical storm over Wellington right now.

boring down here, with nothing happening after dark when I was expecting a good show to the west

[BeaconHill]

Impressive start to this evening around Wellington.

Photo is from local Twitter user @Almightyallan. (Posted here with his permission). Taken from above Houghton bay looking due south as the cell moved into Cook Strait.

Rain radar image is from maybe 10mins prior.

9880B977-8ACB-4849-880C-AD95BFBCA178.jpeg

DE243B5F-13F8-4894-9677-492B24149ABE.jpeg

[Thunder081]

Wowsee! just finished up an awesome chase. Started off at the top of Mt Kaukau where I recorded 60 - 95 kph NW wind gusts then saw the first thunderstorms move from cook strait to Wellington's southern and eastern suburbs looking from Newlands. Then at 8:44pm I was in the Ngauranga Gorge and got hit by very heavy rain and pea sized hail but it only lasted for a couple of minutes. Then went north and stopped at Pukerua Bay at 9:26pm and watched more thunderstorms come in from the sea. There was flashes of lightning every minute and when one of these cells moved over between Plimmerton and Pukerua Bay there was a strike that knocked the power off in Pukerua Bay for 10 seconds at around 10pm. After that I tried to get ahead of the front but couldn't as it was moving to fast there was lots of lightning from Paikok to Otaki.

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[RODALCO]

Couple of good lightning strikes and claps of thunder with heavy rain in Titirangi 01:15 - 01:25 hours.

[Thunder081]

Intense conditions at 8:44pm last night in the Ngauranga Gorge in Wellington!

[Nev]

Main rainband brought some heavy falls here between about 2am and 4am this morn, with plenty of distant lightning observed - 17mm so far today.

Here's Blitzortung's CG's over the last 24 hrs to 6am this morn…

[NZstorm]

We havn't seen a cold pool like this in a while. This mornings IR.

[spwill]

Distant thunder and lightning here early morning.

[RichyDunedin]

Snow settled and still snowing in Mossburn, Southland

[David]

A most miserable morning, rain and 11C. Didn't notice any thunder in Howick last night. Did hear some heavy rain though.

[Cyclone Tracy]

Models suggested 5 to 10mm for here this morning on the 12z run, currently 20mm so far Frontal rainband slowed more than expected. Some big temperature difference between the Tasman and 500 hPa today. Quite unstable for parts of the NI.

[NZstorm]

25mm hail sized hail stone recorded in Wellington last night.

https://pbs.twimg.com/media/Dd1H0NWU8AEubpk.jpg

[Razor]

Looks like some of the models pushing more settled stuff in last week with a ridge settling in

[spwill]

The high comes in for early to mid next week.