General May Weather

[NZ Thunderstorm Soc]

A day of clagg with some drizzle this evening. 14C for today.

[Nev]

Minimum temps have ranged between 18.4C and 20.0C here so far this month.

Here's a few May overnight minimum temp records from MS so far...
https://twitter.com/MetService/status/1 ... 5317359618

Note that Whitianga Aero and Kelburn actually equalled their 2003 and 2016 records respectively.

[Nev]

Apart from eastern areas, its been pretty wet and cloudy for the rest NZ over the last 6-7 days.
More than a month's worth rain has fallen in some parts.

MetServcie Cumulative rainfall for 7 days to midnight May 05.png

Notable rainfalls (mm) for the 7 days to midnight on May 05
410 .. Kaikohe
276 .. Kerikeri Aero
244 .. Kaitaia Aero
160 .. Whangarei Aero
161 .. Rotorua Aero
171 .. Whakatane Aero
112 .. Whenuapai

[NZ Thunderstorm Soc]

Calm day here with a high cloud cover with a line from north to south showing clear skies. 17.7C for today.
Some Cs with halo this evening.

[spwill]

An active looking front is modelled to come onto the North Island on Tuesday.

[Storm Struck]

The polar blast due through mid week will be a good dusting for the mountains, most of the earlier snow around March and early April has since all melted.
The latest models suggest that the east coast of the South Island is in the firing line, especially Canterbury.
Heavy rain and gale force winds, snow looks to be around 300m although thermal temperature layering comes down to -16C on Thursday so could be down to 200m by then.
There is also a low that deepens off the coast which also could ramp things up, and change dynamics of this also.

[TonyT]

The polar blast due through mid week will be a good dusting for the mountains, most of the earlier snow around March and early April has since all melted.
The latest models suggest that the east coast of the South Island is in the firing line, especially Canterbury.
Heavy rain and gale force winds, snow looks to be around 300m although thermal temperature layering comes down to -16C on Thursday so could be down to 200m by then.
There is also a low that deepens off the coast which also could ramp things up, and change dynamics of this also.

What kind of witchcraft is "thermal temperature layering"?

[David]

14C on Thursday is gonna feel like a real shock after not dipping below 17C at all in the last week

[Storm Struck]

The polar blast due through mid week will be a good dusting for the mountains, most of the earlier snow around March and early April has since all melted.
The latest models suggest that the east coast of the South Island is in the firing line, especially Canterbury.
Heavy rain and gale force winds, snow looks to be around 300m although thermal temperature layering comes down to -16C on Thursday so could be down to 200m by then.
There is also a low that deepens off the coast which also could ramp things up, and change dynamics of this also.

What kind of witchcraft is "thermal temperature layering"?

Haha yes good call, although I should have just said the 700mb temperature.
I was more looking at the variability in the upper Temperatures compared to what we have had in the past.

[NZ Thunderstorm Soc]

A generally overcast and gloomy day with mid range cloud overcastellalism.
14C with not much wind. Some light showers especially this evening with 2.8mm for today.
Fine but misty this evening.

[spwill]

See if we can get a thunderstorm here tomorrow afternoon with the front, it will mark the end of this period of sub tropical warmth. The current Auckland dew point is 17.6C, Cairns currently has a dew point of 20C, Darwin 17C. The Gold Coast is in the cold air with a dew point of -3C.

[Nev]

Tomorrow afternoon's T-storm Outlook certainly looks ominous, particularly with the risk of squalls and possible damaging tornadoes for Northland, Auckland and the Coromandel...

MetService Thunderstorm Outlook

The active front moves eastwards across the upper and central North Island during the afternoon and evening, bringing heavy rain as detailed in the SEVERE WEATHER WARNING. A moderate to high risk of squally thunderstorms spreads east across Northland, Auckland and the Coromandel Peninsula during the afternoon and evening, and there is a moderate risk of these thunderstorms becoming SEVERE producing localised torrential rainfall rates in excess of 40 mm/h and a slight chance of a damaging tornado. A moderate risk of localised downpours extends further south from Waikato and Bay of Plenty to Taranaki and Taupo from late afternoon into the evening, with a low risk of thunderstorms.

Unstable northwesterlies affect the South Island West Coast from northern Fiordland to Buller through the period with a moderate risk of thunderstorms, however this risk eases in northern Fiordland by evening. A low risk of thunderstorms extends over Tasman and the Marlborough Sounds, and with a southerly change from Dunedin to the far south of Canterbury as depicted on the chart.

No thunderstorms or severe convection expected over the remainder of New Zealand.

MetService T-storm Outlook for May 09 pm (is. May 08, 9.27am).png

Issued: 9:30am Mon, 8 May
Valid from noon Tue, 9 May to midnight Tue, 9 May

[NZ Thunderstorm Soc]

Interesting but boring day here today with variable high cloud and hardly any wind. Misty this morning and this evening.
Only 14.5C for today.

[spwill]

More thunder risk arrives here later tomorrow associated with the big cold system sweeping the country, the first very cold upper trough of the year for northern NZ.
Cold showers here on Thursday with a risk for thundery showers/hail.

[harveyt86]

MS thunderstorm outlook looking pretty ominous for today. Looks odds on for some damage/flooding in places but hopefully nothing too widespread.

[Nev]

MS now have gusts greater than 110 km/h and an extended tornado risk for the upper half of the North Island for today...

MetService Thunderstorm Outlook

An active front moves eastwards across the upper and central North Island during today, bringing heavy rain as detailed in the SEVERE WEATHER WARNING and WATCHES. A high risk of squally thunderstorms spreads east across Northland, Auckland and Coromandel Peninsula during the afternoon and evening, and there is a moderate risk of these thunderstorms becoming SEVERE producing localised torrential rainfall rates in excess of 40 mm/h, damaging winds gusting greater than 110 km/h, and a slight chance of a damaging tornado. A SEVERE THUNDERSTORM WATCH is in force for these areas.

A low to moderate risk of thunderstorms extends further south from Waikato and Bay of Plenty to Taranaki and Taupo from mid afternoon into the evening, bringing a risk of strong winds gusting 90 to 110 km/h, a low risk of thunderstorms and small tornadoes possible, but with a greater risk of of localised downpours of 25 to 40 mm/h, or possibly more.

Unstable northwesterlies affect the South Island West Coast from northern Fiordland to Buller through the period with a moderate risk of thunderstorms, however this risk eases in Fiordland by evening. A low risk of thunderstorms extends over Tasman and the Marlborough Sounds, and across to the Horowhenua and Kapiti Coast, and with a southerly change from Dunedin to south of Canterbury.

No thunderstorms or significant convection expected elsewhere during this period.

MetService T-storm Outlook for May 09 pm (Is. May 09, 7.59am).png

Issued: 8am Tue, 9 May
Valid to midnight Tue, 9 May

[harveyt86]

Going by radar it looks like we may get that intense band earlier than MS are forecasting.

[spwill]

Dark here for the time of day. Up to 35mm here now, much of it falling in the last hr.

[David]

That radar is looking pretty impressive north of here. Could be right in the firing line soon

[Razor]

2 severe storms warned at present:

Severe Thunderstorm Warning

Area: Kaipara, Far North, Whangarei

Forecast: At 11:07 am, MetService weather radar detected severe thunderstorms near KAWAKAWA, KAIKOHE, KERIKERI, OKAIHAU, MOEREWA, NGAWHA SPRINGS and OPAHI.

These severe thunderstorms are moving towards the southeast, and are expected to lie near KAWAKAWA, TOWAI, MOEREWA, OPAHI and PURUA at 11:37 am and near WHANGAREI, HIKURANGI, MAUNGATAPERE, TOWAI, PURUA and KAMO at 12:07 pm.

These thunderstorms are expected to be accompanied by torrential rain.

Torrential rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous.

A Severe Thunderstorm Watch remains in force for AUCKLAND, GREAT BARRIER ISLAND, COROMANDEL PENINSULA and NORTHLAND.

Severe Thunderstorm Warning

Area: Kaipara, Auckland City, Waitakere, Whangarei, Rodney, Albany

Forecast: At 11:00 am, MetService weather radar detected a line of severe thunderstorms lying from MARSDEN POINT to PORT ALBERT to HUAPAI.

This line of severe thunderstorms is moving towards the eastsoutheast, and is expected to lie from RUAKAKA to WELLSFORD to HENDERSON at 11:30 am and from HEN AND CHICKEN ISLANDS to WELLSFORD to AUCKLAND at Midday.

These thunderstorms are expected to be accompanied by torrential rain.

Torrential rain can cause surface and/or flash flooding about streams, gullies and urban areas, and make driving conditions extremely hazardous.

A Severe Thunderstorm Watch remains in force for AUCKLAND, GREAT BARRIER ISLAND, COROMANDEL PENINSULA and NORTHLAND.

[Razor]

And MS modelling 70mm in 2 hours late afternoon for Auckland.

[harveyt86]

Sounds like things are getting a bit hairy out west again. Worst of the rain for now over/soon to be over out that way looking at the radar. Hopefully..

[harveyt86]

And MS modelling 70mm in 2 hours late afternoon for Auckland.

Think that forecast rain is what we are getting now. Hopefully the worst will be over in the next hour or two....

Really coming down outside in Otahuhu now

[spwill]

A quick 42mm here, memories of the January storm.

[Brassnz]

We got 63mm in two hours, lots of flooding and sirens outside. Shades of 27/1 for sure.