General November Weather

[jamie]

Looks like the warm front is sending rain north and south of me. Hopefully the cold front can deliver.

[NZstorm]

That thundery line will cross this morning. Modelling indicates CAPE is high up (above 700mb).


The afternoon could get interesting as well due to strengthening NWers with 50knot gusts possible in parts of Auckland. Will warm up to.

[Manukau heads obs]

yes, I am thinking we will get some really strong winds here as the NWer arrives

[spwill]

Possible Tstorm with the front in about an hr, lightning tracker.

[Manukau heads obs]

blitzortung has been tracking it well
but acitivity has been decreasing

[Nev]

Here's this morn's T-storm outlook - not much change from last night…

MetService - Thunderstorm Outlook

Valid to: Midnight Monday 17 Nov 2014
Issued at: 10:37am Monday 17 Nov 2014

CHART AMENDED TO ADD IN POSSIBLE SIGNIFICANT GUSTS WITH THUNDERSTORMS OVER NORTHLAND AND AUCKLAND...

A deep low lies west of the North Island this morning with its associated warm front moving down over the north. The low and associated fronts should cross the North Island during the afternoon.

There is a moderate risk of elevated thunderstorms across Northland, Auckland and northern Coromandel Peninsula this morning and early afternoon. These thunderstorms are likely to boost rainfall rates into the 10-25mm/hr range....Being elevated, the associated convective wind gusts with these storms should remain above the surface, but there is a risk that wind gusts of 110km/hr could reach the surface... A lower risk of thunderstorms extends north of a line from Mt Taranaki to East Cape this afternoon.

In addition to this low risk, there is a risk of wind gusts in the 90-110km/hr range from western Waikato to north Taranaki this afternoon as a cold front passes through.

In the far south of the South Island, an active cold front is expected to spread onto Fiordland at night. There is now a high risk of thunderstorms with the front, and these are likely to generate locally heavy rain, strong winds.

MetService T-storm Outlook Map - Oct 17, update.png

Edit: Outlook udated

[Manukau heads obs]

don't write it off just yet

[Nev]

Yes, offshore lightning appears to have got a second wind.

Also not too often you see 50 kt gusts forecast for the Hauraki Gulf this arvo…

[mikestormchaser]

Nice to see you north Islanders getting some action up there. Wensday still see's thunderstorms in canterbury and judging by the total totals index even Christchurch may even get a storm.

[David]

Nice rumble of thunder here just now.

[spwill]

There are more thunderstorm cells out to sea, very random who catches a storm.

I see the dewpoint at Kaitaia is now 18C, still only 12C here, will rise here very shortly

[David]

Wind is still cool NE here, guess the NW change is running late...

[spwill]

Change not too far away now.
Parts of Northland and the outer Gulf really catching the lightning last hr

[Manukau heads obs]

windy here but not out of the ordinary
big jump in the temperature from this morning

[Manukau heads obs]

Ok, now its getting windy

[NZstorm]

Nice to see you north Islanders getting some action up there. Wedensday still see's thunderstorms in canterbury and judging by the total totals index even Christchurch may even get a storm.

The total totals tend to skew into big numbers within the polar airmasses.

But severe hail could occur Wednesday if the E/NE surface wind can develop. Good flow aloft.

[Paul Mallinson]

RE possible Greymouth tornado

I had a look at this yesterday and decided on balance it was a gust. But it was a highly sheared moist environment so a tornado was defintely possible.

Thanks NZstorm.

I tend to agree about it being a gust but one can't rule out a weak tornado.

Cheers,

Paul

[Paul Mallinson]

Nice to see you north Islanders getting some action up there. Wedensday still see's thunderstorms in canterbury and judging by the total totals index even Christchurch may even get a storm.

The total totals tend to skew into big numbers within the polar airmasses.

But severe hail could occur Wednesday if the E/NE surface wind can develop. Good flow aloft.

Yes, the Total Totals does 'blow out' in cold air masses. We have 'normalised' this index so that the key value of 50 applies to a much wider range of airmasses. We call it the Normalised Total Totals and it works pretty well.

Paul

[NZ Thunderstorm Soc]

If the situ, event does come to fact on Wednesday, Mikey, it would be a good analysis to discuss here on Saturday.

[jamie]

Getting rather gusty here. Gusts are really hitting with a thump. Not a consistent wind at all.

[SnwAddct]

Hi All

Have a event planned at home in West Auckland this Saturday and I can see on the GFS Maps that there may be some rain creeping in Saturday evening. Could you give your opinion on this and how much rain you think there will be? Heavy or Light?

Any info shared would be much appreciated

[spwill]

Hi All

Have a event planned at home in West Auckland this Saturday and I can see on the GFS Maps that there may be some rain creeping in Saturday evening. Could you give your opinion on this and how much rain you think there will be? Heavy or Light?

Any info shared would be much appreciated

I think it is bit early to make a call on the timing of the front for Saturday, the day may stay dry. Warmish temps.

[Manukau heads obs]

often this time of year in a NW flow you can get relatively low cloud (high humidity) on the west coast...and even mist patches...

[NZ Thunderstorm Soc]

Back to gusty NW here again , how boring

[Dale]

Some seriously heavy hail laced showers this morning.. awaiting on this thundery rain but if the last few mornings pre 5am have been anything to go by, thats when the winds & intense bursts pick up.

Good call re the possible Tornado, Paul M.. I've looked further & spoken to a few people in town (Greymouth isn't as big as you think it is) and although some.. of the parameters were there, looks to a couple of us like more isolated straight line wind damage.

Cheers.. Dale.