Thunderstorms- NI- 12th -13th November

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Tornado Tim
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Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

Looks like Thunderstorms are possible over parts over the North Island on the 12th and 13th.

The 13th looks like a convergence line/sea breeze setup with unduly cold upper temps, the breeze should provide sufficient moisture.

Metservice has got a moderate risk from the mid to upper north island.
Metservice wrote:A deep pool of cold air should move slowly east across the North Island on Tuesday and widespread showers are expected. There is a moderate risk that afternoon heating will produce thunderstorms where sea-breezes converge from about Taupo northwards. Any thunderstorms that form may have hail 10 to 15mm in diameter and rainfall rates approaching 25mm per hour.

There is also a low risk afternoon heating may produce isolated thunderstorms over central Otago.

Elsewhere, no risk of thunderstorms or significant convection.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

I didn't expect this today, just has a fairly close strike here!
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Manukau heads obs »

was some brief but heavy clearing showers this morning, so not surprised to hear things have beeded up inland this arvo
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Thunderstorms- NI- 12th -13th November

Unread post by jamie »

Had some heavy showery rain. Before but never heard thunder
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Re: Thunderstorms- NI- 12th -13th November

Unread post by spwill »

I did wonder about thunder for Waikato today as recent GFS runs have bought upper level cooling in a bit earlier and radar has showed showers lines down there.

The clearance of that high cloud has reached West Ak, some TCu around.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

Metservice has amended the Thunderstorm outlook 2 times today :)
The latest:
Amended to push thunderstorm risk areas into Waikato.

A cold southerly change is spreading up the North Island. There is a moderate risk of thunderstorms developing on the leading edge of this change over the central North Island from Taumarunui to inland Hawkes Bay to Waikato and a lower risk over a larger surrounding area. Any thunderstorms that do develop may be accompanied by hail 10-15mm in diameter and heavy rain with rates 10 to 20mm per hour.

Also, there is a low risk of afternoon heating triggering thunderstorms over the ranges of northwest Nelson.

Elsewhere, no thunderstorms or significant convection expected.
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Thunderstorms- NI- 12th -13th November

Unread post by jamie »

Thunder and hail in Hamilton according to Facebook. Had what seemed close to hail here earlier. But now suns out again.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Manukau heads obs »

heavy and very slow moving cell over west auckland...been building/weakening/building for hours now in the same spot
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

Thunder here now :)
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Re: Thunderstorms- NI- 12th -13th November

Unread post by NZstorm »

I thought at lunch time there would be a storm or two in the Waikato later today due to the 13C dps.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

Here is a shot of the storm (inc Gust front):

The Gust front is now acting as a trigger for more rapidly developing convection......
Watch this space.

More Thunder just occurred :D
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Re: Thunderstorms- NI- 12th -13th November

Unread post by spwill »

This evening I did a drive south along the motorway to the Bombay Hills.
Photos, towering Cu showers over north Waikato.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by David »

Nothing too significant here but a welcome moderate shower this evening, MTD rain up to 12mm
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

spwill wrote:This evening I did a drive south along the motorway to the Bombay Hills.
Photos, towering Cu showers over north Waikato.
Nice, hopefully you can come to Hamilton tomorrow. It looks much more promising than what happened today.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Manukau heads obs »

I might be able to chase tomorrow, would be keen to meet up in bombay...
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Re: Thunderstorms- NI- 12th -13th November

Unread post by spwill »

There was a storm over northern Waikato last 30mins, but there was no real sunshine down there today

I will chase tomorrow, likely meet up with NZstorm. Brian, we could meet up at Bombay , will confirm a time in the morning but we will probably start the day earlier rather than later, perhaps meet up around lunch time
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

Keep me in the Loop and I may be able to join up with ya :)

Ill PM you Simon with my cell if your keen.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by NZstorm »

500mb chart for 1pm tomorrow. Classic spring thunder hail scenario.

It was almost a year ago to the day there was the big hail storms over Rotorua Nov 14 2011.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by David »

Tomorrow's risk updated to high :D
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Re: Thunderstorms- NI- 12th -13th November

Unread post by spwill »

Tornado Tim wrote:Keep me in the Loop and I may be able to join up with ya :)

Ill PM you Simon with my cell if your keen.
Yes, perhaps we can meet up tomorrow
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Thunderstorms- NI- 12th -13th November

Unread post by jamie »

Chase on!
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

jamie.haultain wrote:Chase on!
Chase on alright!
We are under a moderate risk of severe storms, woohoo :D
Metservice wrote:A deep pool of cold air should move slowly east across the North Island on Tuesday and widespread showers are expected. There is now a HIGH risk that afternoon heating will produce thunderstorms where sea-breezes converge from about Taupo northwards. Any thunderstorms that form may have hail 10 to 15mm in diameter and rainfall rates approaching 25mm per hour. Within this area over western Bay of Plenty, eastern Waikato and northern parts of Taupo, there is a moderate risk that some of these thunderstorms will be SEVERE producing rainfall rates up to 40mm/hr and hail up to 20mm or so due to slow storm motions.

There is also a low risk afternoon heating may produce isolated thunderstorms over central Nelson, Buller and Marlborough, and also central Otago and central Southland.

Elsewhere, no risk of thunderstorms or significant convection.
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Re: Thunderstorms- NI- 12th -13th November

Unread post by Tornado Tim »

Some respectable CAPE and LI Numbers being pulled tomorrow afternoon. 800j/kg and LI down to -3 in areas of the Waikato.

Upper level temps cooling to a very chilly -26°C, Hail is definitely in the mix if any decent convection takes place.
SFC forecasted temps across the Waikato region are around 19°C to 17°C.
Attached CAPE/LI Chart and Forecasted Sounding for the 13th at 3 PM NZDST.
Note: GFS can often underestimate a Sea Breeze's Moisture content, even if Sea Breeze occurs so keep that in mind when using the sounding
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Thunderstorms- NI- 12th -13th November

Unread post by jamie »

Awesome. I can't wait. I'll wait for things to develop and will go after some thing good and close.
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Thunderstorms- NI- 12th -13th November

Unread post by jamie »

Will this rain be messing up the chances of storms?
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