Thunder risk for North Island for week starting June 17th

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Re: Thunder risk for North Island for week starting June 17th

Unread post by madaero »

seems to be clearing up now to my north and west.
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Thunder risk for North Island for week starting June 17th

Unread post by jamie »

The rain radar paints a good picture of where got hit but the intensity was much worse than the colors showing.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by cbm »

Did get a small amount of hail mixed with rain here from the second surge.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Tornado Tim »

David wrote:Wow at the vertical rainfall line on Tim's weather graphs! What was the max rain rate Tim?
I was traveling home when the storm hit and was inadvertently chasing it. Cars had to slow to 30km/hr in the core as many peoples window wipers couldn't handle it.

Weather Console shows the max instantaneous rain rate at 443mm/hr, that beats the 2010 rainrate record hands down (but I am comparing the consoles values directly, not calculated rainfall rates).

I have calculated from the logs that 18.6mm fell in 12 min with the highest rain rate of being 2.6mm/min which occurred 2 times in the storm so thats 156mm/hr.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Tornado Tim »

jamie wrote:The rain radar paints a good picture of where got hit but the intensity was much worse than the colors showing.
I agree, the problem with rain if its too big it will get smaller as it travels towards ground, so I have a suspicion there is a maximum echo intensity that a rain droplet can get, beyond that you need to get hail to get a larger echo.

There were quite a few fantastic CG's, one positive which you could see clearly as return stroke stayed visible for a longer amount of time.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Manukau heads obs »

we missed the shower lines here today...for a change!
(they went either side of us)
20C it got to here!
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Thunder risk for North Island for week starting June 17th

Unread post by jamie »

Photo of the water on the ground. This all fell through the ceiling.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Weather Watcher »

Tornado Tim wrote: I agree, the problem with rain if its too big it will get smaller as it travels towards ground, so I have a suspicion there is a maximum echo intensity that a rain droplet can get, beyond that you need to get hail to get a larger echo.
This is sort-of correct. There is a "maximum" size of rain drops, as large rain drops break up into smaller drops. Radar reflectivity is however proportional to both the size of rain drops and the concentration of drops, so high rainfall intensity produces high dBZ values. Nevertheless, high radar reflectivity values (above about 50dBZ) in New Zealand are generally associated with hail.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by NZstorm »

Looks like a good deluge there Jamie!

The convection Thursday pm will be very squally for Auckland/Northland.
Have to see how the gradient tightens up with the low but does look like Auckland/Northland could get squall gusts of 50knots with the hail and isolated gusts 70kts possible.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by jamie »

yea and some very very cold temps aloft! a pool of -30*C 500mb temps and even colder moving over the area.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Tornado Tim »

Interesting t-storm outlook for tomorrow afternoon:
Metservice wrote:The trough that is expected to move onto the North Island Wednesday morning should continue to move east during the afternoon and evening. There is a moderate risk of thunderstorms from Northland down to Taranaki, including the Coromandel Peninsula. These storms could be accompanied by heavy rain of 10-20mm/hr, hail and strong wind gusts of 90-100km/hr. In the evening the thunderstorms risk decreases to low about eastern areas of Auckland, and inland areas of Waikato and Waitomo.

As the trough moves east across the Bay of Plenty there is a moderate risk of thunderstorms near the coast Wednesday afternoon and evening. These storms could be accompanied by heavy rain, strong wind gusts and small hail.

In Buller, western Nelson and about the Marlborough Sounds during the afternoon,there is also a moderate risk of thunderstorms with the possibility of heavy rain of 10-20mm/hr and hail.

Additionally, there is a low risk of thunderstorms in a broader area in other central and northern regions of the country as indicated on the map.

No thunderstorms expected over the remainder of New Zealand.
Could get a rouge storm tonight hopefully :)
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Tornado Tim »

Todays T-storm outlook for reference:
Metservice wrote:A broad complex trough is expected to move east onto northern and central parts of New Zealand today. Some thundery showers are expected in exposed areas associated with this feature, especially where the relatively warm sea surface enhances the instability.

There is a moderate risk of thunderstorms in coastal Buller and the far northwest corner of Nelson. These storms could be accompanied by heavy rain and small hail. A low risk of thunderstorms for this afternoon covers a slightly broader area over the South Island and Kapiti as indicated on the map.

There is a moderate risk of thunderstorms in the north of Taranaki and the west of Waitomo and Waikato as indicated with heavy rain and small hail.

In Auckland, Northland and the north of Coromandel Peninsula there is a moderate risk of thunderstorms with heavy rain, strong winds gusts, around 90 km/h and small hail.

As the trough moves east this afternoon there is a moderate risk of thunderstorms for the remainder of Coromandel Peninsula and the coast of the Bay of Plenty with heavy rain and small hail.

A moderate risk covers a broader area over the upper North Island as indicated on the map.

No thunderstorms expected over the remainder of the country.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by littleheaven »

Was absolutely black over North West Auckland as I drove home from the school run half an hour ago. Now just starting to rain in Glenfield. Some of the street lighting has come back on.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by bmo »

Have had one rumble so far in Kaukapakapa but just had some heavy rain, will see what they day brings thunder wise.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by spwill »

Some thunderstorms occurring over Northland. Cool conditions here today due to cloud cover, current 14C, dp 13C, no wind
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Re: Thunder risk for North Island for week starting June 17th

Unread post by DTNZ »

Distant thunder heard in Whangarei, real dark out there at the moment
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Re: Thunder risk for North Island for week starting June 17th

Unread post by DTNZ »

Change that thunder directly overhead... deep low rumbles... real dark out there... *turns on lamp* ah light can see now :)
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Re: Thunder risk for North Island for week starting June 17th

Unread post by DTNZ »

IC flash just now... don't think it was CG strike.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by DTNZ »

lots of IC and deep low rumbles of thunder overhead at moment... rains fair chucking down too... visibility approx in rain 20 metres.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by DTNZ »

not really, really cold though... mild to warm, walking around in shorts and a light pullover jersey. rain easing some what.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by DTNZ »

Storms moving on... light to moderate steady rain, not so heavy as it was earller... skies becoming lighter *reaches for lamp switch and turns it off* that's my report from Whangarei.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by jamie »

check out the mess of showers on the western edge of the radar appearing.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Tornado Tim »

CB's going up south and west of me, but there is heaps of low cloud so it is hard to any any CB tops etc.

Update: can hear some thunder going on with the cell down to the south.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Tornado Tim »

Quite a nice storm nearing 60dbz! Lightning is starting to get more frequent too going by the detector.
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Re: Thunder risk for North Island for week starting June 17th

Unread post by Tornado Tim »

Reports via WeatherWatch that a Tornado occurred just south of Hamilton this afternoon in Paterangi.
Link to article: http://www.weatherwatch.co.nz/content/p ... h-hamilton

No Time was provided so I am not sure which cell dropped it.

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