Complex Trough crossing N.I. - July 3-6

[Tornado Tim]

I was expecting at least a one strike wonder with the passing of that front around Auckland. There was some around Northern Coromandel however.

I find it a crackup that if this event say happened in the Waikato or elsewhere, it wouldnt be on the TV News much like the storms we had in Late Jan 2010 (where that sight was very very common), but if its in Auckland it gets main stage.

[jamie]

It's all about number of people affected Tim.

[Nev]

Bit belated but, thought this weeks events should really warrant its own thread.

[spwill]

.
I find it a crackup that if this event say happened in the Waikato or elsewhere, it wouldnt be on the TV News much like the storms we had in Late Jan 2010 (where that sight was very very common), but if its in Auckland it gets main stage.

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I watched TV ONE and they had a fairly short segment on the Auckland weather about the fifth story in.

[Tornado Tim]

Looking north looks quite dark with that area of convection around north Waikato.

[spwill]

I heard there was a good hail storm at Waihi Beach late yesterday, a good covering of hail there.

[spwill]

A nice afternoon here, 15-16C , can see thundery cloud tops west of Northland from here

[Manukau heads obs]

the new lightning network is plotting that CB nicely

[treetop]

some data on the waihi bch storm midnight mon to midnight tues 295 mm 6 30pm to 9 30pm 205mm ! Very localised ,lots of thunder/lightning and hail up to 250mm deep while omokoroa and Tauranga had only 20 to 40mm through that eve period, Obviously a slow moving cell. WE caught it here in Katikati, a lot of shops /houses flooded, roads closed ,driveways washed out etc.Been here 30 years have seen simalar events 3 or 4 times.

[Tornado Tim]

some data on the waihi bch storm midnight mon to midnight tues 295 mm 6 30pm to 9 30pm 205mm !

That figure looks very suspicious!

Looking through the radar archives I have of yesterday, it seems Tauranga/Waihi was on the receiving end of a flanking line where convection quickly developed over sea and blew south of the area and dissipated rapidly when it reached further inland making it look like the storm was stationary.

Echos from the BOP Radar indicate the rain was quite heavy around the 40 to 55dbZ mark but it wasn't constantly around 50dbz+, which in my option means that the station you were quoting was over-reading.

The Welcome Bay Weather Station only got 33mm from that event aparently.

If a Metservice meteorologist could get a rainfall total estimate from the radar that would be very much appreciated

[NZstorm]

There's a limit to the amount of rain you can get from any given situation. Rainfall rates of 40mm/hr wouldn't be a bad guess for Tuesdays set up. Anyway, looks like they had a good storm with the hail accumulating the way it did.


According to the media it was a weather bomb.
http://www.bayofplentytimes.co.nz/news/ ... s/1440627/

[tgsnoopy]

It friggen hosed down. Very similar to the May 05 event in terms of rate. The figures quoted wouldn't surprise me at all. I don't care what radar etc says, it was a very significant event when I drove through it.

[Manukau heads obs]

it certainly seemed to fire up once it got a feed off the warmer water in the BOP

[treetop]

Thanks for the support tgsnoopy, the figures work in well with many orchard rercordings that evening. My orchard had 100m wide by 600mm high water flowing at 5 km/hr from a 20 ha catchment, quite a sight , this area seems to attract such events.7 years ago we [katikati] recieved 110 mm in one hour,.2 hrs later tornadoes caused a lot of damage in Kawerau,.In 1988 we rcorded 175mm in 2 1/2 hrs. In the early 90s a dairy farm close to the Kaimais recieved 150mm in under an hour ,the farmer escaped death by climbing on the milking shed roof.All 200 cows were found the next day floating in the Tauranga harbour 5 km away.[incidentaly there was no rain one km away.!]

[tgsnoopy]

KaimaiKid & I chased the infamous Tornado Whisperer day. If we hadn't stopped for photo's of damage at Pongakawa we would have witnessed first hand at Kawerau.

[Tornado Tim]

I do believe that large amounts of rain can fall in a short amount of time, back in 2010 A stationary redeveloping storm dumped 160mm of rain in a few hours over here (Matangi), the only thing is the radar echos in that situation matched the rain rate.
Radar signals can get attenuated from time to time in very heavy rain, but it usually occurs on the outer edges of the radar coverage when the really heavy stuff is closer to the radar beam.
Would you mind telling us was equipment you were recording your rainfall? (this will add more validity to your claims).

[NZstorm]

7 years ago we [katikati] recieved 110 mm in one hour,.2 hrs later tornadoes caused a lot of damage in Kawerau

Was that March 25th 2005 treetop. I remember that day well as we had a big storm in Auckland in the morning then it moved across to BOP and became tornadic. The airmass was fairly tropical.

As for heavy rain at this time of year, the ground is at field capacity and you get almost 100% runoff. Thats why Auckland became submerged the other day.

[tgsnoopy]

Aaron Wilkinson aka Tornado Whisperer picked the risk of a Tornado that day and was pretty much on the money, hence he earned the nickname... Haven't searched to see the actual date though.

[treetop]

tornado Tim, I understand your point, certainly no electronic measuring equipment used that I know of . Most farmers and orchardists rely on anything from a bucket to the funnel in a tube.So an average of all readings considered . A normal once a year extreme event here would be 150/200 mm in 12 hours.What was unusual here ,the rain did not vary in intensity for 2 1/2 to 3 hours, the first time I have been scared of heavy rain. Im not going to be judge and jury on measuring equipment, all I can say is wish u were here to talk to and experience it. My family were in bed with pillows over their heads for the duration ! Most other notable rain/hail events in the bay involve single or clusters of cb cells unlike the frontal variety that effects Auckland, most of those storms burnout before getting here. The BOP storms drift south or SE with upper level winds from north or NW as they clear the coromandel surface moist air is pulled in at 90 deg to the upper air flows. As the storms approach land [kaimai,mamakus,east cape] lifting is enhanced. In extreme cases if the southward drift of the storms matches the speed of the back building of the flanking line then there will be a prolonged period of intense rainfall over a small area. Its like they hit the mountains and get trapped there. Hope that makes sense