NZ Weather Forum

I have decided to do a little investigation into New Zealands deadliest tornado in History.

Since this tornado occurred in August the 25th it must have been a cold season tornado.
Reports state that this tornado was associated with a thunderstorm, but was this an atypical thunderstorm for that time of year or was a strong cold front (with an embedded thunderstorm?)

But what I would like to know was this Tornado linked to a cold front or not.

Does Metservice have any archived isobaric maps of that time in 1948 (since they didnt exist then I wonder if they have them) ?

Based on the reports I have read the tornadoes that have greeted Hamilton have all taken a similar track, both ended up dissipating in the Matangi/Tamahere area.

Very interesting reading.....

Might make up a page on my site later on with my findings....

Will be interesting, for sure. Will still be within living memory for some up there? only 63 years ago.

But what I would like to know was this Tornado linked to a cold front or not.

I had a look in the NZ Herald once to see if there was a synoptic chart and I couldn't find one. They had a two page story on it though.

Tornadoes in winter would need the support of a front given there is no diurnal heating. The upper flow in tornado situations is typically strong NW, the near surface flow NE or E, and fairly moist air (relative to upper level temps).

I remember reading the Frankton tornado come in from the NW.

NZstorm wrote:

Tornadoes in winter would need the support of a front given there is no diurnal heating. The upper flow in tornado situations is typically strong NW, the near surface flow NE or E, and fairly moist air (relative to upper level temps).

I realize that, but I want to cover all bases just to make sure as weather at times can be very unpredictable and sometimes doesn't abide by our type of knowledge of the atmosphere (there is still heaps that we don't know about).
Other info I want to find out is the Sea SFC temp, what type of weather pattern was in effect at the time?
My suspicion atm is El Nino but dont know until It can be confirmed.

The reanalysis site begins in January 1948:

http://www.esrl.noaa.gov/psd/data/reana ... ysis.shtml

SOI for various years (average from June to Nov):

http://www.longpaddock.qld.gov.au/produ ... ation.html

he reanalysis site begins in January 1948:

Thats quite a useful site tunster, thanks for link.

In reply to this post:
Yes that tornado caused damage that it seems is quite abnormal for NZ tornado which is usually the land spout variety.

Which leads me to believe this is was a supercellular based tornado and not strong landspout one, since this came from just west of Frankton and headed into Hamilton East then into the Country, I would say it had a 5k + path.

That damage (seen in the video) I doubt would have been attributed to a landspout based tornado.

I just wish I could back this up with more meteorological evidence (which would be rare in 1948...)

Of Note: the 2005 Tornado and this this tornado took a very similar path, but with the 2005 one developing a little later and doing most of the damage in Hamilton East.

it would have been a mesocyclone for sure on a very strong/active cold front

Yes that tornado caused damage that it seems is quite abnormal for NZ tornado which is usually the land spout variety.

My thoughts on landspouts in NZ is that are generally too weak to do damage. The tornado damage in NZ is the product of strong near surface shear coincident with strong low level convergence. So they are related to supercells with a low level mesocyclone.


I had a look back at the NCEP reanalysis page and while you have to doubt upper air data from 1948, it does give the 500mb temp as being -26C over Waikato that day. So that pretty much ties in with what we expect. A cold unstable airmass.