NZ Weather Forum

A bit more light reading for you all

Extremely fortunate that nobody was hurt.

That wooden pole snapped in multiple places was a feature I saw a lot of in the devastation after the Moore tornado.

The roofing iron wrapped around the power lines is draping the 11 kV and would have cut power to a significant area.

The Queens Wharf webcam gives us a glimpse of Devonport weather around 6pm, Oct 8th. This image shows the weather was clearing by 6.11pm. The 6pm image shows rain. Images provided by http://www.snapithd.com/

A map here showing the 3 locations with damage (yellow). The blue arrow indicates the upper NW steering flow. Looks to be a damage track.

The red dot at the bottom is where roofing iron/timber was found.

There was some light damage through to Torpedo Bay not shown on that map.

My analysis indicates the surface boundary would have crossed the area about 6.05pm. Tornado would have occurred right on the boundary. There would need to have been a surface NNE flow feeding into the cb for a tornado to develop.

NZstorm wrote:My analysis indicates the surface boundary would have crossed the area about 6.05pm. Tornado would have occurred right on the boundary. There would need to have been a surface NNE flow feeding into the cb for a tornado to develop.

There was little or no cloud structure/ base apparent over this part of town, we were under a dying Cb here. However the Queens Wharf cam suggests a decent cloud base near Devonport at 6.11pm.

there was good NNE wind ahead of the CB line...you can see that in Rick'ys data

For what it's worth, Vector say the Telecom pole was snapped at 'about 6.15pm', although the fact that they're referring to it as 'wind squall' does make one wonder whether the timing was based on media reports rather than their own records?

to me, there must be a general maximum windspeed you are going to reach with a collapse of a CB
what is that?
is that enough to cause the damage seen?
to snap a telecom pole like that would take more than a wind squall!

the key here is that collapse occured on the south side of the waitemata

Manukau heads obs wrote:to me, there must be a general maximum windspeed you are going to reach with a collapse of a CB
what is that?
is that enough to cause the damage seen?
to snap a telecom pole like that would take more than a wind squall!

The Waikanae storm back in July 9 2011 did a lot of tree damage a blew over a farm building. Almost certainly outflow winds as a tornado unlikely in that type of set up. Possibly 80knot winds.

I think the Telecom pole was most likely hit roof debris. But yes, going by what looks like bits of a Fibrelite fence that smashed through the glass-door and embedded into an internal wall, my best guess would be wind-gusts of around 120-160 km/h (65-85 kts).

to do that sort of damage, at least 85 knots
my 2 cents worth