Hobsonville Storm Damage Track

Archive of NZ Weather & Climate
Forum rules
These topics are a read-only archive and may be subject to out-of-date information.

For today's weather discussion head to: New Zealand Weather & Climate
spwill
Posts: 9907
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 839 times
Been thanked: 866 times

Re: Hobsonville Storm Damage Track

Unread post by spwill »

METMAN wrote:
First pic Hobsonville Microburst
No sign of a microburst in that photo of a shower over the Gulf there METMAN :>
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Hobsonville Storm Damage Track

Unread post by NZstorm »

Would be interesting to see if the 1 minute WP AWS data did indeed show a significant pressure-spike?

Rickys weather station dropped 2.4hpa in the 25minutes before the convective line crossed and then jumped 1.4hpa with the onset of heavy rain. That's fairly representative of what happened across west Auckland. As for the damage path, an AWS would have to be in in the path for us to know exactly what the pressure did there.
User avatar
Nev
Moderator
Posts: 6216
Joined: Tue 07/03/2006 15:24
Location: Waiheke Island, Hauraki Gulf
Has thanked: 468 times
Been thanked: 1064 times

Re: Hobsonville Storm Damage Track

Unread post by Nev »

^ Totally agree Steven. That's why I have a problem with this somewhat ambiguous statement...
METMAN wrote:This came from MetService
" All the barometric pressures in it's path jumped as the CB passed over"
The common grammatical error also tends to suggest that it didn't come from any official source.
METMAN
Posts: 39
Joined: Sun 13/01/2013 21:15
Location: Auckland
Has thanked: 0
Been thanked: 0

Re: Hobsonville Storm Damage Track

Unread post by METMAN »

APOLOGY
I was misled as to the origin of that picture and guilty of seeing what I wanted to see.
I should have researched it better.
I apologise for misleading the forum however unintentionally
METMAN
Posts: 39
Joined: Sun 13/01/2013 21:15
Location: Auckland
Has thanked: 0
Been thanked: 0

Re: Hobsonville Storm Damage Track

Unread post by METMAN »

Nev wrote:^ Totally agree Steven. That's why I have a problem with this somewhat ambiguous statement...
METMAN wrote:This came from MetService
" All the barometric pressures in it's path jumped as the CB passed over"
The common grammatical error also tends to suggest that it didn't come from any official source.
From an email from a manager metservice
METMAN
Posts: 39
Joined: Sun 13/01/2013 21:15
Location: Auckland
Has thanked: 0
Been thanked: 0

Re: Hobsonville Storm Damage Track

Unread post by METMAN »

NZstorm wrote:
Would be interesting to see if the 1 minute WP AWS data did indeed show a significant pressure-spike?

Rickys weather station dropped 2.4hpa in the 25minutes before the convective line crossed and then jumped 1.4hpa with the onset of heavy rain. That's fairly representative of what happened across west Auckland. As for the damage path, an AWS would have to be in in the path for us to know exactly what the pressure did there.
I don't know where Rick's weather station is located but email said that pressures jumped as CB went over
Well the CB in question tracked WP to HB and then SE so probably did not pass over Rick's weather station. I don't know. I believe the damage path was caused by strong wind arc streaming SE ahead of CB. Base of CB would have been wider one to two km.
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Hobsonville Storm Damage Track

Unread post by Manukau heads obs »

that pressures jumped as CB went over
yes...but just after...the pressure actually dropped just prior to that pressure rise (which is typical of a frontal CB passage)
(I even recorded a pressure dip this far away)
it almost seems MS are cherry picking the data to suit the theory of a microburst?
in any case, its been like a big whodunnit detective case!
not sure if the jury is out on a microburst type event
in any case, was something you dont normaly see occur in NZ, was more like something from the midwest USA!
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
spwill
Posts: 9907
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 839 times
Been thanked: 866 times

Re: Hobsonville Storm Damage Track

Unread post by spwill »

Yes, it was a warm season event, the Auckland storm season tends to be cold season, the cooler drier lower level air in winter limits the severity of our storms.
jamie
Posts: 5907
Joined: Fri 25/02/2011 21:35
Location: Hamilton NZ
Has thanked: 22 times
Been thanked: 273 times
Contact:

Re: Hobsonville Storm Damage Track

Unread post by jamie »

yea my friends laugh at me as every time i have been to the USA storm chasing there has been a decent tornado somewhere in NZ every time i have gone. They say im silly paying all that money when i can just stay here. If only they knew the scale of things over there :crazy: :lol:
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Hobsonville Storm Damage Track

Unread post by NZstorm »

An another parameter that would indicate a microburst would be the temperature. I would expect a sharp temperature drop from a cb collapsing.
METMAN
Posts: 39
Joined: Sun 13/01/2013 21:15
Location: Auckland
Has thanked: 0
Been thanked: 0

Re: Hobsonville Storm Damage Track

Unread post by METMAN »

NZstorm wrote:An another parameter that would indicate a microburst would be the temperature. I would expect a sharp temperature drop from a cb collapsing.
Thats correct
User avatar
Nev
Moderator
Posts: 6216
Joined: Tue 07/03/2006 15:24
Location: Waiheke Island, Hauraki Gulf
Has thanked: 468 times
Been thanked: 1064 times

Re: Hobsonville Storm Damage Track

Unread post by Nev »

METMAN wrote:I don't know where Rick's weather station is located...
Ricky's PWS is in Grey Lynn. It's considered by local weather-buffs to be one of the most reliable PWS's around Akld and also a very good representation of the central Akld urban area.

Ricky's graphs for Dec 6 here, and a bit more info about Ricky here. :D
METMAN
Posts: 39
Joined: Sun 13/01/2013 21:15
Location: Auckland
Has thanked: 0
Been thanked: 0

Re: Hobsonville Storm Damage Track

Unread post by METMAN »

Tks for info Nev but Grey Lynn is too far away.

MetService has confirmed damage at WP and HB was caused by downburst (microburst) but have not yet made public reason's for this.
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Hobsonville Storm Damage Track

Unread post by NZstorm »

Ammended version of damage track.

Its a bit wider than the original.
You do not have the required permissions to view the files attached to this post.
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Hobsonville Storm Damage Track

Unread post by NZstorm »

There is an anemometer on NZWP base near the end of the runway, about 200m from the damage track, thats where the 69kts would have been recorded I'm guessing.
spwill
Posts: 9907
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 839 times
Been thanked: 866 times

Re: Hobsonville Storm Damage Track

Unread post by spwill »

Thanks NZstorm, yes I did notice a couple of spots where your damage track needed to be a little wider :smile:

I hope to get back out to Hobsonville in the near future to look at the tree damage on some of the private land before it all gets cleaned up.
spwill
Posts: 9907
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 839 times
Been thanked: 866 times

Re: Hobsonville Storm Damage Track

Unread post by spwill »

Nev wrote:
There's a video interview with the guy that was inside that site-office/container, which rolled across Scott Rd, then rolled back again, which would mean winds roughly from the NE, then from the SW.
There was also a lunch room which was blown around by the wind and ended up in the nearby cemetery, I think about 100 yards away. I had a chat with someone recently who was at that work site at the time. He said the winds started from the NE and turned west/ southwest, this location is on the west side of the damage track.
Generally the damage on the east side of the track looks largely to have been caused by N/NE wind while the damage on the west side of the track shows much more variation in wind direction with a lot of southwest wind showing up.
Last edited by spwill on Mon 04/03/2013 16:04, edited 1 time in total.
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Hobsonville Storm Damage Track

Unread post by Manukau heads obs »

its almost like it was a "Derecho"
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
User avatar
Vertigo
Posts: 1184
Joined: Sun 09/12/2007 23:50
Location: Henderson, Auckland
Has thanked: 0
Been thanked: 12 times

Re: Hobsonville Storm Damage Track

Unread post by Vertigo »

dont forget this video of the event, taken in the west harbour area. very distinct wind direction changes.
http://www.youtube.com/watch?v=f9CYQof-ZL8
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Hobsonville Storm Damage Track

Unread post by Manukau heads obs »

thats only at the surface wind direction change too
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
spwill
Posts: 9907
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 839 times
Been thanked: 866 times

Re: Hobsonville Storm Damage Track

Unread post by spwill »

But there are no clips showing the very distructive winds at Hobsonville/Whenuapai, the damage zone is very well defined. Tree damage shows there were multiple wind directions in that damage zone , we also have to consider storm momentum which would tend to take debris forward of the track.
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Hobsonville Storm Damage Track

Unread post by NZstorm »

dont forget this video of the event, taken in the west harbour area. very distinct wind direction changes.
It looks to have been an outflow boundary at the surface from convection further west. Alot of west Auckland did catch a wind change before the wind went NE again.

The subtropical jet stream was a major player in the severe weather bringing upper level diffluent flow across the area.

Still doing a study on the event.
Manukau heads obs
Posts: 12305
Joined: Mon 10/03/2003 16:30
Location: West Coast Road, Manukau Peninsula, North Island
Has thanked: 0
Been thanked: 0
Contact:

Re: Hobsonville Storm Damage Track

Unread post by Manukau heads obs »

The subtropical jet stream was a major player in the severe weather bringing upper level diffluent flow across the area.
YES
thats it
it was very much a system that developed on the "exhaust area of the jet stream"
i.e diffluent flow area as you say
(conducive to forming lows normaly in that area (will have produced enhanced cooling aloft, helping this CB along big time)
now that I think about how it all came together
Image
Brian Hamilton, weather enthusiast. My weather dataEmail: [email protected]
spwill
Posts: 9907
Joined: Sun 29/06/2003 22:39
Location: Mt Eden Auckland
Has thanked: 839 times
Been thanked: 866 times

Re: Hobsonville Storm Damage Track

Unread post by spwill »

Photo shows two large trees in very close proximity which have been blown over in opposite directions. These trees are on the west side of the damage track at Hobsonville and lie roughly east and west.
You do not have the required permissions to view the files attached to this post.
User avatar
NZstorm
Posts: 11333
Joined: Mon 10/03/2003 19:38
Location: Grey Lynn, Auckland
Has thanked: 342 times
Been thanked: 361 times

Re: Hobsonville Storm Damage Track

Unread post by NZstorm »

I see the insurance bill for this event was $8.7m. The sum may not include Hobsonville Village which is a defence area.

My thinking on this event was that it was a mesovortex tornado.
Locked