No sign of a microburst in that photo of a shower over the Gulf there METMANMETMAN wrote:
First pic Hobsonville Microburst
Hobsonville Storm Damage Track
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Re: Hobsonville Storm Damage Track
- NZstorm
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Re: Hobsonville Storm Damage Track
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.
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Re: Hobsonville Storm Damage Track
^ Totally agree Steven. That's why I have a problem with this somewhat ambiguous statement...
The common grammatical error also tends to suggest that it didn't come from any official source.METMAN wrote:This came from MetService
" All the barometric pressures in it's path jumped as the CB passed over"
Re: Hobsonville Storm Damage Track
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
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
Re: Hobsonville Storm Damage Track
From an email from a manager metserviceNev wrote:^ Totally agree Steven. That's why I have a problem with this somewhat ambiguous statement...
The common grammatical error also tends to suggest that it didn't come from any official source.METMAN wrote:This came from MetService
" All the barometric pressures in it's path jumped as the CB passed over"
Re: Hobsonville Storm Damage Track
I don't know where Rick's weather station is located but email said that pressures jumped as CB went overNZstorm 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.
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.
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Re: Hobsonville Storm Damage Track
yes...but just after...the pressure actually dropped just prior to that pressure rise (which is typical of a frontal CB passage)that pressures jumped as CB went over
(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!
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Re: Hobsonville Storm Damage Track
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.
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Re: Hobsonville Storm Damage Track
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
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Re: Hobsonville Storm Damage Track
An another parameter that would indicate a microburst would be the temperature. I would expect a sharp temperature drop from a cb collapsing.
Re: Hobsonville Storm Damage Track
Thats correctNZstorm wrote:An another parameter that would indicate a microburst would be the temperature. I would expect a sharp temperature drop from a cb collapsing.
- Nev
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Re: Hobsonville Storm Damage Track
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.METMAN wrote:I don't know where Rick's weather station is located...
Ricky's graphs for Dec 6 here, and a bit more info about Ricky here.
Re: Hobsonville Storm Damage Track
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.
MetService has confirmed damage at WP and HB was caused by downburst (microburst) but have not yet made public reason's for this.
- NZstorm
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Re: Hobsonville Storm Damage Track
Ammended version of damage track.
Its a bit wider than the original.
Its a bit wider than the original.
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- NZstorm
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Re: Hobsonville Storm Damage Track
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.
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Re: Hobsonville Storm Damage Track
Thanks NZstorm, yes I did notice a couple of spots where your damage track needed to be a little wider
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.
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.
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Re: Hobsonville Storm Damage Track
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.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.
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.
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Re: Hobsonville Storm Damage Track
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
http://www.youtube.com/watch?v=f9CYQof-ZL8
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Re: Hobsonville Storm Damage Track
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.
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Re: Hobsonville Storm Damage Track
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.dont forget this video of the event, taken in the west harbour area. very distinct wind direction changes.
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.
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Re: Hobsonville Storm Damage Track
YESThe subtropical jet stream was a major player in the severe weather bringing upper level diffluent flow across the area.
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
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Re: Hobsonville Storm Damage Track
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.
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- NZstorm
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Re: Hobsonville Storm Damage Track
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.
My thinking on this event was that it was a mesovortex tornado.