Tasman low

spwill · Unread post by **spwill** » Sun 18/09/2005 03:51

Squally heavy shower woke me.
Greylyn is showing 16.3mm in the last hour

Manukau heads obs · Sun 18/09/2005 06:58

that turned out to be the main front
wind dropped away alot
baro starting to drop again now
sat pic shows tight center with squally cb's rotating around, center now moving SE, after was more ESE
should pass just to the south of auckland
will get very windy this afternoon
on time for the storm chase meet
prognosis map has 972 center

Gary Roberts · Unread post by **Gary Roberts** » Sun 18/09/2005 07:00

Manukau heads observer wrote:that turned out to be the main front
wind dropped away alot
baro starting to drop again now
sat pic shows tight center with squally cb's rotating around, center now moving SE, after was more ESE
should pass just to the south of auckland
will get very windy this afternoon
on time for the storm chase meet
prognosis map has 972 center

Looking good for you guys up there.

squid · Unread post by **squid** » Sun 18/09/2005 07:07

main front dropped 14mm here in Dargaville recorded wind gusts to 65kph now it fairly calm with bro starting to drop quicker now sitting on 980 big cb's everywhere i am picking that the wind will pick up again soon and we will get thoses gales that we have been promised

Manukau heads obs · Sun 18/09/2005 07:10

ricky's station shows that was a very heavy rain event the city got!
you guys got 9mm more than me

GraemeWi · Unread post by **GraemeWi** » Sun 18/09/2005 07:20

13mm overnight, the barometer continues to drop - currently 986mb. At the moment the wind is pretty low.

1007mb @ 2pm Saturday
1005mb @ 4pm
1003mb @ 9pm
1002mb @ 10pm
1000mb @ 11pm
998mb @ 12am Sunday
996mb @ 1am
994mb @ 2am
992mb @ 3am
990mb @ 4am
988mb @ 5am
986mb @ 6am
984mb @ 8am
982mb @ 9am
981mb @ 10am
980mb @ 11am
979mb @ 12pm
979mb @ 1pm
978mb @ 2pm

[edit - midnight to 5am extrapolated]

Cheers,

G

spike_01 · Unread post by **spike_01** » Sun 18/09/2005 07:49

Nothing unusual here... Has been rain, but not now... High cloud... It is windy though... My willow tree is losinf small branches...

Willoughby · Unread post by **Willoughby** » Sun 18/09/2005 08:06

Heaviest rain in NZ as a city has fallen here in Hamilton, 12.6mm in the hour to 6am, 26.8mm in the 3 hours to 6am. 37mm since middnight!
Baro: 982mb and has been in rapid decline from 6am to now.

Rotorua is getting the heaviest rain now by the looks of the 7am obs with NORTHERLY GALES

Rain band has cleared here fined up even a little, now we're just in for a day of squally showers and/or thunderstorms !!

Big anvils and Cb's to the distant south of Hamilton

Manukau heads obs · Sun 18/09/2005 08:53

baro now 983hpa here
thats the lowest reading i have recorded in a long time

tgsnoopy · Unread post by **tgsnoopy** » Sun 18/09/2005 09:21

Baro here saying 988, but I doubt it's accurate (Weather station definitely getting closer to the top of my shopping list). Baro has now dropped 18 points since about 5pm last night.

We are in the calm behind the first front presently. The initial front comprised of heavy rain, medium strength winds, no obvious lightning from my perspective.

Trying to decide which direction I'm going to head to observe this incoming weather.

Manukau heads obs · Sun 18/09/2005 09:23

http://www.metservice.co.nz/default/ind ... key=212868

you dont see wording like that every day!

squid · Unread post by **squid** » Sun 18/09/2005 12:43

bro now 974 and it has been on that for a few hrs this is a record for me and having wind gusts to 114kph from the NNw plenty of squally showers coming through

ricky · Unread post by **ricky** » Sun 18/09/2005 12:51

NZ Police CommCens Alert 11:00 18-09-2005 Auckland City

Location of incident: Upper North Island area

Incident Type: Various weather related incidents

There have been numerous reports of damage and associated problems due to the weather in upper North Island today.

(1) Large barriers blown across the roadway, partially blocking it, on Sunset road, Sunnynook, Northshore.

(2) Tree fallen across road blocking both lanes, Dale road, Whenuapai, Waitakere, bringing down power lines.

(3) Mudslide and trees blocking road, SH30, Lake Rotoma, Rotorua (prior to lake frontage area, Westbound) Large treet also fallen near this area.

(4) A Tree has brought down a power pole over SH 1B, Eureka, Waikato, with wires approx 2m off the ground, road blocked.

(5) Power cables blown across road near Golf course, Wainui Road, Silverdale, Rodney. Crossing 2 lanes prior to Orewa Road.

(6) Southern m`way, approx 1 km from off ramp, northbound, Hingaia /GSR area, Conifer Grove, Papakura, large amount of timber plywood blown from a vheilces trailer.

(7) A large canopy, measuring 50m x 30m has come adrift off a service station (Caltex) in Victoria Street, Dargaville, causing road to be closed.

(7) Fire Service responding to an address in Pukepoto road, Kaitaia, where part of the roof has blown off.

(8) Tree blocking northbound lane, 200 meters north of Pukenui, Houhora, Far North.

(9) Treet across south side of road, approx 2km from railway line, SH 1 Kawakawa. Road blocked partially.

03Stormchaser · Unread post by **03Stormchaser** » Sun 18/09/2005 13:21

http://www.rambocam.com/
Boats along Aucklands waterfront damaged or sunk in overnight high winds

tgsnoopy · Unread post by **tgsnoopy** » Sun 18/09/2005 13:53

My (unknown accuracy) Barometer dropped down to 979 here now! That's an impressive drop of 28 isobars (from 1007) in approx 20 hours!

What are the requirements for a weather bomb? I thought it was a change of 25 in 24 hours, this has exceeded this, so I thought it would have been called a weather bomb?

Temperature hasn't dropped that much so far. It's currently about 16Â°C outside. Not that much wind so far either... I'm still waiting with anticipation. Hopefully We'll get some kind of action weather.

GraemeWi · Unread post by **GraemeWi** » Sun 18/09/2005 14:01

tgsnoopy wrote:What are the requirements for a weather bomb? I thought it was a change of 25 in 24 hours, this has exceeded this, so I thought it would have been called a weather bomb?

As I understand it - a weather bomb is the depression itself deepening by approx 20mb in a day rather than the pressure dropping at a static location.

I'll have a hunt on the net and see what I can turn up on it.

[edit - found it on a US site:

Weather Bomb

Weather bombs are the most severe of all winter storms. They are characterized as intense low-pressure systems with a central pressure that falls 24 millibars or more in a 24-hour period. ]

Cheers,

G

tgsnoopy · Unread post by **tgsnoopy** » Sun 18/09/2005 14:28

Ok, my bad, I misunderstood that

Thanks for the clarification.

GraemeWi · Unread post by **GraemeWi** » Sun 18/09/2005 16:08

Just browsing through the met service website -

In one of the notable weather events archives they refer to a "bomb" storm of 1996:

The depression responsible for the storm crossed southeast Australia on 17 November with a depth of 992 hPa, then it deepened rapidly as it moved into the Tasman Sea during the morning of the 18th, falling 14 hPa in 12 hours - certainly of "bomb" proportions

There may be different categories of bombs - report from a 2000 storm in the South Island:

So its pressure dropped from 1002 to below 980hPa - most of this occurred in 24 hours, and at latitude 45ÂºC a drop of 20hPa in 24 hours is defined as 1B (one bomb).

and also

The low deepened from 970hPa at 52Â°S to 944hPa at 60Â°S in 24 hours to midday on the 18th, rating it 1.13B (anything 1.0 or greater is rated a â€œbombâ€).

Interestingly the record for the lowest pressure in NZ was "954 hPa (28.19 inches of mercury) at Taiaroa Head in 1939."

I'm going to do some more reading on these bombs..

[edit - found it: bit hard to write in plain text!

NDR = (pressure change / 24 hours) (SIN 60Â° / SIN latitude)
NDR = 1 Bergeron

second edit - not sure I copied the formula correctly!
http://www.weatheranswer.com/public/SH_NH_Bombs.pdf
]

Cheers,

G

jrj · Unread post by **jrj** » Sun 18/09/2005 16:44

Currently 973mb (accurate) here and falling. No wind to speak of.
Lowest pressure here in my (50 year) memory.

Gary Roberts · Unread post by **Gary Roberts** » Sun 18/09/2005 17:02

James wrote:Currently 973mb (accurate) here and falling. No wind to speak of.
Lowest pressure here in my (50 year) memory.

973 hPa in Mission Bay, Auckland too, and still falling.

The wind's turned solidly east here in Omarama now. Any thoughts on that, anybody?

Graeme, I don't come here for math lessons! How dare you? I have a headache now.

GraemeWi · Unread post by **GraemeWi** » Sun 18/09/2005 17:06

Gary Roberts wrote:Graeme, I don't come here for math lessons! How dare you? I have a headache now.

Silence in the back row! - don't make me trot out some of the numerical forecasting formulas I use

Cheers,

G

spike_01 · Unread post by **spike_01** » Sun 18/09/2005 17:07

Levin reporting in... Nothing special here... Just a bit of wind and rain...

Looks like this system will miss us...

Gary Roberts · Unread post by **Gary Roberts** » Sun 18/09/2005 17:10

GraemeWi wrote:
Gary Roberts wrote:Graeme, I don't come here for math lessons! How dare you? I have a headache now.
Silence in the back row! - don't make me trot out some of the numerical forecasting formulas I use

Cheers,

G

Yeah? Well buddy you ain't the only one who can use numlicly frocet...nucleam...chimeras...ahhh, whatever!

TonyT · Unread post by **TonyT** » Sun 18/09/2005 17:11

spike_01 wrote:Levin reporting in... Nothing special here... Just a bit of wind and rain...

Looks like this system will miss us...

Tut tut, there's always someone "doing a Gary" isnt there...

(Sorry guys, couldnt resist!)

Gary Roberts · Unread post by **Gary Roberts** » Sun 18/09/2005 17:12

spike_01 wrote:Levin reporting in... Nothing special here... Just a bit of wind and rain...

Looks like this system will miss us...

It's been a beautiful warm and sunny day here. Just the big fluffy clouds drifting along the divide, but otherwise great. I really don't know what to think about the forecast.