Another deep (Tasman) LOW: Jul 29-Aug 1st

[Manukau heads obs]

NWer just arrving here in a rush
64 (118kmh)knots at Manukau heads signal station now
also gusting to over 60 knots at channel island too

[kaimaikid]

they did a great job of covering the storm - somehow I get the feeling tomorrow night will be just as busy as the southerners cop it...

[gllitz]

This photo appeals to my sense of humor! A friend of mine took it this morning in the Kauaeranga Valley near Thames. There is a ford under this wee bit of water that at usual height, is only about 3 inches high!

Use English spelling please on this forum, I get offended by USA spelling

JohnGaul
NZTS

OT here...
So, if (God forbid) an American signed up to this forum and spelled "colour" the "wrong" way....??? I sure hope you are joking, because that's being a bit pedantic, don't you think?

I would have thought that as long as a word's meaning is understood and not how it's spelled is what matters...a word is a word is a word...whether it be "Queen's English," Australian English, New Zealand English, or American English...

/OT rant...

[jamie]

crikey this NWer is blardy strong. Sounds like thunder the way its shaking the apartment building

[David]

Wind has dropped away here as the light rain to the north has starting arriving.

[Paul Mallinson]

Quote:
by Vertigo on Wed 30/07/2008 15:33

"these lows arent any different to any regular low, except they are deeper. thats pretty much it, they form the same way as well"...

I agree with this statement. Both of these very deep lows formed with the asssitance of strong upper divergence associated with the jet stream we have noted over and east of the Queensland area of late. The dynamic forcing was very strong and so they deepened rapidly. When you consider how the cloud band that wrapped around the low evolved... we actually see this happen all the time on satellite loops. It just so happens that this development occurred in such a place that brought these two very deep lows over us in succession. Actually, it is often the way that lows develop in families like this - a number form in succesion and and fire through the same or similar area. The situation arises out of the large scale troughing in the area (in our case over the Tasman Sea at this time). Then as significant short wave troughs move through the large scale trough, development happens in a similar location. Over time (perhaps a week or two) the large scale trough (very slow moving because of its wavelength) starts to move away and the sequence of events changes and so we move to a new regime of weather.

..."true cyclones are warm-cored and a totally different beast, keeping their intense structure intact by drawing energy from the warm tropical oceans. once cyclones pass into cooler waters, they begin extra-tropical transition into storms similar to these. worth checking out on wikipedia, good read".

Yes this is true. It turns out that both these deep lows actually formed a warm core which these days we have come to call a seclusion. This invokes the idea of a T bone frontal structure where early in the process, the warm front is ideally drawn into the low centre and the cold front is drawn some way out from the low centre at some large angle to the warm front - thus forming a T bone shape. It was this warm air aloft that limited the thunderstorm activity with both these lows. The more traditional structure is the Norwegian model where the cold front and the warm front start out in the centre of the low and occlude out of the centre as the low deepens. This commonly happens and we frequently analyse maps this way.

I mentioned in an earlier post that there is a rough rule of thumb used with Atlantic storms to estimate the central pressure of the low... you count the number of hemispheric arcs of the wrap around cloud and for each you subtract 10 hPa from 1000 hPa. So for a system with a cloud wrap of 3 hemispheric arcs, the central pressure would be 1000-30 = 970hPa. Give it a try.

Paul

[Manukau heads obs]

56 knot gusts here at the moment!
73 knots at the manukau heads signal station!

[ricky]

41 knot gusts here is starting to feel pretty wild with the average windspeed slowly but steadily increasing

[Vertigo]

just heard a bang, my girlfriend thought it was thunder.. turned out to be a wheelie bin falling over

[David]

Thats so weird...its only gusting 42km/h (23knots) here.
Doesn't sound that windy at all. Perhaps it'll come roaring in when I turn the light off for sleeptime.

Edit 5mins later gusting 54km/h.

[Captain K]

Bit of a worry isn't it, when one spelling mistake launches another low pressure system! Should have found this sight in the summer and prevented the drought!

[Brassnz]

Very windy here, some ferocious gusts roaring through the bush. Lost power abt 45mins ago. Still off...

[Cook]

This is the sting in the tail, the low is dumbelling around itself packing in the pressure gradient over the upper North Island. Okahu Island has been reporting strong winds, mean spead 61 knots gusting 73 at 5 pm today, 47 gusting 58 at midnight.

64 knots mean wind speed is hurricane force on the Beaufort scale...

I like the Beaufort scale very much: http://en.wikipedia.org/wiki/Beaufort_scale

[Manukau heads obs]

1 am, power back on after going off at 10pm with some big gusts!
signal station gusting to 75kts at the moment,.,,
wind increasing here slowly again after peaking at 10pm

[Nev]

WHATS THIS???
I'd like to know what unnamed MetService spokesman said this?
It's got to be one of the DUMBEST things I've ever read!

From this mornings NZ Herald re yesterday's Tauranga tornado ...

'Mini-tornado causes major damage'
5:00AM Thursday July 31, 2008 - By Juliet Rowan

...The man said the twister was about three-quarters of the width of the two-lane road, and was carrying letter boxes and rubbish.
The MetService said the twister could be classified as a mini-tornado because it was not as large as a full-scale tornado, and had been generated by strong wind off the coast. ...

[jamie]

Bah i hate that word

Waikato River still rising at a fast rate. With heavy showers turning to more widespread rain in the area forecast today, that should help it have a higher peak. Might go for a drive do to Mercer this afternoon. I have now idea when it will be at its heighest though. Ill just have to keep watch online.

[Vertigo]

so, whats happening with the storm? havent heard much from the southerners!

[Razor]

so, whats happening with the storm? havent heard much from the southerners!

Try the other thread mate

[kaimaikid]

Bah i hate that word

Waikato River still rising at a fast rate. With heavy showers turning to more widespread rain in the area forecast today, that should help it have a higher peak. Might go for a drive do to Mercer this afternoon. I have now idea when it will be at its heighest though. Ill just have to keep watch online.

need some photos please - passed through there last week in the truck and the river was looking more like a lake...

[jamie]

Bah i hate that word

Waikato River still rising at a fast rate. With heavy showers turning to more widespread rain in the area forecast today, that should help it have a higher peak. Might go for a drive do to Mercer this afternoon. I have now idea when it will be at its heighest though. Ill just have to keep watch online.

need some photos please - passed through there last week in the truck and the river was looking more like a lake...

Yep ill have my camera for sure.

Looking at the Waipa river levels down in Otrohanga there is still a heck of alot of water still to come down. And with the new heavy rain warnings from the MS in the Hills of southern Waikato there could be even more to come down. So i am thinking it will not peak in places north of Hamilton untill at least tomoro. Maby even Saturday.

[Razor]

Not to mention it looks like more significant rain for the North island on the weekend....

[jamie]

Looking at the river levels i think i will hold off going for a look and save petrol and go on Saturday. River levels at Mercer are only just now getting past the levels ther were at on Sunday which i have already seen. There is still a heck of a lot of water to come. Im thinking now Saturday will be the best day to go for a look (busy all day tomorrow).

EDIT: sonce i was last to post ill ust edit to save cloging up.
got this of EW web site http://www.ew.govt.nz/PageFiles/3/Sitreport12.pdf i might have to go on sunday jugding by this.

[Manukau heads obs]

just drove through a very heavy shower, had to slow right down
I see a big macroparpa tree down from last nights big winds beside the main road
and some branches down from other trees
also I had to spend 4 hours with the neighbours from our new house sight picking up polysterene....those big slaps that they use with concrete blew away and hit a fence and got shreded into the neighbours padocks last night

[Willoughby]

Just went down to the Gardens again and checked out the river... very high, but still no where near the 1998 July event!



We're quite lucky in Hamilton in that the banks are well below the city level mostly... but I fear that the likes of Huntly and Mercer would be copping it badly!

[nzlizzie]

Foggy, those photos are great. What fantastic reflections!