Depressing Depressions!

TonyT · Unread post by **TonyT** » Sun 28/09/2003 16:45

John, if you follow the link Brian posted to the quickscat winds, you will find real time wind data from the oceans, sensed via satellite, and presented in the conventional barb formatm and also colour coded for wind speed. The detection algorithm is a bit iffy under rain, so the barbs where rain is detected are coloured black. Its a great site to look at when strong winds are blowing over or around NZ, you can see some surprising patterns in the coastal windflow which help explain some of the cloud patterns we get on the satpix (eg in a strong SE you can see the 'river of wind' running from Cook strait past Taranaki which correlates with the band of cloud often seen there.).

NZ Thunderstorm Soc · Sun 28/09/2003 16:49

OK Tony, thanx for that

JG
NZTS

NZstorm · Unread post by **NZstorm** » Sun 28/09/2003 16:50

Photo of Thunderstorm arriving in Grey lynn about 15minutes ago.

Manukau heads obs · Sun 28/09/2003 16:52

its a real shame there is that big gapping hole in the data right in the mid tasman!
We should get a good SWer up this way tomorrow by the looks
wind back in the NW now, black again out west
we are getting rapidly forming frontal squall lines on this very dymanic system!
some lightning counts recorded today, but nothing like yesterday
milking time now....

Dean. · Unread post by **Dean.** » Sun 28/09/2003 16:52

Far Out!!!

NZ Thunderstorm Soc · Sun 28/09/2003 17:00

All I have to say about that photo, Steven is 'Effing ahh soles" !!!!!!

JG
NZTS

NZstorm · Unread post by **NZstorm** » Sun 28/09/2003 17:19

A wide angle view of the approaching storm. Not a good shot here because I needed to get more cloud in. A runner came past me when I was photographing and commented on how spectacular the cloud was. It was, I just havn't managed to catch it with my camera.

Steady rain here. Thunderstorm has eased off.

TonyT · Unread post by **TonyT** » Sun 28/09/2003 17:49

Rain still heavy here, winds now S-SE 20-25 knots, pressure now steady but temp has fallen to 5 deg.

The latest forecast model winds for Chch are a little lighter for tomorrow morning, so the risk of gales for Canty has eased a bit, but look stronger for Kaikoura through Southern Wairarapa - could easily reach storm force there during the morning.

NZ Thunderstorm Soc · Sun 28/09/2003 17:50

What's that in the far left corner of the photo(s), looks like a funnel trying to develop!!!

JohnGaul
NZTS

Thunder · Unread post by **Thunder** » Sun 28/09/2003 18:18

Yes John, first thing I noticed in the picture was that thing in the top left hand corner, is it a funnel or just virga? (as I think to myself) Please be funnel, Please be funnel. Steven, do you know?

Cool Pictures Steven!

Raining steadily here still, has been all day, the wind has dropped off alot though.

Cheers
Aaron Wilkinson

TonyT · Unread post by **TonyT** » Sun 28/09/2003 18:43

Earlier reports of 15cm snow on the upper Plains and 20cm on the foothills may double by dawn with the temp here now down to 4deg and 3deg at Chch Airport. Winds still SE/20-25 here, stronger to come. I fear major stock losses from this storm, even though our clients were warned of it last Wednesday, there is only so much you can do.

NZ Thunderstorm Soc · Sun 28/09/2003 19:06

Yes Tony,
I'm concerned with the lambing and stock loss potential of this event.

BlueSkies/MetService gave good warning of this event.
I hope that alot of farmers took advice of this and did their upmost to protect stock. I can't understand why sheep are shawn so early when there is a potential for an event like this. It's still September coming onto October, so cold weather is still on the cards.

JohnGaul
NZTS

Manukau heads obs · Sun 28/09/2003 19:59

i think its becuase, from memory,
shawn ewes feel the cold faster/better, and so look for shelter for them and their new lambs better.....and the lambing paddoks usualy have shelter belts....
also, it thickens up and makes the wool grow faster afterwards

tich · Unread post by **tich** » Sun 28/09/2003 20:50

This seems to be shaping up as a major snowfall event for inland Canterbury. Down to about 3-4C in central Chch this evening. Probably won't snow in the city (but who knows, anything could happen), but I wouldn't be surprised if there's some on the tops of the Port Hills by tomorrow morning. Strange also that Chch Airport is a bit colder than Ashburton.
Coincidentally, there was snow to low levels on the plains almost a year to the day this time last year (on the last Sunday of September 2002), though last year's fall was more short-lived and localised to inland mid-Canterbury, and was the result of some convection within a cold front.

TonyT · Unread post by **TonyT** » Sun 28/09/2003 21:13

We are getting small hail in with the rain now, the wind has gone more S-SW, very cold, 3 degrees. Must be snowing not too far inland.

Thunder · Unread post by **Thunder** » Sun 28/09/2003 21:34

This is an image from Pete Mchgee up in Northland from that spectacular night time lightning storm/s you had the other day. He managed to get a few on film and emailed me this one today so I thought I'd put it up here for all to view. Enjoy!!

Cheers
Aaron Wilkinson

NZ Thunderstorm Soc · Sun 28/09/2003 21:47

LOVELY photo Aaron, a must for the 2005 NZTS Calendar.

JohnGaul
NZTS

TonyT · Unread post by **TonyT** » Sun 28/09/2003 21:52

Ok, we are now getting snow flakes mixed in with the rain, probably about 50%, with icy sludge starting to accumulate on horizontal surfaces. We are right by the coast, so thats basically snow to sea level. (No doubt MetService are reading this and will update their forecasts shortly).

I have to admit that while we seem to be about right with the quantities, the snow has fallen to lower levels than we forecast, and much lower than Metservice predicted. Also much lower than you would expect from the thickness and 850Mb temps (which is what the forecasts are mostly based on). While we allowed for the lower levels we see with a warm advection event (vs cold advection), getting snow to sea level out of a storm with 850Ts of -4 and THK of low 530s (probably around 533) confounds conventional forecast ideas. Unless of course the models have got it wrong and the Ts and THKs are significantly colder than that.

tich · Unread post by **tich** » Sun 28/09/2003 22:12

Ok, we are now getting snow flakes mixed in with the rain, probably about 50%, with icy sludge starting to accumulate on horizontal surfaces. We are right by the coast, so thats basically snow to sea level. (No doubt MetService are reading this and will update their forecasts shortly).

I think Amberley is a little above sea-level, but no more than about 50 metres. Tony, are you closer to the sea? - I know there's an embankment between the town and the sea. Still raining steadily in Chch and about 3-4C, but the wind hasn't picked up yet. BTW, it looks like gales are now affecting the West Coast, the AA warning of high winds near Whataroa. TV1 Weather also mentioned Greymouth only reaching 9C today - normally there'd be a fohn effect in easterly/southeasterly flows over there, but there must've been cloud cover and possibly rain today.

While we allowed for the lower levels we see with a warm advection event (vs cold advection), getting snow to sea level out of a storm with 850Ts of -4 and THK of low 530s (probably around 533) confounds conventional forecast ideas

The weather does seem to sometimes act in ways that surprise even experienced forecasters; take thunderstorm activity in Chch during a weak northwesterly (1991) Makes the weather more interesting, though.

TonyT · Unread post by **TonyT** » Sun 28/09/2003 22:25

tich wrote:I think Amberley is a little above sea-level, but no more than about 50 metres. Tony, are you closer to the sea? - I know there's an embankment between the town and the sea.

Yes, we are right on the edge of the embankment or terrace that you are referring to, less than 1km from the coast and nearer Amberley Beach than Amberley itself. Probably about 20-30m above MSL.

tich wrote:The weather does seem to sometimes act in ways that surprise even experienced forecasters; take thunderstorm activity in Chch during a weak northwesterly (1991) Makes the weather more interesting, though.

Amen, just when you think the computers have got it all sown up, up pops a curly one and its all on again. You gotta love it

Its been a tough day at the office today, I'll be back for the aftermath tomorrow. Thanks to everyone for contributing to this thread - its been fascinating to read (and see, thanks for the photos folks) the weather from this event evolving during the day. Much more interesting than the old days of sitrting by the window wondering what was happening elsewhere...

NZ Thunderstorm Soc · Sun 28/09/2003 22:38

[quote="TonyT"

Amen, just when you think the computers have got it all sown up, up pops a curly one and its all on again. You gotta love it

Its been a tough day at the office today, I'll be back for the aftermath tomorrow. Thanks to everyone for contributing to this thread - its been fascinating to read (and see, thanks for the photos folks) the weather from this event evolving during the day. Much more interesting than the old days of sitrting by the window wondering what was happening elsewhere...

[/quote]

Yes Tony, go and have a lie down.

More storms on Tuesday !!! ?

JohnGaul
NZTS

NZ Thunderstorm Soc · Sun 28/09/2003 23:30

It's late now but I'm picking up a few sferics.
At 11pm here it was 4c, with 22.5mm in the rain gauge since 9am this morning. Still overcast and raining. Calm.

JohnGaul
NZTS

Dean. · Unread post by **Dean.** » Mon 29/09/2003 05:21

Heavy rain still in Ashburton at 5.20am.
Only 2.6 degrees.
Must be some serious problems inland by now!!!.
Off to work.......Bugger

Michael · Unread post by **Michael** » Mon 29/09/2003 06:57

what awful gales overnight and now have got worse this morning

NZstorm · Unread post by **NZstorm** » Mon 29/09/2003 07:12

We had very windy conditions overnight in Auckland with winds reaching gale force at times. Wind has eased here now.

I notice New Plymouth recorded 105mm yesterday. Auckland 32mm.

An 8 yr old boy was struck by lightning at Whangamata (Coromandal) and
survived.(NZ Herald)

Pete McGhees lightning photo is outstanding.