Unsettled Period Late September 2009

[Tornado Tim]

It seems NZ is going to have some quite interesting weather over the remaining weeks of September.
NZ atm has a HIGH leaving and with it being replaced by a Low it seems.
With this and fronts combined has the potential to bring some heavy downpours , some thunderstorms and some stronger winds when a deeper low is expected to develop over the southern Tasman Sea.
This is low has been picked up by the M/S Rain forecasts and GFS which means they have a element of error until the time comes closer.
The low is predicted to be around 976 hPa on Monday next week and coming into contact with the South of the SI around Wednesday next week.
This low is still "up in the air" atm but in the mean time we can focus on these fronts and the minor Low pressure system coming onto the NI.
My forecast program is picking up on possible thunderstorms later on this week so heres hoping!
Attached forecast Graph, the "Up in the air" forecast and Thunderstorm outlook for tomorrow for reference:
Update: Some chance for Thunderstorms in the South Island tomorrow! (go chasing on the behalf of me if it looks good)
Linkback to M/S rainfall forecast: http://www.metservice.co.nz/public/maps ... 7-day.html
Linkback to M/S T-storm outlook: http://www.metservice.co.nz/public/weat ... storm.html

[NZstorm]

I'm hopeful we'll see some unstable weather here later in the week. Friday morning looks interesting on todays 00Z.

Chart here for 9am Thursday looks interesting. It shows 850mb temperatures. Polar air over the South Island while a subtropical airmass spreads over the upper North Island behind a warm front.

[mikestormchaser]

Whats chances for storms tomorrow? for Canterbury? no one seems very interested in it at the mo?
Any reasonable numbers for tomorrow afternoon?

[NZ Thunderstorm Soc]

Should be a good chance tomorrow Mikey and maybe with Foggy in town a good opportunity for his influence for such an event to happe ????

JohnGaul
NZThS

[TonyT]

Whats chances for storms tomorrow? for Canterbury? no one seems very interested in it at the mo?
Any reasonable numbers for tomorrow afternoon?

Still marginal. but the best chance of the spring so far I would suggest...

[mikestormchaser]

Whats chances for storms tomorrow? for Canterbury? no one seems very interested in it at the mo?
Any reasonable numbers for tomorrow afternoon?

Still marginal. but the best chance of the spring so far I would suggest...

Oh well thats rather positive Tony.
By sounds its going to be a bit of a late sharp cold snap tomorrow night, so heres hoping a thunderstorm will develop along the wind change.
Oh and 999 posts now, little bit of a mile stone coming up for me, thought i would add that

[NZ Thunderstorm Soc]

Congrats Mike on your posting
Keep your fingers and arse crossed about thunder possibilities tomorrow.
I have a 2 chance in 5.
Foggy is in town and we have to impress him somehow?.

JohnGaul
NZThS

[Storm Struck]

John what happened to the coloured risk numbers you used to put up, i enjoyed those even if they were just numbers .
The thing i like about tomorrow is the winds are generally more lighter allowing a coastal NE to develope before the change right down to about Oamaru.
A S-SW flow is established without too much of a westerly beforehand, maybe more so on the West Coast.

[Lacertae]

And of course it has to happen the day I work from 1pm till midnight ...
No chance to chase and I'm sure something will happen !!!

[Manukau heads obs]

SW change through here now.,...start of a different weather pattern..."start of the equinox gales"

[Michael]

Not here yet but once the roof fills with pineneedles and male pollen like bees flying in 10 mins we will know,just drizzle here.

[Michael]

Wasnt much rain from this though,ground wet but thats it,clearing now,the ecwmf shows a moist NW later in the week.

[Razor]

Seems to be something bubbling away to the SW of us here in ChCh already.

[03Stormchaser]

And of course it has to happen the day I work from 1pm till midnight ...
No chance to chase and I'm sure something will happen !!!

Thats why God invented sick days!!

[Storm Struck]

I see the High Risk no longer withstands for down south now, but a moderate risk now extends to north of Christchurch with 5-15mm hail even.
Not sure why the sudden change but it wont be updated until 11am anyway.
Looking back on the rain radar this morning there has been some red blotches in South Canterbury and offshore, but the main cold front surger is just south of Stewart Island at the moment.
Currently 18C with blue dome skies, but a breezy westerly wind.

[CHCH Weather Chaser]

Yes living at the Southern end of Christchurch I have been able to watch out the window the stuff "bubbling" away to the south. Rather interesting looking. Got to 17 degrees at 9am this morning but a breezy Southerly had kicked in (SSW to be precise) and has put the temp back to 15.5 degrees. It feels warmer than that though, still mild at this stage.

[gllitz]

M/S are now saying high risk for many parts of CANTY...10-20mm hail?!? Ouch...we'll see if any storms get here to CHCH...I've got a pretty good view to the S and SW from being 10 stories up in my office building...I think Razor has a good vantage point as well?

Foggy, you must be good luck! Taking the weather with you, as it were...good man!

[Storm Struck]

Yes a high risk now and hail size upgrade, not as big as the hailstones that fell over South Australia yesterday 2cm in size.
Should be an interesting afternoon wind has gone from westerly to SW now which isnt always a bad thing, means a NE could kick in before the entrance of the next front.
Bit of CU starting to build here and there now too.

[NZstorm]

Non of the modelling is indicating a NE breeze today for Canterbury. Too early in the season for the sea breeze effect to get going. Typically from mid October I think although this spring has been far from typical.

[gllitz]

Not to burst any bubbles, but 10-20mm hail isn't exactly tiny ...still enough to hurt you if you are caught out in it and borderline able to do damage to cars and what-not...and once again went to work without camera...d'oh-eth....

[Razor]

M/S are now saying high risk for many parts of CANTY...10-20mm hail?!? Ouch...we'll see if any storms get here to CHCH...I've got a pretty good view to the S and SW from being 10 stories up in my office building...I think Razor has a good vantage point as well?

Foggy, you must be good luck! Taking the weather with you, as it were...good man!

Unfortunately I'm NW facing only second story. Will get a good view round Hagley Park at lunchtime though...

[Storm Struck]

Some nice CU developing now and getting rather scatterd further back to the S-SW, and two trackers ive looked at both picking up strikes south of Christchurch now.

[Lacertae]

11am rain radar image :

Picture 1.jpg

[gllitz]

WHERE did you get THAT fantastic image??

[Tornado Tim]

Some thunderstorms already!
Chase ppl chase!
Yes where on earth did you get that image, Ben?