Ye Olde Cold front - 10th & 11th June 2010

[Tim S]

The upcoming cold front due to start crossing the Fiordland region in around 20-24 hrs looks like being more like the frontal features I expected New Zealand to get during winter. Fast moving with a strong NW flow ahead of the frontal feature and a strong cold unstable SW flow immediately behind the front. Not like these lazy tasman lows we've been getting lately, as much fun as they've been of course!

The speed of the front is the thing that gets me about this front, judging by the metservice forecast charts it looks to be expected to be pushing through at 40kn+, although I have a feeling the charts might be slightly off. Although they do have the frontal feature less than half the way across the Tasman at 18+ hours and about to go through Cape Reigna in 42+ hours.

Rainfall wont be that high for most of us although the areas covered by the warnings look to be getting a fair amount, totals look like being enhanced by a surface low developing off the west coast as the front passes through. Rainfall intensities look like being fairly good though, which wont be good news for the sodden areas around the BoP and elsewhere.

[NZ Thunderstorm Soc]

Yes, there seems to be a change in weather pattern with this system coming in from the SW.
Looks crucuial which would be good if it were summer as there would be lots of thunderstorms moving over Canterbury with hail. Well, not good really except for us weather enthusiasts.
A large anticyclone should follow.

JohnGaul
NZThS

[NZstorm]

Looks like 2 to 3 days of unstable thundery weather for the south, west and north of the country. Tonights front ticks all the boxes for winter thunderstorms, regions with good exposure to the NW will be most affected (particularly upper South Island, Taranaki, Waitomo, upper Northland). Thunderstorms will bring hail as well. Maybe an isolated tornado.

Otago ski fields should get some good snow out of this weekend system.

[Richard]

Ya lucky buggers,going to be a rather boring event on this side

[Michael]

Will be here too after the front.

Ya lucky buggers,going to be a rather boring event on the side

[spwill]

Perhaps some rare low level snowfall for WestCoast southIsland but sleet and snow for much of the SI at some stage over the weekend, looks wintry for the SW of NI as well.

[Richard]

The thing is with winter SW flows that run parallel over the South Island is that the flow tends to be deviated out wide of each of the coast lines because so much of the lower South Island covered in snow.
I noticed on the TVNZ weather they had showers forecasted on Sun on both sides of the SI, it far more likely that both sides will be fine apart from from Southland and Banks Peninsula

[spwill]

The more widespread precipitation will be with Frontal activity also in a SW flow cold Fronts tends to turn the flow more westerly ahead and more southerly behind if only briefly

[Razor]

Well the severe thunderstorm outlook looks exciting for northern and western folk....

[Tim S]

The Taranaki & Waikato regions seem to be the lucky ones in the latest update of the rain forecast, with some fairly high rainfall intensities for them from around midnight to around 3pm tomorrow. Although the last rain forecast I looked at had the NW corner of the South Island getting some reasonable falls too but that has mostly disappeared off the latest run. How often does the Metservice update the rainfall outlook, is it every 3 hours?

Either way as NZstorm said above any areas of both island exposed to the NW should fair well out of this feature. Are any of these areas still suffering severe deficiencies in rainfall over say the last 3-6months? I am guessing not as May seemed to bring good rains to almost all the areas in desperate need of a good drenching.

The cooler air behind should also bring some good falls all of the southern alps including the Rainbow ski field judging by the models with the snow level low enough over that area for a while during some of the rainfall. Although if we get another Tasman low it will probably all wash away!

[Talbotm]

The metservice have got on the outlook low confidence of heavy snow for north canterbury and marlbourgh also the central plateau. If its a SW flow how does it get into north canterbury wouldnt it just run up the westcoast??

[Dean.]

The metservice have got on the outlook low confidence of heavy snow for north canterbury and marlbourgh also the central plateau. If its a SW flow how does it get into north canterbury wouldnt it just run up the westcoast??

Im pretty sure that will be dropped today

[Storm Struck]

Or the fact the forecast has changed 3 times for Christchurch on Monday in the past 24hrs , Snow yesterday and last night when i looked it was fine with westerly winds.
Now its showers a SW easing, what wheetbix packet are they getting thier forecast information from .
-4C here this morning so the best frost so far YTD, currently 7.5C with the barometer dropping quickly down to 996.0hpa from 1001.4hpa at 8 this morning.
I am thinking of a possible weak thunderstorm and hail set up for Canterbury on Saturday night, just the typical winter type CB's a few claps of thunder thrown in here and there.

[Talbotm]

Metservice have dropped the outlook for heavy snow in canterbury but it remains in the central plateau. Looks like this is just a short sharp cold snap with little amount of moisture. No good for us snow bunnies if we are lucky we will get a flick with very little settling.

[NZstorm]

Front out to the west has got a bit more active looking last couple of hours on sat pic.

[Nev]

Front out to the west has got a bit more active looking last couple of hours on sat pic.

Yes, good burst of CG's about 30 mins ago...
.

[Tim S]

Leading edge of main frontal band coming through here now, very gusty with reasonably heavy rain, not overly though. Still a fair amount of heavier rain still the NW though by the looks of things. A nearby private weather station has had gusts up to 48km/hr so winds are fairly strong.

[Nev]

Mean-winds were up to 48km/h in Akld's Waitemata Harbour at 9pm. Out here, Tiritiri's mean-winds are up to 59 km/h atm.

[spwill]

The NE a bit gusty here this evening. A mild 14C, dewpoints on the rise, now 13C. Looking very unstable out to our West/NW on the Sat pic.

[David]

Quite a bit of lightning being picked up in the Tasman now

[drew]

Well, its rained solidly for the last 5 hours now, with some very heavy falls in there (incl the one that woke me up!).
Some distant thunder earlier on too.

Very mild again.

Drew

[Vertigo]

Oh my lord... reviewing the lightning loop, it was solid before and after, but completely died when over Auckland. It avoided me! ARRGH.

[Richard]

just thinking of the children

[NZstorm]

Oh my lord... reviewing the lightning loop, it was solid before and after, but completely died when over Auckland.

Its the NW flow, Auckland seems to get sheltering when there is an upper NW flow.

[David]

Yes all that has eventuated is a few showers, not even heavy....typical!