NZ Weather Forum

Looking like a good cold snap as the deep low that effected the North Island moves away.
Heavy snow likely with the remaining moisture levels in the fairly high end.
East of the South Island bearing the brunt of some fairly cold showers.
Could amount to a day off work at least.

Looks very brief and insignificant to me?

Karsh, you are a man possessed...I personally don't see it, but hey....good on ya for keepin' the faith...

There is some potential for near sea level snow moving through Otago Wednesday night and through Canterbury Thursday. As the gfs has been all over the place last day or two we will need to leave it for a few more runs.

I agree now looking at some latest model runs, the low crosses central SI around midnight Tuesday and into early Wednesday dragging up some very cold polar air.
A snowfall event possibly at this stage only a few days out, but thats slightly more promising certainly i would think.
Dont even get me started on the low at the end of the week .
Busy week ahead then .

and the 12Z gfs changes with Saturday being the day with a credible snow threat.

I still reckon we've got a chance here in otago of low-snow wednesday, i'd say down to 100-200m if it comes early wed morning. Saturday looks like very cold air but a minimal amount of precip with it just 'clipping' the coast like that last dump to sea level in Dunedin back in June, but sat is miles away, fingers crossed that things change and that low is 500km west of where they expect it to be sat.

Every possible snow event has turned out to be a fizzer. These two events on Wednesday 15th July and Saturday 17th the same , cold grey some showers for Christchurch.

I have given up the idea of snow for christchurch this winter.
Sorry christchurch it doesn't seem to be happening.

Any thoughts on this from the experts

Theres been "fizzers" ever since forecasting begun

sentastorm wrote:Every possible snow event has turned out to be a fizzer. These two events on Wednesday 15th July and Saturday 17th the same , cold grey some showers for Christchurch.

I have given up the idea of snow for christchurch this winter.
Sorry christchurch it doesn't seem to be happening.

Any thoughts on this from the experts

Yeah,even i'm getting fed up with the error margins on these models,latest suggests it has now been pushed out till Sunday, and a very cold one at that ,but not thinking it might happen now.

The pattern this winter has been for a lot of Ridging onto the South Island with the cold air. Some troughing with cold air for the SI later in the week perhaps.

Bitterly cold this morning for the SI, Qtwn was -5C at 9am, Timaru -3.

Bitterly cold this morning for the SI, Qtwn was -5C at 9am, Timaru -3.

This station http://www.croxford.co.nz/weather.html, halfway between Wanaka and Lake Hawea recorded -8°C this morning!

Good Set up in this run for the weekend temp wise and 500 thickness values suggest snow to near sea level. Just need the moisture values to increase. I think we will see this one change dramatically either to nothing at all or something significant. It hasnt known what to do at all last couple of days.

Aww yeah i like the latest metvuw charts, if things don't stray much from those predicted charts we should get a good dump in otago for sure.

Sorry to appear a weather-dumb Mark but any chance you could explain these thickness values? Is it predicting the thickness of the cloud?

southerly-hunter wrote:Sorry to appear a weather-dumb Mark but any chance you could explain these thickness values? Is it predicting the thickness of the cloud?

This will definately help your thickness... query

http://www.weatherforum.org.nz/phpBB3/v ... kness#p862

southerly-hunter wrote:Sorry to appear a weather-dumb Mark but any chance you could explain these thickness values? Is it predicting the thickness of the cloud?

I wouldn't fret too much about them anyway, it deals with such a fat layer of air (the 1000-500 anyway) that it misses the subtleties. Good for a general overview but little more.

In inland areas of SI, it seems to be so cold at the moment that almost any moist airmass could bring snow to low levels.

southerly-hunter wrote:Sorry to appear a weather-dumb Mark but any chance you could explain these thickness values? Is it predicting the thickness of the cloud?

For snow to sea level we are looking for 500 thickness values of 520 or less ideally. Unfortunately the system has backed off and they have gone from 518 to 530 with moisture totals way down again. The low to the east is so deep and nasty but its way too far east atm unfortunately. The centre has air pressure of 948hpa!

The pattern this winter has been for a lot of Ridging onto the South Island with the cold air. Some troughing with cold air for the SI later in the week perhaps.

I guess everyone has noticed the massive trough lying just east of NZ for much of the last 6 weeks, downstream of the persistent high pressure around Macquarie Is. If this long wave feature had been sitting some 10 deg longitude further west the Sth Island would have copped some very stormy conditions (far more severe than the odd little flick such as we've had). The position of slow moving upper air troughs/ridges pairs play such a big role in surface conditions it's a shame long range forecast is so dependent on less direct influences e.g. la nina/el nino, SOI index, etc.

The 500 THK values from what i believe need to be 525 or lower, generally the 850mb will match up when the thk levels go down.
I tell these models are all over the show how frustrating, still snow to very low levels early wednesday morning but nowhere near the precipitation amounts it was showing last night boo.
I just hope Canterbury gets something this winter its all been everywhere else but here, apart from endless days of overcast rain and showers.
Having blabbed on August is meant to be the stormy month as most people tend to say, and our winter seems to be dragging further afeild into spring these days so i guess we still have until mid October for snow yet.

Cheers for the info Mark, better understanding now, much better than nodding in oblivious agreement anyway haha.
Any idea what the thickness values were back in June when Dunedin had a short sharp burst of snow to sea level? That wasn't that thick but it was much the same depth at sea level as it was at say 200m on the hills, was damn cold and good dry snow instead of the usual sea level slush.
The southerly lining us up for late sat-sun looks like a damn cold one by the forecast maps but we'll see.

Mark i do think you read into the models and thickness a little much and yes the moisture levels will differ through out an up coming event.
You will worry yourself sick each time, 5 days from a possible event
Maybe have some suspense and not look at the models until 2 days before the event or if at all.. and wait with baited breath!! just for a change perhaps?

Was a very cold start this morning indeed NZstorm i heard on radio this morning at 9am it was -1 and didn't really warm up to much at all either.Should be another cold one tomorrow morning brrr!1 to hard to get up in the morn!

I see it's 8 on stewart island with a 50km norwester, only 3 on campbell island with a 35km westerly and showers, cold on the way but i usually find when we get snow to sea level-200m it's when campbell island has had temps of -1 or 1 degree, see how low it is down there this evening.

Looking forward to see what happens in the next 12 hours,not very hopeful of anything signifignant, but you never know.