NZ Weather Forum

New thread for a notable easterly period coming up

Interestingly GFS is not budging at all run-to-run on it's prediction of -4C or -5C over Canterbury for this period, a good 2-3C warmer then most of the other models...

the culprit is high pressure having to go under a low in the south tasman, which then drags up some very cold air around the top of it
sort of a "beast from the east" type setup that Europe can get in the winter sometimes almost?

Cant see sea level snow with this one though with air having to move over more ocean than a straight southerly, that and no air flow off the ice shelf feeding into it.

Richard wrote: ↑Wed 03/08/2022 17:41 Cant see sea level snow with this one though with air having to move over more ocean than a straight southerly, that and no air flow off the ice shelf feeding into it.

My relatively limited knowledge tells me that some of Canterbury’s more significant snow events (to at or near sea level) have been from East or South Easterly systems. Happy to be corrected (obviously it takes a lot more than the wind direction to make it happen).

Yes some of Canterbury’s more significant snow events in past have at higher elevations, but to near not sea level.

Richard wrote: ↑Wed 03/08/2022 18:04 Yes some of Canterbury’s more significant snow events in past have at higher elevations, but to near not sea level.

June 2006?
I can't remember exactly what wind direction that came from but it was definitely warm advection with 850hpa temps only suggestive of snow to around 200-300m certainly not 20cm to sea level.

Richard wrote: ↑Wed 03/08/2022 18:04 Yes some of Canterbury’s more significant snow events in past have at higher elevations, but to near not sea level.

July 2011 comes to mind as an easterly event.

Would that have been the 23-26th July event?

darcyplumb wrote: ↑Wed 03/08/2022 18:13

Richard wrote: ↑Wed 03/08/2022 18:04 Yes some of Canterbury’s more significant snow events in past have at higher elevations, but to near not sea level.

July 2011 comes to mind as an easterly event.

Yeah that was -9C at 850hpa that event so it didn’t give the ocean warmth component a chance for it to kill the sea level
snow, it was just so cold…

Richard wrote: ↑Wed 03/08/2022 18:28 Would that have been the 23-26th July event?

Possibly. I was living a few minutes north of Ashburton at the time and we had at least 30cm.

I'm certainly no expert but my instinct is to agree with Richard here. There was a similar event in 2013 I think which looked like almost certainly sea level snow but was just a bit too much easterly in it in the end. Hope for you snow lovers down there I am wrong though!

Either way it looks like a decent system that will cause havoc for a number of people and their livestock. An interesting few days ahead.

A lot of events here tend to be S - SE, but not too much E or it's just rain. Chuck some sw in and it's usually dry

darcyplumb wrote: ↑Wed 03/08/2022 18:30

Richard wrote: ↑Wed 03/08/2022 18:28 Would that have been the 23-26th July event?

Possibly. I was living a few minutes north of Ashburton at the time and we had at least 30cm.

25 July 2011 was a SW event, was fine and dry in Canterbury south of Rakaia, was probably the 14-16th August event.

snowstormwatcher wrote: ↑Wed 03/08/2022 19:03

darcyplumb wrote: ↑Wed 03/08/2022 18:30

Possibly. I was living a few minutes north of Ashburton at the time and we had at least 30cm.

25 July 2011 was a SW event, was fine and dry in Canterbury south of Rakaia, was probably the 14-16th August event.

Thanks for the correction

darcyplumb wrote: ↑Wed 03/08/2022 19:07

snowstormwatcher wrote: ↑Wed 03/08/2022 19:03

25 July 2011 was a SW event, was fine and dry in Canterbury south of Rakaia, was probably the 14-16th August event.

Thanks for the correction

August 2011 was a southerly event

That's a nice looking radar! Managed to snowboard down to the valley floor from coronet peak after one of the dumps that month.

harveyt86 wrote: ↑Wed 03/08/2022 20:12 That's a nice looking radar! Managed to snowboard down to the valley floor from coronet peak after one of the dumps that month.

Coronet Peak must be having the best season this year in many years. The cold easterly event next week will bring them dry weather but good for artificial snow making.

Enjoying today's weather. Change is "in the wind"

Razor wrote: ↑Thu 04/08/2022 12:25 Enjoying today's weather. Change is "in the wind"

Stunning day down the road here too. A good opportunity to dry things out before it gets wet again next week.

Can someone be kind enough to explain abit more behind how snow to sea level works in a E-SE flow? Some models are not quite picking this with warm upper air and warm mid layers too which can often help with advection prediction outputs.
I do remember perhaps around 2007 we had a day that was particularly cold with a SE flow, that was bringing in showers and snow to 200m. For about half an hour it was grappling/ hail with enough to settle as well.
So these sort of set ups can happen.
An active period once again from tomorrow onwards, the water tables have gone nowhere so any extra rain is going to cause further issues.
I will get a few photos of my work to share.

Storm Struck wrote: ↑Thu 04/08/2022 13:27 Can someone be kind enough to explain abit more behind how snow to sea level works in a E-SE flow?

Its not complicated. Snow forms, and doesn't melt before it hits the ground. The end.

TonyT wrote: ↑Thu 04/08/2022 14:15

Storm Struck wrote: ↑Thu 04/08/2022 13:27 Can someone be kind enough to explain abit more behind how snow to sea level works in a E-SE flow?

Its not complicated. Snow forms, and doesn't melt before it hits the ground. The end.

yes that is a very precise yet simple answer, I like it.

I do see the latest models show 850mb temps of -8C now so that's certainly good.

Latest EC ensemble is saying 15 of 50 members indicating snow for Christchurch so around a 30% chance