23-25 June

Outcome (27 June):

There was about 90 cm of snowfall in aggregate for this event on my best estimate, a bit under half of which came with the lead-up system starting Tuesday night … which I barely rated initially. Ho hum; wrong again.

It’s interesting to look at where the 500 hPa spaghetti plot finished up, for future future calibration. The blue line did not reach the alps:

Spag plot for Friday morning

 
(Note that the blue contours there are drawn for 5760 m. The more usual June blue contours at 5700 m would have plotted even further south.)

Update #3 (21 June):

Ok, so tonight has clearly surprised on the cold — and therefore white — side, with upwards of 15 cm of snow already on the ground at Perisher Valley (at 10:00pm, although the coldest burst has probably passed). Surprised me that is; BOM forecasters called it pretty much spot on. It now looks like there’s an aggregate half a metre in this event, with the first snow depth measurement of the year on Thursday morning likely to be near 20 cm. And there’s potential for Thursday night — Friday to surprise on the high side given the embedded storm activity showing on BOM’s ACCESS-R model.

Update #2 (19 June):

This now looks to be a fairly powerful system with plenty of moisture, but I suggest you treat hype about up to a metre of snow with care. It’s true that BOM’s ACCESS-G model is suggesting some remarkable falls Friday-Saturday, but international models have the system arriving earlier (Thursday night) and moving away quickly (gone by Friday night). At this range the European ECMWF model probably has the best record, and it would be difficult to see much more than 40 cm depth gain off its pattern.

ECMWF for Friday morning, via Levi Cowan

GFS for early Friday morning, via Levi Cowan

Update #1 (17 June):

Well that is looking interesting. Still early days though…

GFS for 23-25 June, from Levi Cowan

 
ECMWF is not dissimilar — even marginally more interesting.

Original post (15 June)

This week will see something of a repeat weather pattern, with an upper trough potentially developing into a southward-tracking east coast low and bringing extensive weekend rain — though it looks less severe than the previous one. The wave behind that again builds a snow system in week following, and again it’s not especially exciting. If it progresses well it could be in the 20 cm class.

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