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2015 August 11-12th : Mt Bryan summit - overnight snow showers and snow carpet.

Summary

Overnight snow showers and a snow carpet on the summit of Mt Bryan in the Mid-North, and no reports of snow anywhere else in South Australia.

Rating on minimum 1 to maximum 10 scale: 3

Primary cause: Looking at BoM's surface weather charts only, a source of the below zero air mass over Mt Bryan was down towards Antarctica a long way south-west of Western Australia. The cold air mass was brought north-eastwards by complex movements of Southern Ocean lows.

End of summary

I'm basing this report on the experience as posted onto social media of intrepid South Australian snowchaser Mark Dawson. On the late afternoon of 11th August 2015 he climbed Mt Bryan and spent much of a freezing moonless night on the summit, witnessing overnight snowshowers falling in below-zero temperatures and a carpet of snow.

This is the only successful onfoot snowchasing ascent and overnighting of a South Australian mountain I've yet encountered!

Mt Bryan the mountain is north of Burra and just east of Hallett in the Mid-North. According to Bonzle here the highest mountain in SA is Mount Woodroffe (Ngarutjaranya) 1,427m, Mount Bryan in the Mid-North is 929m and Mount Lofty is 727 metres.

Commenting on the experience, Mark said: "Was quite a cold night with the temperature dipping to -1.5 with strong winds. It was cold enough that even orographically formed drizzle was frozen and sticking to things. Watching the cold front come in was also a highlight, unlimited visibility and minutes later down to 50m with heavy fog and rain." Source: Weatherzone forums.

I gather from messages from the summit Mark posted elsewhere on social media that at 7.11pm South Australian time it was snowing lightly, and at 315am it was 1.5cm settled.

Here's a link to one of his photos from the night: "Snow on my tent (which has been knocked over by wind lol)"

I've not been able to find any reports of snow falling elsewhere in South Australia on Tuesday 11th - Wednesday 12th, although meteorological conditions were forecast on the afternoon of the 11th to be favorable for a period during the night for snow showers on the highest peaks of the Mid-North and southern Flinders Ranges and perhaps down to about 700 metres. By late afternoon of the 11th it was forecast that snow was unlikely to fall on the summit of Mt Lofty during the night.

So unless any other reports turn up in the media or on the social media, or the Bureau has received any reports, Mark Dawson's account and photos are the only record of snow reaching the ground in SA during this weather system.

Below is the BoM Adelaide (Buckland Park) 256 km Radar Loop (IDR642 via http://theweatherchaser.com) for:
Tues 11th 2:40:00 pm South Aus time (11 Aug 2015 05:10:00 GMT) to
Wed 12th 10:30:00 am South Aus time (Wed, 12 Aug 2015 01:00:00 GMT).

See : 256km Radar Loop for Adelaide (Buckland Park), 05:00 11/08/2015 to 01:00 12/08/2015 UTC

 

Below are links to the BoM Adelaide (Buckland Park) radar loops - 256 km and 512 km - (IDR642 via http://theweatherchaser.com) for
Tues 11th 9:40 am South Aus time (11th Aug 2015 00:10:00 GMT)
to
Wed 12th August 12:30 pm South Aus time (12 Aug 2015 03:00:00 GMT).

See : 256km Radar Loop for Adelaide (Buckland Park), 00:00 11/08/2015 to 03:00 12/08/2015 UTC

See :
512km Radar Loop for Adelaide (Buckland Park), 00:00 11/08/2015 to 03:00 12/08/2015 UTC.

Now to an hour by hour sequence of infrared satellite images for the four and a half day period 8th to lunch time 12th August 2015 inclusive, using an approx 10mb gif file showing each image for one second. I've started it on 8th so you can see how the weather system evolves. The source of the below zero air mass over Mt Bryan is down near Antarctica a long way south-west of Western Australia and the cold air mass moves relentless north-eastwards towards southern South Australia and arrives behind a cold front. Two Southern Ocean lows are involved - it's complex! The images were sourced from a BoM satellite image archive here ftp://ftp2.bom.gov.au/anon/gen/gms/

Now to a gif file of BoM 6 hourly mean sea level pressure charts from 10am EST 9th August to 4pm EST 12th August 2015. Source: Bureau Home > Australia > Weather Maps > Analysis Chart Archive http://www.bom.gov.au/australia/charts/archive/index.shtml . "This service provides free access to archives of Mean Sea Level Pressure (MSLP) Analyses, Upper Level Analyses and Tropical Gradient Wind Analyses, for the Australian, Southeast Asian / Western Pacific and Southern Hemisphere regions."

The lowest overnight (hours of darkness) half-hour temperature recorded at the Mount Lofty AWS at a height of 685 m was 3.1 at 03:30am, and the lowest half hour temperature recorded at the Clare High School AWS Station at a height of 395 m was 3.6 at 3:00am. This suggests (rather speculatively) that the near-surface air temperature in the Mid-North overnight may have reached significantly lower levels than for the Mount Lofty district. The half hour temps overnight for these two AWS stations can be found here:

http://sasnows.com/2015/LoftyAWS11-12thAug2015html.html

http://sasnows.com/2015/ClareAWS11-12thAug2015html.html

End of report.

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