18-22 July 2013

According to most models a follow-up event is coming mid next week, with lots more rain initially. But this one looks to have snow in the tail, maybe as much as 30 cm Thursday into Thursday night, with more to come into the following weekend.

Update:  The snow action in this event has drifted later: more like Friday night into Saturday; 30 cm is looking very optimistic.

Update 2 (14/7): Back to thinking 30 cm is possible, Friday night through Sunday. Note the date drift.

Update 3 (19/7): This event (and the season) is starting to look ugly. Over 50 mm of rain already — most at over 6°C — equal warmest July day on record in Melbourne (in 158 years) … and there’s more to come. Short range, the best predictor is probably the Bureau of Meteorology’s ACCESS-R model. It is suggesting that snow might not now arrive until very early Saturday morning. I still think up to 30 cm is possible through to Monday night, but a lot of that is going to fall on bare ground.

Outcome (22/7):  There’s been more rain than I expected (~60 mm at Perisher), but more snow too.  The Perisher automatic weather station temperature fell rapidly through 1°C about midnight Friday, probably near the onset of snow.  By midday Monday there had been 58 mm of precipitation since that time, which would be ~58 cm if it all fell as fluffy dry snow (some did). The resort is claiming 65 cm (yeah, sure guys). We’re now close to the end of the event, but ACCESS-R suggests there’ll be a bit more Monday night.

Prediction score:  7/10 … basic system character right, timing right after first update, magnitude low.

2 comments to 18-22 July 2013

  • theflyingfordanglia

    How much rain will there be before the snow? How likely is it that the models will change again?

  • Gerg

    I expected up to 25 mm in the current event, and so far Perisher only has 4 mm; Hotham is near 25 mm. The temperature at Hotham has been around 2°C (top of hill), so 25 mm will have melted a whole 0.4 cm of 150 kg/m³ snowpack. As I said earlier, rain at this time of year is hugely over-rated as a snow destroyer.

    My take is that this week’s rain will be pretty similar. We’re at +132hrs on the follow-up snow, at which point the EC model has tended to be pretty near the right answer.