Hello again from the Snowy Hibbo. Due to timing, this will be now the last long Range update for the Australian season. Today, we will look at the models and drivers that matter, and then have a look at it from a different angle. Let’s get into it…. 9-11 Sept
GFS features a deep low that brings moderate-heavy snowfall, beginning late on the 9th, continuing through the 10th and waning off on the 11th. EPS Control doesn’t agree.
EC Monthly shows this period to feature quite a bit of rain on the above dates. CFS also seems to agree with a similar scenario.
EC Monthly shows this period to feature very heavy rainfall on the above dates. Good for the farmers I guess. CFS shows some prefrontal rain, then a decent snowfall on the 18th.
EC Monthly shows this period to feature moderate snowfall from the 21st, persisting over the day and becoming light the next day. CFS shows some rainfall associated with a trough on the 22nd.
The cold behind the previous system and precipitation associated with the Tasman low to the Northeast, collide to form some moderate-heavy snowfall from 24th mid morning easing in the evening. CFS doesn’t show anything until a moderate-heavy snowfall on the 25th.
Apart for a brief visit to our region in the short term, the model consensus is for a neutral MJO well into September.
The AAM is forecast to stay neutral until a rise to positive values in Mid September. This is negative for Australian Snowfall.
The Stratospheric Polar Vortex above Antarctica is showing strong signs of weakening, as Spring comes upon us. A sudden or strong warming would increase the amounts of systems coming north to Australia, but the precipitation will increasingly become clear as September progresses.
The SAM is currently positive and is forecast to be it, minus perhaps a slight neutral interlude, for the first half of September. This means less snowfall and an end to the train of coldfronts earlier this month.
ConclusionIn short, the prognosis of a mostly rainy September with pockets of snowfall doesn’t look great. Instead of concluding, I will play devil’s advocate to that scenario. The EC Monthly mean (not the Control run above) shows ridging during the second half of September into October. CFS mean shows ridging throughout September for the Alps. This would help people who want sunny spring conditions for resort cruising or backcountry touring. With the MJO and AAM out of play, and the SAM positive into Early September, this is quite a decent chance. The SAM in particular will be crucial to watch during September to see whether the rain stays away.
Disclaimer: There is low skill asssociated with using long range model forecasts to find snow systems. All systems you see here will change, as the date gets closer and may not eventuate all together. I don’t give much accuracy to these forecasts, but you can give these a bit of your time and your dreams might come true. The climate driver and Antarctic node forecasts tend to have a bit more skill than the precipitation and temperature forecasts, but certainly don’t put all your money on them. However, climate drivers are an awesome tool to explain the weather around us.
Thanks so much for reading this blog update into the Australian long range snowfall forecast, please follow me on Twitter @longrangesnow and join my email list on the top bar of this blog. As said above, this is the last update of the season. I hope you enjoyed this season’s worth of updates. Looking back to my Seasonal outlook, you could say it was a bit more than “slightly above average”. We can certainly cut this down to a big season of negatives from the SAM. Next month, I will upload the first outlook for Japan, Europe and North America for the 2018-19 season, and expect more in the lead up to the first long range updates coming Late November. I look forward to doing it all again then. Until then, stay cool!