How to Forecast Snow in Australia: A guide to crystal ball gazing…

13 May

Snow forecasting in Australia is a niche skill — part art, part science. Unlike the deep winter systems of North America or Europe, our snow events are often marginal, elevation-sensitive, and brief. This post breaks down how to forecast snow here, from the macro-scale synoptic drivers to the local effects that determine whether flakes fall — and settle.

Macro-Scale Drivers: The Right Setup Matters

Most Australian snow events rely on cold air advection from the Southern Ocean, dragged northward by a strong front or low. Look for these synoptic features:

Strong Cold Fronts: Cold fronts supported by upper-level troughs can bring snow to the Australian Alps, especially when they originate from south of 50°S.
Cut-off Lows: These slow-moving systems can wrap cold air around their western flank and deliver prolonged snowfall to elevated areas — sometimes even after the front has passed.
East Coast or Tasman Sea Lows: Particularly relevant for NSW, these systems can produce upslope snow on the windward side of the ranges when cold air filters in behind.
Negative SAM Phases: These allow westerly systems to push further north, increasing frontal activity over southeastern Australia and boosting snow potential across NSW, VIC, and TAS.

Key Thermodynamic Ingredients: It’s Not Just About Surface Temperature

Snow doesn't happen just because it's cold at ground level. You need a supportive temperature profile through the atmosphere. Focus on these:

850 hPa Temperature: This level (~1.5 km up) is crucial. You typically need -2°C or colder for snow to reach elevations near 1200 m — the lower range of most mainland Australian ski resorts and almost the minimum requirement in TAS.
Wet-Bulb Temperature: Surface wet-bulb temps of 0°C or lower allow melting snowflakes to survive to ground level. Evaporative cooling can drag the wet-bulb temp down rapidly during onset.
Thickness (1000–500 hPa): Values below 5400 m are often quoted for snow, but with dry air and strong cooling, snow can fall with higher thicknesses.
Moisture Depth: Look for saturation through the dendritic growth zone (~ -10°C to -20°C). This supports flake formation and decent accumulation.

Elevation: The Defining Factor

In Australia, snow is a story of elevation. Most ski resorts in VIC and NSW sit between 1300–1800 m, and reliable snow often stays above 1600 m. Outside of the ski fields:

NSW/ACT: Snow may be observed down to 1000 m semi-regularly, and very occasionally to 700–800 m (e.g., Oberon, Orange, Blue Mountains) during significant events.
VIC lowlands: Settling snow below 700–800 m is rare and typically limited to bursts of heavier convective snow or overnight drops under calm, clear conditions.
Tasmania: The bar is lower — snow impacts become noticeable below 600 m. Central Highland localities, the upper Deerwent Valley, the Huon Valley are no strangers to snow, and even Hobart's higher suburbs can get dusted when cold pools arrive.

Micro-Scale Modifiers: Why One Hill Gets It and Another Doesn’t

Even with the perfect setup, snow is fickle. Local geography plays a huge role:

Aspect and Exposure: Windward slopes facing incoming moisture will accumulate more snow; leeward slopes may remain dry or rain-shadowed.
Ground Conditions: Wet or warm surfaces inhibit accumulation — a dry prelude increases the odds of snow settling quickly.
Time of Day: Snow reaches lower elevations more readily overnight. Marginal setups often transition to rain after sunrise.
Convective Bands: These can produce brief bursts of heavy snow at unexpected altitudes, even if broader conditions aren't ideal for snow.

Forecasting Checklist

Here’s what to look for in models and obs if you’re trying to forecast a dump of snow:

850 hPa temps below -2°C over your region of interest
1000–500 hPa thickness under 5400 m
Surface wet-bulb temperature near or below 0°C at your elevation
Sufficient moisture depth and upward vertical motion through the snow growth zone
Model agreement on timing and frontal passage — particularly post-frontal

These values will vary depending on your altitude, but the values quoted work for alpine areas of Australia.

Final Word

Snow forecasting in Australia is an exercise in precision. A few hundred metres of elevation, a degree of temperature, or an hour of timing can be the difference between a snow-covered paddock and cold wet grass. But by combining synoptic context with model diagnostics and ground-level understanding, it’s possible to beat the odds — and pick the right moments to expect snow where it matters.

Daniel Lester