99 codes for weather.

“A change in the weather is sufficient to recreate the world and ourselves” (Proust)


“Every weather is enjoyable if your feelings are delightful” (Ehsan Sehgal)

Weather is everything on Maatsuyker.

Weather determined when we got here. It drives us out of bed at 5:30am every morning to document it. It influences what we eat, what we wear, what we talk about, and what we do. It creates most of the maintenance and chores that fill our days. And it determines the rhythm, timing and abundance of all island and ocean life about us.

There are 99 codes for describing it.

The island lies in the roaring forties – a band of prevailing westerly winds that circle the southern hemisphere virtually unimpeded below 40 degrees south. These winds produce some of the largest non-cyclonic wind gusts and ocean swells in the world.  

An unconfirmed record suggests that Australia’s highest non-cyclonic wind gust occurred on Maatsuyker in August 1991 – 112 knots or more than 207 km/h. The official record is 185 km/h in June 2015. Gale force winds (greater than 63 km/h) are recorded up to 166 days a year and wind gusts of more than 130 km/h have been recorded during every month of the year.

This is what 150 km/hour winds and upwards rain looks like. Noisy. From our laundry window.

In 1930, the Melbourne newspaper, The Argus, reported that Maatsuyker’s gales “have been known to blow domestic animals and poultry to destruction over the cliffs and into the sea”. We don’t doubt it. The live chickens have not been replaced, but a paper mâché chicken some previous caretaker made and tied into the old chook shed also blew away a couple of weeks ago…

These winds and deep low-pressure systems that move south of Tasmania produce some of the biggest sea swells in the world. One freak wave off the west coast of Tasmania measured 20 m in height. The topography of land around Maatsuyker tends to limit the swell heights that end up hitting our coastline, but swells of 11 meters have still been recorded.

Rough as a box of dogs….ruff, ruff, ruff….

The science of meteorology first evolved to better enable efficient and safe passage of 19th century sailing ships. With lighthouses being all about guiding safe passage of ships, the marriage of lighthouses and weather observations was inevitable. While GPS has diminished the crucial role of lighthouses, Tasmanian weather data gathering priorities are still largely driven by the safety of boats (and now aircraft).  

Red sky morning, sailors warning…..

Official rainfall observations started on Maatsuyker in October 1891, just 5 months after the lighthouse was opened. The Bureau of Meteorology installed a weather station on the island in 1936 –a Stevenson screen and wind vane. A barometer and a handheld anemometer (to measure wind speed) were added later.

Curiously, the Stevenson screen was designed by Thomas Stevenson (1818–1887), a Scottish civil engineer who also designed lighthouses! (He was also the father of author Robert Louis Stevenson). The Stevenson screens still used by weather observers today have changed very little in their design since the 1880s.

Maatsuyker weather observations were initially collected at a site beside the lighthouse. In 1987, a dedicated office was built a little further up the hill behind the head lightkeepers cottage. An automatic weather station was installed on the island in 1996. Weather readings have come a long way – automatic weather station readings are now published over the internet every 10 minutes. But the automatic equipment has lots of problems with rainfall and wind readings here. Rain blows right over the top of the automatic gauge, and winds can curl around the island sending the automatic anemometer into hula hoops or just blow straight up the cliff missing the anemometer altogether. Which is one of the reasons we are here – because machines are still unable to catch horizontal precipitation or walk to the edge of the island to work out how big the easterly gale really is.

What a daily total of 57 mm of rain looks like. From the Bureau of Meteorology weather observation shack.

We log weather observations in a hand-written ledger and by computer twice a day (06:00 and 09:00). This involves reading four thermometers housed in the Stevenson screen. We classify the clouds, their type, height and cover, as well as record the height, direction and period of ocean swell.

David reading the four thermometers in the Stevenson Screen. Bureau of Meteorology weather observation shack to the left.

And we describe the weather using one of 99 codes.

Codes are ordered in regards to importance, or how exciting the weather is – code 99 being the most exciting (heavy thunderstorm with hail). Sometimes working out which code applies is not very straightforward, especially when lots is happening at once or it all changes before you can write it down.

Mist? Fog?

Some things we have learnt about coding weather.

  • Rain bounces. Drizzle doesn’t.
  • Fog is not mist.
  • Soft hail is a thing. And it isn’t snow.
  • Complete darkness (ie weather observations before dawn) is not an excuse for being unable to see the weather.
  • Muslin cloth and cotton thread are still the pinnacle of technology for measuring wind chill.
  • A well-fitting beanie is critical when one is outside observing hurricane winds.
  • Seas classified as “moderate” can be distinctly immoderate.
  • Clouds are classified biologically – by genus, species and variety. This doesn’t make it any easier…I am sure that David’s “fracto-bacillus” clouds are not a thing….
  • 06:00am is very early in the day for arguing with the one you love about whether it is stratus, stratocumulus, altostratus or nimbostratus…or is it altocumulus??? And by the time you have finished arguing, the clouds have all changed anyway….
Definitely clouds. Mist? Fog?

Codes 99 – 91. Thunderstorms

Thunder – if you can actually hear it over the wind – with or without rain, snow, hail, dust or sand storms. These weather codes are the real deal and always associated with the big mama of all clouds, Cumulonimbus.

Codes 90 – 80. Showers

Classifying showers can be a curious pastime. Showers can be slight, moderate, heavy or violent. Rain, snow or hail. And soft or hard. Including the hail. By the way, soft hail can be easily compressed between your fingers. Hard hail is, well, hard.

Codes 79 – 70. Frozen precipitation

Not to be confused with showers of hail and snow. I still don’t know the difference between “ice pellets”, “star crystals”, “snow grains”, “ice-prisms” and regular, off-the-shelf “snow”. We are unlikely to need to know any time soon as minimum temperatures on Maatsuyker very rarely fall below freezing (while it is almost always cool and damp, the coldest ever recorded is minus 1.0 C). But I would like to know….

Codes 69 – 60. Rain

Ten types of good old-fashioned rain. Except it could be freezing rain (which, let’s be clear, is not frozen precipitation). And rain or drizzle mixed with snow. Its all very simple.

Codes 59 – 50. Drizzle.

Ibid. Rain bounces. Drizzle doesn’t.

Drizzle can also be mixed with rain. And it can be freezing. Like I said. All very simple.

Codes 49 – 40. Fog.

Not mist. Code 49 – or fog that deposits rime (all the wet stuff in fog) – is a particular favourite. When you can’t see your nose on your face for the fog, ‘rhyme’ deposits can be very entertaining…. There once was a bloke on Maatsuyker/who wanted to be a mountain biker……

Codes 39 – 36. Blowing and drifting snow.

But not frozen precipitation. Got it? If its above eye level, its blowing. If its below eye level, its drifting. Essentially a blizzard. Of course, eye level in these conditions should be in a book, beside the heater, with a glass of whisky, but I’d still love to be the first to have to use this weather code on Maatsuyker.

Codes 35 – 0. All the rest…

The remaining codes are an odd assortment of weathers – from sand and dust storms and whirls (unlikely ever to be required on Maatsuyker, no sand, constant rain and being in the middle of the ocean and all), funnel clouds (really, really want to be able to record this code sometime!), virga (the most Zen of all weather types – if rain falls but does not land, has it rained at all?), mist (ibid. Not fog), haze, and smoke (this is the one we hope never to have to use….).

The Eye of Sauron. Or a sun pillar. On a rare calm morning.

The elusive code.

Sadly, rainbows do not have an official code of their own. We have found that there is nowhere better in the world to see rainbows than here on Maatsuyker. All the conditions are right: lots of showery precipitation, big clouds, sun in all the right positions. Rainbows are frequent, grand and supremely glorious here.

Did you know that rainbows are also very personal? Billions of raindrops contribute to the rainbow you see and, because they are falling, the refraction of light through the raindrops is constantly changing and different depending on where you are standing. A person standing right beside you sees a different rainbow produced by a different set of raindrops. The rainbow you see is, therefore, yours alone.

While they might not technically be “weather”, we reckon rainbows deserve a code all their own. And it seems obvious what that code must be…100.

Weather code 100.

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