Cold front passage July 8 2014

A sharp front was expected during the evening on this day, with damaging winds likely to accompany it. In Port lincoln a 117km gust was recorded, and so I decided to head to St Kilda after watching radar for most of the day to get a decent view of it. The cold front itself was relatively strong, however it wasn’t to kick up much moisture and rainfall along the boundary was quite limited. However it did produce a half decent roll cloud and some 90km or so gusts in coastal areas.

Cold front structure on approach

Roll cloud as the front approached

A few kilometres away, looking north.

A few kilometres away, looking south.

As the OFB neared, I noticed spray being whipped up off the ocean a couple of kilometres away. I watched closely as it eventually spun up into a gustnado, marked by rising motion, especially on the back end, moving rapidly towards the coast. It was quite dynamic, especially in the later stages near the shore, where it ran aground, throwing around a little debris before falling apart in the mangroves. Gusts accompanied this feature while I was videoing, with gusts around 80-90km, it was rather wild for a brief period. It is interesting to note this gustnado was about 50m wide and had decent vertical motion, perhaps some of the local damage associated with cold front and convective lines in winter could be attributed to this phenomena.

Line of strong outflow whipping up spray off the coast.

Gustnado which had now formed throwing up spray.

Gustnado running aground, sorry about the shakiness, telephoto and very windy makes it hard.

And a timelapse of the roll cloud from the car with the mobile phone.


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