In reply to Bernard's comment That's a very interesting video in that it
doesn't show the usual Foehn gap: For starters, the main ridge producing
this is perhaps 15-20 miles away and hidden behind the nearby hills. There
was a lot of cloud on the upwind side around Mt Buller, Mt Useful, etc. You
can see the occasional roll cloud bits on the lower left of the frames.
Often, the pre-frontal NW winds are quite dry and we get a lot of blue wave
days with only isolated lennies.
In reply to Noel's comments: It puzzles me though as it turns into mammatus
immediately behind its leading edge. That usually indicates severe
turbulence but the wind sock remains nearly dormant. Did you obtain met.
details for the day? Uwe Radock did a lot of research re. that system in the
fifties and date may
be available from Melb. Uni..
I think it is the same mechanism as mammatus - a moist layer above a dry
layer with mechanical action (in this case wave flow) forcing the cloud down
into the dry air. You can see the protrusions going back up, indicating
stable air that is producing the wave.
Re the slack windsock - I think this depends a bit on the location of the
wave itself. Some days, we have howling winds locally with wave and others
very light on the ground. Normally, with a dry Northerly, it arrives with a
bang as the flow breaks up the inversion that had disconnected upper and
lower winds. On windy nights, we often lie in bed at night listening to the
rotors thrashing towards us and have, on 1-2 occasions, heard a deep, almost
subliminal rumbling of the wave. This is something I've described for the
Canterbury Plains wave cloud in NZ.
Re the met: yes, I have this detail if interested. The 00Z YMML trace shows
a lot higher winds than forecast and some intense drops and jumps in dew
point (25 degC over 200m) indicating several moist and dry layers.
Re the system: Uwe Radok (who I knew when I was a sprog in the MU Met Dept
in the early 70's) worked on the Warburton Wave off Mt Donna Buang whereas
this is coming off Mt Wellington NE of Licola. I used to fly the Warburton
Wave in my Ximango out of Lilydale and have two 25,000' climbs in it from
there. These days, I live at Lake Glenmaggie.
Cheers
John
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