.... just looked up the WMO catalogue for w'w' (present weather for a
METAR) and I'm pretty sure that this use is incorrect. 'VA' is listed
in the column for 'obscuration', i.e., meteors causing marked
reduction in visibility. The report has VVVV = 9999 (10km or more),
and as such doesn't require a present weather. I suspect they are
looking at what we are seeing elsewhere (haze, whether surface based
or elevated).

There's a lot of restlessness in the aviation world now (big
boys/commercial) and I suspect that we'll see some movement over the
next 12-18 hours on all this. The envelope of risk as indicated in the
VAAC bulletins is no doubt correct - whether the ash/dust/etc., is all
the same density/threat throughout that envelope is doubtful.

See:-
http://news.bbc.co.uk/1/hi/business/8628034.stm

Martin.



--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023