Synoptic Charts - High pressure ridge

[Ozgrade3]

On the MSL synoptic charts years ago they shows a high pressure ridge with a line. I think it was a _._._ type line where as a trough is a ---------type line.

Can anyone verify that BOM have dropped the ridge line markings on the charts these days, and on the legend, only showing the troughs. Have searched throug the whole BOM website and no reference to the change.

[gfunc]

The ._._._ line is currently used for the monsoon trough. Granted I've only been in Oz for three years, but I've not seen a ridge line drawn on any synoptic chart (I work in meteorology, but stand to be corrected). There isn't any on the BOM archive going back to 2000 (Analysis Chart Archive (http://www.bom.gov.au/australia/charts/archive/index.shtml)). I can't think of a good physical reason for routinely including them compared to troughs.

Gareth.

[Centaurus]

[QUOTE(I work in meteorology,QUOTE]

Gfunc.

You're the man. Years back I wrote to BoM asking whether there was any record of Tornadic Tubes known to exist in Australia. The reply was they do exist around certain type super cell thunderstorms but not reported due only rare occurences and probably not seen at the time with so relatively few aircraft movements within Australia compared to USA.

It was tornadic tube activity in the clear air between two closely spaced cells, that ripped apart a BAC One-Eleven of Braniff Airways in Nebraska.

I have seen no mention of these phenomena published in Australian Met manuals. Google skirts around the subject and I wondered if you could supply any more information on their existence in OZ

[Slasher]

whether there was any record of Tornadic Tubes known to exist in Australia

We used to see waterspouts up around the Torres Strait
between Oz and PNG in the Wet sometimes when those
rare 60,000 foot buggers moved in and gave us massive
hammerings of water and lightning all afternoon (incl a
diversion or two from HID (+N) down to WP or NTN.

Never saw any in the Gulf or N Coral Sea.

Only visual sightings as wx radar was for girlies and limp
wristers back then.

[gfunc]

Hello Centaurus,

We certainly do have tornadoes in Australia! The response you got from BOM is correct in that they are relatively rare as they are spawned from "supercell" thunderstorms that require a large amount of instability and a quite specific vertical wind profile. The correct conditions exist semi-regularly in the central USA in their spring, but here they are more transient - anecdotally they seem to be most frequent in central Vic and western NSW. You might recall the xmas 2012 storm in Melbourne (which incidentally wrote off my car) was a supercell - this had a radar signature of a tornado and public reports from the area around Bacchus Marsh. Note tornadoes are quite distinct in their dynamics from waterspouts and dust devils, which are associated with convectively forced convergence and can form regularly in quite benign conditions.

What we don't have is a census of tornadic activity in Australia as you need trained spotters and doppler radar coverage to do this well - the problem is that both these only exist in capital cities and there are large swathes of the country not well observed. I know of a couple of researchers look at this at the moment - I'll see if I can dig any results up.

Cheers,

Gareth.