Yesterday was yet another major wind event in Victoria.

So far we have had the frontal wind-storm of the night of Monday 2 September.  Then we had the all-day long pre-frontal northerlies event of Sunday the 15th, followed by yesterday's all day event in a westerly to south-westerly stream.

Does anyone out there have ready access to software and archives such that they could plot for us the Melbourne (and for that matter Mt Bulla) hourly and/or 6-hourly winds through the month as a quick summary of these events?

Looking at yesterday's event, I have put links to a few Victoria maptool plots onto my web-page.
23 UTC 17 Sept
04 UTC 18 Sept
12 UTC 18 Sept

You'll see from the beginning of the event and through the peak (around 04 UTC) there was a westerly stream of around 30 to as high as 50 kts across the state and for the last six or so hours it swung slightly southwesterly. Looking at the synoptics, the strong pressure gradient is associated with the high over the continent and the low at almost 60 S.  The high is fairly strong (1026 hPa) and the low is as Noel would say, humungous (944 hPa) but its a long way South.  I have put the theta and thetae maps on my web-page too, where you'll see that the only classical front (in terms of air-mass boundaries) is the one of a couple of day's earlier which is already way out in the Tasman at about 160E).

So... it seems to me the reason for the strong winds is not so much the deep low at almost 60S, but rather the fact there is a mid-latitude trough poking way up to about 25S  in the Tasman, at around 160E.  Looking at the 500 hPa flow, (my web-page)you can see this trough and polar jet poking up to about 20S.
In my mind, the reason for yesterday's strong winds was the simultaneous presence of the higher latitude low and the Tasman Sea trough, thus directing a westerly and later southwesterly stream across the south east corner of Oz.

Are there any people with a good grounding in mid-latitude dynamics out there (Harald?, Christian?).  We have baroclinic instability as a theoretical framework for why cyclones develop in the westerly stream.  Does anyone understand this phenomenon of mid-latitude lows extending to lower latitudes like this.... I mean in general terms, the basic underlying principle... this being a Weather Bureau, we should know and understand these things.

cheers
John McB

 P.S  I wanted to look at the soundings, but can't find them.  Someone in the Adelaide Office has put together a nice web-page whereby you can punch in a station and a date and the f160 pops out.  Can someone send me the URL please?
John McB

Elly Spark

Re 18th: Extreme winds in NSW on Tuesday and particularly Tuesday night,
caused lots of damage particularly in the Illawarra. All the models
indicated the event. We issued our fist land wind warnings for
ST/Illawarra/South Coast for Tuesday on Monday morning based on LAPS data,
which had W winds in excess of 35knots ALL over the Southern Tablelands.( at
.9875 sigam level).

With W winds, strong mountain waves develop in the lee of the Divide, making
for a very bad situation for the Ill/SC area and adjacent coastal waters.
The mountain waves were visible on a number of the Tue sat pics, but I did
not save any.

The models did not pick up the extreme winds in the lee of the ranges.
However, please don't take this as a criticism. I am not expecting the
models to forecast mountain waves.

Elly Spark, NSW