Gedday,

The front that went through Vic on Sunday is an absolute classic in terms of
its structure as it leans back across Australian once it has passed in to the
Tasman.

Look at the sequence of figures on my web-page of 900 vorticity as the front
moves through   The blue line of negative/cyclonic vorticity marks the passage
of the front.

900 hpa vorticity maps:      00Z 6 Jan
                                           12Z 6 jan
                                           00Z 7 Jan
                                           12Z 7 Jan

What I really want you to look at though is today/last night's maps of theta
and of thetae.

Looking at the theta map, you can see the wedge of warm (high theta) air ahead
of the front has moved across the east coast into the Tasman and has actually
taken the body of warm continental air (the geographical front associated with
the land-sea barrier) out into the Tasman.

Now, look at the theta-e map: The front has moved across into the Tasman, the
cold-dry, low-thetae air has moved up over eastern Australia behind the front
and we have an absolutely beautiful theta-e front lying across eastern
Australia.

Looking at this picture, it seems to provide some information on the question
we were discussing a couple of weeks ago: Are these trailing fronts (CAFÉ
experiment-type fronts) true residuals of the front that moved across south
eastern Australia, or rather are they the result of a new frontogenesis that
occurs when the high builds up behind the front?

I believe this picture provides evidence for the latter scenario.   What has
happened is the front has moved through.  Cold dry air has moved up over
Southern Oz behind the front all across eastern Australia and has hit the
barrier of the warm moist air associated with the Coral sea trades.  So...
what would have happened if we had a westerly monsoon flow across
northen Oz?

I'll get out of your way now

John McB