In terms of overall rainfall, looks like most of our region will probably just get modest totals at best, and hardly anything at worst (given the NW flow and being near the thinner northern end of the frontal band)... although there still looks to be some instability ahead of it with profiles moistening up through a decent layer albeit for a short time....so if any storms did manage to form somewhere, maybe the outside chance that some could approach severe thresholds (very strong shear in the order of 50kt in the 0-6km layer in some places and 20kt in the 0-1km layer....ACCESS-R CAPE fields currently have 500-800j/kg in places and up to 1000-1500 around some parts of the Mid North Coast).
The catch is, will the approaching cloud cover/patchy precip hold off just long enough for sufficient heating to help with any storms (and cause localised higher rainfall totals), or will it come over too early and dampen things down too much.
There can also be some times when even if cloud/precip holds off til afternoon, it still just results in sparse localised embedded thunder inside a patchy rain band.
On a side note, I happened to have a really vivid dream the other night about witnessing a tornado drop down a few metres away here in Brisbane tornado but I regret to say that hardly any of my dreams end up being true
Anyway this forecast sounding for Wed afternoon in Brisbane will probably be fairly self explanatory for the technically minded sounding fans but I've basically selected the forecast effective inflow layer used by storms to calculate the CAPE (which in this case, works out to 434 J/kg for that time and close to the mixed layer CAPE of 554J/kg). In this sounding, parcels rising from the layer which provides the most unstable CAPE gives a CAPE of 1428J/kg).
The WATL map below is valid between 10pm Tue and 10pm Wed.
All in all, nothing to get that excited about with this marginal setup (setups with a good moisture-rich NNE flow, higher instability and a S'ly change are far better than this one for severe storms) although probably still unwise to rule out that outside chance of severes altogether.