Gedday,

Well... back in the saddle again after a week on my honeymoon (there are now two McBrides in the Bureau..... arrrrghh!!) and a week at the American Meteorological Society Conference on Hurricanes and Tropical Meteorology, held in San Diego.

As always, there are all kinds of interesting things happening in the current synoptic situation.  I'll go briefly through some of them, and if time permits, I'll discuss some in depth in the next day or so.  I don't have any interesting questions to ponder over for these situations yet... but as I point them out, they may trigger a respionse from someone out there.

a)  The terrific low high pair over south-west WA and eastern Australia.

    It looks like the current pattern of a high over eastern Australia and a low out over the Indian Ocean near WA has held up for over a week now.  Looking at the 200 hPa jet-stream display (see my web-page),  the basic configuration of a block and split jet over most of Australia, with the upstream join in the jet over the eastern Indian ocean existed on 26 April, and is still there today.   The pattern has evolved, however, with 120 kt jet cores over the two sub-tropical jet branches of the block.  I guess we could interpret the layer-upslope cloud over the Coral Sea as being associated with left-entrance divergence from one of these jets.

The low off southwestern WA associated with the WA jet core ( the join in the jet, upstream of the block) is a beauty.  Are there any particular forecast problems associated with this? (see current MSL-P chart)

                    12 UTC 26 April                                                                12 UTC 6 May

b)  Frontal passages

    We are not really getting any fronts pass through south-eastern Oz at the moment; as those during the past week have all slipped south below the blocking high.  Despite that, it seems the character of fronts has changed from the good cool-changes we have discussed over recent months to mobile "rainbands that actually move through the parent trough, with no appreciable temperature change, or even any appreciable discontinuity in wind or temperature across them".  This difference between south-eastern Australia summer fronts and winter fronts is something I am intensely interested in....expect more comments and questions as the winter evolves.

c)  Stratocumulus behind the front off WA.

When I arrived at work this morning I looked at the current polar IR loop  (which I have put on my web-page).  There is a mass of stratocumulus off WA in the westerly flow behind the front in the Bight.  As you look at the loop, you see the stratocu dies out at the coast.  This is an interesting large scale effect.  Looking at GASP surface theta charts (on the NMOC GASP page) the land is still warmer than the sea out there, even overnight; so presumably this is simply a thermal effect.
 

d)  The tropics -- twin vortices

As was discussed in my absence there has been an interesting blow-up of convection over the Indian ocean over recent days.  I have put links to three Eumetsat images on my web-page, because they are absolute beauties:   The images are for 0100 UTC on the 3rd, 5th and 7th of  May.    From the first image, you can see a beautiful set of twin vortices straddling the equator at about longitude 65 E.  They have drifted slightly northward and westward over the subsequent 4 days but still form a beautiful symmetric pair.  The southern vortex has been named (cyclone Kesiny), while the northern one is expected to develop within the next 24 hours.

Unfortunately as I type this  (Tuesday afternoon) the CDC NOAA page is down, so I can't see what sort of westerly wind anomaly exists in the Central Indian Ocean associated with this.... I'll have a look tomorrow morning.