As described on my Morning Glory Australia home page, the formation of a low pressure trough through Northern Queensland and an associated high pressure ridge along the Cape York Peninsula is required the day before a Morning Glory. The MSL analysis chart to your right for is from the 30th September 2006. This trough shown here encourages the formation of seabreezes around the Gulf and a prevailing north easterly flow.
The upper air charts show a marked veering of the winds aloft
in the SE Gulf region above the lower seabreezes.
This 850hpa
analysis chart shows the wind at around 5,000 feet to be south east.
This
wind shift at altitude associated with a
subsidence inversion resulting from the mild mid level high pressure
system.
At 10,000ft the 700hPa analysis chart shows the wind getting around to wards southerly. This mid level high pressure system is generally only associated with dry season weather and the underlying sea level trough tends to be a wet season phenomenon. Once these mid level highs disappear in late October, this effectively “lifts the lid” on convection and the thunderstorm season commences.
By the time we get to 18,000ft the winds are around further to the south west as shown on this 500hPa analysis chart.
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The sort of wind changes and inversions at altitude that are shown in
the above upper air charts are ideal for the formation of standing
air-mass wave systems …sometimes known as sheer or inversion
wave. Press play on the video to the right and you will see
that the brightly lit mid-level cloud on the upper right is the
crest of a standing wave around 15,000'.
These videos are copyright to Aerial Video Australia
The video to the right is part of a video sequence taken from Burketown looking towards Normanton as a poorly formed Morning Glory system is passing. The upper standing wave system that can be seen has a curve on it that approximates the south eastern corner of the Gulf.
Little research has been done to determine the effect of upper air wave systems in the formation of Morning Glory Clouds. The upper air inversions and flows are certainly important in providing appropriate wave guides for the Morning Glories and the upper air synoptic charts on "Glory Days" are always similar to the ones shown above. It is not well understood what effect the upper atmoshere has in the creation or energising of multiple glory waves