|Wind and Tide
"It was floating last night"
The prevailing winds in the lower Lake Eyre region are southerly, tending westerly the more south west you are on the Lakes. The influence of this wind is evidenced by the north-south alignment of the longitudinal dunes in the surrounding desert. It is interesting to note that this alignment is almost west-east as nearby as Anna Creek. The dunes are graphically illustrating the presence of the Central Australian high pressure zone and the relatively sharp "corner" of this zone that appears to occur at the Lake.
Winds from all compass points can be expected in calmer weather due to sea/land breezes, with northerlies being the second most common wind after the southerlies.
The Lake, being an extremely shallow, almost flat basin, is dramatically altered by wind. So much so that wind can move the entire Lake, when very shallow, from one part of the basin to another in a matter of days. This is commonly called a wind tide - the scientists call it Seiching.Wind tides of 300mm were reported by early navigators on the Lake. LEYC members have experienced tides of 600mm! .See below. To the average mariner such a comparatively small tide would be thought of as irrelevant. To the Lake Eyre navigator it can be a catastrophe. 600mm less water can mean a few kilometres of mud now lies between the craft and the Lake!
The lesson to be learnt is to view mooring depth with regard to expected strength and direction of the wind if you want to leave early the next day.
"We arrived late afternoon and were pleased to find the Lake lapping within 20m of the "edge" in a light northerly breeze. It appeared fuller than expected and tomorrows launch looked like an easy task compared to other trips. We retired thinking we will be sailing the next day.
During the night one of those southerly changes blew up and by morning it was a constant stiff breeze. A walk from the camp to the Lake edge dune revealed - shock horror - no water at all. The southerly had blown the water out about 2 kilometres over night! It could barely be seen on the horizon.
After three days waiting one propective member gave up as he had run out of holidays. The wind stopped mid morning and the water was back by lunch time. We sailed that afternoon! "