Tides rise to extraordinary levels
TIDES in parts of south east Queensland rose to 30 centimetres above the highest recorded for the year overnight Tuesday due to powerful southerly influence in the Tasman Sea.
The squeeze between a low pressure system in the Tasman and a high over South Australia generated strong southerly winds that pushed water up the coast.
A phenomenon first noticed in 1902 by Swedish scientist Vagn Walfrid Ekman and now known as the Ekman Spiral was responsible for an upwelling of water that increased the Highest Astronomical Tide at Scarborough by 30cm.
On the Sunshine Coast new moon high tides Tuesday night saw water over top retaining walls to the Maroochy River.
The United States National Oceanic and Atmospheric Administration's education service advises that when surface water molecules moved by the force of the wind, they, in turn, dragged deeper layers of water molecules below them.
Each layer of water molecules was moved by friction from the shallower layer, and each deeper layer moved more slowly than the layer above it, until the movement ceased at a depth of about 100 metres.
NOAA explained that like the surface water, however, the deeper water was deflected by the Coriolis effect - to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
As a result, each successively deeper layer of water moved more slowly to the right or left, creating a spiral effect.
Because the deeper layers of water moved more slowly than the shallower layers, they tended to 'twist around' and flow opposite to the surface current.
Bureau of Meteorology forecaster Jess Gardner said in theory with the southerly winds due to ease the elevated tides should also drop off.
Tonight's high tides at the Mooloolah River bar would reach 2.07m at 9.01pm, 2.07m at 10.32pm at Picnic Point in the Maroochy River and 2.23m at the Noosa River bar.
Picnic Point would peak at 2.08m on Thursday night at 10.50pm, the Mooloolah River bar at 2.08m at 9.48pm and the Noosa bar at 2.23m around 9.40pm.