1. Low astronomical tides amplified the effects of severe turbulence in the water. 2. Some coastal flooding is possible, particularly around times of high astronomical tide . 3. Remember that astronomical tides do " not " include weather effects. 4. The distant cyclone sent large swells toward Tonga and Samoa, coinciding with high astronomical tides . 5. Near Channel Point, the cyclone brought a storm surge of, barely surpassing the highest astronomical tide in a few areas. 6. Vertical clearances, e . g . below a bridge or cable, are given relative to highest astronomical tide ( HAT ). 7. At West Quay in Bridgwater where the river is tidal the highest astronomical tide level is above ordnance datum ( AOD ). 8. Special care is needed when assessing the size of a " weather surge " by subtracting the astronomical tide from the observed tide. 9. The pressure effect and the wind set-up on an open coast will be driven into bays in the same way as the astronomical tide . 10. Consequently, bridge clearances etc . are given relative to a datum based on high tide, such as Highest Astronomical Tide or Mean High Water Springs.
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