Unusually High Summer Tides

Friday 16th July 2010

Unusually High Summer Tides

Many people will have noticed that the tides on the 14th and 15th July have been unusually high for the summer.  Water levels in Lerryn have been very close to causing flooding in low-lying areas.

The height that the water reaches in Lerryn is dependent on 4 main factors:

1  The predicted tide height  (5.6m on Wed night:  5.5m on Thurs night)

2  Atmospheric pressure (high pressure lowers the water level; low pressure raises the water level)  (pressure on Wed and Thursday nights was fairly low: 995mb)

3  Wind strength and direction.  Strong winds from the S & SW force more water up the river (Wed - the wind was approx 22 Knots or 25mph from the SW;  Thursday - the wind was approx 45 Knots or 52mph dropping just before high tide to 15 Knots or 17mph from the SW)

4  The flow of water coming down the river from the moor (thankfully, very low at the moment).

The actual height of the tide on Wednesday night was 5.92m (0.32m or 12ins above predicted) and on Thursday night was 6.07m (0.57m or 22ins above predicted).  (thanks to Fowey Harbour Office for this information)

The wooden posts around the Red Store parking area were very nearly covered by the water.  Several cars parked in this area suffered severe damage earlier in the week.  It is interesting to compare the high tide and low tide photos on the Photo Gallery for the area around the Red Store.  Notice the wooden posts just showing above the water at high tide.

See photos of the tides



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