Observations at the Old Quebec station.

Figure 2. Observations at the Old Quebec station. Graph showing that the area of low pressure near the Cabot Strait produced a suction effect, holding back water from the Atlantic Ocean and thereby causing a decrese in the amplitude of the tide in the Gulf of St. Lawrence and the St. Lawrence River. The effect on the next high tide was spectacular, with water levels lower than the predicted tide values (negative surge) on September 8. A negative surge value of -118 cm was recorded at Quebec City­.

Legend :

Observed water level – red line

Predicted level – black line

Atmospheric pressure – orange line

Black vertical lines – difference between the observed water level and the predicted tide