Several key weather factors played a part when the flooding occurred in downtown Squamish.
According to local meteorologist Jason Ross, the variable weather conditions leading up to the king tide played a part in the flooding in downtown Squamish.
“The worst-case scenario happened on Dec. 27,” he said.
Ross said the combination of a low-pressure system with storms with heavy precipitation added to the water level of the tide on that day
Moreover, the barometric pressure between Dec. 26 and 27 dropped from about 1,000 millibars to a low of 978.7 millibars at approximately 9 a.m. when high tide was nearing.
A one-millibar difference from the average could have a one-centimetre of difference in the height of the tide, according to the National Oceanography Centre in the U.K., with low pressure adding to the height and high pressure subtracting from the height. According to the centre, this height difference peaks around 30 centimetres.
The mean barometric pressure for Squamish in December is approximately 1,018 millibars.
Additionally, Ross said the heavy precipitation added to the issue.
The Squamish airport recorded about 197 millimetres of precipitation from Dec. 24 through 27. The 67.5 millimetres recorded on Dec. 24 and the 52.3 millimetres recorded on Dec. 26 were new records for both of those days, according to Environment Canada.
The temperature also elevated dramatically during this time and the freezing level rose to an altitude of about 2,000 metres.
“On Boxing Day, it was a very strong front; the temperature shot way up,” Ross said.
Fortunately, Ross said there was little to no wind so it did not play a part in this instance.
— When is the next king tide? —
In late January 2023, the tides may once again be an issue for areas around Howe Sound, if another variable weather pattern combines with the predicted high tides.
Tides occur from the gravitational pull of the moon and the sun, with the moon’s gravitational pull influencing tides more as it is closer to Earth. The water moves vertically, ebbing and flowing with the gravitational pull from the orbiting moon and sun. This creates relatively predictable cresting and falling tide times.
On Jan. 23 and 24, the tide is predicted to be about 5.1 metres high for Squamish, according to Environment Canada, which is the same predicted height that occurred on Dec. 27, 2022.
These predicted high tides also coincide with a new moon and lunar perigee on Jan. 21. A new moon occurs when the moon is between the sun and Earth and all three are nearly in alignment, thus combining the pull of both the sun and moon on the ocean.
Lunar perigee is when the moon is closest to Earth during its elliptical orbit, whereas apogee is when the moon is the furthest. The lunar perigee on Jan. 21 is predicted to actually be the closest the moon will be to Earth for 2023.
Combining these factors with a similar weather pattern that occurred on Dec. 27 may result in flooding for low-lying areas around Howe Sound. But, Ross said, it is far too early to confidently predict the weather.
“Best case scenario, we have a nice, stable pattern with no storms,” said Ross about the weather for late January.
Ultimately, Squamish experiences king tides and high tides regularly without flooding. But as we saw on Dec. 27, the impact of the weather can heighten the water to the point of flooding the downtown core with the current sea dike protections.
As a result, in the days leading up to Jan. 23 and 24, it could help nearby residents and business owners be more prepared for possible flooding if they are keeping an eye on incoming weather patterns.
