Port Alberni King Tides

[Sharphooks]

I was surprised to see people remarking in a YT video that the King Tides in Port Alberni were the “highest they’d seen in 10 years”.

Question: Does anybody know what the barometric pressure was in Port Alberni on 03/04 January?

Reason I’m asking:

In 2022 we had King Tides in my neighborhood just after Christmas. The stated high tide was 12.5 feet and at the peak of that tide it put 1 1/2 meters of water in my back yard and about 15 cm into my house





So this past Sunday we had a 13 foot tide, approx. 15 cm HIGHER then the KIng Tide we had in 2022 that destroyed all that property in my neighborhood

So why did I go to bed Saturday night being quite confident that my house wouldn’t get water intrusion from what would be a much higher tide?

Barometric pressure.

In 2022 the barometer reading was 28.5 inches of mercury. That differential below normal sea level barometric pressure, based on the inverse calculation that for every millibar of pressure below normal sea level barometric pressure (1,1013 millibars or approx. 29.9 inches of mercury) we get an approx. one (1) centimeter rise in water level

If you do the math, that 28.5 inches of mercury in 2022 represented a 48 centimeter (!!!!) rise of sea level. So a 12.5 foot tide turned into a 14 foot tide. Add a bit of wave action and the water level in some places was measured at 15 feet above normal sea level

Last Saturday night I took note that the barometric pressure was approx. 29.4. I calculated that worst case that 13 foot tide last Sunday would turn into a 13’ 7” tide and would probably put my dock under water by approx. 4 cm but the water wouldn’t come into my yard

I woke up at 6:30 Sunday morning at the peak of the tide and saw by flashlight that my calculation was almost exact. And so it was Monday and this morning, three 13 foot tides in a row that were harmless (a steady rising barometer saved the day)

So that’s why I ask about the barometer in Port Alberni. I’m not sure the tidal readouts would have been all that different from what we had and what Port ALberni had so to have gotten all that water in the CLutesi parking lot that had people hyperventilating that it was the biggest tide they’d seen in 10 years, there must have been a big dip in barometeric pressure

Can anybody confirm what it was?

 

[Pineapple Express]

Very interesting!

I got a chuckle out of your mixing of imperial and metric measurements...even within the same sentence!

 

[MRWood]

Here in Nanoose our latest high tide was 17’ and low tide was 1’. At the Nuttal Bay beach we don’t usually need to worry about the king tide unless a big NW wind comes at the same time. The bay is protected from SE winds. With that being said one of the old timer neighbours told me about a king tide in the bay during a SE wind that pushed the water up higher than he’d ever seen it. Floated dinghies away that were thought to be untouchable. I wonder if that was due to an extreme low pressure at the same time. Seems likely.

 

[Sharphooks]

Very interesting!

I got a chuckle out of your mixing of imperial and metric measurements...even within the same sentence!

It's logical to use metric when talking millibars when one drop down of a millibar represents a one centimeter rise in sea level....Makes it nice and tidy.

I did notice Enviro Canada uses kilo pascals when discussing barometric pressure

I did a bit of research which indicated Port Alberni was posting 90 kilopascals on 04 January which would've bumped up the highest tide by approx. 23 cm on 05 January...not huge but I guess enough to put the Clutesi parking lot under water

 

[BC Coast Pilot]

It's logical to use metric when talking millibars when one drop down of a millibar represents a one centimeter rise in sea level....Makes it nice and tidy.

I did notice Enviro Canada uses kilo pascals when discussing barometric pressure

I did a bit of research which indicated Port Alberni was posting 90 kilopascals on 04 January which would've bumped up the highest tide by approx. 23 cm on 05 January...not huge but I guess enough to put the Clutesi parking lot under water

Here's the actual numbers for the 4th, what you haven't considered is freshet from runoff

 

[Sharphooks]

OK, I get it now. Incoming tide stacking up against a big river.... Thanks for that!

 

[Squire]

This site below use to be part of my daily checklist in the fall for monitoring flood conditions on our logging roads. I could predict a downstream flood from the water level trend at the upstream station along with predicted precipitation levels and the tides were always a part of my equation in spite of the number of miles upriver the potential flood would occur. I also considered the tides to help predict how long it would take for the water to recede once it breached the road. I can understand how the opposing forces of a high outflow and a flooding tide could cause a significant rise of water levels anywhere near the estuary of a river.
Combining these forces with a low barometric pressure really would be the ‘perfect storm’.

Real-Time Hydrometric Data - Water Level and Flow - Environment Canada

wateroffice.ec.gc.ca