From the Cliff Mass Weather Blog
By Cliff Mass
King Tides represent unusually high water levels, which occur when the geometry of the sun and moon are just right.
But this year, the predicted tide got a major boost in Seattle, thanks to the atmosphere.
On Friday around 9:15 AM, the water level in Seattle rose to 14.47 feet above sea level and probably was higher in the 20 minutes before (there was an outage at the site between 8:42 and 912: AM)
The previous record high tide in Seattle was 14.51 ft in December 2012. We very well might have beat it.
The result was coastal flooding throughout the area.
Near Alka Point that morning (courtesy of the West Seattle Blog).
Below is the predicted (blue) and actual (red) water levesl at Seattle from the NOAA Tide and Currents website since January 3. Friday’s prediction (around 12.5 ft) was WAY too low (by about 2 feet). (a red arrow indicates Friday)
Something greatly increased the high tide!
The secret was a vigorous low-pressure system and front that was going through EXACTLY at the right time (see sea level pressure forecast for 8 AM Friday, syncing in perfectly with the astronomically forced high tide.
Sea level pressure (solid lines)
And a trace of pressure at SeaTac Airport documents the pressure plunge (see below). Pressure dropped all the way to 990 hPa from ~1025 hPa…. which is a big and rapid change.
Why is low pressure important? Because low pressure causes water surfaces to rise in what is known as an inverse barometer effect (see below)
Courtesy Naval Postgraduate Schoo.
But as in a late-night commercial: WAIT there’s More!
The passage of the trough caused winds to turn southwesterly (from the southwest) over Puget Sound, pushing water into Eliot Bay, Seattle’s harbor (see below). Even higher sea level!
You might ask how does the weather-related boost of the high tide compare to the steady increase observed over the past century.
Good question. Below is a plot of sea level over the past 120 years.A very steady increase with little sign of recent acceleration upward. The sea-level rise has been about 2.06 mm a year or 8 inches per century. So the weather-related enhancement of about 24 inches dwarfed the steady rise of sea level over the past century, some of which may be associated with global warming.
RE: Photo Caption “Near Alka Point that morning…” Did you mean ‘Alki Point’?
I live on the water In Nanaimo BC, so had first hand experience with the king tide last week. It was a big one but nothing as big as the one in Seattle. There was some coastal flooding to the north of us, mainly due to the high tide and high onshore wind. It was high enough so that the cross bars on the pilings on our dock were in reach, I’m 5″7″. The fellow that runs the charter business here was checking the boats and managed to bang his head pretty good on one of them. Of course, the local loonies were all about sea level rise. I commented that the annual sea level rise was virtually unnoticeable which set off the usual hornet’s nest. The high tide here runs somewhere between 4 to 5 metres and if you can notice 2 mm in that spread good on yah.
Relative sea level has gone down in Nanaimo due tectonic uplift.
I know that the USGS has at times adjusted the standard for what is “0” feet above sea level for elevations.
Are such adjustments effecting the reported rise is sea levels?
While SLR will be need to be dealt with, and can be. To my point of view we do not want to see sea levels dropping. Not significantly at least.
Not in the lifetime of any individual living today but the current cycle of glaciation began 400 years ago. Glaciation should be apparent by the end of the current millennium as more snowfall fails to melt each year.
Without intervention, ocean level will drop about 20m in the current precession cycle over the next 10,000years before stabilising near that level for the next 10kyr then continuing down.
Humans could probably intervene by dusting snow to make certain it melts when the sun hits it each June.
“Without intervention, ocean level will drop about 20m in the current precession cycle over the next 10,000years before stabilising near that level for the next 10kyr then continuing down.”
What possible intervention would prevent this from happening?
Dusting the snow with soot (black carbon). This causes the snow to absorb warmth from the sun, not reflect it away. This warming snow melts faster. I would imagine, it doesn’t matter much in the southern edge of the snow pack, it matters where the snow pack might never melt at all during the summer months.
Deleted: ooops, I was wrong!
Good post. The king tides that sometimes ‘flood’ some Miami Beach streets (to a depth of 6 inches) usually have similar weather rather than climate related origins, except Miami Beach is also subsiding as it’s fill compacts. Ditto for Las Olas Isles in Fort Lauderdale.
I photograph nature along the coast from Biddeford, Maine, along coastal New Hampshire and to Plum Island, Massachusetts. Generally speaking, high tides on the new moon, with the moon centered between the earth and the sun, at the closest point of the earth to the sun, will produce the highest high tides. This was the case January 3-4, 2022, along the road from Newburyport to Plum Island.and in the salt marshes near the Merrimack river. I am not sure that air pressure, as discussed in these comments, has any meaniful effect short of the impact of gales and hurricanes.
On the Texas coast with astronomical tides the same order of magnitude as this increase (~2feet) we get these fairly often. What is really impressive are high pressures during severe freezes leaving boats dry, rarely up to a meter. Contrary to informed opinion still occur.
So very bogus – look at the NOAA tide guage for Port Townsend IF you really want to know what is happening re sea levels !
Hard to believe a 1/2 psi change can raise water levels 2ft.
Makes me appreciate the power of hurricanes more.
According to this website, 0.5 psi is the equivalent to 13.84 inches of water.
More gas & water vapour in the column of air above you would normally increase air pressure at ground level. I would expect global warming associated with GHG emissions to lead to an increase of global mean air pressure. Maybe the extra pressure elsewhere temporarily pushed more water to the northwest at that time but this doesn’t mean rising global MSL.
Let’s not get confused between weather, climate & climate models.
Molecular weight of nitrogen N2 = 28
Molecular weight of oxygen O2 = 32
Molecular weight of H2O = 18
Water vapour is lighter than dry air.
CO2is heavier than air but is only present as 0.04% by volume of the atmosphere
A critical property of water that is key to developing convective potential in an atmospheric column. The main reason why open ocean surface temperature can never exceed 30C over an annual cycle.
Must be caused by climate change 🤪
Of course, everything is caused by climate change.
Dr. Mass ==> As you know, it is not unusual for NOAA’s Tides and Currents to fail to predict the tides precisely. While the Earth’s tidal ‘system’ is well understood and predictable in a general sense far into the future, precise prediction is not really possible.
It is the other contributions to the tides, other than the Moon etc, that cause this disconnect.
Air pressure is one of the largest of these, but there are other factors as well, like wind direction, slight variations in ocean currents, tec.
Global insolation has been declining since 1585. That was the last year perihelion occurred before the austral summer solstice.
The decline in global insolation is the result of a reduction in the Southern Hemisphere insolation being greater than the increase in the Northern Hemisphere insolation. With water dominating the Southern Hemisphere, the insolation over oceans has declined since 1585. That slows down net evaporation and lowers ocean upwelling meaning the oceans are retaining more heat. In other words oceans are warming up as the insolation over them reduces.
There are four factors contributing to sea level rise now:
It is worth mentioning that none involve CO2.
The atmospheric pressure change from 102.5 kPa to 99 kPa (hPa is an unconventional unit but then again, I like mmHg) produces an uplift of the water of 14 inches.
King tide plus storm surge.
Reminds me of Big Wind Sandy in NYC.
We had a similar event here in Newcastle the other day with the impact of the cyclone to the north and sun and moon being just right for king tides.
Was the shortest trip to carry the kayaks to the waters edge in ages!
From the article: “So the weather-related enhancement of about 24 inches dwarfed the steady rise of sea level over the past century, some of which may be associated with global warming.”
Was that really necessary? You could have left this speculation out of your article as this kind of speculation adds nothing to the article. I don’t understand it.
Remember that Cliff has been criticized, and suffered personal and professional attacks, for his weather observations because he didn’t adopt the reflexive “it’s-all-due-to-climate-change” for whatever happened. His reference to “some of which may be associated with global warming” should be read in that context, with an emphasis on the “may”.
My belief, which perhaps Cliff shares, is that greenhouse gases may contribute some small amount to global warming. That’s a matter for better minds than mine to debate the physics of. I really don’t care, because I can see for myself that increases in temperature can’t all be due to GHG’s; that the overall temperature increases are trivial and taking place over long periods of time; that warmer weather is overall a benefit, not a danger; and that mitigation of any effects is far preferable to killing economies by reducing fossil fuels.
When we insist on intellectual purity or group think, we lose a lot of potential allies who might sign on with the most important things we all agree on, but be excluded because they differ on on insignificant matters. We need all the allies we can muster.
How does 1 local area have the water rise whil islands in Pacific have the sea receding and more land being the result? At a recent climate conference they took pictures and the sea was marked at the same points as a 1921 photo. No change in tides.
Some years ago I was talking to a teacher friend and her 6 year old nephew. I was quite surprised by how well he reasoned using all the facts he knew. His reasoning was faultless but he did not realized he was missing some key facts so his conclusion was in error.
This is well illustrated by Cliff Mass who looked for the missing scientific facts to explain the unsually high water levels in Seattle. Climate alarmists, who believe they are following the science, would deduce that these are due to global warming. If they factor in the missing scientific facts, they will see their argument is flawed. If honest they will change their views but if ideological they will fight against admitting they are in error.
As an aside – having lived for over two decades in three very different coastal areas – tides, storms and flooding are particularly fascinating. I especially love seeing a combination of a spring equinox high tide with a powerful storm. Seeing the forces of nature on display, should be a humbling experience and reminder that there is no way we can control these as do those who think that we can engineer climate. That is the height of human arrogance.
Seattle is in Puget Sound where the sea level is affected by all the inflowing rivers etc. The closest open ocean station is Neah Bay – which displays a completely different sea level trend due to isostatic rebound as shown in the attached image.
Is the Seattle tide gauge connected to an altimetric GPS beacon ?
The relative 2.06 mm/year actual level rise in Seattle should, in my opinion, be corrected with a slight local ground subsidence of 0.5 mm/year since the average of many GPS-corrected tide gauges throughout the world is about 1,5 mm, not 2 mm.