A persistent area of fog has spread over the central and southern Sound, and some of the pictures are stunning.
The 6 PM view from the Space Needle cam is simply beautiful, with some of the taller buildings extending above the murk. The lighting of the fog from below....
From the hills east of Seattle, the fog layer spread to the Olympics, with a beautiful sunset glow above.
Picture taken by Kristi Benda.
Not to be outdone, the image from space captured by the NASA Aqua satellite this morning was extraordinary, with fog and low stratus clouds constrained by local terrain.
Why so foggy?
Blame it on high pressure and clear skies aloft, which produce a strong inversion, in which temperature warms with height in the lower atmosphere.
Clear skies allow good radiational cooling of the surface, and high pressure aloft creates the clear skies and produces sinking air aloft, which warms the air by compression.
Want proof of the inversion? Below is a plot of the temperature change with height at 6 PM around SeaTac Airport.
Temperatures warm from the mid-30s near the surface to about 50°F around 2000 ft. That is a strong inversion! Inversions are associated with great stability, which means they suppress mixing of the air in the vertical. Good for keeping the fog in place!
Unfortunately, inversions have a major downside; they also keep pollutants in place, suppressing vertical mixing, which improves air quality near the surface.
Below are the current pollution levels (something called PM2.5), based on the PurpleAir network.
Moderate air quality at lower elevations (yellow colors) but far better at higher elevations (green colors).
This situation should continue tomorrow, but will dissipate on Friday.
Happy New Year!
What is it about the area in question that influences the development inversion-induced fog? Up in Western Whatcom County we aren't seeing much fog despite saturated (or nearly so) air and the presence of the strong temperature inversion.
ReplyDeleteThe winter of 1976-1977 had a similar though much more persistent western ridge/deep eastern trough or vortex over North America. For many days at a time, and recurring week after week, the PNW had monotonous foggy weather while lake-effect snows buried many Great Lakes shorelines and exceptional cold covered eastern parts of the continent. Even southern Florida had snow one day.
ReplyDeleteI'm getting tired of the west coast ridges recently -- atmospheric rivers & flooding, alternating with inversions as described above. The year is over and we've barely reached freezing in Seattle & vic.
ReplyDeleteYes and it looks like there's a possibility after around Jan 10, we will be under a huge ridge for many days. That's the amplified patterns that we are seeing more often. Deep lows and huge ridges stuck in place and atmospheric rivers with moisture being pulled up in the middle. Climate change may be a factor but whatever the cause, there are more pronounced and persistent extreme weather events and a "stuck" atmosphere at times. We've had enough rain, thats for sure, but now we need some mountain snow. In a La Nina year it shouldn't be a problem but it's been too warm so it's really not a typical LA Nina pattern, yet. It could be worse. Parts of Europe are too warm and have been rather dry. Some lower elevation ski resorts have no snow.
DeleteScott6...there is no evidence that the evidence that the atmosphere is more "stuck" today. Nor any evidence of more pronounced or extreme weather events...cliff
DeleteMr Mass is there any research that correlates inversions with long term droughts and global warming , asking for the times (Nails on chalkboard sound)
ReplyDeleteAmong the most significant December monthly temperature records set at sites within the NWS Seattle CWA include:
ReplyDeleteBremerton recorded a monthly mean temperature of 45F - its 2nd warmest December in 127 years of records and the warmest December since 1958.
Clearbrook recorded a monthly mean temperature of 42.3F - its 4rd warmest December in 123 years of records and the warmest December since 1950.
Diablo Dam recorded a monthly mean temperature of 39.4F - its warmest December on record, tied with December 1939, in 112 years of records
Everett recorded a monthly mean temperature of 45.1F - its 3d warmest December in 132 years of records and the warmest December since 1950.
Hoquiam recorded a monthly mean temperature of 46.2F - its 2nd warmest December in 73 years of records and the warmest December since 1976.
Longmire recorded a monthly mean temperature of 38F - its 3rd warmest December in 117 years of records and the warmest December since 1950.
Longview recorded a monthly mean temperature of 46.8F - its warmest December in 101 years of records and beating the previous record of 45.2F recorded in December 1950 by a margin of 1.6 degrees.
Mud Mountain Dam recorded a monthly mean temperature 43.4F - its 3rd warmest December in 87 years of records and warmest December since 2023.
Ross Lake recorded a monthly mean temperature of 37.8F - its 3rd warmest December in 66 years of records and the warmest December since 1989.
KSEA recorded a monthly mean temperature of 45.2F - its 3rd warmest December in 81 years of records and the warmest December since 2023.
Upper Baker Dam recorded a monthly mean temperature of 39.7F - its warmest December in 61 years of records and beating the previous record of 38.4F shared between the Decembers of 1966, 1980, and 2024 by a margin of 1.3 degrees.
Even more significant and extreme December temperature records were set at locations within the NWS Spokane and Pendleton CWAs. More to come...
Could this mean that there will be another 117 or more years now before we see another record?
DeleteDon't forget Juneau AK,at the opposite end of the temp/snowfall spectrum!
DeleteIce cold fog day in and day out. Difficult to tolerate after awhile. Need some warm sunshine.
ReplyDeleteThis content was exactly what I needed. Thanks a lot!
ReplyDeleteI love fog, not the easiest to drive in if not daylight. Had to drive in the stuff last week when heading into to work in the dark (leaving at 6AM roughly to get to Kent from Tacoma by 7AM), Coming home, not an issue as I'm in Tacoma by the time it begins to get dark, though with light traffic between Christmas and NY's means I'm in town by 4:15PM, which means still daylight for roughly another 15 minutes or so.
ReplyDeleteI love to walk in the thick pea soup. Driving can get semi tricky if super thick as I can't see the oncoming lights a block or 2 away. It's nice when the fog is higher up but the tree tops are are in the fog. Yes, that means cold, but that's how it is.
I recall in 1985, we had one of these inversions and the fog haze stayed around for most if not all day and I was working at Domino's here in town as a delivery driver. Oh to be 18 or so again... (60 now).