During the past few days, a very strong inversion has formed in the lowest few thousand feet.
So strong that I call it a SuperInversion.
A SuperInversion is characterized by an increase in the vertical of more than 20°F in 2000 ft or less.
Consider the situation at Mount Washington, near I-90 and above Chester Morse Lake. 56F at the top and lower to mid-30s at the base. Several hikers emailed me today about spring-like temperatures on top of local peaks.
The cool low-level air was associated with dense fog, which developed overnight as the Earth emitted infrared radiation to space. Let me show you remarkable images from the Seattle PanoCam on top of the Seattle SpaceNeedle.
Yesterday (Tuesday) at 4 PM, the skies had cleared in Seattle.
With the sun down, the Earth's surface cooled by emitting infrared radiation to space. The air was cooled to saturation (100% relative humidity) and fog and low clouds were evident by 8 PM.
And then was higher than the Space Needle
Homes in the hills above Bellevue, roughly above 1000 ft, were just above the fog, as shown by the picture below.
Picture courtesy of Kristi Benda.
The inversion was so strong that it acted as a lens producing a superior mirage in which objects and clouds are shifted higher in the sky and distorted (see below, purple arrows show the mirage. It isn't really there!).
Picture courtesy of Peter Benda
Tomorrow morning will be a repeat.
But the days of the SuperInversion and low-level clouds are numbered. A fairly strong cold front will move through on Saturday (see surface map for 1 AM on Saturday, blue line is the front). The strong low-level winds will result in mixing that will scour out the low-level cool air and remove the warmer air aloft.
Inversion over. I will miss it.
We are at 1100'. And the last hour the temp. went from 34 to 44
ReplyDeleteCliff, the fog and stratus here in central Washington has persisted for 10 days now. Hoping this next system actually scours the entire Columbia Basin.
ReplyDeleteAt Mission Ridge it is currently 18 degrees at the lodge and 41 degrees at the summit.
ReplyDeleteIt's made for decent cycling mornings.
ReplyDeleteExcept if, like me, you want daylight to ride both to work and home from work, you are out of luck until at least late February. It just isn't safe in the dark.
DeleteQuestion about fog droplet size... 12/4 at 10pm in low hills west of Bremerton I observed floating particles in the dense fog only visible in a flashlight beam. The closest PWS read 34 F and dewpoint of 33 F. About 160' uphill and 0.3 mi S of oyster bay -- easy to spot because we have an indoor purple air, only one around there.
ReplyDeleteIt seemed a bit too warm for ice fog and wrong conditions, but I don't think I've ever seen such large fog droplets. They sure did look like a fine snow if not quite needles, and my wife thought it was snowing.
In Puyallup and the fog was here this morning but gone before 10AM. Looking at mostly blue skies at 11 here. Yesterday it didn't lift at all.
ReplyDeleteI've found it at least slightly intriguing watching the thermometer in my car as I drive home. I think it was Tuesday night, I saw it climb 2 degrees going up a maybe 50 foot total rise in the freeway, and then drop 4 degrees going down about 200 feet. Last night the same effect occurred, although not as dramatic.
ReplyDeleteDefinitely more significant than the usual 3 degrees per 1000 feet estimate, and of course, inverted.
The BPA balance chart shows almost zero wind for the region for a week. The fossil/biomass has been almost steady and Nuclear has not had even a small dip. Wind facility investors will be thrilled to feel that cold front greet them on Saturday.
ReplyDeleteNow, Friday afternoon in lovely S. Everett, I can see-finally-that the trees in my neighborhood are beginning to gently sway a little...this is the beginning of the end for that inversion! That is good, as the stagnant air quality was beginning to deteriorate!
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