Here is a wonderful picture from Stephen Van Dyck that was taken at Poo Poo Point (1820 ft) on Tiger Mt. yesterday afternoon a 4 PM. The same view will be available today. Hiking through a sharp inversion is a real treat. If you don't like hiking, drive up to the top of Cougar Mt. Park and bask in the sun.
The inversion is lower and stronger this morning. The first graphic below is the vertical sounding at Quillayute on the coast based on a balloon-carried instrument package (radiosonde). Temps (red) in C and heights in pressure (850 is about 5000 ft, 700 about 10000 ft) Very strong surface-based inversion. The blue dashed is the dewpoint...air is saturated near the surface but VERY dry aloft.
Next, I have the Seattle temperature aloft...the inversion is very strong, with the base now below 400 m (1300 ft).
The surface temperatures at 6 AM are plotted in the next figure. Big variations...from the mid-30s in the coldest locations to 55F up in the mountains. Want to warm up?...go up Keep in mind..if you are driving in fog and the temps are in the mid to lower 30s, be very careful! Black ice on the roadway is a real possibility.
Finally, air quality has held up until now, but a few locations (e.g., Olympia and South Park) have slipped into moderate...look at the latest air quality map from Puget Sound Clean Air Agency I have include.
