|A foggy morning in the Avenues|
Photo taken 7:20 AM MST 6 Dec 2012
|Looking southeast toward the Wasatch Mountains from the Avenues|
at 5:15 PM MST 5 Dec 2012 (click to enlarge)
The sounding from yesterday afternoon tells the story pretty well.
The surface temperature and dewpoint were 47ºF and 45ºF, respectively, which equates to a relative humidity of 93%. This is high enough for haze particles to form, but not high enough for those particles to grow into larger cloud droplets. Thus, clouds formed only in a few places at the top of the cold pool where there was just enough turbulence, lift, or moisture for the atmosphere to reach 100% relative humidity.
Above the cold pool, the relative humidity was lower and the air less polluted. The visibility in this layer, which extended to cloud base, was outstanding.
Overnight, fog and low clouds formed over the valley. These can be seen from the photo from the top of Snowbird, which is framed well by ice on the lens.
Don't worry, the inversion is weak. The fog will probably lift and dissipate today, and we should be further stirring things up the next couple of days as cooler air moves in.