Inversion Fog

For the last 3 weeks, and forecasted for the next 2 weeks, we have been stuck in a weather pattern with inversion fog and cloudiness starting in the early morning hours.

Just above the golf course looking down on the valley

This a very unique weather pattern due to our situation down in a valley, or hole.  All around us are higher bluffs that are about 800 ft in elevation above the valley floor.  The nights are clear leading to a cooler temperature and frost forming overnight.  Then the sun is visible many mornings right away, but as the temperature raises and moisture comes off the ground and atmosphere, a very dense fog layer forms, just like a cloud cover.

A view from the valley floor below the fog layer

It is known as Tule fog and is primarily found in the Grand Central Valley area of California, but with our rivers running through the valley floor adding to the moisture content, it is also very popular in our valley from fall to spring. It is compounded by our higher relative humidity in our area and also causes temperature inversions at lower altitude.

Right now this weather pattern is impacting the golf course by allowing frost to form most mornings and then fog is trapping in the cooler air, blocking out the sunlight and prolonging our frost delays with some a cool damp cloudy feeling in the air.  Typically it burns off by midday and then we have the same pattern the next morning.

Tule fog typically forms below 2000 ft in elevation and can be seen from the top as you drive the surrounding area above the fog.  Here are a few more pictures from above the valley on the highway that heads out of town.