Dangers & Annoyances
As thick as the proverbial pea soup, tule (too-lee) fog causes chain collisions each year on area roads. In 2007, more than 100 cars and big rigs collided on a stretch of Hwy 99. At its worst, these dense, immobile clouds can limit visibility up to a foot.
Tule fog, named after a marsh grass common here, is thickest from November to March, when cold mountain air settles on the warm valley floor and condenses. The fog burns off for a few afternoon hours, just long enough for the ground to warm again and perpetuate the cycle.
If you find yourself driving in fog, turn on your low beams, give other cars extra distance and maintain an easy, constant speed. Avoid passing.