Sunday, November 19, 2006

Tule Fog Is Back!

Here is a great representation of Tule Fog. It comes every year. The last few years it has been mild. But it seems to have come early this year.

For those of you who don't know Tule Fog is a thick ground fog that settles in the San Joaquin Valley and Sacramento Valley areas of California's Great Central Valley. Tule fog forms during the late fall and winter (California's rainy season) after the first significant rainfall. The official time frame for tule fog to form is from November 1 to March 31. This phenomenon is named after the tule grass wetlands (tulares) of the Central Valley. Accidents caused by the tule fog are the leading cause of weather-related casualties in California.

There is not much one can see in tule fog. Visibility is usually less than an eighth of a mile (about 600 feet), but can be less than 10 feet. Visibility can vary rapidly; in only a few feet visibility can go from 10 feet to near zero. Satellite and overhead photos of the San Joaquin Valley show the fog where agriculture and cities like Fresno or Sacramento can be seen. The variability in visibility is the cause of many chain-reaction pile-ups on roads and freeways. In one such accident on Interstate 5 near Elk Grove south of Sacramento, 25 cars and 12 big-rig trucks collided inside a fog bank in December 1997. Five people died and 28 were injured. In February 2002, two people were killed in a 80-plus car pile-up on California State Route 99 in Selma. The visibility at the time of the accident was zero.

Now that you have a little understanding of our fog season I wanted to add how very much I love the foggy season. This was not always the case. I was so afraid when the children would drive to High School. (Their high school was in Visalia and we lived in Hanford about 30 miles away....these were 30 miles of back streets, tractors, cows, and just about anything else). I was so worried about accidents. Every year teenage children are killed in car accidents. Especially during fog season. But now that my kids are grown and off on their own, I must confess I really love walking Momo on a foggy night. You come in feeling like you are in some London novel. Hair is drenched in mist. It is so quiet you can hardly hear yourself walk. There is a lovely hush all over the world. Even the train whistle is muted! I have a
! on my computer as I type, it is letting me know there is a severe weather alert here in Hanford. I am so glad I am inside. Good thing too since the visibility is down to "O". So if you ever drive this way be sure to consider the fog. It is our winter friend, but can be deadly if not respected.


Geno said...

i also love fog season. i wish it was always foggy. kelly says that's what england is like. fog and rain.

i didn't know some of those things about tule fog. nice.

love you

Marti said...

Thanks for the tule fog lesson. Who knew?
I'm still jealous because that means it's cool there. It was 92 here today.
Bring some of that coolness when you come down next week. Oh wait. you can't help it - you're cool wherever you go. =D