Foggy Tuesday kept CHP busy with crashes, and more mist is coming

Fog hovers over Tullock Lake after rolling in from the valley as the sun sets at the reservoir Tuesday.
Fog hovers over Tullock Lake after rolling in from the valley as the sun sets at the reservoir Tuesday. Modesto Bee

Fog kept Highway Patrol and other law enforcement officers busy with crashes along Northern San Joaquin Valley highways Tuesday morning, and forecasters predicted more murky weather this morning.

According to the National Weather Service, patchy fog is expected before 10 a.m. today in the Modesto area. Other areas of the valley can expect the same.

Clear morning weather is forecast Thursday and Friday, but foggy mornings should return to the region Saturday and stick around through early next week.

The California Highway Patrol sent out a clear message to morning commuters:

Reduce your speed.

Turn on your low-beam headlights.

Leave home earlier.

Keep both hands on the wheel and eyes on the road.

"One hundred percent of your attention should be on your driving," said officer Tom Killian, a spokesman for the CHP's Modesto-area office.

Tuesday from 5 to 11:30 a.m., the CHP responded to nine crashes. Six of those occurred from 6:52 to 9 a.m., Killian said. Two crashes resulted in minor injuries and seven were noninjury crashes.

About 4 a.m. on Highway 99 near the south end of the county, CHP officers in patrol units conducted "round-robins," in which officers drift back and forth across traffic lanes with emergency lights on to slow traffic.

Officers use round-robins when a major crash is ahead or on highways when visibility drops to less than 500 feet.

Killian said the CHP can't use these maneuvers if all available officers are busy responding to crashes.

He said drivers Tuesday were not reducing their speed to adjust to the low visibility, and some of them were driving without their headlights on.

"They think everything is OK because they can see out their windows," Killian said. "The headlights are there for everyone else, so they can see you."

The fog also affected other forms of travel. At least one flight from Modesto to San Francisco was delayed because of the fog, according to the Federal Aviation Administration.

Bee staff writer Rosalio Ahumada can be reached at rahumada@modbee.com or 578-2394.

Safety Tips
  • Drive with lights on low beam. Never drive with just your parking or fog lights.
  • Reduce your speed.
  • Avoid crossing traffic unless absolutely necessary.
  • Listen for traffic you cannot see.
  • Use wipers and defroster as necessary for maximum vision.
  • Be patient! Don't pass lines of traffic.
  • Don't stop on any freeway or other heavily traveled road unless absolutely necessary.
  • Consider postponing your trip until the fog clears.
  • Tips For Pedestrians And Bicyclists
    • Wear bright clothing.
  • Bikes should have lights and reflectors.
  • Cross streets at intersections where traffic lights are present.
  • Be aware that drivers may have difficulty seeing you.
  • How Fast Is Too Fast?
    Safe auto speeds for reduced visibility
     Visibility Speed 
     300 feet 56 mph 
     250 feet 50 mph 
     200 feet 43 mph 
     150 feet 36 mph 
     100 feet 27 mph 
     50 feet 16 mph 
     20 feet 8 mph 
    About Fog

    The color of the day in winter in the Northern San Joaquin Valley is often gray and can last for days on end. The fog contributes to vehicle accidents - some of which become major pileups - and is known to delay the start of school because it is too dangerous for students to walk or be bused through the soupy weather.

    • Fog is formed when cool air can no longer hold any more water vapor. Rapid cooling of air over warm ground causes the vapor to form tiny water droplets that become suspended in the air.
  • Foggy weather usually runs from mid-November to the first week of February in the valley, according to the National Weather Service.
  • The National Weather Service classifies fog as "dense" when visibility falls to less than 55 yards.
  • In 1998, the state Department of Transportation implemented the Caltrans Advance Warning System (CAWS), a series of electronic billboards, to warn drivers of congested traffic and bad weather ahead on the highways. Messages such as "Foggy Conditions Ahead," "Dense Fog Ahead" and "Caution Slow Traffic Ahead" give drivers a chance to slow down and avoid accidents
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