SAN DIEGO — California Highway Patrol is encouraging San Diegans to stay off the roadways Sunday as Hilary arrives in the region.

Unless you absolutely must, CHP has advised drivers to avoid traveling in what’s expected to be rainy and windy conditions.

“We have sediment on the roadway. It’s pretty slick right now, so it makes for very dangerous situations,” said CHP Sgt. Brian Pennings.

This is especially true for mountains, deserts and the coastal foothills where high winds are expected.

“We have a unique situation in San Diego. There’s several locations in our mountains that act as a funnel in some of these valleys, and they go directly across Interstate 8 and they funnel the winds,” Sgt. Pennings explained. “Sometimes, we have big rigs blow over. It can be very dangerous.”

Some places where he says these big rigs tend to tip over include places like Pine Valley, Descanso and Crestwood.

For those who do need to travel, CHP says the main tips they can offer is to simply “slow down” and “back off.”

“You have to maintain a huge following distance between you and the vehicles in front of you, but probably the most important out of all of them is maintain a high visual horizon,” said Sgt. Pennings. “You look as far down the road as you can possibly see so you can perceive and react to possible flooding, hazards, brake lights, other vehicles changing lanes so you can be prepared.”

More tips on driving in heavy rain conditions can be found here.

Hilary — which was downgraded to a tropical storm Sunday morning — is still forecast to bring heavy rain to the region, according to the National Weather Service.