PHILADELPHIA (WPVI) -- Dense fog is creating poor visibility for drivers Thursday morning - and then there's the rain.
If driving in the fog, the National Weather Service says to slow down, use your headlights and leave plenty of distance ahead of you.
This is all foreshadows more treacherous conditions to come.
AccuWeather is forecasting the likelihood of icy conditions on Friday. So, officials from PennDOT are urging people to prepare for a mess on the roads.
Tony Goreski, Pennsylvania Department of Transportation's senior highway safety manager for Delaware County, said brining the roads ahead of a forecasted freezing rain event is a waste of time.
"All that material that we once had when it started as rain will be diluted and washed off. You are dealing with a completely clean slate on the highway. So, brining would not be in answer to this," he said.
What road crews do instead is wait for the best moment after the freezing rain begins to start spreading salt and sand.
A computerized device called a road temperature gauge helps a lot. Those devices are employed on most of PennDOT's big plow trucks.
Goreski said the device comes in really handy when temperatures take a quick and steep dip.
"When a flash freeze occurs you could have a temperature drop into the upper 20s very quickly. When that starts to happen our truck basically will get the heads up, hopefully, they are deployed where they should be on standby. When that does happen we immediately start to deploy material on the highway," he said.
RELATED: How to make a Winter Weather Emergency Kit for your car and yourself
Meanwhile, if your plans have you traveling this coming Friday, AAA recommends packing a winter vehicle emergency kit complete with jumper cables, a flashlight, a first aid kit, wiper fluid, and blankets just in case.
"If you or anyone else you travel with takes medication on a regular basis or eats a special diet, infants, toddlers, seniors, make sure you have at least a day or two worth of those medication doses and any special food or dietary needs," said AAA Spokesperson Jana Tidwell.