As the U.S. prepares to take on another bout of cold weather, the term "polar vortex" is getting thrown around. But what is it?

A sharp temperature drop arrives this weekend, but will there be any wintry precipitation? Here's what we know and don't know.

Experts say the safe amount of time outdoors depends on the dog's size and breed, but when the temperature drops below 20 degrees, all dogs are at risk of hypothermia. Owners are advised to keep walks short and monitor their pet's behavior.

Following a weekend storm, temperatures are expected to drop in the Philadelphia region, with wind chills expected to hit temps below zero on Tuesday.

After a chilly Tuesday, southwest winds will warm temperatures into the 40s on Wednesday and into the 50s on Thursday. Another blast of colder air will begin to move in late Friday, triggering a few rain showers on Friday before temperatures turn significantly colder on Saturday.

Temperatures moderate then plunge to single digits before snow begins, with 60-90% probability of 6 or more inches across the region and potential travel disruptions Sunday into Monday.