The first wave of Arctic air has arrived in the Philadelphia region, but an even stronger blast will follow on Saturday morning.
The plummeting mercury plus strong winds out of the northwest will produce some dangerously cold wind chills, according to the National Weather Service, which has issued a wind chill advisory from 6 p.m. Saturday to 9 a.m. Sunday.
Less than a half inch of snow is possible across the area on Friday night, but forecasters said they are eyeing a winter storm that could bring "significant" snow early next week.
But first the bitter cold setup, beginning Saturday.
Temperatures will drop through the daytime with winds gusting at 40 to 50 mph. The low temperature on Saturday night will range from about 8 degrees at the Delaware Beaches to 12 below in the Poconos. The low in Philadelphia will be around 3 degrees.
Wind chills, however, will be much lower: from 10 below in South Jersey to 30-below in the Poconos, and about 12-below in the city.
Forecasters cautioned that wind chills that low are dangerous to people and their pets.
A Cold Blue weather emergency is in effect through 9 a.m. Monday in Montgomery County to alert residents that winter conditions pose a threat of serious harm or death to individuals without shelter.
In Camden County, officials have declared a Code Blue every day through Sunday from 6 p.m. until 7 a.m. the next morning.
Philadelphia health officials have a Code Blue in place until further notice.
People are encouraged to take precautions to stay warm for the duration of the cold snap.
Winds will decrease through Sunday as the sun returns, but temperatures will top out around 17. Northwest winds are expected in the 9-to-14-mph range, with gusts as high as 24 mph.
Beginning Monday night, a storm system could dump significant amounts of snow and lead to possible widespread icing due to freezing rain, the weather service said. As many as 3 inches of snow accumulation looks possible in some areas. But the rising temperature on Tuesday will likely see the precipitation turn to heavy rain that could cause flooding in areas with poor drainage. Some places could see as much as 2 inches of rain on Tuesday. Meteorologists are likely to fine-tune their forecasts over the weekend.
There is a small chance of southerly wind gusts to 50 mph Tuesday.
A high pressure system and drier, cooler air will move in behind the storm as it moves north.
Here is the forecast through Tuesday:
Tonight
Scattered snow showers, mainly before 4am. Mostly cloudy, with a low around 21. Southwest wind 5 to 15 mph becoming west after midnight. Winds could gust as high as 28 mph. Chance of precipitation is 30 percent. New snow accumulation of less than a half inch possible.
Saturday
A chance of flurries with isolated snow showers between 8am and noon. Partly sunny, with a temperature falling to around 14 by 5pm. Wind chill values as low as -6. Windy, with a northwest wind 23 to 30 mph, with gusts as high as 46 mph.
Saturday Night
Partly cloudy, with a low around 3. Wind chill values as low as -12. Blustery, with a northwest wind 16 to 20 mph, with gusts as high as 37 mph.
Sunday
Sunny, with a high near 17. Northwest wind 9 to 14 mph, with gusts as high as 24 mph.
Sunday Night
Mostly cloudy, with a low around 13.
Monday
A chance of snow before 3 p.m., then a chance of rain and snow. Mostly cloudy, with a high near 35. Chance of precipitation is 40 percent.
Monday Night
Snow likely. Cloudy, with a low around 31. Chance of precipitation is 70 percent.
Tuesday
Snow likely before 8 a.m., then rain and snow likely between 8 and 10 a.m., then rain likely after 10 a.m. Cloudy, with a high near 47. Chance of precipitation is 70 percent.
Tuesday Night
A chance of rain before 1 a.m., then a chance of rain and snow. Mostly cloudy, with a low around 33. Chance of precipitation is 40 percent.