TONIGHT: Clouds build and overnight, rain arrives as the coastal storm we've been discussing for the last several days finally arrives. The low: 41.
WARNING: The National Weather Service has issued a WINTER STORM WARNING Saturday into Saturday evening for Chester, Montgomery and Bucks counties and all areas north.
SATURDAY: Our coastal storm moves north from the Carolinas, bringing rain to most areas by dawn. As this occasionally heavy rain pulls down cold air to the surface, we expect the rain to change to and mix with heavy, wet snow, beginning in places like the Poconos, Lehigh Valley and Berks County during the afternoon.
The Poconos could actually see mainly wet snow all day, with the Lehigh Valley not changing over until later in the day. The rain then changes over to snow around Philadelphia on Saturday evening. Even parts of Southern New Jersey and Delaware could see snow flakes toward the end of the storm.
As for accumulation, the Poconos and Lehigh Valley could see as much as 3-6" and while most of this will end up on grassy surfaces and tree branches, roads could become slushy, especially later in the day and evening.
Farther south across Bucks, Montgomery, Chester and Mercer counties, we expect 1-3", mainly on grassy surfaces. A coating to 1" is possible in the I-95 corridor and even into parts of South Jersey and Delaware.
Our relatively warm ground and high sun angle should help keep roads just wet in areas outside of the 3-6" accumulation zone, which is what we'd generally expect in October (early in the cold weather season).
Having said that, every cold weather storm is its own animal with its own particulars. If you have travel plans on Saturday and Saturday night, it will be wise to keep a close eye on road conditions and react smartly if roads become slick and slushy unexpectedly.
It's wet or white all day, by the way, with a high of 42 early in the day and temperatures sliding into the 30s during the afternoon in Philadelphia.
TREE ISSUE: Where the snow is heavy enough, its weight could bring down tree branches and power lines.
WHEN DOES IT END? The precipitation will not end until between midnight and 3am in most spots.
SUNDAY: The second half of the weekend will feature lots of sunshine with temperatures staying on the cool side. The high is 47, which is roughly the game time temperature for the 5pm Union play-off game at PPL Park in Chester against Houston. It will be in the low to mid 40s by the time the Eagles take the field Sunday night at Lincoln Financial Field for their big showdown with the Cowboys. Both games will be chilly but dry.
MONDAY: Halloween looks like a treat rather than a trick with partly sunny skies and a high of 51. Trick or treaters will need to dress warmly as they head out in the evening, but at least it will be dry. Winds should also be relative light.
TUESDAY: Another round of clouds and sun is probable with a shower around. The high: 55.
WEDNESDAY: Assuming the latest long-range prognosis is correct, we turn back to mostly sunny skies and dry conditions with a high of 57.
THURSDAY: Another round of rain is possible. The high: 60.
FRIDAY: It's partly sunny with a high of 58 the way it looks now, but to tell you the truth, the long-range model timing of these end-of-period fronts has been very changeable, and more adjustments are likely coming.