Simply put, this week's weather will have us on a roller coaster. The recent spell of cold eases out for a couple of days before a second round of cold air pushes in after a soaking rain on Wednesday afternoon and evening.
We go from winter to soaker to winter within the course of a week. At least you can't argue that the weather pattern ahead is boring!
Monday's precipitation plethora is due to warm air pushing in aloft over the cold air in place at the surface. Temperatures will be slower to warm above freezing the farther north and west you are from the city, with the result being some periods of freezing rain or freezing drizzle that could lead to slippery travel for a time during the morning and early afternoon before temperatures creep above 32. That said, despite air temperatures above freezing, the ground is still cold after a week of subfreezing temperatures. This means it could take a while for the surface to thaw out a bit. The Poconos could see temperatures fail to get above freezing until late Monday night and could have a decent round of icy rain.
Tuesday is the transition to warmth ― areas of fog, drizzle and lots of low clouds around as temperatures hang in the upper 30s and low 40s for much of the day before we see a more substantive warmup Tuesday night into Wednesday. Wednesday's temperatures could hit 60 in a few spots ahead of the cold front as mild southwesterly breezes push the warm front through the region and give us a window of warmth. Of course, the front that pushes in on Wednesday afternoon and evening has a lot of pop to it and will produce a steady and soaking rain for the region. Many spots could see an inch, perhaps a bit more than that, which could cause flooding issues along area streams as the ground may remain frozen despite the thawing ahead of the likely rainstorm.
After the front moves through Wednesday night, it gets colder for the latter portion of the week. Snow showers are possible on Friday and again on Saturday night or Sunday with a pair of clipper disturbances tracking through. We could see similar light snowfalls along the lines of what fell this past Friday ― modest, but enough to whet the appetites of the snowstarved among you.
January's temperatures will likely close out above average but they will not be as mild as they had been through last Sunday. We've averaged twelve degrees below average from Tuesday through Saturday in Philadelphia – our longest streak of significant cold around here since February 2007, even though overnight lows didn't get below what we experienced a couple of Januaries ago. Despite this slap of cold, we were several degrees above average as recently as last Sunday and given our warmth to close out January, we'll likely end up with an above average month on temperatures. Just not as mild as December.