Adam Joseph 6abc around 6pm on Facebook a couple hours ago:
POST CHRISTMAS STORM
First off, thankfully Christmas Eve & Christmas Day will be quiet! Santa will have some strong winds helping him make the rounds, and only a few sprinkles are expected near lunch on Christmas Day. Highs both days in the middle 40s.
Now, to Friday!!! A piece of the nasty storm in California will break off and head across the country setting its eyes on the Mid Atlantic for Friday afternoon and night. The issue will be a large area of Artic High pressure in southern Canada. This will send down very cold air from the surface to thousands of feet up. Cold air is dense and heavy so it will be locked in as the storm arrives. The issue then becomes warm air trying to move in in the upper atmosphere as the storm ramps up. Warm air is light and buoyant, so it wants to settle where the precip forms in the storm in this kind of setup. Precip cannot turn to snow after it forms if the air temp is above freezing, so this is crucial in a mixed storm. Depending on the column of air temps from the layer where precip begins, to the ground will supply either rain (above freezing at all levels), freezing rain (shallow cold at only at surface), sleet (deep cold layer under the precip formation zone), and snow (below freezing at all levels). Our area will see all this mess.....the question this far out is where those areas set up. I do not see much rain with this system right now....more snow, sleet, and freezing rain. Some areas will see over 3" of snow!
I will be off enjoying two days with my family and will be back to guide you through it all on Friday. Please tune it to Payton and Brittany for the latest. Just wanted to give you a heads up and my current thinking. Right now, this is our thinking and it will be fined tuned the next two days. Please share this in case people are not watching or on social at this time:
TIMING: snow for all mid to late afternoon Friday
HEAVIEST: falls near dark Friday through Midnight
CHANGEOVER: Snow flips to ice in much of the area starting Friday evening.
ALL SNOW: looks to be north of the PA Turnpike with less mixing with ice.
AVOID TRAVELING: late Friday afternoon into Saturday morning.