Horst:
Monday, January 14, 2019:
The second half of January may be a wild ride, both in terms of storms and temperatures. While generally colder than recent weeks, I can still see a mild day every now and then...thus, making precipitation type a tricky matter as a parade of storms move by. I expect we'll see a system of import pass by here every 3 or 4 days--this will make for lots of heavy lifting for meteorologists as there could be up to four storm threats before month's end.
Short term, Monday through Thursday morning will be quiet with seasonable temperatures and no precipitation. Then comes system #1 (a fast-moving clipper) on Thursday afternoon and night with a 6- to 10-hour period of snow changing to wintry mix...ending as drizzle. South of the Turnpike this type of system typically yields a coating to an inch or two, whereas central PA and the mountains could get 2 to 4 inches. Of course, those are "typical numbers" for a system like this--check back here Tuesday for me to issue my actual forecast for Thursday night's clipper system.
A shallow shot of cold air will slice in on Friday, behind the exiting clipper. Meanwhile storm #2 will be gathering in Texarkana...and this system will race our way with abundant Gulf moisture in tow. Precip should arrive here (as snow) Saturday afternoon, however, a change to wintry mix or perhaps even rain seems more likely than not Saturday night into Sunday morning. Of course, the storm is still 5+ days away...and it's much too early to lock in the details. But with very little downstream blocking, I expect the shallow cold air will retreat from southern PA and, thus, the inland track with a changeover is the more likely outcome. (Snow lovers can hold out hope of a more eastern/colder track for a couple more days--the critical disturbance won't even come into the US west coast until Thursday AM.) Another possibility...is the storm will begin as snow, then change to rain Saturday night, then end as a period of snow midday Sunday, as Arctic air gets drawn into the back end of the exiting storm. Realistically, however, it will be Thursday until this storm can be dialed in--check back then!
Beyond that, a windy/cold Monday will follow...and next Monday night could be the coldest of the year so far if high pressure builds in over fresh snow cover. But again, without downstream blocking to hold in the cold air, milder air will return our way just as storm #3 approaches sometime in the Wednesday PM to Friday PM time frame. We're now talking 10 days in the future--so this can all change--but I can see this becoming another changeover storm for the Lancaster area.
Summing: I rather storm period is developing with above-average precipitation likely for the second half of January. But if you want all snow from these next three storms, then move to Bradford PA...because here in Lancaster all three systems may involved a changeover. This will make for challenging forecasts...and sleep deprivation...for this guy! (grin)