2:15 PM | **Sunday night/Monday winter storm could produce significant snow across much of Pennsylvania and icing south of the PA/MD border**

Discussion

Overview One storm is hitting California today and a second and stronger system - currently still out over the Pacific Ocean - will hit that state from tomorrow into Saturday. Today’s storm will weaken as it crosses the country this weekend, but the second system will cause big problems in the Mid-Atlantic region on Sunday night and Monday. There is likely to be a dangerous combination early next week of brutally cold Arctic air slowly dropping southward into the Mid-Atlantic region at the same time copious amounts of moisture associated with the second California storm arrives here from our southwest. The result could be a major snowstorm across much of Pennsylvania and southern New York and significant ice and some snow is possible just south of the Pennsylvania/Maryland border including in the DC metro region.

Very preliminary details Precipitation should arrive in the Mid-Atlantic region on Sunday night and it may be in the form of rain or sleet for awhile, but as colder air filters in from the north, the precipitation is likely to change to all snow across much of Pennsylvania and southern New York and eventually to all snow south of the PA/MD border, but perhaps not until after an extended period of icing. Precipitation continues through the day on Monday and likely winds down Monday night or very early Tuesday. Brutally cold air will follow by mid-week in much of the eastern half of the nation.

Model comparisons The GFS computer forecast model has been predicting a relatively “colder’ solution for this upcoming event in recent model runs with more in the way of frozen precipitation across much of the Mid-Atlantic I-95 corridor whereas the European computer forecast model has been going back and forth between a “cold” and “warm” solution. Today, the Euro model has blinked and has now joined the GFS with a “colder” solution indicating more in the way of frozen precipitation for the Mid-Atlantic I-95 corridor and less in the way of plain rain. Stay tuned, this event is still days away, and the storm is not yet over the "data-rich" land mass of the western U.S. which can have an impact on computer model forecast output.

Short-term forecast on the Siberian express A “Siberian” cold front is currently plowing across central Pennsylvania and is causing snow showers and heavier snow squalls in the central mountains (e.g. near State College). Some of these snow showers - and perhaps even a heavier snow squall - will make it into the eastern part of Pennsylvania, New Jersey, southeastern New York later today along with gusty winds of up to 40 mph. Single digit temperatures can be expected for overnight lows in many locations along the I-95 corridor and brutally cold weather conditions will continue on Friday.