Friday Technical Discussion

Synopsis:

Some light snow on Friday will signal the ends of the Arctic air mass that has been sitting over the state this week.  Behind the snow we will have a shot of cool air for the weekend, but will stay warmer than the past few days. Another stronger system will approach the state on Monday and bring a wintry mix before changing over to plain rain.

 

Short Term (Fri-Sun):

A clipper system is phasing with a southern piece of energy to provide a light to moderate snowfall to much of the mid-Atlantic region. Precipitation is moving in faster today than the models had predicted. Most models expect precipitation to begin around noon in western Pennsylvania, but as of 10:00AM snow is moving into the state.  So snow should begin 2-3 hours earlier than previously expected. Banding will move into southwestern Pennsylvania, leading to a moderate snowfall in that region. Areas of southern Pennsylvania near the Mason-Dixon Line may also see some moderate snow as a vorticity maximum swings along the PA-MD border later this afternoon. Total accumulations are expected to be 2-4" across the state with lesser amounts in the northeast and higher in the southwest where 4-6" is possible in higher elevations. A weak cold front will push through behind the snowfall with a reinforcing shot of cool air. This air will not be as cold as this past week, but will keep temperatures in the 20's for Saturday and Sunday statewide. A strong high pressure system at 1034mb will move in for the weekend leading to sunny skies Saturday and Sunday.

 

Long Term (Mon-Tue)

Models show a system moving up from the south on Monday into the cold air in the mid-Atlantic. This will lead to a CAD situation with many areas of the state seeing precipitation starting as snow, sleet, or freezing rain. As the system continues to push north, it will bring up some warmer air from the south that will eventually overtake the cold air damming and change precipitation over to rain. The southerly flow from this system will bring much warmer air for early next week and by Tuesday some areas may find themselves in the upper 50's.