By Justin Drabick
PHILADELPHIA (CBS) – A large area of high pressure currently over the region will lock in a cold air mass for the rest of the weekend. This will set the stage for a mix of snow, sleet and freezing rain as moisture from the deep south moves into the Delaware Valley on Sunday.
As a disturbance moves out of the southern U.S. on Sunday, light snow will begin to develop early to mid afternoon across the Delaware Valley from south to north. The timing will depend on how long the dry air can remain in place. High temperatures on Sunday will range in the low to mid 30s. Milder air will begin to surge northward during the evening and begin to change the snow over to sleet and then eventually all rain by late Sunday night. The transaction of precipitation will occur from south to north.
Some freezing rain is possible late Sunday night for the Lehigh valley and Poconos as the cold air stays in place longer in those locations. By Monday morning, all areas except possibly the Poconos will have changed over to plain rain. Periods of rain will continue through the day on Monday with milder temperatures in the 40s.
Winter weather advisories have been hoisted for the North & West suburbs, Lehigh Valley and Poconos for Sunday PM through early Monday AM. Snow and sleet accumulations of a coating to 1″ are possible for Philly and the N&W suburbs and 1-2″ for the Lehigh Valley & Poconos. Some light ice accumulation of less than .10″ is possible for the Lehigh Valley and Poconos late Sunday night. Untreated surfaces will become slippery and travel will be slow late Sunday afternoon and night.