On Sunday night, our attention will turn to an area of low pressure moving along a frontal boundary. The system will not feature a strong center of low pressure, like a nor’easter, but rather an area of intense convergence caused by two air masses pressing into one another and low pressure that will move along the boundary.
Warm, subtropical air to the south will battle frigid air to the north over the weekend. The area of convergence between the warm air to our south and the arctic air to the north will be the track upon which an area of low pressure will develop Sunday into Monday. Areas to the north of the convergence zone will experience a moderate to heavy snow event, with areas to the south receiving a soaking rain. In the middle, a wide range of precipitation types is expected including rain, sleet, snow, and even freezing rain. A significant period of icy conditions can be expected in this zone.
Central Maryland, including Baltimore and Washington DC, looks to be in the convergence zone with light rain on Sunday night transitioning to sleet and then snow by Monday morning. The change from mixed precipitation to ice and snow will occur due to the low pressure reaching the coast, and the wind shifting to the north which will bring in colder air toward the center of low pressure. An accumulation of snow certainly appears likely in central Maryland with amounts ranging from 3 to 6 inches in Baltimore and Washington DC. Colder air to the north will ensure that places like Philadelphia receive a more significant accumulation of snow, although some sleet may mix in there as well. An accumulation of 6 to 9 inches is likely in Philadelphia.
This complex weather system will need to be monitored, for a shift of twenty or thirty miles will have a significant impact on our local weather. The temperature gradient on either side of the convergence zone will be stark with sub-freezing temperatures and snow only one hundred miles from temperatures in the 40s and 50s with rain. A shift to the north would bring more mixed precipitation and/or rain into Baltimore and Washington DC. A shift to the south could bring heavier snow into these cities.
By Monday evening, snow showers will begin to taper to flurries in the major cities with the exception of coastal Maryland and Delaware where snow will continue into the overnight hours.
Here are the specific forecasts for your location in the Middle Atlantic region:
NWS forecast for Philadelphia, PA
NWS forecast for Baltimore, MD
NWS forecast for Washington, DC
NWS forecast for Richmond, VA
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