12:45 PM | **”It ain’t over till it’s over”…late week and weekend snow threats as winter plans a comeback**
Paul Dorian
06Z GEFS 850 mb temperature anomalies for early Saturday with a frontal boundary zone (black line) providing a pathway for low pressure systems; courtesy tropicaltidbits.com, NOAA/EMC
Overview
“It ain’t over till it’s over”. Winter is not over yet and there may be at least a couple of chances for accumulating snow in the Mid-Atlantic region later this week and during the upcoming weekend. One of the keys to this unfolding scenario will be a frontal boundary zone that is likely to set up to the south of the Mid-Atlantic region and this will act as a pathway for low pressure systems to ride along. At the same time, strong Arctic high pressure will set up to our north and northwest and this potential combination could lead to an impressive comeback for winter.
12Z GFS forecast map for early Friday with snow in blue, rain in green; courtesy tropicaltidbits.com, NOAA/EMC
Details
The next couple of days will see much milder conditions push back into the Mid-Atlantic region as high pressure pushes off the east coast allowing for low-level southwesterly winds to develop around here. Showers are likely to accompany this warm up later tonight, tomorrow and tomorrow night and temperatures could reach 60+ degrees for highs in much of the I-95 corridor during the next couple of days.
After that, however, dramatic temperature changes will begin to unfold as a cold frontal system slides through the area and then sets up shop to the south of here. This frontal boundary zone will act as a conduit in subsequent days for low pressure systems to ride along at the same time Arctic high pressure builds to our north and northwest – this is a potential wintry combination.
12Z GFS forecast map for early Sunday with snow in blue, rain in green; courtesy tropicaltidbits.com, NOAA/EMC
The first wave of low pressure that could impact the Mid-Atlantic region is likely to ride along the frontal boundary zone and arrive in the Thursday night/early Friday time period. This system will not be all that strong and it will have only marginally cold air to work with. As a result, the precipitation could be more wet than white; especially, in areas south of the PA/MD border. Nonetheless, there is the chance for some snow accumulation and it is possible that a narrow band of pretty impressive accumulation sets up somewhere in the Mid-Atlantic region. Many details still have to be ironed out including exactly where this potential heavier snow band could set up and what proportion of the event would be snow versus rain.
12Z Euro snowfall map for the weekend storm
Over the weekend, there is potential for a stronger storm to trek eastward from the Central Plains and it would likely have colder air to work with when it arrives in the Mid-Atlantic region as strong high pressure will build into SE Canada following the first system. As a result, snow is more than likely to be the main precipitation type with this potential weekend system – even down into the DC metro region – and it could become a significant snow event. However, the track is not yet set in stone and there is always a chance that this system gets suppressed to the south which would lessen chances for significant snow in at least the northern Mid-Atlantic.
Meteorologist Paul Dorian
Vencore, Inc.
vencoreweather.com