It’ll be mild again today in the Mid-Atlantic/Northeast US, but a cold front pushes through in the overnight hours leading to a much colder weather pattern for the upcoming week. In the wake of the cold frontal passage, strong high pressure will slowly build into the southeastern part of Canada and this will be a key player over the next few days when two separate storm systems impact the region.
Our first storm system will have “marginal” cold air to work with during its initial stages in the early morning hours of Monday, but as colder air moves in from the building high pressure system to the north, the rain is likely to change over to snow to the north and west of the big cities in the DC-to-Philly-to-NYC corridor during the late morning or mid-day hours. In the suburbs of Washington, D.C., the changeover to snow on Monday may be limited in time to the very late stages of tomorrow’s event restraining accumulation potential to a coating to an inch or two. However, in the Philly and NYC metro areas, tomorrow’s storm will be a little more robust in terms of snowfall potential as compared with areas south of the PA/MD border. In fact, the late morning or mid-day changeover to snow in these two areas could result in a few inches of snow before the precipitation winds down later in the day.
A second disturbance will cross the southern states on Tuesday and head towards the Mid-Atlantic coastline for a mid-week rendezvous. This second system will be able to gather plenty of moisture from the Atlantic Ocean and the cold air source to the north (i.e., strong high pressure over southeastern Canada) will be better established at its start as compared with tomorrow’s initial storm system. As a result, the chances for snow and ice will increase at mid-week in the Mid-Atlantic region and in some areas to the north and west of the big cities, it can be significant.