2:00 PM (SUN) | *****A stormy week with Monday storm that begins with rain in the Mid-Atlantic and then accumulating snow for some…major storm at mid-week to bring significant snow, ice and rain*****
Paul Dorian
An initial storm on Monday will begin with rain in the Mid-Atlantic region and then accumulating snow in some areas. Map courtesy NOAA, tropicaltidbits.com
Overview
This will be a stormy week in the Mid-Atlantic region with two storms to deal with during the next few days. The first storm on Monday will begin with rain in all areas of the DC-to-Philly-to-NYC corridor, but as colder air filters from a strengthening high pressure system to the north, a changeover to accumulating snow is likely to take place in suburban areas to the north and west of the big cities. A second and powerful storm will arrive at mid-week and it is likely to result in significant snow, ice and rain for the Mid-Atlantic region with a mixture possible in parts of the metro areas, heavy snowfall to the north and west, and primarily rain near and along coastal sections of southern New Jersey and the Delmarva.
The upper-air pattern will be set up for a major storm system at mid-week that will produce significant snow, ice and rain in the Mid-Atlantic region. An important cold air source (i.e., strong high pressure) will be present across the southeastern part of Canada. Map courtesy NOAA, tropicaltidbits.com
Details
It’ll be very mild today in the Mid-Atlantic/Northeast US, but a cold front pushes through in the afternoon 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 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 accumulating snow chances will be a little bit more robust as compared with areas south of the PA/MD border. In fact, the late morning or mid-day changeover to snow in these two metro 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 accumulating snow and ice will increase in the Mid-Atlantic region for the mid-week event and in some areas to the north and west of the big cities, total snowfall amounts may end up being substantial and the highest seen since the late January 2016 snowstorm. The possibility of a changeover or snow to sleet, freezing rain and/or plain rain is fairly high in the DC metro region and mixed precipitation cannot be ruled out in the Philly and NYC metro regions as well. An extended period with mixed precipitation would be a limiting factor for snowfall accumulations and this will be something to watch for; especially, to the south of the PA/MD border.
Significant snowfall amounts this week are predicted by the 00Z EPS in much of the Mid-Atlantic region with small amounts during the initial storm and substantial amounts from the mid-week event. Map courtesy ECMWF, Weather Bell Analytics
One final note, winds are likely to become a big factor during this mid-week storm with a strong pressure gradient between the intensifying storm near the Mid-Atlantic coastline and the strong high pressure system to the north. These potential high winds could very well result in some blowing and drifting in those areas that receive significant snowfall amounts and could result in power outages including in areas where freezing rain falls for an extended period.
12Z EPS has a wide area with greater than 90% probability of 6 or more inches (red) from the mid-week storm. Map courtesy ECMWF, Weather Bell Analytics.
Some final thoughts on the mid-week storm and these are still subject to change:
the highest snowfall accumulations may run from the I-81 corridor of northern Virginia-to-south central PA and northeastern PA-to-northern NJ-to-coastal southern New England
as far as timing goes, the snow may arrive in DC during the morning hours on Wednesday, mid-day in Philly, and early-to-mid afternoon in the NYC metro region
in the DC metro region, snow is likely to change to a period of sleet and/or freezing rain and then perhaps change back to snow
in the Philly and NYC metro regions, snow is likely to be the main precipitation-type during this storm and there can be substantial total snow accumulation amounts. A mixture of sleet and/or freezing rain in those two metro areas is possible, but likely for a brief period of time only
while Boston could end up with a significant snowfall, it appears that the mid-week event will not have an important impact on VT, NH or ME.
Stay tuned…certainly an interesting weather pattern for the upcoming week and don’t dismiss tomorrow’s initial storm system as it can be an “over performer”.