1:30 PM Fri. | ***Significant storm to impact eastern US from Sunday to Monday…snow, ice, rain, coastal flooding, damaging winds all on the table…front-end accumulating snow/ice for I-95 corridor***
Paul Dorian
A low-level jet streak will play a role in this upcoming event with high and potentially damaging winds possible along coastal sections of the Delmarva Peninsula and New Jersey. Map courtesy ECMWF, Weather Bell Analytics
Overview
Many ingredients are coming together for a high impact type of storm system in the eastern third of the nation from Sunday into Monday with accumulating snow, ice, heavy rain, coastal flooding, and even high (potentially damaging) winds all on the table. The upper-level wave of energy that will be the catalyst for storm development has come ashore and it will dive to the south and east over the next couple of days. Low pressure will develop by early Sunday morning in the southeastern states and this system will then make a move to the northeast and it’ll encounter an Arctic air mass that will be quite reluctant to give up its ground. As a result, a significant snow and ice event is likely to take place across interior sections of Georgia and the Carolinas on Sunday morning and mid-day. After that, precipitation will push into the Mid-Atlantic region with cold, dense air in place and a period of snow and/or ice is likely in most interior sections with plain rain a likelihood along coastal areas. The DC-to-Philly-to-NYC corridor is in line for accumulating snow on the front-end of this storm followed by a period of icing given the expectation that the dense, cold low-level air mass will be tough to dislodge.
Lots of colors on this surface forecast map for early Sunday evening with a range of precipitation from :ordinary” rain (green), heavy rain (yellow), snow (blue) and sleet/freezing rain (purple/pink). Map courtesy NOAA, tropicaltidbits.com
Details
Numerous ingredients are going to come together this weekend for the development of a powerful storm system that will have a high impact on the eastern third of the nation. The first ingredient is a vigorous upper-level disturbance that will drop southeastward over the next couple of days and it’ll phase together with a disturbance riding along in the northern branch of the jet stream to form a potent upper-level low over the south-central states by Saturday afternoon. At the same time, cold, dense Arctic air - which will pour into the Mid-Atlantic/NE US in the overnight hours - will become well established thanks to strong high pressure that will build into the southeastern part of Canada. An example of the bitter cold air mass will be able to seen with the televised NFL playoff game tomorrow night in Buffalo where they’ll experience one of the coldest playoff games in history. Two other factors that will play crucial roles in this unfolding storm system will include a powerful jet streak that will form in the lower part of the atmosphere and there will be an influx of tropical air on the warm side of the storm containing very high moisture content.
12Z NAM forecast map of 500 mb vorticity field as of 7PM, Sunday with a strong disturbance centered near the western part of the Carolinas. Map courtesy NOAA, tropicaltidbits.com
By early Sunday, the potent upper-level system will reach the Deep South and surface low pressure will begin to take shape at the same time the Arctic high to the north moves to a position over New England. Cold, dense low-level air will pour down the east side of the Appalachians (cold air damming) setting the stage for lots of frozen precipitation on Sunday in the interior sections of Georgia and the Carolinas as the surface low begins its push to the northeast. In fact, the stage may be setting up in this region for a significant and dangerous snow and ice event on Sunday.
By late Sunday, moisture from the storm will arrive in the Mid-Atlantic region and encounter cold, dense air in the lower levels of the atmosphere. As such, snow is likely to break out in the DC metro region in the late afternoon, in the early evening hours across Philly and NYC and some front-end accumulations are quite likely. An early estimate for snow totals are as follows: 2-5 inches in the DC metro region, 1-4 inches in Philly and 1-3 inches across NYC. In all three metro areas, the highest amounts will tend to be to the west and northwest of the big cities and in all three areas, this storm will feature very strong winds. The storm looks like it will take a track slightly inland near or over Route I-95 and milder air will push in from the ocean. This will result in a changeover of the snow to sleet and then eventually to plain rain although icing on some surfaces can continue for an extended time in the northern and western suburbs as temperatures struggle to get above freezing in those normally colder locations. In fact, the icing may turn out to be a bigger problem than the snowfall in parts of the I-95 corridor region. The heaviest snowfall amounts from this storm are likely to fall to the west/northwest of the big I-95 cities in the region extending from western Virginia/western Maryland/eastern West Virginia northward to western, central, northeastern PA and then up through western and central NY State and into interior New England.
Along coastal sections of the Mid-Atlantic/Northeast US, the rain can get heavy, flooding will be possible at times of high tide on Sunday night and Monday and there can be high and potentially damaging wind gusts given the expectation of a powerful low-level jet (an onshore flow of air).
One final note, the overall weather pattern looks to remain quite a bit colder-than-normal in the central and eastern US as we go through the second half of January - perhaps to include some extreme cold during the week of the 23rd.
Meteorologist Paul Dorian
Arcfield
arcfieldweather.com