1:00 PM | ****An icy mess early tomorrow in the DC-to-Philly corridor; especially, N/W suburbs…plain rain later along I-95 and some will be heavy…major Arctic outbreak into the US later next week****

Much of the Mid-Atlantic region will experience an icy mess from late tonight into Thursday and this includes the I-95 corridor region from DC-to-Philly; especially, in those western and northern suburbs. Map courtesy NOAA, Pivotal Weather

Overview

A powerful storm that has caused problems in much of the nation in recent days will impact the Mid-Atlantic region and Northeast US from later tonight into early Friday. Heavy snow associated with this impactful storm system fell this past weekend in the Sierra Nevada Mountains of eastern California and southern Cascades. Significant snow then fell from Monday into Tuesday across the northern Rockies and Northern Plains and today’s blizzard conditions will extend east to Minnesota and Wisconsin.  Meanwhile, in the warm sector of this large-scale storm system, severe weather including isolated tornadoes broke out yesterday from Texas/Oklahoma to Louisiana and the threat zone today will shift slightly to the east to include Mississippi and Alabama.

By late tonight, precipitation will break out in the Mid-Atlantic region and an icy mess is on the table for early Thursday from DC-to-Philly; especially, in some of the northern and western suburbs of those cities. Increasingly strong easterly winds will pump in slightly milder maritime air later tomorrow bringing about a transition to plain rain and some of it will become heavy at times into the nighttime hours to go along with those strong winds. 

Looking ahead, a major Arctic air outbreak appears to be headed to the US later next week and the frigid air mass will likely last stick around right through the Christmas weekend in much of the central and eastern US.  Arctic cold has gripped Europe for the past several days and this is often a foreshadowing of conditions to come in the US.  The cold weather pattern will remain quite active as well next week increasing the chances for a white Christmas in much of the northern US.

Precipitation arrives in the DC metro region before daybreak moving in from southwest-to-northeast promising an icy mess across the western and northern suburbs for the early morning commute. Map courtesy NOAA, tropicaltidbits.com

Major storm system impacts the Mid-Atlantic/Northeast US from Thursday into Friday

Heavy snow is falling today across the Northern Plains and it is expanding eastward into Minnesota and Wisconsin.  Meanwhile, in the warm sector of this major storm system, strong thunderstorms have formed already today extending from Louisiana-to-Mississippi-to-Alabama and isolated tornadoes will again be a threat in this unstable area. The low pressure system responsible for all of the action from this past weekend to today will grind to a halt over the Upper Midwest as it becomes influenced by the very strong blocking in the atmosphere over central and northern Canada. This action will lead to the development of a secondary storm system on Thursday that will develop over the Carolinas and intensify as it heads towards the Delmarva Peninsula by tomorrow night and then ultimately to a position southeast of Long Island by mid-day Friday.

The precipitation field associated with the weakening initial primary storm system and the newly developing secondary storm system will reach the DC metro region late tonight likely between the hours of 2 and 5am.  Freezing rain is likely to occur in the wee hours of the morning there possibly mixed with sleet and this should last into the morning commute time.  A buildup of some ice is possible; especially, in the far western and northern suburbs…watch out for slick spots.

In the Philly metro area, precipitation is likely to arrive between 6 and 9 am as a wintry mix of snow and ice and there can be small accumulations and, as in the DC area; this is especially likely in the northern and western suburbs…watch out for slick spots during the AM hours. Farther to the north and east, the precipitation shield is likely to hold off in reaching the NYC metro area until about mid-day at which time temperatures should be just above freezing - limiting the chances there for much in the way of icing.

Increasingly strong easterly winds will pump in slightly milder maritime air to the I-95 corridor and this will cause a transition by later in the day from any wintry mix that falls to plain rain and above-freezing temperatures. Map courtesy NOAA, tropicaltidbits.com

In all areas of the I-95 corridor region from DC-to-Philly-to-NYC, increasingly strong easterly winds will develop later tomorrow as the low pressure system intensifies near the coastline and this will pump in slightly milder maritime air. This will lead to a southeast-to-northwest transition of any wintry mix that is falling to plain rain by roughly the mid-to-late morning hours in DC, early afternoon hours in Philly and NYC.  It then looks like quite a stormy night with some heavy rain and strong winds; primarily, in the region from Philly to NYC (i.e., winds down during the evening in the DC area). I do not expect any kind of a freeze-up tomorrow night in the stormy regions as temperatures in Philly and NYC should hold steady or even rise slightly. 

Following this late week storm system, much of the nation will experience below-normal temperatures through the upcoming weekend. Map courtesy NOAA, tropicaltidbits.com

In interior sections of the Mid-Atlantic and Northeast US, significant snow is on the table from later tomorrow into Friday.  There will be icing mixing in across upstate PA likely limiting accumulations somewhat there – probably to the 3-6 inch range from St. College to Scranton. In upstate NY and interior New England -where there will be no relief from the maritime flow of air - several inches of snow can fall from later tomorrow into Friday.  Following the storm system it’ll turn quite cold across much of the nation for the upcoming weekend with virtually coast-to-coast below-normal temperatures.

The European continent from UK to Scandinavia has experience persistent colder-than-normal conditions in the month of December with many places also experiencing some unusual early season snow accumulations (e.g., London, England). Map courtesy NOAA, Weather Bell Analytics

Major Arctic outbreak in the US later next week…Europe remains cold

A major Arctic outbreak is destined to reach the US later next week first arriving in the northwest and north-central parts of the nation and eventually working its way all the way to the eastern seaboard.  The northern part of Europe from the United Kingdom to the Scandinavian countries has suffered through frigid cold for the past several days and this is often a foreshadowing of a colder pattern for the central and eastern US. 

A widespread Arctic air outbreak will spread across the US later next week likely reaching the eastern states by the end of the week and it looks like the eastern half of the nation will remain quite cold right through the subsequent Christmas weekend. Map courtesy NOAA, tropicaltidbits.com

This expected cold air outbreak should reach the eastern US by the end of next week and it is likely to remain quite cold in the eastern half of the nation right through the following Christmas weekend. In terms of the potential for snow , the overall pattern looks to remain quite active next week raising the chances for a white Christmas in many parts of the northern US. In fact, there are early signals that the end of next week could become very interesting in the northeastern states about the same time the Arctic outbreak arrives in the eastern US…stay tuned on those possibilities, still a lot to go through before we get to that point. 

Meteorologist Paul Dorian
Arcfield
arcfieldweather.com

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