The next several days will feature multiple “clipper” low pressure systems across the northern US which are typically rather quick movers from northwest-to-southeast. One such system will track well to the north and west of the DC-to-Philly-to-NYC corridor later today bringing windy and slightly milder conditions to the I-95 corridor along with the threat of a few rain showers. A second “clipper” system will push towards the Mid-Atlantic region on Friday from the Ohio Valley. While this system may begin to weaken upon its approach, it can still produce some snow on Friday in parts of the Mid-Atlantic region including the DC metro and parts of Virginia (a hot spot so far this winter season for snowfall).
Over the weekend, yet another “clipper” system will push east-southeast towards the Mid-Atlantic region from the Ohio Valley, and this one will feature some strong support in the upper atmosphere with a vigorous jet streak. As a result, this is the most impressive to me of all of these “clipper” systems with the highest potential of producing accumulating snow in the Mid-Atlantic region (late Saturday into early Sunday). One final note, the Arctic blast that reaches the north-central US by early this weekend and then the Mid-Atlantic/Northeast US by early next week will feature some of the coldest air yet in this relentless cold weather pattern that began around Thanksgiving Day. Temperatures can drop to twenty degrees below zero by Sunday morning across a wide portion of the Upper Midwest from Minnesota-to-Iowa-to-Wisconsin.
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The cold pattern that has brought relentless cold in recent days from Alaska to the Mid-Atlantic region will continue for at least another week or so. The new work week begins with some frigid air in the eastern states and overnight lows in the DC-to-Philly-to-NYC corridor will drop to their lowest levels of the season so far. “Clipper” low pressure systems will swing cold fronts through the northeastern states during the next few days limiting any chance for a sustained warmup. One “clipper” can bring rain, ice and/or snow to the Mid-Atlantic/Northeast US at mid-week and a second system can bring a touch of snow in the late week. Over the weekend, low pressure may ride along the Arctic boundary zone, and this system could bring some accumulating snow to the Mid-Atlantic region to go along with the well below-normal temperatures that should last into the early part of next week.
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An Arctic blast that resulted in numerous record low temperatures this morning across the Upper Midwest/Great Lakes is on its way to the Mid-Atlantic region, and it will set the stage for an accumulating snow event on Friday in the southern half of the area from DC/Virginia to the Delmarva Peninsula to the southern part of New Jersey. Temperatures in the overnight hours will drop into the teens in many of the suburbs along the I-95 corridor following the passage of an Arctic cold frontal system later today. Moisture on Friday will spread to the northeast from the Tennessee Valley and run into this very cold and dry Arctic air mass and snow will break out early in the day across much of Virginia and the DC metro region...in other words, both the AM and PM commutes can be slippery in these areas on Friday.
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The month of December has gotten off to a cold start across much of the eastern half of the nation and there will be multiple cold air outbreaks in coming days. Two signals that have foreshadowed a cold period include an unusually early season stratospheric warming event and the movement of a tropical disturbance into a position that favors colder-than-normal weather across much of the nation. In fact, there appears to be a second burst of stratospheric warming in the offing for later this month resulting in a “stretched” polar vortex, and the tropical disturbance will likely persist in much of the same “cold” position” for awhile longer...both of these favor the idea of additional cold air outbreaks as we progress through the month.
The cold pattern has been quite active as well and multiple systems will have to be watched in coming days. On Friday, low pressure will develop over the Deep South and head in an northeasterly direction. This system is likely to produce some accumulating snow in the southern half of the Mid-Atlantic region and looks like a light-to-moderate snow event. Another low pressure system may pull out of the southeastern states by early next week and head in an northeasterly direction at the same time a “clipper” moves southeastward across the Great Lakes…we’ll monitor this activity as it could result in some accumulating snow for the northern Mid-Atlantic and Northeast US. Later next week, it appears a couple of other “clipper” systems will drop southeastward from southwestern Canada into the Great Lakes and ultimately, to the Northeast US. Finally, the significant change in recent days of an index value known as the “Southern Oscillation” is raising a red flag that the chance of an east coast storm will be on the rise somewhere down the road as the sub-tropical jet stream likely becomes activated.
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December has begun on a cold note across the northeastern states and below-normal temperatures are likely on average through at least the first half of the month. Two factors that have been pointing us to an extended cold stretch this month include an unusually early stratospheric warming event over the polar region of the Northern Hemisphere, and the movement of a tropical disturbance along the equator that is moving through locations which favor colder-than-normal weather in the eastern states.
The cold pattern will remain active as well with the next storm system to impact the Mid-Atlantic and Northeast US on Tuesday, and this follows a significant Great Lakes snow event late last week and a major snowstorm in the Midwest this past weekend. The best chance for significant snow on Tuesday will be across the interior sections of the northeastern states where several inches of snow are likely and heavy rain is the main threat along coastal areas from southern New Jersey to the Delmarva Peninsula. The I-95 corridor will be in the “battle zone” region for awhile on Tuesday morning with snow and ice likely at the front end that will transition to plain rain for the main part of the storm. Small snow accumulations are possible before the transition to plain rain with a coating to an inch or so possible in some of the northern and western suburbs...watch for slick spots during the AM hours.
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Several inches of snow will pile up this weekend across a large part of the Midwest and Great Lakes (where they are still reeling from some intense lake-effect snow bands) and another winter storm will hit the Mid-Atlantic region and Northeast US on Tuesday. The best chance for significant snow on Tuesday will be across the interior sections of the northeastern states and heavy rain is the main threat along coastal areas from southern NJ to the Carolinas. The I-95 corridor will likely be in a battle zone period for awhile on Tuesday with some accumulating snow and ice possible at the front end, but a changeover to rain is likely; especially, in the big cities from DC-to-Philly-to-NYC.
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The period between Thanksgiving and Christmas will begin with a major Great Lakes snow event from Thursday to Friday and an Great Lakes/Midwest snowstorm this weekend and it could end with a White Christmas in many parts of the country. Two of the factors that have been highlighted here, likely leading to a cold and active stretch of weather, include an unusual early season stratospheric warming event and the likely movement of a tropical disturbance into a location that favors colder-than-normal conditions across a large part of the nation. Both of these phenomena – stratospheric warming and tropical forcing – will likely lead to a “buckling” of the polar jet stream which can lead to the unleashing of multiple Arctic air masses from northern Canada into the US (with intense cold in the table), and an activation of the southern branch of the jet stream which will likely produce multiple snow/ice threats.
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It is looking like a cold Turkey Day across the Mid-Atlantic region with well below-normal temperatures following the mid-week passage of a strong cold front. A secondary cold front arrives later Thursday, and winds will increase markedly on Thursday night and Friday behind this second frontal passage to go along with the colder-than-normal conditions. The chill will stick around right into the upcoming weekend throughout the northeastern part of the country. In terms of snow, this late week Arctic air outbreak will be the catalyst for another Great Lakes snow event in those areas just downstream of the still relatively warm waters and, in some cases, it may be intense with substantial lake-effect snow accumulations. Looking to the weekend, a new storm system could bring significant snowfall to portions of the Upper Midwest, Ohio Valley and again the Great Lakes region.
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There are signals that continue to point to an upcoming cold weather pattern for the central and eastern states as the early part of the winter season gets underway. These signs come from such diverse places as the stratosphere over the North Pole (re: Stratospheric Warming), the stratosphere over the tropics (re: QBO), and the equatorial part of the Pacific Ocean (re: MJO).
To begin, it appears as though there will be a “Stratospheric Warming” event over the polar region of the Northern Hemisphere in coming days which is quite a rare occurrence for this early stage of the winter season. In fact, it appears there have been only two Stratospheric Warming events in recent history that took place during the month of November...2000 and 1968...and in both of those years the month of December was quite cold across the nation. One atmospheric phenomenon that supports the idea of one (or more) “Stratospheric Warming” event(s) this winter season is known as the Quasi-Biennial Oscillation (QBO) which is a changing wind anomaly in the tropical lower stratosphere. When an “easterly” or “negative” phase of the QBO is combined with La Nina conditions in the tropical Pacific Ocean – both of which represent the current situation - there is a strong tendency for an increase in “Stratospheric Warming” events and the disruption of the polar vortex. This particular teleconnection was one of the factors highlighted in the ”2025-2026 Winter Outlook” issued back in October.
Additionally, there is an oceanic-atmospheric phenomenon known as the Madden-Julian Oscillation (MJO) that affects the weather patterns across the globe. The MJO is an eastward moving disturbance of clouds and rain that traverses the planet in the tropics and - depending on its location and the time of the year - it can contribute to colder-than-normal weather patterns across the central and eastern US.
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An Arctic air mass that originated near the North Pole has infiltrated the eastern states today and it will have an impact all the way down to southern Florida by Tuesday morning. In fact, temperatures on Tuesday morning are likely to bottom out in the 30’s across the central part of the Sunshine State and the 40’s in southern Florida. At the same time, many suburban locations along the Mid-Atlantic’s I-95 corridor region from DC-to-Philly-to-NYC will feature the first hard freeze of the season with overnight lows well down in the 20’s in many spots. There is accumulating snow to go along with this early week Arctic blast with favored areas including the Great Lakes, interior sections of the Mid-Atlantic and Northeast US, and the central Appalachians where a vigorous upper-level low is helping to destabilize the atmosphere in a big way.
While there will likely continue to be colder-than-normal temperatures across the northeastern states during the second half of the week, this winter-like pattern does not look like it’ll continue through November. In fact, there are signs for warmer-than-normal conditions to cover much of the nation from next week into the following week and it may include one or more severe weather outbreaks as well. Looking farther down the road, numerous signals point to a sustained colder-than-normal period to start the winter season as we transition into the month of December.
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