The month of December has gotten off to a cold start across much of the nation and it’ll stay colder-than-normal in the DC-to-Philly-to-NYC corridor right through the upcoming weekend. The potential for any significant snow during this time period is quite limited; however, a “clipper” type of low pressure system can bring snow and/or rain showers here from later Wednesday night into early Thursday and small accumulations cannot be ruled out. More important weather impacts associated with this “clipper” system will include powerful winds that can gust past 45 mph or so on Thursday and the influx of another Arctic air mass into the Mid-Atlantic region for the end of the week.
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One of the biggest weather stories going forward is the cold wave that is coming to much of the nation beginning late this week and likely continuing for much of the first couple weeks of December. In fact, this will likely be one of the coldest starts to the month of December in many years and it will have a “Siberian” connection.
Before we get to the cold wave, there will be a lot of weather to go through across much of the nation with significant snowfall in some areas. Low pressure is currently pushing eastward across the higher elevations of the western US resulting in substantial snow accumulations from the Sierra Nevada Mountains of eastern California to the Colorado Rockies. Some of these locations will end up with snow totals on the order of 1-2 feet before this low spills out into the middle of the nation at mid-week.
From there, this low pressure system will move rather quickly across the Tennessee Valley on Wednesday night and to the southern New England coastline by mid-day Thursday. As a result, rain is likely to reach the DC-to-Philly-to-NYC corridor by late Wednesday night and continue into Thursday (Thanksgiving Day). Farther to the north, accumulating snow is likely to fall from early Thursday into early Friday across interior, higher elevation locations of northern PA, upstate NY and interior New England with several inches on the table.
Following the departure of the low pressure system to the western Atlantic, a northwesterly flow of air will develop across the northeastern quadrant of the nation bringing much colder-than-normal air from Canada into the Great Lakes, Mid-Atlantic, and Northeast US. The “Great Lakes snow machine” will get turned on with the much colder-than-normal air flowing over the still relatively warm waters of the Great Lakes from later Friday into Saturday and there is likely to be much more in the way of “lake-effect” snow activity during this upcoming cold wave.
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Low pressure will push eastward across the higher elevations of the western US during the next few days resulting in significant snow accumulations on the order of 1-2 feet from the Sierra Nevada Mountains of easter California to the Colorado Rockies. This same low pressure system will then spill out into the middle of the nation at mid-week and move rather quickly across the Tennessee Valley on Wednesday night and to the Mid-Atlantic coastline by mid-day Thursday. As a result, rain is likely to reach the DC-to-Philly-to-NYC corridor by late Wednesday night and continue into Thursday (Thanksgiving Day) morning. Farther to the north, accumulating snow may fall from Thursday into Friday across interior, higher elevation locations of upstate PA and upstate NY to New England.
Following the departure of the low pressure system to the western Atlantic, a northwesterly flow of air will develop across the northeastern states bringing much colder-than-normal air from Canada into the Great Lakes, Mid-Atlantic and NE US. The “Great Lakes snow machine” will turn on with the much colder-than-normal air flowing over the still relatively warm waters of the Great Lakes. Looking ahead, the influx of much colder-than-normal air into the eastern states by this weekend will begin a cold pattern that is likely to last well into December... one of the coldest starts in many years to the month of December and it will have a “Siberian connection”.
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A strong cold front passed through in the overnight hours with a band of heavy rainfall and gusty winds and colder air has followed into the Mid-Atlantic region. Surface low pressure has formed along the northern Mid-Atlantic coastline, and instead of pushing to the north, it will be “forced” to rotate around as it becomes increasingly influenced by strong blocking high pressure to the north. As such, an area of moisture now over the northern Mid-Atlantic will loop back around and impact the entire region by later tonight and through the day on Friday.
As the atmosphere turns colder, the precipitation will mix with snow and/or ice pellets by later tonight in the DC-to-Philly-to-NYC corridor and then likely to all snow for awhile on Friday in much of the area. In fact, small accumulations are possible on Friday across many of the northern and western suburbs along the I-95 corridor. Significant snowfall of at least 6-12 inches is coming to much of the Appalachian Mountain chain including in the region from West Virginia to the Laurel Highlands of southwestern PA, and from the Poconos in northeastern PA to the Catskills and Adirondacks of upstate NY.
Looking ahead, there are signs for multiple cold air outbreaks to make their way from northern Canada into the central and eastern US as we push through the remainder of November and into the early part of December...quite a wintry look to the unfolding weather pattern that will include additional threats of snow for the Mid-Atlantic/Northeast US.
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If you are a skier in the northeastern part of the country then this upcoming storm system will be quite good news as early season significant accumulating snow is likely in much of the Appalachian Mountain chain including in the region from West Virginia to the Laurel Highlands of southwestern PA and from the Poconos in northeastern PA to the Catskills and Adirondacks of upstate NY. In fact, snow is quite possible during this event all the way into the I-95 corridor and small accumulations are possible on Friday in some of the northern and western suburbs; especially, to the north of the PA/MD border.
A deepening trough of low pressure in the upper atmosphere will slide south and east to a position over the Mid-Atlantic by tomorrow night and this will help to spawn a (secondary) low pressure system near the northern Mid-Atlantic coastline. This system will become a slow-mover thanks to intense blocking high pressure to the north that will be parked over northeastern Canada. In addition to the threat for the first snows of the season, the northeastern states will experience very beneficial rainfall on the storm’s front end as a cold front pushes through from late today into early Thursday…and that won’t be the end of the precipitation.
Looking ahead, there are signs for multiple cold air outbreaks to make their way from northern Canada into the central and eastern US as we push through the remainder of November and into the early part of December.. It is quite a wintry look to this unfolding weather pattern that will include additional snow threats…perhaps one late next week right around Thanksgiving Day.
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The weather map is quite busy currently across North America with intense high pressure ridges combined with deep troughs of low pressure and on top of that we have some tropical moisture on the playing field as well. A deep trough over the northeastern Pacific Ocean will help to spawn a rapidly intensifying storm system that will slam into the Pacific Northwest from later today through tomorrow with hurricane-force winds, tremendous rainfall in low-lying areas, and substantial snowfall in the inland, higher elevation locations that will be on the order of several feet in some spots. This storm system will become a slow-mover and there will be lingering effects from northern California to Oregon and Washington all the way through the second half of the week.
Another upper-level trough will slide south and east during the next couple of days from the north-central states and deepen markedly as it reaches the Mid-Atlantic/Northeast US by later Thursday. An initial low pressure system will head to the Great Lakes while a secondary forms near the northern Mid-Atlantic coastline. This unfolding storm system will also become a slow-mover during the latter part of the week and will bring with it beneficial rains, accumulating snows across inland, higher elevation locations, and a prolonged period of strong NW winds.
Looking ahead, there are signs for multiple cold air outbreaks to make their way from northern Canada into the central and eastern US as we push through the remainder of November and into the early part of December...quite a winter look to the overall pattern that should include threats of snow as well.
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Quite an active and somewhat unusual weather pattern is developing across North America and one that will feature multiple intense upper-level ridges of high pressure and deep troughs of low pressure. One result of this overall pattern will be a powerful storm system that will slam into the Pacific Northwest from later tomorrow into Wednesday. This storm will feature explosive intensification with as much as a 70 millibar drop in 24 hours of its central pressure yielding the strength of a “category 4” hurricane and easily classifying it as a “bomb cyclone”. Another significant storm system will develop in this active weather pattern during the late week bringing with it rain, accumulating snows, and a sustained period of strong winds across the Great Lakes, Mid-Atlantic, and Northeast US.
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The first half of the new work week will be relatively quiet and mild in the Mid-Atlantic, but the weather turns quite active later this week as a deepening upper-level trough slides into the eastern states. This strong upper-level trough will become a slow-mover thanks to intense blocking high pressure to the north over northeastern Canada. At the surface, an initial low pressure system will head towards the Great Lakes in the late week time period and then a secondary low should form near the northern Mid-Atlantic coastline. The end result of this unfolding scenario will be rain and possible thunderstorms in the Mid-Atlantic region from late Wednesday into early Thursday and then windy, colder conditions to follow for the next few days. Accumulating snow is likely during this event across interior, higher elevation locations of the Mid-Atlantic region from update PA to upstate NY, and interior New England can get hit hard as well by the end of the week.
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It is not all that unusual for the “last hurrah” of an Atlantic Basin tropical season to be followed by an influx of winter-like cold into the central and eastern US and, in some cases, it is a “pattern-changing” type of event. One such example of this kind of scenario unfolded with Hurricane Sandy at the end of October during 2012 which was then followed by a colder-than-normal month of November in almost all areas east of the Mississippi River. (In fact, cold air not only followed Hurricane Sandy, but actually wrapped into it with as much as 3 feet of snow piling up in portions of West Virginia during that event). It appears that this tropical season may finally wind down after the ultimate demise of the latest system now over the Caribbean Sea and cold air intrusions into the central and eastern may become much more commonplace beginning late next week. The tropical system is likely to intensify into a named tropical storm (“Sara”) in the near-term, but an extended time period over land will likely reduce its potential impact on the US Gulf coast.
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It is not all that unusual for the “last hurrah” of an Atlantic Basin tropical season to be followed by an influx of winter-like cold into the central and eastern US and, in some cases, it is a “pattern-changing” type of event. One such example of this kind of scenario unfolded with Hurricane Sandy at the end of October during 2012 which was then followed by a colder-than-normal November in most areas east of the Mississippi. (In fact, cold air actually wrapped into Hurricane Sandy with as much as 3 feet of snow in West Virginia during that event). It appears a tropical system now forming over the Caribbean Sea may cross the Yucatan Peninsula by early next week and it then can take a turn to the northeast. Hopefully, this tropical system will weaken during its encounter with the Yucatan Peninsula and before a possible northeast turn towards the state of Florida. At the same time, cold air will be charging southeastward from Canada into the central states and other very impressive-looking cold shots are destined to work their way into the central and eastern states later in the month.
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