Confidence continues to grow for a major - and perhaps crippling storm - for the Mid-Atlantic region at the end of the week and weekend. It looks like it'll be a high-impact and long-lasting storm that has the potential to dump 1-2 feet of snow on the I-95 corridor region from DC-to-Philly-to-New York City. It is entirely possible that somewhere in the Mid-Atlantic region there will be 30+ inches of snow accumulation from this upcoming system. Numerous overnight computer forecast models support the idea of a major winter storm for the Mid-Atlantic region including the European which had a "southern spasm" yesterday, but "corrected" itself in its latest run back to a more "northwest" storm track and positioning of the zone of heaviest snowfall. The timing has changed a bit to a slightly later starting time - likely mid-day to early afternoon on Friday in the DC metro region. This storm is likely to include some serious blowing and drifting, coastal flooding and beach erosion and perhaps there will even be some thunder snow and lightning. Wind gusts could reach 70 mph at coastal locations later Saturday and 50 mph at inland areas. There is a chance for a changeover to or a mixing with rain and/or sleet for awhile during this storm; especially, to the south and east of the big cities. Stay tuned for updates.
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Today’s GFS computer forecast model run had a slight shift to the south and east in its storm track for the late week system, but it still had DC and Philly metro regions in the “sweet spot” for significant snow accumulations. The very latest European model run, however, has shifted the storm even farther to the south and east compared to the GFS and - while it keeps the DC area in the heavy snow area - it generates a sharp snowfall accumulation gradient on the storm’s northern edge and diminishes snowfall amounts substantially in Philly and NYC and points to the north and west. While the Euro’s shift to the south in the storm track is much more dramatic than most other models, it suggests that nothing is set in stone yet for this potential storm. My gut feeling is that the Euro is now too far south with the storm track and will shift back to the north and west as the event time closes in – not uncommon in the models for big coastal storms - but we’ll just wait and see if this is the beginning of a trend that may be picked up by other computer models.
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All systems are go on the latest GFS model for a major – and potentially crippling – snowstorm at week’s end in the Mid-Atlantic region including the DC-to-Philly-to-NYC corridor. Low pressure will pull out of the Tennessee Valley on Friday and head towards the Mid-Atlantic coastline. This storm will undergo explosive intensification between Friday and Saturday as it will be supported by a vigorous wave of upper-level energy. At the same time, “banana-shaped” cold high pressure will set up to the north and northwest of the surface low pressure system – a classic signature for Mid-Atlantic snowstorms.
This is the type of storm that can easily generate 1-2 feet of snow in DC-to-Philly-to-NYC strip, but there are still a few days to go and some details still have to be ironed out. In addition to the snowfall, winds will become a major factor as a tight pressure gradient develops between the strengthening low pressure system and the high pressure to the north and northwest. As a result, blowing and drifting is likely to become an issue and beach erosion will be a concern at coastal regions; especially, given that a full moon is coming on Saturday when winds will be at their highest (potentially 60 mph at the coast, 40 mph inland).
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Very cold conditions will continue today in the Mid-Atlantic region with afternoon temperatures generally confined to the 20’s, but they will relax a tad on Wednesday ahead of a weak system that could produce light snow around here tomorrow night. The big story is the potential for a late week major storm as low pressure pulls out of the south-central states and intensifies rapidly near the Mid-Atlantic coastline this weekend. The potential is there for significant snowfall up and down the I-95 corridor from DC-to-Boston in the Friday/Saturday time period which could include some serious blowing and drifting as winds will get quite strong.
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Low pressure will pull out of the south-central states late this week and should reach the Mid-Atlantic coastline by Friday night or early Saturday strengthening all along the way to a powerful – and potentially news making - system by the weekend. The potential exists for a major snow event in the I-95 corridor in the Friday/Saturday time period, but there are still a few days to go and several details have to still be ironed out. The upper-level feature that will help to generate this potential powerful storm is still out over the Pacific Ocean and it won’t come ashore onto the US west coast until Tuesday night and then it should slide to the south-central states by Thursday night (500 millibar forecast maps from 12Z NAM). As a result, while the numerous computer forecast models are in general agreement on a big storm, high confidence will have to hold off until Wednesday or so as it won’t be until then that there is better data sampling over land of the all-important upper-level system that will play a crucial role. By the way, there is potential for another big storm by the middle or latter part of next week.
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Earlier last week, some spots in the I-95 corridor received their first snowfall of the season as numerous snow showers broke out with an Arctic frontal passage. Yesterday, other areas received their first snow this winter as a period of steadier snow associated with a coastal low produced accumulations of a dusting near the big cities and a few inches at the New Jersey coastline (Atlantic City 2.8"). You get the feeling the momentum has shifted and winter is saying "I am back". Indeed, winter could return in full force later this week as there is potential for a major snowstorm at week's end.
The atmosphere has evolved in recent days to one with high-latitude blocking across Canada and Greenland which is providing the cold air for the eastern US and an active "El Nino-enhanced" southern branch of the jet stream to provide the moisture. The next couple of days will be very cold as yesterday's Arctic frontal passage ushered in some of the coldest air of the season so far. As a result, afternoon temperatures will generally be confined to the 20’s for the next couple of days and it doesn’t look like a quick warm up during the mid-week time period either as colder-than-normal conditions should persist. A light snow event is possible around here during Wednesday night and then the potential exists for a major snowstorm in the Friday/Saturday time frame from a storm that will pull out of the Mississippi Valley and heads towards the Mid-Atlantic coastline. One final note - and as far as winter's momentum is concerned - there are signs for another big storm late next week. Stay tuned.
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Low pressure will be pushing off the Southeast US coastline in a northeastward direction early Sunday morning while at the same time a vigorous upper-level wave of energy will be dropping southeastward across the upper Great Lakes. The strength, movement and timing of this “northern branch” wave of energy is critical to the ultimate track and strength of surface low pressure off the Mid-Atlantic coastline late Sunday and Sunday night. As it stands right now, it appears that even though the “northern branch” wave can generate snow showers or steady light snow in the Mid-Atlantic region late Sunday, more substantial precipitation is likely to stay off the coast – however, it is a close call and bears watching.
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Low pressure will develop off the Southeast US coast line later today and ride northeastward over the next 24 hours to a position off the New England coast on Saturday. This system will bring rain to the DC metro region from later today into early Saturday and then some clearing will take place during the afternoon. An Arctic front arrives late Sunday and this will have strong upper-level support with it and the result could be snow shower activity ot steady light snow in the region during Sunday PM. Much colder air follows this next Arctic frontal passage for the early and middle parts of next week - the coldest air so far this season - and there can be another storm threatening us at the end of next week or during the following weekend.
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Low pressure will push northeastward on Friday from the Southeast US and to a position off the New England coastline on Saturday. Temperatures will be warm enough for rain in the immediate I-95 corridor from tomorrow night into early Saturday before some clearing takes place late in the day. Another system will pull out of the Gulf of Mexico region on Sunday at the same time a dynamic upper-level wave of energy drops out of Canada and over the Great Lakes. It appears the southern system will not hug the coastline as it turns northeast on Sunday and our main player will be the upper-level wave to our northwest associated with another Arctic blast. As a result, snow showers will be the main threat around here for Sunday night and any steadier or heavier snow looks like it’ll be confined to areas well to our northeast.
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Temperatures will modify noticeably today compared to yesterday’s Arctic chill and it’ll stay milder to end the work week as well. Moisture from the southern states will advance our way during the day on Friday and rain is likely to break out tomorrow night and last into early Saturday. It’ll turn colder behind the early weekend system which ultimately will develop into a strong storm just off the Northeast US coastline. By Sunday, colder air will push into the Mid-Atlantic and an Arctic front with strong upper-level support could generate snow shower activity in the region.
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