January 22-25 Potentially Historic Winter Storm

A potentially historic winter storm looks to be unfolding for portions of the Eastern U.S.

Tropical Tidbits

A low pressure system is forecasted to develop in the South US and push northeastward to the area just offshore the Mid-Atlantic, with this coastal storm fully unfolding around January 23rd-24th. The above image shows the GFS 500mb geopotential height contours and mean sea level pressure values for the morning of January 24th. We see the snowstorm located fairly out to sea, at approximately 985 millibars. This track would produce the snow map below, taking this solution verbatim.

Tropical Tidbits

This solution would bring about 6-12" of snow to the Kentucky and Tennessee region, extending into extreme southern Indiana and a good chunk of southern Ohio. We also see similar amounts into northern Arkansas and southern Missouri, as well as North Carolina. Amounts on the order of 12-24" are outlooked for West Virginia, particularly the southern part of the state, into the majority of central Virginia, New Jersey, and eastern Pennsylvania into southern New York, with some slightly lower amounts further east into Massachusetts. Long Island is also forecasted to receive upwards of 12" if this solution were to verify.

Tropical Tidbits

To emphasize how critical the placement of this system will be, take a look at the ECMWF model's 500mb geopotential heights and mean sea level pressure values for the morning of January 24th, the same timeframe as the GFS graphic. We see the system at 984 millibars, pretty similar to the GFS, but the system is clearly displaced further west. Given how anomalously warm the Atlantic currently is, this shift could easily push those two to three feet amounts inland, and leave the coastline with rainy conditions. This run of the ECMWF has snowfall amounts of over 30" in central Virginia, but lesser accumulations the further north and east you go.

Tropical Tidbits

The GEM model shows amounts in the 6-12 inch range for most of Missouri into the southern parts of Illinois, Indiana and Ohio, as well as much of Kentucky and northern Tennessee into western North Carolina. Amounts in excess of 30" are forecasted from Maryland into Pennsylvania, certainly an incredible amount of snow, but not entirely off the table given how strong and persistent this system may end up being. Again, the placement of this storm will be critical to who gets the heaviest accumulations, and we likely won't know who will receive this jackpot until the storm is actually happening.

Tropical Tidbits

One last bit of advice, do not bite on any particular model run for this storm. The strength of this storm, as well as how long-lasting it will be, among other factors, makes me way too uneasy to trust any single solution, hence why I presented a plethora of models here. The above graphic shows GFS ensemble spread in MSLP values for this storm. The warmer colors to the left and right of the system indicate increased uncertainty with where the storm will track. Again, this emphasizes how no single solution is set in stone, and thus should not be taken at face value. A lot of change will happen in the next several model cycles, and the heaviest amounts could plausibly shift a substantial bit as these changes unfold.

To summarize:

- A potentially historic snowstorm is forecasted to occur along the East Coast over the January 22-25 period.
- Currently, the Maryland/Virginia/Pennsylvania region is on track to receive the heaviest amounts.
- The heaviest accumulations could reach or exceed 30".
- Enough uncertainty still exists to change the storm track substantially, as well as shift the heavy snow axis and amounts.

Andrew

Winter Coastal Storm Threat Enhanced From Warm Atlantic Waters

It does appear that the threat for significant East Coast winter storms is on the rise, as we have seen rapid and significant warming of the Atlantic waters along the coastline in the last few weeks.

ESRL

The above image shows daily sea surface temperature anomalies for September 15th. While there are a number of variables we could analyze in depth, I want to focus on the situation unfolding in the central Atlantic today.

Take note of strong positive SST anomalies from the East Coast through Nova Scotia, partially reaching into the open waters of the Atlantic before being stopped by a swath of below-normal SST anomalies west of Europe. These well-above-normal water temperatures could be a focal point for the coming winter.

Coastal storms that develop along the East Coast can turn into Nor'easters, infamous for dropping massive amounts of snow on inland Northeast communities, and sometimes large rain amounts along the coast. If we are to see this warmer than normal body of water maintain itself along the East Coast, both in position and strength, it's quite likely we will see an enhancement of any coastal storms that do develop along the East US. This would occur as the warm waters feed additional moisture and energy into the storm system, increasing precipitation and strengthening the storm system.

To Summarize:

- Warmer than normal water temperatures off the East Coast may increase the threat for stronger coastal winter storms in the coming cold season.

Andrew

March 16-20 Potentially Significant Storm System

I'm watching for a potentially strong storm system in the March 16-20 timeframe.

WeatherBell

The image above shows 500mb height anomalies over the North Pacific, valid on the morning of March 10. If we look at Japan, we see deep purples over the island nation, indicating the presence of anomalously low heights. This tells us there is a storm system afoot; the purples indicate the storm is of the stronger variety when compared to other systems. How can weather in Japan relate to weather here in the US? If we use the 6-10 day correlation, explained by Joe Renken, which states that a storm system in Japan can affect the United States 6-10 days later, we find that this storm system would be expected to create a storm in the United States during a March 16-20 time period. Even more interesting is how models bring two strong storm systems through Japan during this March 10 time period, meaning we could be in for a significantly stormier and cooler than normal mid to late March.

We can actually figure out the projected track for this storm as well, by using a tool titled the Lezak Recurring Cycle. The Lezak Recurring Cycle, or LRC, is a tool developed by meteorologist Gary Lezak that, in essence, can enable forecasters to predict the overall weather pattern months in advance. The gist of the LRC involves a cycling weather pattern that develops in October and November of each year; no pattern is the same from year to year. Around mid November, the LRC begins to repeat, meaning we start to see a similar weather pattern in mid November that we saw in early October. This means that the cycling pattern has begun, and it will continue to cycle on a regular, unchanging 40-60 day interval for the next ~10 months before it dissipates over the following summer. Since this season's cycle has been holding at around 57 days, we can go back from the March 12-17 period and arrive around the  January 16-20 time period. The image above shows observed 500mb height anomalies from the January 16-20 timeframe, where North America is located on the upper right portion of the image. If we look at what the atmosphere was like in that mid-January period, we find a defined northwest flow scenario, with strong ridging over the West Coast leading to deep negative height anomalies across the East Coast. The jet stream below for the same January 16-20 period reflects this northwest flow.

If you're a weather buff, you probably know where I'm going with this. If not, pay close attention. The northwest flow scenario involves the jet stream shooting north into Alaska due to that massive ridge of high pressure, before plummeting south into the Southeast and then north again across the East Coast. In the January 16-20 period, we also saw support from the subtropical jet stream, which helped to enhance wind speeds and phase the two jet streams. If a storm were to come along during this northwest flow scenario, it would most likely become enveloped in the jet stream, and become a coastal storm. To sum up, if the LRC cycles again to be even somewhat close to what we saw in mid-January, it's possible this ends up being an East Coast storm. However, because we're so far out, we don't even know if this storm will even happen. This is just a heads-up for a part of what could be a very stormy mid-March.

Also see: March 12-16 Potentially Significant Storm System

Andrew

Atmospheric Pattern Discussion: Short Range, Long Range, Storm Systems

This is a pattern discussion which will highlight my thoughts for the short range period, the medium/long range period, and the long-long range time period into February.

Satellite imagery last night showed the development of a Kona Low just north and east of Hawaii, as the swath of enhanced water vapor shows in the bottom center part of the satellite image here. Satellite animation shows that this Kona Low is already flexing its muscles, inserting its moisture into the subtropical jet stream. The Kona Low typically not only enhances the subtropical jet stream, but also strengthens the chances of a negative Pacific North American (PNA) pattern, which involves stormy conditions in the West US and high pressure in the Central and Eastern US. This development of the Kona Low jives well with the predicted weather pattern in the next week or so, which should involve that stormy weather in the West US and quiet, warmer weather in the nation's heartland and along the East Coast.

This warmer weather will be weaving in an out of occasional storms and cool shots, as the Pacific jet is starting to rev up near the Gulf of Alaska. As the jet stream starts to head towards the nation, water vapor imagery tells us we can expect some storm systems to hit the west coast of North America in the next few days, and medium range ensembles agree, bringing a storm into the Central US in the next 3 to 4 days, and also bringing a second storm system ashore in southwestern British Columbia. It is this second system where we will find ourselves reverting back to the pattern that just brought us record-breaking cold as the polar vortex swiped us to the north.

The GFS Ensemble guidance believes we will see a piece of the prevalent polar vortex (shown above as being located in northwest Canada on January 12th) break off and begin to push southeastward into the United States. This piece of the vortex will force weak ridging located in the Central US out of the way, which will allow that polar vortex to push east. At the same time, as the piece of the vortex pushes east, we will see that suppressed ridging in the northeast Pacific (which looks to be putting up a very impressive Pacific jet stream) shift eastward, and actually form another situation where high pressure intensifies along the West Coast. This ridge intensification then permits the piece of the polar vortex to deepen and slow down, as the West Coast ridging tries to create a blocking situation.

By January 15th, we can clearly see the situation I described above, with the ridging intensifying along the West Coast and allowing the piece of the vortex to deepen and press further south. However, this event will be different than the one we went through earlier this workweek. When this next cold outbreak comes along, high pressure will be more suppressed and placed more to the east than before. This looks to be a consequence of that intense Pacific jet stream, which will allow high pressure to extend east and actually prohibit certain parts of the Rockies and Plains from getting in on this second wave of cold weather. Because of that eastward propagation of the ridge, I think we will see the Central Great Lakes into the Northeast really get in on this cold outbreak, with the western Plains and parts of the southern Plains getting snubbed by high pressure.

The next item to discuss is that January 17-21 potential Colorado Low / Panhandle Hook storm. If you recall, I have been touting this idea of a storm system for a while now in recent posts.

The pattern in the couple days prior to this time period looks a lot like what you see above, but another piece of the vortex looks to break off and deepen again in the Central and Eastern US to provide another cold weather opportunity. This storm will really depend on where high pressure will be located in the Western US, and how it will affect potential high pressure development off the East Coast. If we see the ridging centered more west, I can see better potential for this Colorado Low / Panhandle Hook storm verifying. However, if it is centered more to the east, the storm might not be able to pull off its act, as ridging may overpower it. Model guidance is pretty cloudy on just how this event will evolve, so right now I'll leave it as the storm being possible. I had previously had higher confidence, and still do in the sense that there will be some wintry weather in this timeframe, but location issues of this possible storm mean that this high confidence is somewhat reduced.

Confidence is reduced because of the projected East Asian weather for January 12th. Knowing that a storm in East Asia results in a storm in the US 6-10 days later, we can use that January 12th Japan storm that is shown above to project a storm in the timeframe of January 18-22. That falls right in the other timeframe for this storm. The reason my confidence is reduced in addition to the potential ridging issues is because that Japan storm is pretty far north in the country, almost to the north of the country itself. This may indicate that our storm system between January 17-22 may actually be more to the north than we thought. I'm not going to jump to conclusions, just something to ponder.

ECMWF Ensemble 500mb height anomaly guidance for January 24th shows us that the nation would be in for a cold but progressive weather pattern. This is exhibited well by the intense ridging along the western Coast of North America into the Gulf of Alaska. That intense ridging is the same high pressure pattern that made the environment conducive for a brush with the polar vortex earlier this workweek. However, we see some stormy weather just to the east of Greenland, and that tells me that the chances of seeing prolonged cold outbreaks and persistent west coast ridging are low. When you have stormy weather near Greenland, it results in a positive North Atlantic Oscillation (NAO), which means the pattern wants to keep everything moving west-to-east, not letting any high or low pressure system staying in one place for a long period of time. Thus, I expect we will see a cool end to the month, gradually easing up as the upper stratosphere has been cooling recently.

I have also been talking about a January 24-28 winter storm that may be either an Apps Runner or Nor'easter per my latest post. Now, we can add onto that with new data.

This image shows observed weather on November 27th. We can use data from the past to predict the future by utilizing the Lezak Recurring Cycle (LRC). The Lezak Recurring Cycle, or LRC, is a tool developed by meteorologist Gary Lezak that, in essence, can enable forecasters to predict the overall weather pattern months in advance. The gist of the LRC involves a cycling weather pattern that develops in October and November of each year; no pattern is the same from year to year. Around mid November, the LRC begins to repeat, meaning we start to see a similar weather pattern in mid November that we saw in early October. This means that the cycling pattern has begun, and it will continue to cycle on a regular 40-60 day interval for the next ~10 months before it dissipates over the following summer. Considering this LRC season cycle length is 57 days, give or take a day or two, we can extrapolate November 27th out 57 days to get the reoccurrence of this coastal storm system. When we go ahead 57 days from November 27th, we arrive at January 23rd. And if you look closely, you'll find that it matches right up (off by a day, but who's counting?) with the January 24-28 timeframe for a coastal storm. Considering we have support from multiple indices at this point, confidence continues to grow for a late January coastal storm. Unlike some uncertainties with the Panhandle Hook storm, this East US storm looks more promising with this new data.

As we head into February, I'm thinking we will continue on the road of gradually easing out of the cold weather pattern we will have been in for much of January. Despite this, long range indices tell me we could see some continued stormy weather, and I'll be monitoring that potential in coming days and weeks.

An early Super Bowl forecast: Be on the lookout for a storm system on the East Coast in the couple days after the big game. Depending on the Pacific pattern, some cold air may be available to sweep east into the Northeast if an early February coastal storm does come to fruition.

Andrew

January 24-28 Potential Apps Runner / Nor'easter Winter Storm

There is the potential for an "Apps Runner" or Nor'easter winter storm around January 24-28, as a storm begins to traverse the Bering Sea in a favorable position.

This is the ECMWF 500 millibar anomaly forecast for the afternoon of January 5th, the day this post was published. You can see the deep negative geopotential height anomalies over the southwestern portion of the Bering Sea, and I drew a line outlining a rough track of where this storm system is projected to go in the next few days. Around January 6, the storm begins to cut north across the central/eastern Aleutian Islands, and then turns a little northwest to swirl in the Bering Sea. This is a telltale sign that we may be in for an Apps Runner or Nor'easter winter storm, as Joe Renken's Bering Sea Rule describes.

The Bering Sea Rule states that by watching storm systems make their way across the Bering Sea, one can identify where and when a storm system will show up in the United States. The general timeframe is 17-21 days after a storm appears in the Bering Sea, a storm will appear in the United States. This rule is already in use with the January 17-21 potential Colorado Low, and now it looks like the Eastern US might encounter some stormy weather if the Bering Sea Rule verifies correctly (which it has, when used previously).

The storm in the Bering Sea skirts in the southern portion of the waters across the January 5-6 time period, before cutting north on the January 6-7 time period. If we extrapolate that time frame 17-21 days out to use the Bering Sea Rule, we end up with roughly a January 24-28 period that we should watch for a potential winter storm. The reason I am labeling it as a possible Apps Runner or Nor'easter is because of how far east it cuts north. Joe Renken indicates that the further west storms cut north in the Bering Sea, the further west they end up 17-21 days later in the United States. In this case, our storm system here cuts far enough east that an Apps Runner or Nor'easter scenario does seem viable. The Bering Sea system is also displaying traditional characteristics of a Nor'easter scenario, where the storm moves in the southern waters of the Sea before cutting north quickly. A Nor'easter forms in a similar fashion, where the energy traverses the Southern US before shooting north along the East Coast.

To sum up:
There is potential for a winter storm over the January 24-28 time period, and indications are it could affect the Ohio Valley via an Apps Runner, or the Eastern Seaboard by way of a Nor'easter storm system.

Andrew

November 25-27 Nor'easter Final Update

Mid-level vorticity analysis reveals that the two pieces of energy that will combine to form the Nor'easter are currently moving in their projected directions, and should merge in just a handful of hours.

It is expected that the rather strong piece of energy in Texas will shift eastward, as that system in Canada drops to the southeast. As we go through the next day or two, the two pieces of energy will merge and shift northeast to provoke a heavy rain event and substantial snow event over parts of the Northeast and Mid-Atlantic.

Snowfall forecasts over the next 60 hours have totals either flirting with or above the 12 inch mark along western New York, west Pennsylvania and northeast Ohio. Lighter amounts are anticipated in the higher elevations in the New England area, but will still allow for plowable amounts. Lower elevation areas should receive a couple of inches from this system, while coastal areas will receive some major rain amounts.

Rain amounts along the coast should push above 2 inches, making this system quite a wet one. I find it possible that some areas will experience flooding, though I'm not sold on a huge flooding event. The more likely scenario is rather heavy rain for most of the Eastern Seaboard in the Northeast and Mid-Atlantic, with lighter amounts inland. Bear in mind that while this forecast shows significant precipitation for the inland areas in line for snow, it's likely that the snow will be heavy, as this is only November, thus light, fluffy snow is rather unlikely.

Stay tuned to your local weather service if you are at risk of this winter weather. Winter storm watches (navy blue), advisories (purple) and warnings (pink) have already been hoisted across the Northeast and Mid-Atlantic as this first snow event begins to unfold.

Andrew

Thanksgiving Potentially Significant Nor'easter

I believe that the probability of a Nor'easter around the timeframe of Thanksgiving is now high enough to be labeled as potentially significant.


Model guidance has been somewhat consistent on the development of a coastal storm system out of two pieces of energy, one from the Gulf Coast and one from Canada. The prognosis right now is that the piece of energy along the Gulf Coast will push east along the coast before the Canadian energy drops down far south enough to pick up the coastal energy. When the two pieces of energy begin to interact, it is expected that the Canadian energy will pick up the Gulf Coast system, the two will shift northeast and form one coastal storm system that will then become a full-blown Nor'easter. Now, model guidance is not completely on board with this system. The European ECMWF model has been in favor of a Nor'easter for a while, but the GFS model has been flipping back and forth between a storm or no storm. For reasons of consistency with the ECMWF, and agreement among the prestigious ECMWF ensemble prediction system (EPS), we will go with that model system.

Precipitation projections are tricky right now, as model guidance is still not 100% sold on the Nor'easter even occurring. However, if it is to occur, it is anticipated that coastal regions will receive rain while inland areas get potentially significant amounts of snow. This is due to a variety of factors, including the proximity of the storm to land, the anomalously warm water temperatures along the coast, and the fact that it's only November, and therefore there will still be warm temperatures to interfere with snow prospects for some areas.

This ECMWF image gives you an idea of what kind of snowfall could be seen with this storm system if it occurs as is shown right now by the model system. It is still subject to potentially drastic change, so this is just shown to give you an idea of possible snowfall amounts with this storm.

So, what do we have to go on that supports this potential likely winter storm? We'll start with data I discussed on Wednesday's post.

As I've told on this blog, there has been a storm forecast to hit East Asia just two days ago. It ended up verifying, and the text from a post on that discussion a handful of days ago is below.

This is a forecast from the GFS Ensembles out to the Hour 60 timeframe. While all of the colors and lines may seem a little overwhelming, we're only going to focus our attention on East Asia, which is under the deep blue swath in the top left part of the left panel. Another correlation that has been proved effective is how weather in East Asia can be reciprocated in North America 6-10 days after the weather anomaly in East Asia. This includes the presence of storm systems or high pressure in East Asia. The November 18 forecast from both the GFS Ensembles and ECMWF model indicates that a deep negative height anomaly swath will slide down over Japan. If we extrapolate November 18th six to ten days out, we come up with a potential cold weather and storm system time frame of November 24 to 28. This narrows down the timeframe previously set out by the Bering Sea correlation, and if we match up the two timeframes (November 24-28 for the East Asian connection and November 25-29 for the Bering Sea connection), we come up with a November 24-29 potential timeframe for a storm, which can be isolated into the November 25-28 period, which is shown by both connections. Based on these two connections coming up with a common timeframe for a potential US storm system, confidence is quickly rising that this event will happen. 

The evidence doesn't stop there- here's text from a post on this storm potential I made back on November 13:

Take a look at the Bering sea in this two-panel reanalysis of the weather on November 8th. If you look closely, you can see that the Bering Sea was in the midst of a decent storm system on this date, just three days ago from today. This storm system passed along those waters in the midst of a mammoth ridge of high pressure just to the south. The 500mb height anomaly chart on the left best reflects this storm system, but its presence is confirmed on the right panel, which displays mean sea level pressure contour lines and denotations, as well as cloud cover. This Bering Sea storm has a connection to this potential Thanksgiving winter storm. Based on research done by Joe Renken, weather in the Bering Sea correlates to weather here in the US approximately 2.5 to 3 weeks after the Bering Sea weather anomaly occurs. This storm system in the Bering Sea happened on November 8th, and extrapolating that out 2.5 to 3 weeks ( 17-21 days) leads us to a potential storm system impacting the US around November 25 to 29. Considering November 28th is Thanksgiving, there does appear to be at least decent potential for a winter storm around the Turkey Day timeframe. (End post)

The East Asian and Bering Sea correlations alone are enough for me to be decently confident in this event occurring, but there are other items that further enhance the probability of a winter storm along the East Coast.

This is the North Atlantic Oscillation forecast from the ECMWF for the next 10 days. The North Atlantic Oscillation, or NAO, involves pressure anomalies over Greenland that influences synoptic weather over North America, and around the world. The positive phase of the NAO involves stormy weather around Greenland, and this translates to warmer weather across the US, as well as a zonal flow across the nation. The negative NAO comes about from high pressure stationed over Greenland, and this permits cold weather to enter the East US, and enhances the chances of a coastal storm. The area where this storm may occur is circled in red, and as you can see, the model projects the NAO to be switching phases during this timeframe. It has been demonstrated that when the NAO is switching phases, coastal storms become more likely. Thus, it isn't such a far-fetched idea that a Nor'easter could occur in the day or two prior to Thanksgiving, possibly into Thanksgiving itself.

(Image removed for security purposes)

Now, I've discussed how the GFS and ECMWF are at odds with each other over this storm, but there is one atmospheric feature that they do agree on with this storm system. Both model guidance systems indicate that there will be a rather strong storm system around the far eastern portion of Canada. This is called a "50/50 Low", and is called such because of the presence of a low pressure system around 50 North and 50 West on the latitude and longitude scales, respectively. When a 50/50 Low forms, it is not uncommon to see a coastal storm to occur in the 2-3 days after the phenomenon. That said, I believe the ECMWF when it comes to the projection for this Nor'easter, in addition to the Bering Sea and East Asian correspondents.

I would make an outlook map, but I'd like to wait a bit longer before I do so, mainly because I would like to see the GFS come on board, and I want to see where that snow-rain line places itself, as that will make a big difference in my forecast. But right now, I'm feeling pretty good about a potentially significant coastal storm in a day or two before Thanksgiving, maybe into the actual day of Turkey Day.

Andrew

Thanksgiving Potential Major Nor'easter

There is potential (keyword here is potential) for a Nor'easter to form along the East Coast in time for Thanksgiving, and if true, may drop copious amounts of snow on the inland Northeast.

The overnight 0z ECMWF model projects a rather strong piece of energy to slide along the Gulf Coast in the few days leading up to Thanksgiving, drifting almost due east as the jet stream allocates the energy in that direction. At the same time, another piece of energy will be dropping south and east from Canada, and if you know what phasing is, you know what happens next. The model then has the Canadian and Gulf Coast energies combine into a single system that forms just off the East Coast to form a strong coastal storm, as the forecast below (valid November 27) shows.

The ECMWF model has this Nor'easter bring massive amounts of snow and liquid precipitation to the Northeast, and spreads the wealth north and east to cover most of the interior Northeast. The minimum pressure is projected to be at 991 millibars, which pretty much qualifies the statement that this would be a substantial coastal storm. 

Now, the new runs of the ECMWF and GFS do not show this happening. The ECMWF takes the southern energy and pushes it out to sea as the two pieces of energy do not merge in time to form this possible Nor'easter. So why bring it up? Well, there is most likely going to be a storm system somewhere in the US in the days just before Thanksgiving. As I've told on this blog, there has been a storm forecast to hit East Asia just two days ago. It ended up verifying, and the text from a post on that discussion a handful of days ago is below.

This is a forecast from the GFS Ensembles out to the Hour 60 timeframe. While all of the colors and lines may seem a little overwhelming, we're only going to focus our attention on East Asia, which is under the deep blue swath in the top left part of the left panel. Another correlation that has been proved effective is how weather in East Asia can be reciprocated in North America 6-10 days after the weather anomaly in East Asia. This includes the presence of storm systems or high pressure in East Asia. The November 18 forecast from both the GFS Ensembles and ECMWF model indicates that a deep negative height anomaly swath will slide down over Japan. If we extrapolate November 18th six to ten days out, we come up with a potential cold weather and storm system time frame of November 24 to 28. This narrows down the timeframe previously set out by the Bering Sea correlation, and if we match up the two timeframes (November 24-28 for the East Asian connection and November 25-29 for the Bering Sea connection), we come up with a November 24-29 potential timeframe for a storm, which can be isolated into the November 25-28 period, which is shown by both connections. Based on these two connections coming up with a common timeframe for a potential US storm system, confidence is quickly rising that this event will happen. 

The evidence doesn't stop there- here's text from a post on this storm potential I made back on November 13:

Take a look at the Bering sea in this two-panel reanalysis of the weather on November 8th. If you look closely, you can see that the Bering Sea was in the midst of a decent storm system on this date, just three days ago from today. This storm system passed along those waters in the midst of a mammoth ridge of high pressure just to the south. The 500mb height anomaly chart on the left best reflects this storm system, but its presence is confirmed on the right panel, which displays mean sea level pressure contour lines and denotations, as well as cloud cover. This Bering Sea storm has a connection to this potential Thanksgiving winter storm. Based on research done by Joe Renken, weather in the Bering Sea correlates to weather here in the US approximately 2.5 to 3 weeks after the Bering Sea weather anomaly occurs. This storm system in the Bering Sea happened on November 8th, and extrapolating that out 2.5 to 3 weeks ( 17-21 days) leads us to a potential storm system impacting the US around November 25 to 29. Considering November 28th is Thanksgiving, there does appear to be at least decent potential for a winter storm around the Turkey Day timeframe.

There is something else that must be noted with the ECMWF model I discussed at the top of this post. There has been discussion that the model has a bias, in which it holds energy in the Southwest US for longer than it ends up being there. I have a feeling that if this bias ends up working out in this situation, we would see the merge occur in the Northeast, resulting in that coastal storm. That is, if the energy in the South is able to latch on to the Canadian energy- in the most recent ECMWF model run, the southern energy was unable to phase with the Canadian energy until it was too late and the potential coastal storm was already off to the Canadian Maritimes. To give you an idea of what the snow forecast might look like if this Nor'easter occurred, take a look at the overnight ECMWF forecast below (warning, don't take this as a legitimate forecast just yet):

What I'm saying is, there really is potential here that needs to be monitored.

Andrew