Long Range Thoughts & Potential Thanksgiving Major Winter Storm

**This post is dedicated to all former and active soldiers and veterans across the Armed Forces.**

I was taking a look at the long range this morning, and decided it was time to do a post on what my thoughts for the middle and end of November are. However, as I was sifting through the data I wanted to include in this post, I came upon the realization that this data indicated a threat for a potentially major winter storm around the Thanksgiving timeframe. Let's jump right in. We'll start off with the long range thoughts, and then go into the major winter storm threat. At this time, the winter storm discussion remains preliminary. Nothing is set in stone for this potential, and the reason I include 'major' in the possibility is due to certain composites I have at my disposal that indicate this could be a big winter storm. Again, it's nowhere near certain. But let's begin.

We'll start with the teleconnections, with the Arctic Oscillation up first. The image above shows the GFS ensemble's projection for the Arctic Oscillation from now until a couple days before Thanksgiving. As we stand now, the Arctic Oscillation (AO) is in a strong positive state. The positive phase of the AO calls for a stronger than normal vortex in the Arctic (commonly referred to as the polar vortex), and a tendency for warmer weather to prevail across North America. This has been the case in the last few days for some in the United States, but with the big cold snap coming into the heart of the nation starting today, that warm weather trend will be quickly reversed. Bear in mind that the Arctic Oscillation is not exactly what I consider to be a significant influence on the American weather when compared to the other teleconnections. For one, the AO is based in the Arctic, and while the jet stream is influenced by the AO's actions, the Arctic isn't upstream of North America like the Pacific teleconnections are. Because those Pacific teleconnections are upstream of the nation, they wield significant influence on the North American weather pattern. Regardless of which index wields more power, it is agreed on that the Arctic Oscillation does play at least some role in the US' weather, and this is why it bears watching. With the AO heading down to neutral territory about a week prior to Thanksgiving, and possibly hitting negative territory when Turkey Day comes about, the tendency for warmer weather should gradually let up in coordination with the weakening +AO.

Next, we'll take a look at the close cousin of the Arctic Oscillation, the North Atlantic Oscillation (NAO). The NAO has a positive and negative phase, like the Arctic Oscillation. The NAO is determined by pressure anomalies in and around Greenland- if there is abundant high pressure in Greenland, the NAO is determined to be negative. Similarly, if stormy weather is found in the Arctic landmass, the North Atlantic Oscillation is declared to be positive. Generally, the negative NAO is the index that is the most beneficial for winter weather folk along the East Coast. When the NAO goes negative, the jet stream shifts in a way that not only allows cold air to sink down into the Northeast, but also grabs storm systems from the Southern US and swings them up north to ride the jet stream along the East Coast. This set-up usually leads to the infamous Nor'easter coastal storms. Right now, we see the NAO is in a moderately positive phase. Like the Arctic Oscillation, a positive NAO tends to enhance the likelihood of a warm weather pattern in the US. However, as time goes on and we progress into the middle of November, the ECMWF ensembles (pictured above) project the NAO to gradually shift into a neutral phase, and possibly a negative phase as we move towards Thanksgiving. The ECMWF ensembles don't really show this negative NAO shift at the end of the forecast period, but the American ensemble system is set on the NAO going negative at around the same time as the Arctic Oscillation. These two indexes going negative for the middle and end of November spells good news for winter weather folk across the board, and will influence the potential Thanksgiving winter storm threat.

The third teleconnection we will discuss rounds out the 'Big Three' teleconnections that seem to have the most influence on winter weather in the United States. The image above shows the GFS Ensemble forecast for the Pacific-North American (PNA) index, which is based along the West Coast of North America. Like the previous two indexes, the PNA has a positive and negative phase. In the positive phase, high pressure anomalies are found along the West US and into Southwest Canada. This allows the jet stream to buckle south in the Plains and Midwest, giving those regions cold weather. The shifting jet stream also permits the Midwest and Ohio Valley to receive some decent chances for winter storms. In the negative phase, cold and stormy weather is found in the West US, and this alters the jet stream in the opposite way as the +PNA. The buckling of the jet stream occurs in the West US instead of the East, and this then leads to, you guessed it, warm and tranquil conditions for the East US. The PNA has been slightly negative and still is as of now, but is projected to gradually push into neutral territory in coming days. In the long range, ensemble guidance indicates the PNA should push into positive territory around Thanksgiving. This will be a big factor in the potential winter storm I will discuss later on.

As if this long range discussion wasn't long enough already, we're going to dive into our fourth teleconnection, the East Pacific Oscillation (or EPO). There are two phases associated with the EPO; positive and negative. In the negative phase. warm weather tends to arise along the Northeast Pacific, as a result of ridging in the region. Downstream of those waters, colder weather is favored in the Central and East US. In a similar way, the positive EPO comes about from stormy weather in the Gulf of Alaska (same as the Northeast Pacific waters I discussed with the -EPO), and leads to warmer than normal temperatures across a wide swath of the Central and Eastern US. Currently, the EPO is in a deep negative phase, and looks to stay there for the next week or so. Beyond then, ensembles fluctuate but eventually settle the EPO back down in time for a moderately negative EPO in time for Thanksgiving. This fourth index, while not as significant as the other three, will play a role in the long range temperatures and where this potential winter storm will end up.

The final teleconnection to discuss is the Madden Julian Oscillation (MJO), which is more like a whole other index than a teleconnection. The MJO tracks convection anomalies along the Equator, and, depending on the strength and location of the enhanced convection, is sorted into one of eight phases. Each phase has different temperature and precipitation effects for different times of the year. Per the current MJO analysis and forecast above, we see that the MJO is in the white circle in the middle, meaning it is too weak to have a significant impact on our weather. However, towards the days leading up to Thanksgiving, model guidance indicates that the MJO will strengthen again in Phases 1 and 2.

Composites of November MJO phases 1 and 2 reveal that the West, Plains and Midwest experience cooler temperatures in Phase 1, with a very wet pattern for the Midwest, Gulf Coast and Ohio Valley in that same phase. The East Coast ends up warm and dry for Phase 1, but the opposite is true for Phase 2. The Plains experience warm weather and dry conditions in Phase 2, while the East is bathed in cooler weather. Per the latest teleconnection guidance and MJO forecasts, I would expect a cool Central and East US for the days leading up to Thanksgiving, with the wet pattern possibly persisting across the Central and portions of the East US. Because model guidance has the MJO so weak in the long range, I'm hesitant to say it will have a big impact on the weather pattern for the end of November, but I am confident in saying that it will have at least a slight impact.

Based on all of the teleconnections and indexes presented to me, it looks as if the weather pattern will undergo some change in the next week or two, as a new, more winter-like pattern takes hold near Thanksgiving. This will set the stage for what could be a major winter storm in the US, and that's what we will discuss next.

So what's all of this talk about a Thanksgiving winter storm? It's only November 11- how can I know this is actually a possibility? Well, we know that this is at least a possibility due to the weather experienced in the Bering Sea recently, and the weather East Asia will experience soon.

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. But this is only scratching the surface of this storm's potential, and for that reason, we'll continue on with the investigation into this potential winter storm.

This is a forecast from the GFS Ensembles out to the Hour 168 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 rising that this event will happen.

So, we have tentatively established that there will be a Thanksgiving winter storm. Where would this storm go? Well, we can get a decent idea from not only the aforementioned teleconnection discussion, but also from a set of composites I outlined for the Midwest and Northeast for major storm systems.

Let's outline what we are expecting in terms of teleconnections for the time around Thanksgiving- more specifically, the November 24-29 period for when this storm could occur. The Arctic Oscillation is expected to be neutral or negative for this timeframe, meaning there may be cold air available for a winter storm and not just a regular storm system. The North Atlantic Oscillation should be in neutral or negative territory, which tells us the energy from this storm should be kept south in the Plains, following the probably-positive (or neutral) PNA, which ought to encourage this storm system to head into the Plains, Midwest or Ohio Valley. The EPO will most likely be negative, and this helps out the cold air idea that the negative Arctic Oscillation should try to establish for this storm system. So now that we've established that there should be a neutral/negative AO, a neutral/negative NAO, a neutral/positive PNA, and a negative EPO, let's take a look at some composites I made up for the Midwest for major winter storm systems and their relationships to teleconnections.

Legend on left shows number of storms.

By accounting for a handful of major winter storms in the Midwest, I was able to create a composite of when winter storms are most likely to occur in this region. By looking at a total of 17 major winter storms, I compiled data that indicated a negative NAO, positive PNA, negative EPO and negative AO were most favorable for Midwest winter storms. Do those phases of the teleconnections sound familiar? They should, because they match up nearly perfectly with the forecasted teleconnections around Thanksgiving. I also collected data from these 17 storms on the Madden Julian Oscillation, and that told me that an overwhelming percent of the sampled winter storms involved the MJO being in Phases 5-8, with emphasis on Phases 7-8. This composite doesn't match up as well as the teleconnection information, but as I showed in the MJO discussion earlier, Phase 1 still has a very wet pattern for November for the Midwest and Ohio Valley.

I do have snowstorm composites for the Northeast as well, but the teleconnection composites aren't nearly as definitive on which phase is more favorable as the Midwest composite is. What I did draw from the MJO Northeast winter storm composite, however, is that the latter MJO phases (Phases 7-2) are most favorable for Northeast winter storms. The negative NAO and favorable MJO composite would seem to lend a hand to the Northeast in terms of this winter storm potential, although right now, I personally see the Midwest, Plains and Ohio Valley at risk for this system. But as is with these long range projections, it's not set in stone.

WARNING: This graphic is unlikely to verify as is shown. I am showing it because the GFS may have caught on to this idea for one run, but I am NOT endorsing it in any way, other than just to point it out.

For what it's worth (and it's worth very little), the GFS model caught what could be this possible snowstorm on its 0z run, but has since dropped it. This may give you an idea of my current thoughts in terms of storm placement, but not necessarily the precipitation type.

Andrew

2013-2014 Winter Update: Early November, 2013

This update on the 2013-2014 winter will address what has changed and what has not since the Final 2013-2014 Winter Forecast, as well as what the changes say about the upcoming winter.

What Has Changed

Prognosis on the Arctic Oscillation
The Arctic Oscillation is now anticipated to be rather positive this winter, as October SAI data, when accounted for the full 31 days of the month, shows a rather flat change from October 1 to November 1 over the SAI index area. This tells us that the Arctic Oscillation may not be as negative as previously thought. Also hurting the prospects of a negative Arctic Oscillation is the predicted positive AO for much of November. It is shown that the November Arctic Oscillation value can translate on a positive correlation for the following winter 68% of the time. For example, a negative Arctic Oscillation in November translates to a negative Arctic Oscillation in the following winter 68% of the time. The same goes for a positive AO. This is not good news for those wanting a negative Arctic Oscillation this winter, as the positive phase of the Arctic Oscillation tends to dampen prospects for cold weather. At this time, indications are that the AO may tend to be more positive than negative.

Sunspots
The October sunspot data was released in the last week, and it shows a worrying scenario for the upcoming winter. If we go by the acknowledgement that sunspot spikes precede a warm weather trend by 2-3 months, it's possible we see a solidly warm start to winter, possibly extending beyond December. This is currently to be determined as far as how the sunspots really impact the winter, but I personally don't like this new development as a winter weather fan.

What Hasn't Changed

Plains Outlook for a Snowy Winter
The Lezak Recurring Cycle continues to point to the Plains and Upper Midwest as being in line for a snowy winter this season. Multiple storm systems that have traversed through the region since October 1 indicate that the region of interest ought to have the advantage in the snow department this winter.

The Ocean Teleconnections
The Pacific Decadal Oscillation, Atlantic Multidecadal Oscillation, and ENSO indexes remain on track as forecasted: negative, positive and neutral, respectively.

The Quasi-Biennial Oscillation
Everything still on track for entry to Phase 7 by mid winter. Entry into that phase may be a tad earlier now, but the end half of winter should still see a full-blown Phase 7 QBO.

Practically everything else
The Final 2013-2014 Winter Forecast is looking fairly good at this point.

The warm start to winter still looks on, with a gradually cooler trend going on into winter. Expect a turbulent atmosphere/stratosphere in the end half of winter, as the changing QBO permits stratospheric warming events, and thus helps the chances for a negative Arctic Oscillation. Snow should favor the Plains this winter, with cold weather centered across the Plains, Midwest and Great Lakes. More to come as we press on into winter.

Andrew

November 17-20 Potential Winter Storm

There is a chance of a winter storm to impact the Plains and Midwest over the November 17-20 timeframe.

(From the post on November 6):

Shown above is the 12z GFS projection of 500 millibar height anomalies across the North Pacific, valid for November 10. If you look over by Japan, you will see a swath of negative height anomalies over that area. This is suggestive of a storm system in the area. As some of you may have seen on this blog and elsewhere, it has been discovered that troughing in East Asia tends to lead to a storm system and associated cold weather event in the East US roughly 6-10 days later, per Joe Renken. The image above is valid for November 10th, meaning we are looking at the November 16-20 timeframe for a potential cold weather event and winter storm.

On November 6, I discussed above how we should be watching the November 16-20 period for a winter storm due to a storm system in Japan, as is shown above. Well, the storm system is currently dropping down into Japan, and should go through the area in the next couple of days. This means the November 16-20 timeframe remains on track. And as of this morning, model guidance is beginning to catch on to this idea of a winter storm for someone in the East or, more likely, the Central US.

The ECMWF model shows three major players in its 240 hour 500mb vorticity forecast: a strong piece of energy in the Southwest, a piece of energy in south central Canada, and ridging along the West Coast of the United States. These three factors will influence where this potential storm system ends up, and how strong it may eventually become.

The prognosis is that a piece of energy will enter the Western US at around the same time another piece of energy drops down into the center of Canada. Now, the energy that will be hitting the US will ride up along the West Coast ridge and then drop down into the Rockies as it crawls along the Southwest to eventually push east. As it drops down from going over that ridge, it appears some of its energy will be torn off and push nearly due east, as the main bulk of the system drops down into New Mexico and Arizona. This torn off piece of energy will strengthen and interact with the energy in the middle of Canada to create the blue and green vorticity swirls you see on the Canadian/US border on the forecast image above.

The reason we want to watch this area of vorticity on the border is because it may do one of two things. It may: A) Pull the main body of energy north towards Canada, giving a snowstorm to the Plains and possibly the Upper Midwest. or, B) Have no interaction with the main body of energy, in which case the main body may prefer to move east-northeast and bring a snowstorm to the Midwest and Ohio Valley. The ECMWF does not go out past 240 hours, so we cannot see which solution it prefers (to me, it looks like the ECMWF may be leaning towards option A at this time, but I can't confirm that). However, we can see what the rival GFS model says.

Right off the bat, let's take note of how the GFS and ECMWF are very similar in their set-ups with this event for Hour 240. Both have ridging along the West Coast, both have the two pieces of energy I was discussing in the previous paragraphs, and both models have high pressure in the Southeast, something that will act to try and push the potential winter storm north into the Midwest or Plains rather than east into the Northeast.

The GFS model has the US/Canada border piece of energy further south than the ECMWF, and for that reason, the Southwest piece of energy (shown above in Texas and New Mexico) is weaker and more likely to push north into the Plains. I do believe that it is the US/Canadian border energy that will end up having the most say in where this storm goes, because if that energy is further south like the GFS shows, the storm system in question should push north and hit the Plains. But, if the Canadian system is weaker and more detached from the potential winter storm, we could see the storm affect the Midwest and Plains. And yes, if you're wondering, the Plains is currently in the best spot for this potential storm, but it's all still up in the air for another ~10 days.

An interesting piece to this puzzle is how the North Atlantic Oscillation is projected to evolve over this timeframe. The ECMWF model has the NAO changing phases twice between November 16 and November 21st. As you weather junkies may know, storm systems can be favored in the Northeast and along the East Coast when the NAO is changing phases. The model prognosis from both global guidance systems above would tell me that the storm system is unlikely to head east towards the Mid-Atlantic and such, but the changing NAO makes me want to keep an eye on that region around the November 16-21 timeframe in case something does develop. I'm not saying something will develop, but for all intents and purposes, I'd like to monitor projections over the East Coast in coming days if the projections for NAO changing phases continue.

Here's my current diagnosis on the situation. Bear in mind this is all preliminary, as we are still 240 hours away.

Andrew

November 14-16 Potential Major Winter Storm

There is a chance of a major winter storm in the Eastern US around the November 14-16 timeframe.

The current projection from the European ECMWF model shows a storm system to develop from the Southeast US before moving northeast and along the East Coast. Consequently, the storm system produces a major snow event, as the high-resolution snowfall forecast image shows below, courtesy of WeatherBell. The storm itself is produced as a significant high pressure system slips south from Canada. As the high pressure system pushes south, a storm system originates in the Southeast, and is pushed north and east as a result of this massive high pressure system. Let's take a look at that ECMWF snowfall forecast I told about a few sentences ago.

The ECMWF snowfall forecast is truly remarkable. A swath of accumulating snowfall extends from southern Mississippi to the northern border of Ohio, and from Maine to the Carolinas. Plowable snow is spread from the Northeast to the Mid-Atlantic, but it is West Virginia and the state of Virginia that gets hammered with as much as 36.6'' of snow, per the graphic above. Now, before we elaborate on this graphic further, please know that the chance of this graphic verifying on its own as is is **extremely** low. The chance of this storm happening is low as well, but realize that the 36'' is most likely not going to happen.

The American GFS model is much less enthusiastic with the event, bringing about plowable snow in an area from western Pennsylvania to North Carolina. Obviously this is not as exciting as the ECMWF model, but I'm more supportive for this solution than the European one. I'm not entirely gung-ho on this solution as is, but it's more realistic than the ECMWF projection.

So why don't I think this will be a huge storm? Well, we have to define a few things first.

It is likely that there will be a storm system in the Central or Eastern US during this timeframe. The image above gives an overview of the 500mb height contours and anomalies on the left, as well as cloud cover and sea level pressure contours/markings on the right. This image shows the Northern Hemisphere as of the time of publishing. Take a look over at Japan. If you look closely, you can see a spot of negative height anomalies over the East Asian nation. A rule of thumb in the long range world indicates that stormy times in East Asia correlate to a storm system in the Central/East US approximately 6-10 days later. With the negative height anomalies hitting Japan now, 6-10 days from today would put us in the November 13-17 timeframe, which is when the models project this winter storm to happen. That is a good thing for those of you wanting a snowstorm, but before you get excited, let's continue reading into this possible event.

If you're from the Northeast, you know that one of the most important indices to use in tracking the potential for a big winter storm is the North Atlantic Oscillation. In most cases, Northeast winter storms happen in a negative NAO. Winter storms can (and have) happen(ed) in a positive NAO, but the ratio of winter storms in the negative phase and positive phase decisively favors the negative NAO. So let's take a look at the GFS and ECMWF model forecasts for the NAO.

The GFS model projects the North Atlantic Oscillation to be positive during this timeframe, actually rising to a stronger positive stance as the potential storm unfolds. While there is truth to the idea that Northeast snowstorms can happen when the NAO is changing phases (i.e. positive to negative or vice versa), the NAO is just increasing its already-unfavorable attitude towards this potential snowstorm along the East Coast. I personally find that it would be difficult for this storm to move up the East Coast with such a strong positive NAO in place. Recall that the positive NAO allows a zonal flow (a flat jet stream, not wavy) to set up across North America. It would be pretty tough for a storm system to push north-northeast when the environment favors a west-to-east flow. Lucky for those in the Northeast, there will be a big Canadian high pressure system pushing into the Plains that will help out the chances for a snow event in the Northeast, and I will go more in-depth on that after this NAO discussion.

The European model isn't any better. It agrees with the GFS model in that the North Atlantic Oscillation will be strongly positive during this timeframe, and as I described above, the positive phase of the NAO greatly hampers efforts for this Northeast snowstorm, especially if the storm wants to go north-northeast per the ECMWF if the flow favors nothing close to that. There are always anomalies in the sense that the snowstorm may defy this positive NAO and dart north as a result of the huge high pressure system in the Plains trying to force the jet stream to bend around it, in which case the Northeast would have a decent chance at getting this potential snowstorm. However, the certainty in that proposal is much lower than the idea that the NAO will be moderately to strongly positive during this potential storm's timeframe.

Additionally, if you're one of the weather model junkies who prefer to live by the ensembles rather than the models themselves (a viewpoint that can be accurate when used correctly, but can be detrimental if over-trusted), don't argue the ECMWF and GFS NAO projections- the GFS ensembles and ECMWF ensembles confirm the positive NAO during the November 14-16 timeframe.

Now, the true wild card in those whole potential snow storm is Canada. Well, a Canadian high pressure system, to be exact.

The ECMWF and GFS both agree that a major Canadian high pressure system will slide down into the Plains in the day or so before this potential storm system. The image above, from the ECMWF model valid on November 12th, shows a 1045 millibar high pressure system in Nebraska. For those who aren't familiar with the millibar system, let me tell you that 1045 millibars defines a very strong high pressure system- not just any ol' high pressure system. There is the idea that some energy will ride the jet stream as it buckles south due to the high pressure system, well shown by the GFS model below:

You can clearly see the energy dropping south, right along the contour lines that show a steep ridging across the Western US, and then the downhill slope of contour lines in the Minnesota/Iowa area. This is the potential area of energy that would cause the potential winter storm, and its entrance into the US on the 12th bodes well with the East Asia correlation of a potential cold weather event/storm system between the 13th and 17th. Both the ECMWF and GFS agree on the entrance of this energy into the US around this timeframe, but the question is, how will the energy react when it encounters the rather-zonal flow along the East Coast (to which the positive NAO may be to blame)? Well, as the energy pushes southward, it is expected that some slight ridging will be produced on the waters east of the Southeast states. This would help northeast-ward movement of the storm system, like the ECMWF believes will eventually land it in the Northeast. However, if the ridging is too weak, the system may not move up the coast as eagerly. Or, if the ridging is too strong, it may stay further inland. Per the latest GFS and its ensemble system, the first option would come true, and the energy would meander off into the Atlantic, likely leaving some snow, but not a massive amount. I haven't seen a model call for due-north movement of the system in the event ridging is too strong- it appears to be the ECMWF's north-northeast movement vs. the GFS' eastward motion for this potential storm system.

Let's summarize all of this.

What we know

-There will most likely be a storm system in the Central/East US during the November 13-17 timeframe.

-A big Canadian high pressure system will drop down into the Plains to influence this potential storm system.

What we don't know

-The storm's track.

-The exact strength of high and low pressure systems in the Pacific and West US before and during the aforementioned timeframe.

So what do I expect?

I believe there is a chance of plowable snow (in this case, 2-6 inches) stretching from South Carolina to Massachusetts, but this is a low-confidence outlook. I do think there is a decent chance of snow falling in the outlined area- the question is how much. I prefer to play it safe at the moment and will go with the 2-6'' projection in the Plowable Snow zone, due to GFS/GEFS agreement on such an idea, but if the American models start to side with the pro-snowstorm ECMWF, you may very well see this outlook adjusted accordingly.

Andrew

November 16-20 Potential Cold Shot & Winter Storm

There is a possibility of a cold weather event and winter storm in during the November 16-20 timeframe.

Shown above is the 12z GFS projection of 500 millibar height anomalies across the North Pacific. If you look over by Japan, you will see a swath of negative height anomalies over that area. This is suggestive of a storm system in the area. As some of you may have seen on this blog and elsewhere, it has been discovered that troughing in East Asia tends to lead to a storm system and associated cold weather event in the East US roughly 6-10 days later, per Joe Renken. The image above is valid for November 10th, meaning we are looking at the November 16-20 timeframe for a potential cold weather event and winter storm.

As of now, there is no way to determine which areas may be hit by the potential storm system, and who may be affected by the cold weather. Per the weather pattern in the days leading up to the aforementioned timeframe of interest, I currently see the Plains at the best risk of this winter storm, mainly due to a rather strong high pressure system in the East US. However, as future model runs come out, the situation is bound to change. In the same sense, the potential areas affected are bound to change. This is a very fluid situation, and asking if your area may be affected will not yield any accurate answers, unfortunately.

Andrew