As we close out another week, the Northeastern U.S., in addition to northern portions of the Mid-Atlantic, are hunkering down and preparing for a major winter storm, which will definitely leave its footprint, when it’s all said and done.
A lot of data has come in over the past week, which has increased my confidence in the track of this winter storm, so let’s get right to it.
An Arctic front will be accompanied with the system, and on the leading of this frontal boundary, will be temperatures in the upper 40s to low 50s and there may even be some 60s in some spots. These mild temperatures will extend from New Jersey down into Florida. Keep in mind, that this is Sunday morning, at 7:00 AM, Eastern Time, thus implying that temperatures will increase overnight tomorrow. On the opposite side of the front, will be bitterly cold temperatures! (Figure 1).
Currently, the storm system is starting to re-develop over the central U.S. after slamming the Sierra Nevadas with exceptional 48-hour snowfall, in addition to torrential downpours of rain in lower elevations of California over the past couple of days (Figure 2).
This system is part of a big area of low pressure situated over the southern Plains.
As shown by the surface map, the isobars are tightly packed together around the low, which means that it is very windy in those locations, especially over New Mexico, where winds are brutal right now, sustained at 20 miles per hour (mph) or more. With these tightly packed isobars, and a counterclockwise spin of the low pressure system, moisture from the Gulf gets drawn into the storm system, thereby increasing the storms strength as it moves eastward (Figure 3).
As stated earlier this week, along any typical cold front, thunderstorms will develop along the leading edge of the front. However, with Winter Storm Harper, we are in a rare situation as just stated, where moisture from the Gulf gets pushed into the storm, behind the cold front, consequently forming snow.
As I time things out from here, Winter Storm Harper will start to get its act together and it will start to move much faster over the next five to six hours. By 8:00 PM Eastern Time (7:00 PM Central Time), heavy snow will start to develop over Iowa, and Northern Missouri (Figure 4).
I expect minor snow accumulations in these areas, although southern Iowa and northern Missouri could pick up four to eight inches by 6:00 AM tomorrow (Figure 5). However, I do not expect this to be a high impact event for the Great Plains or much of the Midwest, thus it should be noted that Iowa, along with northern Missouri have the highest uncertainty right now, as to how much snow falls, and how big of an impact this will have on travel.
From 9:00 to 10:00 this evening through 6:00 AM Sunday, Central Time, snow will fall across the Midwest, with minor to moderate impact (Figure 6).
I do expect there to be a heavy band of snow running through central Illinois, central Indiana, and central Ohio, where there could easily be six to twelve inches of snow by Sunday morning (Figure 7), however, areas just north and south of those areas should expect little snow from this system.
The hardest hit area without a doubt, will be the Northeastern U.S. and northern Mid-Atlantic states, not the Midwest or Plains.
Snow should start moving into Pennsylvania by late Saturday evening, tracking Northeast. By 1:00 AM Eastern Time on Monday, all snowfall will come to an end, as the system moves up into New Brunswick, Canada (Figure 8).
The darker the blue shown in the animation represents heavier snowfall. If we have strong winds with this storm as it dumps snow over New England, then this could create blizzard-like conditions for some people, especially if you are in the heavier band of snow.
Models have been very consistent over the past couple of days, so there is really no point in showing them; all models agree that interior New England should be the hardest hit areas.
There will be a widespread 12 to 18 inch swath running from Pittsburgh to Portland, NE and further North and East, up into Syracuse, NY and Burlington, VT. I expect one to three inches of snow for our big cities of Baltimore, MD, Cleveland, OH, Philadelphia, PA, three to six inches for areas near New York City and Long Island, and also over on Nantucket Island and Cape Cod, MA. Boston can expect six to twelve inches of snow if and only if it does not transition to sleet or freezing rain, which is a possibility. (See Figure 9).
Due to the widespread area of snowfall, I wouldn’t be surprised to see some school cancellations and/or delays for counties and cities area-wide Tuesday. It will be a very high impact event, so please drive safe, enjoy the snow, and God bless!
Remember this: “All Weather Is Good, It’s What You Make of It.”
As you continue to dig out from Winter Storm Gia, you might as well leave all of that snow there, because there is a very good chance that many of us in the Mid-Atlantic, and Northeastern U.S. will see a significant winter storm this coming weekend, and I am not talking about a typical snowstorm, but rather a BLIZZARD.
Before anyone gets too hyped up about this, I want to explain to you why it may or may not happen, and why some people will get nailed with snowfall, while others will get little to nothing 50 to 100 miles north or south from the general coverage area.
Aside from the major winter storm potential this upcoming weekend, there is high certainty that we will emerge into a historic Arctic outbreak, from the Great Plains to the Deep South and East Coast.
In regards to that, I do firmly believe as of right now, that this winter storm and Arctic outbreak have a lot of potential, so let’s get right to it.
Temperatures this week will start off below normal, and will gradually moderate closer to the seasonal average locally across much of the East Coast, with some of the Mid-Atlantic and Southeastern States approaching 50 to 60 degrees Friday afternoon (Figure 1).
However, areas like the Midwest, Great Plains, and even areas up in the interior Northeast will do the exact opposite (Figure 2); a big Arctic chill will cause the temperatures to plummet, and that mass of Arctic air will slowly progress south and east over the course of this week.
This mass of cold air will be in “ruling the roost” due to the presence of a very strong Arctic high sitting directly above the Great Plains (Figure 3).
Due to the cold air surging eastward, the warm air will be forced out, and this will form a frontal boundary between the Arctic air and the milder air, a very strong cold front, which us weather geeks like to refer to as an “Arctic front.” This Arctic front is a tremendous Arctic front, as temperatures ahead of the front will be in the 40s, 50s, and 60s, but behind the front will be brutally cold air, possibly record breaking cold.
And indeed, when you look at Friday’s temperatures across the eastern half of the U.S. (Figure 4), you can see a sharp drop-off in temperatures as you head further inland across the eastern states.
For instance, you go from 58 in Columbia, South Carolina, down to 47 in Asheville, North Carolina, and 30s the farther north and west you go.
Typically, along cold fronts, you will get thunderstorms to develop along the leading edge of the front, while dry air fills in behind the front, however with what is about to take place, something different happens.
Because the trough is in place, the moisture from the Gulf gets fed into the cold air through advection, thus there is very heavy rain along the front, with very heavy snow behind the front (Figure 5). This is a very rare situation, and doesn’t happen that often, and this special case has produced many of our biggest East Coast snowstorms on record.
I want to direct your attention to the Northeast, so we will zoom in (Figure 6).
Notice how tight those isobars are behind the Arctic front. Tight isobars imply that winds will be howling out of the northeast during this weekends snowstorm, pounding the Mid-Atlantic and Southeastern states with brutally cold air, thus the precipitation falling will be snow.
Because this is a low pressure system, heavy snow (or rain) will encircle the low as it spins counterclockwise, and with very strong winds in place, that would produce blizzard-like conditions. This doesn’t mean that this weekends snowstorm will be a blizzard for the East Coast; nothing is set in stone yet. In order for it to be a blizzard, it must follow the National Weather Service guidelines.
Winds must be at least 35 mph.
Visibility must be reduced to 1/4 mile or less.
These conditions must last for at least three hours.
Let’s take a look at this by different scenarios.
In scenario one, a little system comes up the coast on Friday, rain will stay to the south and east, while light snow will stay to the north and west. This event will have little impact on most areas across the east coast (Figure 7).
By Sunday, the Arctic front will start to push through the region (Figure 8). As stated warmer air will be ahead of the front, with rain right along that frontal boundary, but behind the front are heavy winds and heavy snow, with very cold temperatures.
Between Sunday and Monday morning, the front will have pushed through bringing in some very cold air and some very impressive snowfall, if the FV3-GFS is correct. (Figure 9). The FV3-GFS has very heavy snow from Richmond, Virginia to D.C. to Philly to NYC, to Boston and even further north.
After the storm rolls through, brutal Arctic air will fill in areas behind it, and with substantial snow cover, strong radiational cooling would allow temperatures as far south as southern Virginia to fall into the single digits and even below zero. Areas north of the Mason-Dixon line will without a doubt fall into the negatives (Figure 10).
Look how cold some of these cities could be Monday morning.
Portland, ME | 2 degrees.
Boston, MA | 7 degrees.
Burlington, VT | -13 degrees.
Hartford, CT | 10 degrees.
New York, NY | 9 degrees.
Binghamton, NY | -6 degrees.
Philadelphia, NY | 10 degrees.
Pittsburgh, PA | -2 degrees.
Washington D.C. | 8 degrees.
Richmond, VA | 13 degrees.
Roanoke, VA | 4 degrees.
Charleston, WV | 1 degrees.
Even look at the Midwestern states, those temperatures are ridiculously cold!
While these temperatures are almost certain to happen, the snowstorm itself may not, and you’ll see why in scenario two.
In scenario one (Figure 11), a the low pressure area forms over southern Colorado, and it will gather moisture being fed from the Gulf, thus strengthening the low as it moves eastward.
Once the low gets closer to the East Coast, it could reform over the Atlantic coast, close to shore, and the low could deepen, increasing the storm’s strength. In scenario one, the low stays closer to the east coast, rather than farther out in the Atlantic, which is good news for snow lovers.
In scenario two (Figure 12), the low pressure area does the same thing at first; it cuts across the U.S. behind the Arctic front, BUT once the low gets to the East Coast, it COULD reform for any given reason over the Atlantic coast, farther away from the shore. This means that as the Arctic front comes through, the rain will transition over to sleet or freezing rain, then to snow, and a quick inch or two could fall, and then temperatures fall off the cliff into the teens and single digits, and that will be the end of the snowstorm, but just the beginning of an Arctic outbreak.
Both scenarios are possible at this point (Figure 13), scenario two is just as likely to occur as scenario one. (I hope scenario one becomes reality, which means a lot of snow for Northern VA, Maryland, D.C., Philly, NYC, Boston).
This could be a historic wintertime pattern for the eastern half of the U.S., not just in terms of possible cold records being shattered over the next two weeks or more, but the snowfall totals if this storm becomes reality, like in scenario one.
I will have much more details on this late week, so please follow me on Twitter, and Facebook for the latest details and updates.
All of the cards are on the table, now it’s time for them to play out right.
You may have heard, but we have a snowstorm coming up this weekend for those of you living in the Mid-Atlantic.
So, with that said, let’s get right to the details.
This here is the operational GFS, or American model, whichever you prefer to call it. This is the latest run, the 18Z, from Friday afternoon, with a timestamp for 6:00 this evening. (Figure 1).
I want you to notice how the snow starts moving into the area sometime between noon and 5:00 this afternoon. The reason that it takes a while to make its way over the I-81 corridor is solely because of the dry air the storm has to overcome.
We have a huge area of high pressure (Figure 2) situated to the north of us (Canadian High), which is causing the winds to blow 10 to 25 miles per hour from the Northeast, which is keeping the continuous flow of Arctic air into the Mid-Atlantic states.
In addition, that flow of cold air is keeping the humidity and water vapor levels down in the atmosphere, therefore allowing dry air to flow into the Mid-Atlantic and Northeast.
Generally, when you have dry air in place, that is not good news for snowstorm lovers, if and only if there is an incoming snow event or snowstorm. However, in our case, it looks to be in favor of snow, as the low pressure system pushes out the dry air temporarily, but the cold air is still locked in, dominated by the Canadian High.
By 12:00 in the morning Sunday (Figure 3), the first heavier burst of snow makes its way into Northern Virginia, Western Maryland, eastern West Virginia, and over southern Pennsylvania. Nothing will be happening at midnight Sunday across central Virginia, including Richmond, but areas north, and west will already be seeing steady snow, while much of Kentucky, North Carolina, and Tennessee are being drenched with rain.
By 6:00 AM Sunday, everyone is seeing moderate snow from Richmond, north, west, and east, maybe even up toward Philly (Figure 4). There is even going to be some significant ice across much of central and northern North Carolina, and near or around Winston-Salem.
By noon on Sunday, everyone is still seeing steady snowfall in Richmond and in areas north, west, and east, while significant ice continues to pile up in northern North Carolina and southwestern Virginia (Figure 5). Much of central and all of eastern North Carolina will be seeing some very heavy rain, maybe as much as one to one and a half inches of rain, as the low pressure moves over the Carolina coast.
By 6:00 PM Sunday, the more moderate snow starts to taper off in Northern Virginia, but still lingers around the Richmond area, as well as in areas near Skyline Drive and Charlottesville (Figure 6).
All of the snow will start to taper off around 6:00 in the morning on Monday (Figure 7), but depending upon how much spin there is in the system, another light to steady band of snow could come back through late Monday morning into early Monday afternoon, however, I am NOT buying that, and I do not think that will happen.
By Monday evening, a few snow showers will linger over northwestern North Carolina and over southwestern Virginia, just to the southwest of Roanoke and Blacksburg, but all accumulating snow will be finished at this point.
***Please note that the European model shows nearly the same timing of this storm system, but I can’t post European maps without permission.
So, how much snow can we expect from Winter Storm Gia? Let’s take a look at some of the models to see what could happen, and then we will look at what I think is possible.
Latest model guidance from the American Models (Figure 8 below), the FV3-GFS, the NAM, and the old GFS still differ greatly, and we are less than 24 hours away from this event!
The FV3-GFS (click the left image), which is the brand new GFS model, says that there could be as much as 4 inches of snow in Washington, D.C. by Monday morning, while there could be 5 to 8 inches across the Shenandoah Valley, central and eastern Virginia.
In addition, the FV3 does show a good 8 to 12 inches across the southwestern Virginia border shared with West Virginia, in addition to a good 6 to 8 inches over central and Northern North Carolina, both of which I believe is sleet being interpreted as snow on the model. Either way, North Carolina is not going to get 6 inches of snow, nonetheless 4.
The old GFS model (click the right image) has gotten a better grasp on this storm, in my opinion, as it shows widespread 3 to 6 inches of snow from Richmond, up into Washington D.C., with 2 inches in Baltimore, and 6 inches or more in the Blue Ridge Mountains as well as in areas along Skyline Drive, and over in the mountainous regions of West Virginia. I also want to direct your attention to how there is a sharp cut-off line just to the south of Richmond. That is where the temperatures will likely get above 32 degrees during this snowstorm, which is why there will be a sharp cut-off in snow totals to the south of Richmond.
And indeed, the NAM model (click the center image) confirms exactly what the old GFS is saying in terms of total snowfall amounts, and with the sharp cut-off line of snowfall accumulations to the south of Richmond.
Aside from the American Models, the Canadian (Figure 9) shows something similar to the FV3-GFS, although it is consistent with the GFS and NAM where it shows a cut-off line of snowfall just south of Richmond. What is different about the Canadian model is how much snow it has across the Shenandoah Valley, Blue Ridge Mountains, Skyline Drive, across the I-95 corridor, and even into D.C. and Baltimore.
Furthermore, the European model shows a widespread 3 to 6 inch snowstorm across much of Virginia, so it is kind of a mix between what the old GFS and NAM are saying and what the Canadian model is saying.
With the data provided, I think there is a high certainty that areas south of I-66 will see 5 to 8 inches of snow by Monday morning; this includes Culpeper, Harrisonburg, Charlottesville, Fredericksburg, Richmond, and Covington, in Virginia.
Areas east of I-95, and north of I-66 have the best chances of seeing 3 to 5 inches of snow; this includes Winchester, Leesburg, Fairfax, Colonial Beach, and Front Royal, in Virginia, Elkins, West Virginia, and Salisbury, Maryland.
Areas north of I-70 and north of the District of Columbia have the best chances of seeing 2 to 3 inches of snow, which includes Baltimore, Frederick, Hagerstown, in Maryland, and Morgantown, West Virginia.
As you go further north, you will see less snow accumulations due to the storm being suppressed by an area of high pressure, so I am only going for 1 to 2 inches of snow north of Baltimore, up into Philly. (See Figure 10).
It isn’t shown on the map, but I do think some areas closer to Richmond could see some significant ice accumulations if the temperature briefly rises above 32 degrees Sunday afternoon, but most of the dangerous ice will be down in northern North Carolina.
For this matter, the National Weather Service has issued Winter Storm Warnings from D.C. and Northern Virginia, all the way down to the northern part of South Carolina, and from West Virginia to the Chesapeake Bay. In addition, areas across the Midwest are still under Winter Storm Warnings because of the current location of the system. It is starting to wrap up in Missouri, and is starting to make its way into Indiana, Ohio, and West Virginia. (See Figure 11).
Due to the widespread area of snowfall, I wouldn’t be surprised to see some school cancellations and/or delays for counties and cities area-wide. It will be a very high impact event, so please drive safe, enjoy the snow, and God bless!
Two of the biggest questions I have gotten over the past few days pertain to sudden stratospheric warming (SSW) and my winter forecast.
Before we go into details, you need to know these three key things:
We got the sudden stratospheric warming.
We have a lot of winter ahead of us.
You should expect mild conditions along the East Coast through mid-January, with colder intervals in between.
Lots of people have come to me, claiming that “winter is over,” and that the forecast is a bust. That may be, and we will see if it is wrong by the end of March. I want to make it clear that I am NOT the only one forecasting a cold and snowy winter. Meteorologists across the country and in Europe are forecasting a rather interesting winter.
Despite our current mild pattern persisting since mid-December, I am not ready to “throw in the towel” yet, and you’ll see why in this article.
Here is the good news; the Southern Oscillation Index (SOI) values have fallen (Figure 1) over the past week, which is a fantastic sign for east coast winter weather lovers.
As stated in the previous video, the SOI values are currently positive, which implies that the El Nino Southern Oscillation (ENSO) is not reflecting El Nino’s effects in the atmosphere, and is only showing signs of El Nino in the Pacific’s Nino 3.4 region sea surface temperatures. Because of this, ENSO is acting more like a La Nina than an El Nino, and if the SOI values were negative, ENSO would act more like a typical El Nino. You can see that they are still positive (left), but the last 30 days averaged, are lower than what they were on December 29 (right).
We can see how the positive SOI values have really impacted the Pacific’s sea surface temperatures over the past month (Figure 3), especially the sea surface temperatures in the Equatorial Pacific and in the Gulf of Alaska. Notice how the warm blob in the Gulf of Alaska has now become a cooler blob. Likewise, the Nino 3.4 region sea surface temperatures are also showing signs of cooling, due to the positive SOI. As previously shown, the SOI values have fallen, and if they continue to fall back into the negatives, that should aid in terminating this mild pattern over the U.S. by mid-January.
However, there is much more to this mild pattern than what meets the eye.
One of the biggest roadblocks is our good old friend, the Madden-Julian Oscillation (MJO). The MJO was stuck in Phase 5 longer than previously expected. Notice how it moves through Phases 1 through 4 easily, but in Phase 5, it stalls, and does a “loopty loop” (Figure 4).
Most weather nerds like myself know that when the MJO stalls in Phase 5, it is NOT good news for any snow or cold weather lover living in the eastern half of the United States. Look how mild these temperatures are (Figure 5). Because of the fact that the SOI values are still positive, the atmosphere is having a La Nina characteristic, thus, the warmth only gets amplified.
Many have been complaining to myself, and others on social media, about how the pattern change to a colder and snowier pattern, seems to be getting pushed back and back each day. The stalling of the MJO in Phase 5 is the sole reason for why the pattern change got pushed back a few days.
However, the good news is that the MJO is currently in the ending stages of Phase 6, and by the looks of it, it will soon be headed into Phase 7 (Figure 6).
When the MJO is in Phase 7, the overall pattern over North America starts to change and head into a cooler state (Figure 7).
Now, looking at the MJO model projections (Figure 8), there is widespread agreement between the American (left), Japanese (middle), and Australian (right) models, about what the MJO should do as we head into mid-January. I want to direct your attention to where it is forecast to go next.
As stated previously, the MJO should soon head into Phase 7, but beyond that, the models are showing, and have been showing that the MJO will head into Phases 8, stay there for a while, then quickly move into Phase 1, and then into the neutral zone.
Beyond the short-to-medium range, long-range models, like this one from atmospheric scientist Dr. Kyle MacRitchie, show that after the MJO heads into the neutral state around January 22, it will move back into Phase 7 or 8 around February 4th (Figure 9).
When the MJO is in Phases 8 and 1, U.S. temperatures turn quite cold (Figure 10), and this is good news for winter weather lovers on the East Coast.
However, we run into yet another roadblock because of the “howling” Pacific Jet. The Pacific Jet is connected to the MJO in some ways, so that stall in Phase 5 is part of the reason for why it is still running strong at the 250 millibar level, way, way up in the atmosphere.
The Pacific Jet is pounding 130 to 200 knot winds into the West Coast of the U.S., forming a persistent trough (Figure 11). over that region, while producing a persistent ridge over the eastern half of the country. Until the Pacific Jet changes, the mild pattern won’t change over the Eastern U.S. despite other factors.
The two main way the Pacific Jet will change is when the MJO moves out of Phase 6, and that looks like a “go.” However, we also are seeing a persistent area of high pressure over China and the Koreas (Figure 12), that is fueling the Pacific Jet by producing strong winds. If we can get that area of high pressure to break down, the Pacific Jet will also break down.
On a brighter note, we have just had the official polar vortex split (Figure 13) due to the recent sudden stratospheric warming, which had and has been developing for a month or more now. You can see how we have two daughter cells; one over Eurasia, and another over North America and the North Atlantic. You can also see that it looks like a third daughter cell is forming over eastern Asia and the eastern and central Pacific, and that would be impressive, but we will have to wait and see if that falls through.
So, what exactly does the polar vortex do (Figure 14)?
When there is no sudden stratospheric warming occurring, like in the left image, we see ONE single vortex centered over the Arctic locking all of the cold air in Canada and over the North Pole, with mild air anywhere south of the polar front. In addition, notice how the jet stream is not wavy.
However, when you have a stratwarm, like in the image to the right, you can see how the jet stream is wavy, and there are two or three pieces of the polar vortex, in which the three tend to be over Asia, Europe, or North America.
When there is a polar vortex split, it does NOT guarantee anything, I will repeat that; it does NOT guarantee ANYTHING for those of you over any one of the three continents.
If you have a typical split, there will only be two vortexes, one of them being over North America, Europe, or Asia, while the other vortex is over one of the other two remaining locations. Sometimes ONE of the three locations will miss out on the split, meaning, mild air floods that location without a vortex. There can be any one of the three combinations of where the vortex centers will locate.
However, when there is a split, and three vortexes form, then everyone, Europe, North America, and Asia get in on the winter fun. Our current split has two centers over Eurasia and the North Atlantic/North America, so it is kind of a different set-up than usual. Furthermore, there is a spot over eastern Asia and the Pacific, which looks to be a third vortex in development, but we are not quite sure whether that will occur or not.
The latest model runs from Dr. Judah Cohen (Figure 15) do show the third daughter cell forming over the Pacific, then moving westward over Asia, over the next week and a half, which would be amazing if it happens.
A lot of people have been concerned that the polar vortex split is a bust because we haven’t seen its effects. That is simply not the case. When we have a polar vortex split, it takes time for that to have an effect on the overall weather pattern. Those of us who understand the weather know that it takes anywhere from ten to fourteen days for the polar vortex split to change the weather pattern and send cold air into the eastern U.S., Europe and Asia. It is NOT an overnight process, it takes time. Patience is key.
Aside from that, what happens to the weather pattern when a split occurs?
When there is a split, the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO) (Figure 16), and the Eastern Pacific Oscillation (EPO) go negative (Figure 17).
When the Arctic Oscillation goes negative (right), the vortex over the North America will deliver Arctic air to the central and eastern United States, while the North Atlantic vortex gets pushed east over Eastern Europe and Siberia, with the Aleutian vortex pushed west. In addition, the North Atlantic ridge, or Greenland block, and the Eastern Pacific Ridge over the Northeastern Pacific to increase in strength, causing the polar vortex to become wavy. Due to the polar jet being sent south, the warm, moist air of the Gulf gets fed into the U.S. causing systems to develop, thereby increasing the risk of east coast snowstorms, known as Nor’easters.
When the North Atlantic Oscillation goes negative (right), the effects are basically the same as a negative AO. A blocking high forms over southern Greenland, while another block forms over the East Pacific, forcing cold air to be pushed into the central and eastern U.S. and over Europe, while Siberia stays relatively normal in terms of temperature departures from the climatic norm.
When you have a negative EPO, the effects are yet again, similar to that of the negative phases of the AO and NAO. Because the polar vortex is split, the Aleutian Low moves back over the Aleutian Islands, rather than over the Gulf of Alaska. This allows a ridge to develop and strengthen over western Canada and the western U.S. causing the polar jet stream to plunge southward over the eastern half of the U.S. bringing in Arctic air out of Hudson Bay.
In addition, when the EPO goes negative, the Pacific-North American Pattern (PNA) typically goes positive since the two are connected. When the PNA goes positive, it too yields a cold eastern half of the United States (Figure 18).
The teleconnections are forecast to go into their negative phases (Figure 19), except for the PNA, which is set to go positive. The Arctic Oscillation and North Atlantic Oscillation are both forecast to go strongly negative, which is excellent news for a true wintry feel. The EPO is also set to go negative, BUT it is not set to go strongly negative, which isn’t terrible, but not great. However the PNA, which is connected to the EPO, is forecast to go strongly positive, which is good news.
The teleconnections are all set to shift between January 8th, and January 10th, and when they do, the Arctic chill will be felt in the Eastern half of the U.S. and over a good bit of Europe and Siberia.
While we have a strong Pacific Jet bringing in mild air across the U.S., shutting off the Arctic flow, there are more things to take into consideration.
The Southern Oscillation Index values are falling, which will help speed things along, ending the mild pattern.
In addition, we have just had a sudden stratospheric warming event over the Arctic, with the bulk of the warmth at the 10 millibar level. These warming events are well correlated with Arctic outbreaks. However, many people who don’t understand how the atmosphere work make ridiculous assumptions and jump the gun by thinking that the Arctic chill will be felt as fast as you can say “snow.” However, you folks got to understand that all of that warmth in the upper stratosphere has to work its way down toward the 500 millibar level, or 18,000 feet, and then the surface in order for the cold air locked up in Canada to split into different vortexes, and be shoved southward over North America, Europe, and/or Asia, it takes time, it is not an overnight process. We officially had the polar vortex split back on January 3, but the effects still take a good ten to fourteen days to change the pattern; the cold is NOT felt suddenly.
Furthermore, the MJO is moving out of Phase 6, and into 7. Alongside the falling SOI values, the polar vortex split, and the upcoming teleconnection shifts, this transition phase of the MJO will aid in speeding up the pattern change, and things could get interesting.
The sudden stratospheric warming and polar vortex split does NOT guarantee anything for anybody, depending upon how many vortexes form and/or where they are located.
Until we get the Pacific Jet to stop “howling,” we will continue to stay mild, with cold intervals off and on. Please keep in mind that we can see snow, even big snowstorms during a mild pattern, but the conditions have to be right for that to occur. However, if the high pressure over China moves or dissipates, the Pacific Jet should slow, and allow the other factors promoting a colder and snowier pattern to fall into place.
It is also worth mentioning that my forecast may be totally wrong, and we stay mild the rest of the winter, but it does NOT mean that the possibilities were out there. All of the cards are on the table, which one we get, is not fully known.
However, if my forecast is right, then it should get cold and stormy by mid-January for the eastern half of the United States, northern and central Europe, and possibly over Siberia if a third vortex, or daughter cell forms. We could get very cold, very fast, and we could stay in that pattern through March.
***Please note that I did not use model temperature forecasts in this Weekly Weather Update because the models are all over the place.
With December drawing to a close, many are asking me, “what will the rest of winter be like for the United States weather-wise?” Many are eager to know what’s in store for the rest of winter after the relatively mild December we’ve had this year.
The short answer is that it should be cold and snowy for the eastern half of the nation, nonetheless interesting to see how the seasonal jet forms and evolves as we head into the new year.
We are going to talk about a lot of things in this article, including the sea-level air pressure in the Western Pacific, to El Nino/La Nina, the Madden-Julian Oscillation (MJO), to analogs, and model runs. So, sit back, relax, and enjoy!
This first image (Figure 1) shows you the sea-level air pressures in the Western Pacific Ocean on December 29, 2018. You can see how there is a lot of lower pressure all across the region.
Now, why is it called sea-level air pressure?
That is because, as elevation increases, the number of molecules in the air decreases, consequently causing the air to lose density at the same time. Because of this, air pressure decreases. Despite a vast atmosphere, most of the air molecules in our atmosphere are within 18,000 feet (5.6 km) of the ground.
Due to the decrease in air pressure with height, you can not compare air pressure at any two or more given locations, because the elevation at which the site sits is different from one to the other. In order to compare the two or more pressures, you must convert the pressure measured to a value with a common denominator, in which we use sea-level elevation as the common denominator. What this means, is that the raw or measured air pressure reading is converted to another pressure, whose value would be that observed if it were located at sea level.
By January 11, 2019, the sea level pressures in the Pacific will reverse (Figure 2) from where they were on December 29th. They increase as high pressure moves across the region. Now, compare that to the sea level air pressures on the 29th (Figure 1); you can easily see that they will be much higher by January 11.
With that said, we can look at the temperatures in the Equatorial Pacific.
This map (Figure 3) is from eleven days ago, December 19. This is the latest map provided from NOAA. Despite this map being over a week old, the good news is that sea surface temperatures don’t change much in ten days due to the water’s high specific heat capacity, meaning it takes a lot more energy to heat it than other surfaces, such as asphalt, which has very low specific heat.
Now, we are in an El Nino, due to the warm water upwelling in the eastern, Equatorial Pacific, but notice how there is cooler water, and colder than average water at that, along the South American coast, in the equatorial region. This implies that we are in a Modoki El Nino, which holds true since that is what the ENSO meter says.
What is really is interesting right now, is that the Southern Oscillation Index, otherwise known as the SOI Index implies that the past 30 days have been more like La Nina (Figure 4) in terms of the difference in air pressure between Tahiti and Darwin, Australia.
The SOI index and ENSO has an inverse relationship. The two graphs (Figure 5) shown show this correlation. The top is for the sea surface temperatures in the Nino 3.4 region, while the bottom graph is the SOI Index.
The paragraph below from the Climate Prediction Center (CPC) basically sums up what the SOI Index is all about and how it relates to El Nino,
“The Southern Oscillation Index (SOI) is one measure of the large-scale fluctuations in air pressure occurring between the western and eastern tropical Pacific (i.e., the state of the Southern Oscillation) during El Niño and La Niña episodes. Traditionally, this index has been calculated based on the differences in air pressure anomaly between Tahiti and Darwin, Australia. In general, smoothed time series of the SOI correspond very well with changes in ocean temperatures across the eastern tropical Pacific. The negative phase of the SOI represents below-normal air pressure at Tahiti and above-normal air pressure at Darwin. Prolonged periods of negative SOI values coincide with abnormally warm ocean waters across the eastern tropical Pacific typical of El Niño episodes. Prolonged periods of positive SOI values coincide with abnormally cold ocean waters across the eastern tropical Pacific typical of La Niña episodes.”
So, as you can see by this chart (Figure 6, left), the SOI values over the past month have been positive, which implies that ENSO has been acting more like La Nina over that time period. On the other hand, the actual equatorial Pacific sea surface temperatures (Figure 6, right) favor El Nino, obviously, since they are warmer than average.
So, when there is a La Nina, that means one thing with the Madden-Julian Oscillation, and with an El Nino, it means the opposite with the MJO, so there is a lot of battling going on here, that is really making this weather pattern over North America mild and unfavorable for Arctic outbreaks and east coast snowstorms. This means that when the MJO is in phase five or six, while an El Nino is going on, the weather over eastern North America should be cold, but during La Nina, it is the opposite, it’s warm, and that is what we have been seeing.
If you look at the the month-to-date temperature anomalies (Figure 7) over the U.S., you can easily see how they look a lot like the typical temperatures you would see over the U.S. during phases five and six of the MJO. Now, the maps to the right, which show the MJO in phases five and six are the average of both El Nino and La Nina. However, during El Nino, as I already said, these phases mean cold weather for the U.S., but during La Nina, it means the opposite. Because the SOI values have been positive over the past 30 days, the weather has been more like that of a La Nina, allowing mild air from the Pacific to be pulled into the U.S. On the other hand, the water temps are like El Nino, which is what we are officially in, but since we are in this somewhat “confuddled blend,” there has been milder temps across the U.S.
So, if this fiasco gets sorted out, then the SOI values will go down, and the teleconnections will shift allowing cold air to spill into the eastern half of the U.S. between early January lasting through the middle half of March.
These positive SOI values are likely caused by the recent phases of the Madden-Julian Oscillation (MJO) (Figure 8), which is a big line of rotating thunderstorms in the equatorial regions of the Indian and Pacific oceans, which move eastward due to the Earth’s rotation. Back in early December, a lot of thunderstorms developed to the south and east of India’s southern tip.
This meant that the MJO was moving into phases three and four (Figure 9), which means that the U.S. was going to get warm, which sure enough happened. We know the MJO has big implications on U.S. weather and hurricanes, because of recent studies conducted by NOAA and universities across the country.
However, these lines of convection are starting to move east (Figure 10), which is a good sign for winter weather lovers in the eastern ⅔ of the U.S. and Canada and we expect them to stay east with little convection occurring in the equatorial Indian Ocean throughout the winter. We are starting to see more thunderstorms develop to the North and East of Australia, which implies that MJO phases six and seven are underway.
And you can tell that the warmest temperatures are coming to an end as the MJO heads into phases six and seven, but look at how warm is was in New York City over the past week and a half; that 61 degrees was almost a record broken according to the NWS. The bottom line is that the MJO is moving into phases six and seven, and that will start to move us into a colder colder pattern in the U.S.
So, let’s move on to the models and sudden stratospheric warming. The latest model run of the U.S. GEFS (Figure 11) shows very cold temperatures forecasted for the southwestern U.S. days one through five, which implies that the MJO has entered phases five or six.
By days six to ten, the colder air starts moving eastward (Figure 12).
And by day sixteen (Figure 13), the cold air is over the eastern United States, which implies that phase seven is closing out and phase eight is just beginning.
So, with that said, let’s look at the Canadian model (Figure 14), which isn’t necessarily the best model, but it does show a strong trough over the eastern United States. The European ensemble shows it too, but I can’t legally post European maps.
Going back over to the U.S. model (Figure 14), I want to show you how poorly it is forecasting the 500 millibar troughs and ridges. There is simply no way that this scenario presented here is possible. As Joe Bastardi pointed out in his Atmospheric Avenger video, there is just NO way that there could be two troughs in the Pacific, with a ridge in the western and central U.S., with no trough in the eastern U.S. When you have high pressure blocking here to the south of Greenland, with a ridge in the western and central U.S., and two troughs side by side in the Pacific, there has to be an even greater trough in the east.
Now, let’s talk about stratospheric warming. As many are well aware, when you have sudden stratospheric warming, Arctic outbreaks are soon to follow.
However, the main issue with these events is how hyped up the media gets about it. Daily Express UK, which is not new to ridiculous headlines, posted this Article two days ago, claiming that “a terrifying polar vortex will smash Britain for New Years” (Figure 15).
So, is the polar vortex really going to “SMASH” the UK on New Year’s with snow, and an apocalypse?
The short answer is NO and the long answer is NO.
I mean, even FOX Newsdid the same thing (Figure 17), they wrote an article claiming that the polar vortex would make a comeback for New Years, and it just isn’t going to happen. These journalists don’t understand that sudden stratospheric warming, while one of the main causes of Arctic outbreaks, takes a while to be carried out and it takes a while for the cold air to be displaced southward; it takes a good two to three weeks for the effects to start being noticeable. It isn’t an overnight process, nonetheless a one-week process. It takes a good three or more weeks for that warm air to be circulated down into the 500 millibar level, at 18,000 feet, from the 10 millibar level, which is way up near the top of the stratosphere.
This map (Figure 18) here shows you the 10 millibar level of the atmosphere, which as previously stated, is near the top of the stratosphere. Do you see that big blob of orange on day one?
Compare that to day 16 (Figure 19). Notice how the blob gets smaller.
This is because the warm air in the stratosphere is being circulated downward into the 50 and 500 millibar levels. Compare day one of the 50 millibar level to the same level on day 16. (See Figures 20 and 21).
You notice that the 50 millibar level gets warmer in the Arctic, while the upper stratosphere (10 millibar) level gets cooler. And when this occurs, the cold air in the Arctic is forced to go south, and where that ends up is, over Europe, North America, or both. Now, once this warm air gets to the 500 millibar level, it will then, and only then, promote the high latitude blocking in the Arctic, and possibly even over Greenland or Alaska, and that sends the jet stream south, consequently causing Arctic air to plunge into the U.S. and this sets the stage for east coast snowstorms.
The last thing we need to look at before we get to the forecast, are the teleconnections.
The Arctic Oscillation (AO) forecast (Figure 22) shows that it should go negative by January 5. However, the AO forecast shows it going positive after January 15. However, because we are such a long way out, I don’t think the AO will rebound back into the positive phase, but if it does, it shouldn’t last long.
When the AO goes negative, the U.S. gets an Arctic intrusion, with high pressure blocking over the North, Central Atlantic and another block over the Eastern Pacific, which sends the polar jet stream over the Lower 48 and over Eurasia (Figure 23).
The North Atlantic Oscillation (NAO) is also forecast (Figure 24) to go negative, which is also fantastic news for east coast winter weather lovers (Figure 25).
With a negative NAO, the cold air, like during a negative AO, gets sent into the eastern half of the U.S., as well as Europe. This is controlled by high latitude blocking over southern Greenland and another over the Eastern Pacific, driving the polar jet in a wavy pattern.
Last, but not least, we got the PNA, which is forecast to go positive (Figure 26).
When the PNA goes positive (Figure 27), the eastern U.S. once again faces very cold weather with an active east coast storm track. The central part of Europe both north, and south face very cold weather as well, and so does eastern Siberia.
Because all of these teleconnections are in favor for a much colder and snowier January, here is what the air pattern looks like with all of them combined into one favorable pattern for Arctic outbreaks and Nor’easters (Figure 28). You can see that strong trough over the eastern U.S. bringing in cold, Arctic air, with an active coastal storm track, with ridging in the west bringing above average temperatures there. There is strong blocking in the Arctic, and a big trough over Europe and Siberia as well.
With all of these factors in place, it makes the forecast easier to do for January through March.
So, what does all of this boil down to? Well, I should say freeze down to, since it is winter… Anyhow, based off of the data I am seeing, I think there is high certainty that the U.S. will have a very cold and snowy January, February, and March, especially the eastern half of the country.
I think January will feature below average temperatures for almost everyone east of the Continental Divide, with a few Nor’easters bringing substantial snowfall to the Southeast, Mid-Atlantic, and Northeast. In addition, the southern storm track will allow the Southwestern ski resorts to see above average snowfall as well, especially down in Arizona and New Mexico. I expect the Midwest to stay drier than average with less snowfall than normal, however, the temperatures there should be below normal.
The southeast will be colder than normal as well, with above average precipitation. If the air is cold enough, I also see the possibility of one or two good snowfall events. For the Northeast and Mid-Atlantic, I expect multiple snowfall events with a few big snowstorms, especially from southern Virginia to Boston. Across the Pacific Northwest, is where I think normal precipitation should be expected with above average temperatures.
The cold and stormy pattern will continue for the eastern U.S. throughout February and into mid-March, but I expect February to be brutally cold, with the Midwest, Mid-Atlantic, Southeast, and Northeastern states to be hit the hardest with snow and bitterly cold temperatures. See Figures 29, 30, and 31.
This year we have went from one extreme to the next in temperatures. In Northwestern PA, after an unbearable string of days that ranged from 15 to 20 degrees above average temps, we are now experiencing 15 to 20 below average.
Wide temperature variations are making gardening very difficult. First, it was too hot to go and weed IF you were fortunate enough to have gotten seeds and plants in. Now, it has become cold enough that we have lit a fire in the woodstove. We are crossing our fingers that these wide swinging temperatures will not encourage fungus, mold and insect pests.
I am sure this will be a summer full of strange surprises as we venture further into the GSM!