Southeast White Christmas? Part 1

southern snowstorm

We made a post the other day asking our followers when they had experienced their last White Christmas. Quite a few said never. A few others said back in 2010. Since many of our readers live in the Southeast, those responses weren’t all that surprising. Climatologically, having snow on the ground at some point on Christmas Day in the Southeast is exceptionally rare. Though, not impossible. . .

Download Southern Snow

In the coming days, we’re going to discuss those years that the Southeast had a White Christmas. They may be few and far between, but there’s value in revisiting the conditions and overall pattern that brought those rare snowy Christmases.

In this article, we will take a peek at how the pattern will likely evolve from now through Christmas Day. The overall pattern will remain quite progressive. Meaning, most regions of the U.S. will not remain under the influence of troughing or ridging for more than a few days at a time, if that. Unfortunately, such a setup favors lots of swings in temperatures.

For the first time in a while, temperatures MAY actually feel like Christmas on Christmas Day in the Southeast (give or take a day). Most model guidance agrees that a longwave trough will develop across the eastern half of the U.S., as ridging amplifies across western Canada and eastern Alaska. This pattern configuration favors anomalous warmth along the West Coast and into the Southwest. An anomalously cold air mass will sweep across most locations along and east of the Rockies. Even Florida could get in on this chilly air mass!

Projected departure from average temperatures Christmas Day morning

Most reading this post are already wondering, will there be any precipitation to go along with that brief shot of cold air in the Southeast? Maybe. The models indicate that a shortwave could become detached from the main flow and close off into a mid-level low as it approaches southern California and Baja California sometime next week. It would eventually get swept eastward by the southern stream. But features like these can meander for a while or even retrograde westward before getting reabsorbed back into the main flow. If the cold air intrusion is a strong as modeled, there could be about a two-day window, probably a day or two after Christmas, that any passing southern stream system could produce wintry weather for parts of the Southeast.  

Taking a look at projected 500mb geopotential height anomalies from the latest European model, it already has the longwave trough lifting northeastward by the 26th. At the same time, the closed low quickly moves eastward across Texas/northern Mexico. Residual cold air may hang around for a day or two tops, thanks to a departing surface high. This closed low, or any southern stream feature for that matter, would need to encroach upon the Mid-South and Southeast just as the long-wave trough begins lifting out.

Longwave trough lifts out the day after Christmas

If I were a betting man, I wouldn’t put anything down on a White Christmas happening across the Southeast at this time. Yes, there could be a very brief window for some action right after Christmas Day, but that window appears to be short. I’d certainly recommend not getting too hung up on model guidance in the coming days. Large inconsistencies may exist in how models handle any closed low that develops. But hey, a small chance is always something to watch!

Make sure you download our new mobile app that’s dedicated to providing you with detailed snow forecasts. Firsthand Weather recently launched a new mobile app called Southern Snow for iOS devices, which gives you a snow forecast for anywhere in the U.S! If snow starts showing up in the forecast, Southern Snow will let you know.

Download Southern Snow

Be sure to join us on the Firsthand Weather this Saturday at 2pm ET to get our official White Christmas forecast for the entire U.S.

Find out if you’ll have a White Christmas 2020 this Saturday on Firsthand Weather

The featured image used in this post is courtesy of Jennifer Kyzer, who captured a great shot of an early season snowstorm in SC in 2014. 

A response to questions about snow next week

Many of you have heard rumors of snow. Let’s talk about that. We’re over 3 weeks away from the start of meteorological winter, yet next week’s setup is very impressive for this time of year. In my opinion, the real story will be the cold. Most regions along and east of the Rockies will experience temperatures that would be expected during the winter.

Projected temperatures at 7am ET on Nov. 13 2019
Projected temperatures at 7am ET on Nov. 14 2019

Our first frontal passage is moving across the country now. If you check out current U.S. temperatures, you can see the cold front quite nicely. All of the snow talk is about the second cold front moving through early next week. That’s going to bring the real cold.

Basically, a strong mid-to-upper level trough is going to become oriented from southwest to northeast, extending as far south as Texas and Mexico. A strong cold front will be associated with the trough, and a surface low will likely develop to the east of the trough axis. It’s very possible that this surface low will track along the Gulf Coast states, exit off the Southeast coast and skirt parts of the East Coast.

There should be the development of precipitation along and ahead of the cold front. Due to the potency of the air mass moving in behind the cold front, most model guidance shows a transition from a cold rain to snow and sleet on the backside of the precipitation shield. As shown by the European model, you will notice accumulations occurring unusually far to the south. Other models have shown this as well.

Projected snowfall accumulations early next week, a forecast that will likely change significantly between now and then
Projected snowfall accumulations early next week, a forecast that will likely change significantly between now and then

When I’m looking for decent snow accumulations to occur farther south, I like to see a well-developed surface low pressure system. When a trough is oriented from southwest to northeast, the surface low generally remains weak. Thus, any frozen precipitation basically has to occur along a frontal boundary without any well-defined low. It does happen, but a setup like this doesn’t usually produce a big winter storm. Remember when Firsthand Weather busted horribly on a winter storm forecast last year? We expected accumulating snowfall to occur along a strong cold front without a well-developed surface low. We blew the forecast.

I’m a bit more concerned about temperatures dropping rapidly while roads are still wet. Oftentimes, roads are able to dry before temperatures reach freezing, but again, the air mass behind next week’s front is potent. Remember, temperatures will be at levels that we’d typically experience during winter. Some of the model guidance strengthens the surface low off the Southeast coast; thus, I’m not willing to discount accumulations being depicted across parts of North Carolina, Virginia, and northward along the coast just yet.

My hope is that many of you will get to experience a little snow. I suspect that accumulations won’t occur anywhere south of a line that runs from Oklahoma, central Arkansas, Tennessee, and North Carolina. Again, any concerns south of that line would likely be due to black ice, which can be quite dangerous.

I’ll post a more in-depth forecast on the site, if needed. I believe we need to watch everything a couple more days before we put out any detailed forecasts.

Updated Snowfall Forecast

We continue to monitor the chance for snow across much of the South and Southeast from Monday night into Tuesday. Most of this region will see the opportunity for snow accumulations that could impact travel. The worst travel conditions appear to be on Tuesday from northern Louisiana eastward into northern Georgia.

The first areas to experience snow will be far eastern Oklahoma, northeast Texas, Arkansas, western Tennessee and northern Louisiana by late Monday night. The rain & snow will move east and southward by early Tuesday morning into central Tennessee and parts of Mississippi (see Fig. 1) before moving further east into parts of Alabama and Georgia later on Tuesday (see Fig. 2). Parts of upstate South Carolina and North Carolina should get in on the rain & snow later in the day on Tuesday (see Fig. 3).

Fig. 1: Future radar late Monday night (please note: this should be used as an estimate–exact placement of precipitation may change)
Fig. 2: Future radar early Tuesday morning (please note: this should be used as an estimate–exact placement of precipitation may change)
Fig. 3: Future radar Tuesday afternoon (please note: this should be used as an estimate–exact placement of precipitation may change)

Accumulations do look likely from late Monday though Tuesday. The event being a few days out makes it extremely difficult to forecast snow accumulations, however. There are two negative factors for accumulations. I) Monday (the day before the snow) will be warm across this region, which will lead to warmer ground temperatures, and II) the window for snow is only about a 4-6 hour period. Even with these two mitigating factors, this event will be the best chance so far this season for accumulating snow across the South and Southeast.

The snow rates should exceed melting and the best chance for accumulations will across northern & central Mississippi, Tennessee, northern & central Alabama, northern Louisiana and northern Georgia. Guidance is evening indicating some instability, which could lead to convective banding of snow (this is where the heaviest snow totals are possible). It is too difficult to pinpoint where those bands may setup. That is almost a nowcasting scenario. Secondly, areas that see snow pre-dawn on Tuesday will have the best chance to see accumulations and nasty road conditions. Even though it is difficult to forecast snow accumulations this far out, I wanted to provide you with a second preliminary snow accumulations map (see Fig. 4). Please note, this will likely change over the next 48-72 hours as we get closer to the event. It is possible the polygons may need to me reduced or expanded, and snow totals may need to be increased or decreased.

Fig. 4: Preliminary snow accumulation map

The South and Southeast are not the only regions that have snow in the forecast. Coastal areas of North Carolina and Virginia may see snow beginning Monday due to a coastal low that will quickly deepen off the coast. This could allow a band of snow to setup from Virginia Beach down into eastern North Carolina. If this happens, it is possible heavy accumulations may occur, which is why this small area is included in the 2-5″ zone. It should be noted, most numerical guidance indicates the low will be too far off shore to aid in precipitation chances for this area, but we believe the low may closer to the coast, thus, have reflected this in the snow accumulation forecast. Regardless, snow chances increase for this area by Tuesday night into Wednesday. Those snow chances also increase for the rest of the Mid-Atlantic and the Northeast by Wednesday. Parts of the Northeast, Great Lakes and Ohio Valley will see multiple snow opportunities from Sunday through Wednesday so accumulations are likely (see Fig. 5). More than one foot of snow is possible for parts of the Great Lakes region where lake effect snow band establish themselves.

Fig. 4: Preliminary snow accumulation map

Please keep checking back for updates as this is a fluid forecast and changes may be needed!

Accumulating Snow Likely For South And Southeast!

The chance for snow continues to increase for parts of the South and Southeast early next week. An arctic cold front will move out of the Southern Plains into the South by Monday afternoon with temperatures quickly falling to near or below freezing behind the front. At the same time, an upper-level shortwave will move overhead. This shortwave combined with the vertical profile of the cold front will generate a strong upward motion in the atmosphere to allow precipitation to develop along and behind the cold front. Precipitation immediately behind the front will fall as rain Monday night and quickly transition to wet snow by Tuesday.

The first areas to experience snow will be far eastern Oklahoma, northeast Texas, Arkansas, western Tennessee and northern Louisiana by late Monday night. The rain & snow will move east and southward by early Tuesday morning into central Tennessee and parts of Mississippi (see Fig. 1) before moving further east into parts of Alabama and Georgia later on Tuesday (see Fig. 2). Parts of upstate South Carolina and North Carolina should get in on the rain & snow later in the day on Tuesday.

Fig. 1: Future radar Tuesday morning (please note: this should be used as an estimate–exact placement of precipitation will change)
Fig. 2: Future radar Tuesday afternoon (please note: this should be used as an estimate–exact placement of precipitation will change)

While this is not a setup that climatologically produces major snow events, it increasing in likelihood that accumulations are likely. The event being a few days out makes it extremely difficult to forecast snow accumulations. There are two big negative factors for accumulations. I) Monday (the day before the snow) will be warm across this region, which will lead to warmer ground temperatures, and II) the window for snow is only about a 4-6 hour period. With that said, this does appear to be the best chance so far this season for accumulating snow across the South and Southeast. The snow rates should exceed melting and the best chance for accumulations will across northern & central Mississippi, Tennessee, northern & central Alabama, northern Louisiana and northern Georgia. Guidance is evening indicating some instability, which could lead to convective banding of snow. This could dump heavy snow amounts for isolated locations. It is too difficult to pinpoint where those bands may setup. That is almost a nowcasting scenario. Secondly, areas that see snow pre-dawn on Tuesday will have the best chance to see accumulations and nasty road conditions. Even though it is difficult to forecast snow accumulations this far out, I wanted to provide you with a preliminary snow accumulations map (see Fig. 3). Please note, this will likely change over the next 48-72 hours as we get closer to the event. It is possible the polygons may need to me reduced or expanded, and snow totals may need to be increased or decreased.

Fig. 3: Preliminary snow accumulation map

Please keep checking back for the latest updates!

Monitoring Winter Weather Potential For Southeast

We are keeping an eye on the upcoming work week for the Southeast for the potential of wintry weather. The first chance for wintry precipitation begins Tuesday night into early Wednesday for parts of the Carolinas and northeast Georgia. A weak ridge will build eastward (as a trough moves into the Plains), allowing moisture to stream into the region late-Tuesday. At this time, the Arctic air currently in place, will have begun to modify, but surface temperatures will still remain cold. As the moisture begins to move into this region, it is possible drizzle or light rain will develop Tuesday night. The low-level temperatures *could be cold enough for light freezing rain to fall Tuesday night into early Wednesday. Forecast soundings for this timeframe show wet-bulbing will occur possibly allowing for light freezing rain in the highlighted areas (see Fig. 1). As moisture continues to move into the region, temperatures will rise above freezing by late-Wednesday morning. This will minimize accumulations and allow the freezing rain to transition to all rain.

Fig. 1: Areas that have the best chance to see freezing rain

The next opportunity for wintry precipitation arrives late Wednesday into Thursday. The aforementioned trough will continue eastward, sending a cold front into the Southeast. Numerical guidance has trended towards the trough becoming neutrally tilted as it moves east of the Mississippi Delta, which would allow surface temperatures to fall rapidly behind the front. It is possible lingering moisture will be present behind the cold front, which could allow a 2-4 hour window for rain to mix with or change to light snow (see Fig. 2). At this time, it does not appear significant accumulations are likely. We will have to keep a close eye on this event as we get closer to Wednesday night and Thursday. A slower departure of moisture could allow for more meaningful snowfall to occur.

Fig. 2: Areas that have the best chance to see rain/snow

Another upper-level feature could aid in wintry precipitation as we head into the weekend for the Southeast but this is too far out and confidence is low. Keep checking back for updates.

Early-Season Winter Event Looking More Likely For Parts Of The Southeast

It’s only December 6th and we’re already talking about the potential for a winter event across parts of the Southern Plains and the Southeast. Since we’ve already covered the forecast for the Southern Plains, I’m going to focus primarily on the Southeast. A system earlier in the week moved across the Northern Plains and has now trekked northeastward into Canada. A cold front associated with that system pushed across the eastern U.S. earlier in the week and has now made its way to the Gulf coast and along the East coast. Behind the front, a broad trough has become established over the eastern two-thirds of the nation. With this kind of setup, mid to upper-level wind flow across the southeastern U.S. is generally from the southwest; thus, the initial cold front has already slowing down and will eventually stall out near the Gulf coast and East Coast. The shortwave feature that will be responsible for bringing snow to Texas is going to interact with the broad trough and a second shortwave feature. This interaction is going to sharpen the trough, which will eventually extend into the Southeast. Given that the frontal boundary will be stalled out near the coast as all of this is unfolding, this is going to induce the development of a surface low pressure system that will ride along that boundary along the Gulf coast and up the East coast.

For those in the Southeast, most who have lived in that region for any extended period of time know that most winter storms that unfold across that region involve a low pressure system developing near the coast along the Gulf of Mexico, which then crosses over and moves off or along the East coast. Since cold air is often limited, forecasting these events can be challenging throughout the extent of the event. Since it’s still early December, that even adds additional challenges.

First and foremost, it should be noted that most of the model guidance suggests at least some wintry weather (snow!!) across the Southeast (more on specific locations in a bit). However, snowfall accumulation projections range from no accumulations to several inches of snow for parts of the Gulf coast northeastward to the East coast. For events such as these, I either like to see that a pre-existing colder air mass has become established over the region before the event, or that there is going to be sufficiently cold air provided by a certain atmospheric feature in time for the event (for example, high pressure over the Northeast). The first cold front that has now pushed through the region has brought in much colder conditions, but given the broadness of the trough and the time of the year, there really needs to be an additional source of colder air spilling into the region. Throughout the day on Thursday, the colder air to the north-northwest of the area will continue pushing southeastward, but despite that, we’re still going to be dealing with the classic borderline winter storm/event in the South.

The NAM model has generally been the most aggressive with snowfall accumulations across the Southeast, which extend those accumulations down the Gulf coast. The hefty snowfall accumulations occur for most locations later on Friday into Friday night, even though it has precipitation (mostly rain) spreading across many locations in the Southeast tomorrow. If you’re looking to get noteworthy accumulating snow, it’s best this event occur later on Friday like what the NAM is showing for many locations, and given that it would be getting dark or already dark, this would greatly increase the odds that temperatures would be sufficiently cold throughout the atmosphere to support snow or a transition from rain to wet snow. This would also allow more time for colder air to seep southeastward. The GFS is less aggressive, primarily because it has the heaviest precipitation moving out more quickly. The European model, which is generally more reliable, falls somewhere in between with accumulations. Remarkably, all of the guidance is at least showing some accumulating snowfall for some locations in the Southeast. However, it should be noted that these maps depict a 10:1 snow to liquid ratio, but given the warmer ground temperatures and the fact that rain will mix in (at least initially), these totals could be overestimated for some locations on all three models. However, higher snowfall rates across some locations could offset some of these hindrances for snowfall accumulations.

NAM model snowfall map

Figure 1: NAM model snowfall accumulation forecast for the next 72 hours. Source: Tropical Tidbits

GFS model snowfall map

Figure 2: GFS model snowfall accumulation forecast for the next 72 hours. Source: Tropical Tidbits

European model snowfall map

Figure 3: European model snowfall accumulation forecast for the next 90 hours. Source: Ryan Maue

Remarkably, residents living in southeast Louisiana, southern Mississippi and possibly extending into western parts of Alabama have the greatest chance of this event unfolding for them. Since this region will be some of the first locations to feel the effects of the colder air mass digging southeastward, precipitation developing and moving across the region will have the greatest chance of making the transition to snow either late Thursday or early Friday. Predicting snowfall accumulations from eastern parts of Alabama into Georgia and South Carolina gets quite challenging. The later this event unfolds for those locations on Friday, the better for accumulating snowfall. The more aggressive snowfall totals that span across parts of North Carolina into southeastern Virginia are warranted. That’s another region that I feel has a pretty decent chance of this event unfolding.

Due to the uncertainty that exists, this will require me to post a follow-up update tomorrow. However, residents in the general swath of accumulations that are being depicted by the model guidance should prepare for this event. I expect the majority of accumulations to occur over grassy surfaces; however, issues on the roadways could occur for localized regions where the snowfall rates are higher. That will be something that we’ll have to determine tomorrow. Nonetheless, it is still very early in the meteorological winter, and it’s remarkable that we even have an event such as this to forecast! Firsthand Weather will keep everyone updated as much as possible before and during this event and will be posting numerous updates on our Facebook page.

Everything You Need To Know About This Upcoming Winter Storm

As promised, I will keep this article brief and to the point. I have provided you with a lot of details on this upcoming winter storm already, but given that I have put out numerous updates on social media and the website at different times, I’m sure some of you have missed some important information.

Just to reiterate, a lot hasn’t changed with my overall forecast. This winter storm will be a significant winter storm for many across the United States, and it is definitely showing similar characteristics to some of the historic winter storms of the past. Overall, the forecast model guidance is in agreement other than on some of the specifics. The European model came in slightly north with its overall track and the GFS jogged slightly south. Surprisingly, I’m not in strong disagreement with the actual track that the models take this system. With that said, a jog as little as 25-50 miles north or south can make a HUGE difference, so be aware of that.

Okay, take special note of all the bullet points that I listed below:

• Snow/sleet will fall across northern Mississippi, eastern Arkansas, western Tennessee, and possibly as far south as extreme northern Louisiana on Friday. Many of those regions will start out as rain, but the transition to frozen precipitation will occur on Friday. Accumulating snow, which could be locally high in places, could fall especially across the northern third of Mississippi, the eastern third of Arkansas, and western Tennessee. Some accumulations will be possible in the other regions mentioned, too.
• A stout warm nose will be present just above the surface, extending across much of Alabama, Georgia, and eastern Tennessee. This will originally cause most of the area to start out as a cold rain, but a transition to snow/sleet will eventually occur. This will cut down on overall snowfall accumulations, but regions as far south as Atlanta and Birmingham could get some accumulating snow once the transition occurs. The heavier accumulations should occur just north of those bigger cities.
• As I have mentioned several times, there will likely be a cold air damming scenario that sets up as far south as northeast Georgia and Upstate and northern South Carolina. I expect a potentially significant ice storm (accumulations of ¼ inch of ice) to unfold across these regions starting on Friday. High ice accumulations will likely also occur across central and eastern North Carolina (likely excluding the near coastal regions). Forecast models tend to handle these scenarios horribly, but I have noticed that the guidance is handling this well today. Models could be slightly underestimating how far south this freezing rain falls. Please read the next bullet point.

Probability of greater than 1/4 inches of ice accumulations from Thursday night to Friday night:

Ice Storm Probability

• A transition to snow will eventually occur across most of the regions mentioned in the last bullet point, and the heavier accumulations will fall the farther north one goes. Snow could fall as far south as Midlands SC, but accumulating snow will be higher the farther north was one goes. I can’t even rule out some snow falling along the northern South Carolina coastal regions and near the North Carolina coast, as the cold air rushes in behind this system and moisture gets wrapped around the coastal low.
• The bullseye of very heaviest snowfall accumulations will likely fall from Kentucky into West Virginia and Virginia, including the Washington, D.C./Baltimore areas, southeastern Pennsylvania, including Philadelphia, Maryland, Delaware, and New Jersey. A region of heavy accumulations could also fall in western and north-central regions of North Carolina. This is going to be an extremely close call for New York City and Long Island, as a slight shift southward in track will remove NYC and Long Island from seeing as high of snowfall amounts. Many of these areas will be measuring snow in feet.
• Extreme southern regions of the Ohio Valley could get accumulating snow from this system, too.

Probability of greater than 4 inches of snow falling from Thursday night to Friday night (probabilities for amounts lower than 4 inches aren’t included):

snow prob map 1

Probability of greater than 4 inches of snow falling from Friday night to Saturday night (probabilities for amounts lower than 4 inches aren’t included):

snow prob map 2

I including every region that could possibly be impacted by this system. If you are on the edges of any of the regions that I just mention, be aware that a slight jog 25 miles north or south could be the difference between getting snow accumulations or very little snow at all. Also, as energy gets transferred to the coast, a dry slot will probably eventually set up somewhere. Keyword SOMEWHERE. Nailing that down will be pretty difficult, and wherever this sets up, this could cut down on overall accumulations for some of you.

Overall, I’m very pleased with the forecast. Hopefully this clears up some of your questions. Most of you are well-aware of how a slight change in track could change the forecast significantly for some of you, especially if you’re on those borderline zones. I will have continuous coverage tomorrow on this winter storm.

By the way, the image used as the feature image in this article was from last winter, taken in Grafton, MA by Sevag Sarkisian. I figured it was fitting for this article!