Latest Snow Forecast For Southeast

The forecast remains on track for a winter storm to impact the South and Southeast beginning late tonight and continuing into Tuesday. Rain will transition to snow initially across parts of far northeast Texas, east Arkansas, west Tennessee and north Louisiana as early as late tonight. The transition line (from rain to snow) will move east and south by early tomorrow (Tuesday) morning into central Tennessee and Mississippi before moving east into parts of Alabama and Georgia later in the day tomorrow. Parts of upstate South Carolina and North Carolina should get in on the rain & snow later in the day on Tuesday.

Let’s break down the timing of when the changeover to snow will occur:

11:00PM-2:00AM Central: central Tennessee, northwest Alabama, northern & central Mississippi, southern Arkansas, northern Louisiana and far east Texas

2:00AM-4:00AM Central: central and eastern Louisiana, southern Mississippi, central Alabama, northwestern Georgia and eastern Tennessee

4:00AM-6:00AM Central: southern Alabama, northern Georgia and western North Carolina

6:00AM-10:00AM Central: central Georgia and upstate South Carolina

Timing for a few major cities:

Jackson: Around 2:00AM Central

Atlanta: Around 8:00AM Central

Birmingham: Around 4:00AM Central

Snow total will vary quite a bit depending on location but overall much of the region will see flakes fall. The heaviest zone is 2-4″ with isolated amounts closer to 6″. It should be noted, within this zone, most areas will see totals closer to 2-3″. Where banding sets up and locations above 1,500′ will see amounts on the higher end of the zone category.

Let’s break down how much snow may fall in a few major cities:

Jackson: 2 – 4″

Atlanta: 1″

Birmingham: 2 – 3″

Fig. 2: Snow accumulation forecast

Travel will become difficult across parts of the South and Southeast tomorrow. This has allowed local National Weather Service offices to issue Winter Storm Warnings and Winter Storm Advisories for a large part of the region (see Fig. 4). One issue that may make roads extremely dangerous is the potential for the initial rain to freeze on roads once surface temperatures drop. This glaze of ice would then be covered by snow; making road conditions extremely hazardous.

Fig. 2: Current winter weather products

Please keep checking back for updates!

High Impact Winter Storm To Impact South & Southeast

The forecast is still on track for a high-impact winter storm to impact the South and Southeast beginning Monday night and continuing into Tuesday. Rain will transition to snow initially across parts of far northeast Texas, east Arkansas, west Tennessee and north Louisiana by late Monday night. The transition line (from rain changing to snow) will move east and south by early Tuesday morning into central Tennessee and Mississippi (see Fig. 1) before moving 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 early Tuesday morning
Fig. 2: Future radar Tuesday afternoon

It should be noted that this may map need to be tweaked over the next 24 hours. Locations further west on this map (east Texas and western Louisiana) may see lesser totals that what is indicated on this map. It depends on how quickly the rain transitions to snow and also how much moisture is available in this region. Most areas within the 2-4″ zone will see 2-3″ of snow with scattered 4″ amounts. Some of the higher terrain with this 2-4″ zone will see amounts closer to 6″.

Fig. 3: Snowfall accumulation forecast

It is likely that travel will become difficult across parts of the South and Southeast on Tuesday. This thought has allowed local National Weather Service offices to issue Winter Storm Watches and Winter Storm Advisories for a large part of the region (see Fig. 4). One issue that may make roads extremely dangerous is the potential for the initial rain to freeze on roads once surface temperatures drop. This glaze of ice would then be covered by snow; making road conditions extremely hazardous.

Fig. 4: Latest winter weather products

Please keep checking back for updates. An additional article will be published later this evening for locations further north.

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!

What’s All Of This Talk About A Southern Winter Storm Next Weekend?

Is it really that time of year again already? For most of us, we skipped fall and went straight into winter last month. Although wintry precipitation has already impacted parts of the United States, the first legitimate chance for a winter event farther to the south will come in about 6 or 7 days. The goal is never to address local-scale specifics in the long-range, but we can begin discussing the pattern that could support a winter storm. This allows us to establish an initial framework by looking at the big picture first, and then we can build upon that foundation with specific details in the coming days.

Will the mid and upper-level atmosphere support an early-season winter storm across portions of the South?

The first step, especially at this point, is to look at what’s currently going on well-above the surface and attempt to determine how that pattern will evolve over time. From this, it’s possible to infer what could occur at the surface without it being necessary to look at modeled surface output at this point. A closed mid-to-upper level low pressure system was located over the central U.S. yesterday (Saturday) and has now moved northeastward over the Great Lakes. A cold front, associated with a surface low that developed in response, will push all the way through Florida by mid-week. Broad troughing will remain established over the eastern U.S., keeping an anomalously cold air mass in place.

Now, here’s the main reason I made a post on November 29th about the possibility of a winter storm. A split-flow regime is expected to become established over the far western U.S. Let me explain what that means. With this setup, the jet stream splits into northern and southern components. The northern component (the polar jet) will extend well into western Canada and Alaska, while the southern component (the southern jet) will eventually dip into Baja California. Now, check out the map I posted under this paragraph. You can see the broad trough over the eastern U.S., ridging over western Canada and Alaska, and a shortwave extending into southern California and Baja California. I drew arrows to indicate mid and upper-level flow. Do you see how the flow begins to merge back together over the central U.S.? When this occurs, this is called confluence. As this confluence occurs, this will result in sinking motion over the Great Plains and will support the development/maintenance of strong high pressure over that area. Winds flow clockwise around a high pressure system in the Northern Hemisphere, and cold, Canadian air, will wrap around on the east side of this high. There’s your cold air source.

GFS 500 mb map

This will allow another cold front to push southward, and a surface low will develop in response to favorable dynamics just to the east of the shortwave over California. As this shortwave treks eastward late week into early weekend, so will the surface low, which will probably ride somewhere along the frontal boundary. This will result in rainfall across drought-stricken southern California and the Southwest and a swath of wintry precipitation that will extend somewhere from the Southwest/Southern Plains to the East Coast.

If you were to ask me how far to the south I believe frozen precipitation will occur, in short, I’ll tell you I don’t know. But, I’ll give you some insight on this. With conditions favoring high pressure over the central U.S., I’m comfortable saying that it wouldn’t be too difficult to get frozen precipitation (snow and/or ice) as far south as parts of Oklahoma, Arkansas, and Texas. Farther eastward into Tennessee and northern Mississippi/Alabama/Georgia, it becomes a bit more of a tough call. I’m especially paying close attention to northern South Carolina, most of North Carolina, and parts of Virginia, due to the potential for cold air damming to establish itself east of the Appalachians as surface high pressure moves eastward. That’s why in our ‘best chance for wintry precipitation’ map (shown below), we currently depict higher probabilities across those locations. Of course, it should go without saying that we will have to modify this map between now and next weekend, and keep in mind that wintry precipitation is not exclusively snow. We can iron out all of those details later.

southern snow/ice forecast

Conclusion:

Again, we’re simply trying to determine how this pattern will evolve. Any unforeseen changes in that would completely throw off my current expectations for next weekend. Have fun looking at all of the snowfall projection maps, but it’s important to understand the major limitations of accumulation projections this early in the game. And no, I’m not expecting nearly 3 feet of snow in parts of South Carolina like what the European model is showing.

european model snow forecast

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A special thank you to Kimberly Gnat for sharing a picture with us of the snowstorm near Chicago late last month, which we used as the featured photo.