Snow in the South, especially Athens, Georgia, is a fairly rare phenomenon. Cold air and moisture have to meet up at just the right time in order for the white stuff to fall from the sky. More times than not, cold air moves in right as the moisture moves out. However, when the two do meet up, snow can fall turning much of North Georgia into a winter wonderland. In this post, we’ll examine three ways we can get snow here in the Athens area. We’ll start with the least likely way, snow from an Alberta Clipper system. After that, we’ll examine how upper-level low pressure systems can bring the area some snow. And finally, we’ll talk about low pressure systems originating in the Gulf of Mexico. These systems are a southern snow lover’s dream. Are you ready to find out how we get snow in the Athens area? Here we go!
Alberta Clipper Systems:
The glossary of the American Meteorological Society defines an Alberta Clipper as:
A low pressure system that is often fast-moving, has low moisture content, and originates in western Canada (in or near Alberta province). In the wintertime, it may be associated with a narrow but significant band of snowfall, and typically affects portions of the plains states, Midwest, and East Coast.
As these systems dive south towards our area, they can sometimes interact with moisture from the Gulf of Mexico. This can lead to an increase in moisture content. However, these systems do not give Athens its best chance for snow. Why? Cold air is often chasing the available moisture, and a process called downsloping negates much of the moisture that could be available. Since Athens is southeast of the Blue Ridge Mountains, the air flowing down the lee side of the mountains warms up and dries out, thus lessening any kind of snow potential in the Classic City.
As the cold front moves through Georgia, cold air filters in from the northwest and some parts of North Georgia can see a few flurries. The North Georgia mountains, especially the northwest facing slopes, have the best chance of snow with Alberta Clipper systems. Check out this satellite and surface composite from January 21, 2014. You can see an Alberta Clipper system moving south with some clouds across North Georgia. During this clipper event, Atlanta recorded a trace of snow from some passing flurries. Notice the lack of cloud cover in Northeast Georgia.
Upper-level low pressure systems, sometimes referred to as cut-off lows, are defined by the American Meteorological Society as:
A cold low that has grown out of a trough and become displaced out of the basic westerly current and lies equatorward of this current.
These areas of low pressure are detached from the main flow governed by the jet stream. Because they are separated from the jet stream, you’ll often hear the saying, “Upper-level low is a weatherman’s woe.” The trajectory of these systems is hard to determine without much influence from the jet stream. With a pocket of cold air aloft, rising motion, as well as cold surface temperatures, the ingredients for wintry weather, likely snow, are present along the northern fringes of the upper-level low pressure system.
On March 1st of 2009, Athens, Georgia, experienced a heavy, wet snow of 6-7 inches. Why did Athens see so much snow with this system? Take a look at the image below.
The track of the upper-level low on March 1st of 2009 was integral in the amount of snow we saw in Athens. As I mentioned above, snow is most likely on the northern fringes of an upper-level low, and in March of 2009, we were in exactly the right place to see heavy snow amounts as the center of the low was well to our south. A shift of 30-50 miles north or south would have drastically affected our snowfall totals. Snowfall totals were greatest from Athens northeastward into Madison County with the March 2009 storm.
Gulf of Mexico Lows:
Of course everyone remembers the March 1993 “Storm of the Century.” That storm was a special case of a Gulf of Mexico low pressure system as three different jet steams came together to create a phased storm. Not all Gulf of Mexico storms are superstorms, but low pressure systems that form in the Gulf of Mexico bring the best chance of snow to the Athens area. Surface temperatures are the biggest issue with these systems as borderline freezing temperatures can result in a myriad of precipitation types like sleet and freezing rain. Gulf of Mexico low pressure systems have the ability to tap into moisture, which when thrown over-top cold air at the surface can lead to the best potential for snowfall accumulations across the Southeast United States and the Athens, Georgia, area.
Our biggest snow in recent memory, 8.8 inches on January 9-10 in 2011, came from a low pressure system in the Gulf of Mexico. The image above displays the perfect low pressure track in the Gulf of Mexico. For snow in Athens, you definitely want to see a low pressure system that skirts the Louisiana coast and then moves northeast over the northern part of the Florida peninsula. This track is the best possible track because it allows for the most moisture to get north into the Athens area. When the moisture falls through the cold air at the surface, snow is likely to occur. However, if there is warm air aloft and freezing temperatures at the surface, an ice storm can occur.
No two winter storms are the same. The amount of cold air available, the amount of moisture, and the track of the low pressure system will determine what kind of winter storm impacts the Athens area. A minute change in either of these characteristics can lead to a drastically different final result.
Will it Snow in Athens?:
So, in review, when you hear that it may snow in Athens, check to see what type of system is being forecast. If it’s an Alberta Clipper, you can pretty much write off the possibility of accumulating snow. With these systems, snow flurries will be the best bet. If you see that an upper-level low pressure system is in the forecast, check to see what track it’s expected to take. Though, remember that these are hard to forecast since they are detached from the main flow. If you see that the low pressure center is south of Athens, then snow could be possible. Finally, if you see that a low pressure system in the Gulf of Mexico is forecast to affect the area and temperatures are expected to be below freezing, then snow is also possible. Remember that the parameters with these systems can change drastically in a short amount of time! With these tips in mind, you should be able to recognize the likelihood of snow in the Athens area.