November 12-17 is Winter Weather Awareness Week for North Alabama. The National Weather Service holds the Winter Weather Awareness Week campaign each year ahead of the winter season.
While the frequency of winter weather in Alabama and Tennessee is small, when it occurs it can cause significant property damage, injury and even death. That’s why preparing ahead of significant weather events is important.
Here in the Tennessee Valley, we can experience all types of precipitation during winter, ranging from rain to snow.
As precipitation falls to the ground it goes through different levels of the atmosphere and sometimes the temperatures at these levels are different. This will lead to different forms of precipitation we see at the surface.
As an ice crystal falls through the different levels of the atmosphere it encounters different temperature boundaries. As the ice crystal encounters a warm layer, it melts, leading to rain once it reaches the surface. Freezing rain occurs when rain encounters a surface that is at or below freezing and freezes on contact. Sleet are ice pellets found during winter and occur when rain hits a deep cold layer creating ice pellets that stay frozen all the way to the ground.
Winter Weather Alerts:
Extreme winter weather can lead to weather alerts being issued for the area.
These alerts are issued by the National Weather Service Office in Huntsville. The most frequent alert issued is a Winter Weather Advisory. The last time one of these alerts was issued was on February 2nd of this year. While ice storms can occur here, they are not as frequent, which is why it has been more than one thousand days since an Ice Storm Warning has been issued.
A Winter Weather Advisory is issued when snow accumulation is expected to be one to two inches, ice accumulation of up to 1/4 inches is expected, or sleet accumulation of up to 1/2 inches is expected. When this is issued, people are advised to use extreme caution as the wintry precipitation we see could impact travel across the Tennessee Valley.
A Winter Storm Watch is issued when there is 50 percent confidence that the warning criteria will be met within the following 12-24 hours. During a watch, is important to prepare ahead of the event by stocking up on supplies.
When a Winter Storm Warning or Ice Storm Warning is issued, that is the time when you take action. When snow totals are forecast to be greater than two inches in Alabama or three inches in Tennessee within 12 hours, a Winter Storm Warning will be issued. An Ice Storm Warning is issued when freezing rain, or ice, is expected to accumulate to 1/4 of an inch or more.
This event was known as the “Storm of the Century” due to its large scale and widespread recording-breaking snowfall. A strong low-pressure system developed along the Gulf Coast before pushing northward into Alabama. Although this was a fast-moving system, it led to significant impacts across the area.
Snowfall across the Tennessee Valley ranged from around an inch to over a foot of snow. The highest snow totals were seen in the eastern portions of the area. This is where the heaviest of the snow bands set up. Valley Head saw more than 18 inches of snow. Many other locations in northeastern Alabama saw a half a foot to a foot of snowfall.
The snow that fell was the heavy and wet type and the weight of it led to many issues across the area. Power lines and trees fell due to the weight. This knocked out power to thousands and at the height of the storm over 400,000 thousand were without power.
Roofs of homes were damaged and some even collapsed under the weight of the snow. The weight, and the strong wind gust over 50 mph, aided in the damage that was reported across the Tennessee Valley.
The satellite image above was taken a day after the event and shows the snowpack across the area.