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It has been hot and humid in the Tennessee Valley recently, but rain showers have only been spotty due to a lack of a “forcing mechanism” in the region.

In order to receive widespread downpours, an atmospheric disturbance like a frontal boundary or a tropical system is necessary to provide the catalyst for thunderstorm strength and development to occur.

Both options may be available this week, leading up to the July 4th holiday weekend.

Tropical system brewing near the Atlantic Coast

Over the weekend, the National Hurricane Center outlined an area about 200 miles off the Georgia coast with 70 percent chance of developing into a tropical cyclone (the catch-all term for a tropical depression, tropical storm, and/or hurricane).

The tropical system is forecast to move east through the next 48 hours, potentially bringing heavy tropical downpours to the Tennessee Valley Monday night through Tuesday evening.

What’s this about a cold front? Is colder air on the way?!

Right on the tails of the tropical system is a cold front advancing from the northwest. The frontal system will not move particularly quickly, and if anything, it will take about 48 hours to completely clear the region between the Mississippi River and Tennessee River Valleys.

As a result of this rather slow movement, widespread heavy rain and downpours are possible Wednesday, Thursday and Friday. Coupled with the tropical system from Tuesday, another 1″ to 2″ of rainfall is possible through the end of the week, adding up to potentially 2″ to 3″ of rain before frontal passage.

The cold front gets its name because cold air is traveling behind the frontal system — and in the summer, we’re talking about a temperature drop of about 5-10 degrees, so from the low 90s to the low 80s.

Still, the cold front will also bring slightly drier air back to the region, which will help to scrub the muggy tropical airmass and bring a drier, more comfortable feel to the Tennessee Valley. In addition, the cold front will drop the heat and humidity just in time for the Holiday Weekend, so imagine a comfortable evening to view all of the Fourth of July Fireworks!

– Christina

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