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FIRST ALERT UPDATE: "'Snow' way!" Could flakes really fly tonight?

MGN palm trees with snow
Posted at 2:47 PM, Dec 08, 2017
and last updated 2017-12-08 10:28:16-05

MIDWAY, Fla. (WTXL) -- It's one of those intriguing parts of forecasting in a cold-weather situation in the South.  When temperatures occasionally plunge because of an Arctic air mass diving south, sometimes the mention of cold showers raises a question.

Weather enthusiasts and amateur forecasters on social media increase the frenzy, when postings of individual computer forecast models singularly show a possibility of a brief "winter wonderland" occurring in a far southern latitude like ours.

Chatter has increased since midweek about the chances for wintry precipitation in the Deep South, causing some of hope, or wish, that it can happen close to the Gulf coast.

Chances are, no one within our northern Florida / southern Georgia coverage area will gather enough snowflakes, ice pellets, or other forms of frozen precipitation to cause a ruckus.  But, if conditions come together just precisely right, isolated, brief cases of flurries can be produced.

Very cold air from the far northern reaches of North America plunged far south Wednesday, with more upper disturbances through the rest of the week allowing the continued flow of cold air.  The jet stream is set up over the Southeast, carrying moisture through the cold air and creating a steady stream of clouds and occasional rain.

Sunshine is limited, so temperatures aren't able to rebound as much as usual.

Just a few thousand feet up, temperatures can be colder or warmer than at ground level, and how those higher-level temperatures change can often determine what kind of precipitation can form.

That's where the problem lies for supporting any kind of frozen precipitation in the local area.

Even if temperatures are solidly below freezing at a higher elevation, where ice crystals could eventually become snowflakes, ground-level temperatures are not forecast to reach freezing until perhaps Sunday morning, long after the moisture clears out. This will effectively eliminate any chance for accumulating ice or snow, since melting would occur.

Temperatures from ground level all the way up would have to be at or below freezing to support snow development.  Any areas of above-freezing temperatures aloft would cause ice crystals to melt, resulting in mainly cold rain or drizzle.

The National Weather Service diagram above provides visual information of how a warmer pocket of air can effect the type of precipitation experienced on the ground.

As of Friday afternoon's analysis of forecast data, it appears that most of the moisture needed to support frozen precipitation would have departed before temperatures in the lower layers of the atmosphere stay adequately below freezing.  So, the chances for snow (or mixed precipitation) for most locations around the state line are essentially zero. 

A slim opportunity exists tonight through early Saturday morning near the Chattahoochee River vicinity of southwestern Georgia and southeastern Alabama, where just enough moisture may linger and match with falling temperatures aloft to support some flurries for a brief time. 

The pre-winter storm has already produced multiple inches of snow in spots where such snowfall is typically unexpected, like southeastern Texas, central Louisiana, near the Mississippi Gulf coast, and central Alabama.