UPDATE: Tornado warning moves east to Cheatham, Dickson counties, tornado ...

Update at 8:15 p.m.:

A tornado warning moved east to northern Cheatham, eastern Montgomery and western Robertson counties until 9 p.m. Saturday.

A squall line capable of producing tornadoes wrapped in rain was spotted 13 miles southeast of Clarksville.

The National Weather Service also expanded a tornado watch for additional Middle Tennessee counties including Rutherford, Sumner and Wilson counties.

The tornado watch is expected to last until 2 a.m. Sunday includes Macon, Rutherford, Sumner, Smith, Trousdale and Wilson Counties.

Severe thunderstorm warnings have also been issued for the following counties: Wayne, Perry, Dickson, Hickman, Humphries and Lewis Counties. Those warnings will last until 8:45 p.m.

Update at 8 p.m.:

A tornado warning have been issued Montgomery County and other areas in northwest Middle Tennessee until 8:30 p.m.

Benton, Humphries, and southeast Stewart Counties have also been included in the National Weather Service warning.

The alert was issued as a line of severe thunderstorms capable of producing tornadoes wrapped in rain and widespread straight-line winds. The system is moving east at 55 miles per hour, meteorologists said.

The line of storms is expected to hit the Nashville area after 9 p.m.

Update at 7:45 p.m.:

The National Weather Service has issued a severe thunderstorm warning for northwest Middle Tennessee including Clarksville until 8 p.m. Saturday.

Montgomery, Stewart, Houston, Humphries and Benton Counties are all included in the warning.

A tornado warning has also been issued for Henry County directly west of those counties until 8 p.m.

National Weather Service meterologist John Cohen said the storm front is expected to do more damage is beginning to reach Clarksville. The system is expected to reach the Nashville area around 9 or 10 p.m.

Update at 5:50 p.m.:

The National Weather Service has issued a tornado watch until midnight for portions of western Middle Tennessee.

Davidson, Williamson, Dickson, Robertson and Cheatham Counties were all included in the watch in addition to counties west of Interstate 65.

Severe thunderstorm warnings have also been issued for portions of West Tennessee where the storm front has already reached.

Update at 5:20 p.m.:

The severe weather system expected to hit Middle Tennessee Saturday evening has reached West Tennessee and is moving into northwest parts of the region.

Doppler radar shows rain nearing the Clarksville area as of 5:15 p.m. The most severe weather is still expected to hit there between 7 p.m. Saturday and midnight Sunday.

A newly released National Weather Service statement estimates a line of strong storms to pass through the Nashville area around 9 p.m at the earliest.

Winds up to 40 miles per hour are expected before the storm passes through, the statement said.

Some showers are also popping up in advance of the severe weather, but none of that rain is expected to cause problems, said NWS meteorologist Mark Rose.

'I don't think we'll have severe weather until this main line goes through,' he said.

As warm weather lingered in the region before the storm, temperatures became much warmer than average for late December.

Today's high of 73 tied a Middle Tennessee daily record for the date. The only other time temperatures were this warm on December 21 was in 1967.

Update at 3:30 p.m.:

National Weather Service meteorologists expect the severe weather system hitting Louisiana and Arkansas will make its way to Middle Tennessee more quickly than first thought Saturday night.

The weather system capable of producing winds up to 50 miles an hour is projected to pass through the Clarksville area sometime between 7 p.m. and midnight and then move into the Nashville area between 9 p.m. and 2 a.m. Sunday.

Previous forecasts of rapid winds and possible tornadic activity are still in place despite the advanced time of arrival, NWS meteoroloigst Mike Davis said.

A wind advisory for Middle Tennessee was also extended one hour to 4 a.m. Sunday.

Update at 1:00 p.m.:

A severe weather system could pass through Middle Tennessee tonight, according to the National Weather Service. As of mid-day Saturday, the NWS issued a wind advisory in affect for all of North Alabama and Southern Middle Tennessee. The target areas listed in the advisory include Franklin, Lincoln and Moore counties in Tennessee.

The NWS issues wind advisories when gusts could reach speeds up to 35 miles per-hour. This wind advisory will last until 3 a.m. on Sunday morning, said Jason Wright, a senior meteorologist with the Nashville Weather Service. As the weather system passes through, gust speeds could reach up to 50 miles per-hour.

The weather system will likely come through the Nashville area later tonight and will move quickly across the mid-state, moving out of the region by Sunday morning. The weather system could include severe thunderstorms as well as straight line winds, which, Wright said, can reach tornadic speed. The system could spawn isolated tornadoes, though no strong tornadoes are expected. Still, Wright said, people should be careful.

'Straight line winds are very dangerous,' said Wright. 'Please exercise caution tonight while driving.'

Driving in powerful winds may become difficult this evening, according to the National Weather Service, which also warned that lightweight outdoor furniture, trash cans and holiday decorations could be blown around.

The last time a tornado occurred in December in Tennesee was in 2000. The last time a fatality occured with a tornado in December was on Dec. 24, 1988 in Franklin. There have been 13 tornadoes in December on record since the official record keeping began in 1950, eight of which occurred during the 1970s.

Previously Reported:

Severe storms with gusty winds up to 50 miles per hour are expected to pass through Middle Tennessee on Saturday night into Sunday.

While the line of severe weather is capable of producing localized flooding and isolated tornadoes, National Weather Service meteorologist Brittney Coleman said the biggest threat from the incoming system is from the gusts it could produce.

'Anytime you have a severe threat develop, there's going to be a chance for tornadoes,' she said.

A wind advisory for Middle Tennessee will take effect at 10 a.m. today. Meteorologists expect the highest winds from the system to pass through areas around Clarksville and Camden.

The northwest parts of the region also will be hit first by the storm on Saturday from 6 to 10 p.m. , where two to three inches of rain are expected to fall. The Nashville area is expected to receive an inch or two of rain between 8 a.m. Saturday and 2 a.m. Sunday.

The system is expected to pass through areas east of Murfreesboro and Lafayette after midnight Saturday.

While the most damaging parts of the system will hit West Tennessee and then go north, Coleman said the region should still be on alert.

Metro Nashville's Office of Emergency Management partially activated its Emergency Operations Center for Saturday evening. OEM employees will work with National Weather Service officials throughout the day Saturday as the weather system approaches, said office spokeswoman Heidi Mariscal.

Coleman said clear weather is expected through Christmas. Starting Monday, high temperatures will be in the 40s and low temperatures will drop below freezing.