Tornadoes: A 'particularly dangerous situation' tornado watch has been issued for 3 southern states | CNN

Severe storm threat expands to over 40 million Tuesday

02:08 - Source: CNN

Wicked weather 16 videos

Severe storm threat expands to over 40 million Tuesday

02:08

Now playing

- Source: CNN

'I have no windshield': Helicopter damaged by hail during broadcast

02:17

Now playing

- Source: CNN

Massive shelf cloud darkens sky over downtown Chicago

01:10

Now playing

- Source: CNN

video thumbnail man swims street fort lauderdale

Man swims in street during historic flooding

01:48

Now playing

- Source: CNN

man inside van tornado little rock arkansas

Man rides out tornado inside van. See the footage

00:30

Now playing

- Source: CNN

See how California's recent weather crises brought dead lake back to life

03:46

Now playing

- Source: CNN

'Unbelievable': CNN reporter reacts to record snowfall in California

01:53

Now playing

- Source: CNN

A tornado destroyed an Arkansas football field. See what's left

00:58

Now playing

- Source: CNN

Hear how tornado lifted couple up in the air while sitting in their bathtub

02:41

Now playing

- Source: CNN

Watch: Rare tornado tosses debris near Los Angeles

01:04

Now playing

- Source: CNN

Video thumbnail Ed Hawkins warming stripes

Graphic shows all the changes in global temperature since 1850

03:28

Now playing

- Source: CNN

Man builds 12-foot-tall snow tunnel to get out of home

00:45

Now playing

- Source: CNN

Drone video captures the aftermath of deadly California atmospheric river

02:03

Now playing

- Source: CNN

fedex delivery driver falling tree kentucky

Watch dangerous moment FedEx driver encounters on route

00:41

Now playing

- Source: CNN

'Early wake-up call': Storm chaser describes severe storms in central US

02:33

Now playing

- Source: CNN

Dashcam shows speeding semitruck inches from striking state trooper

01:59

Now playing

- Source: CNN

Editor’s Note: Affected by the storms? Use CNN’s lite site for low bandwidth.

CNN —

Numerous tornadoes – including a few intense ones – are possible Tuesday evening for parts of Arkansas, Louisiana and Mississippi as severe storms rake the area, a situation that moved forecasters to issue a special tornado watch alerting residents to an unusual level of risk.

Track the storms as they develop >>

Be prepared for severe weather and tornadoes

• Know where to find your daily local forecast

• Set devices to receive storm and tornado warnings via Wireless Emergency Alerts

• Know the difference between a tornado watch, tornado warning and tornado emergency

• Track the severe storms

A “particularly dangerous situation” tornado watch, reserved for the most significant severe-storm threats and used in only 3% of watches, was issued for central Mississippi, northeast Louisiana and southwest Arkansas, and is in effect until 2 a.m. CT. It is the second such watch issued Tuesday and covers many of the same locations as the first, which has expired.

“An outbreak of severe thunderstorms is underway in the South this evening and is expected to push into the overnight hours,” the National Weather Service said Tuesday. “Severe thunderstorms are bringing strong tornadoes, very large hail, and severe wind gusts across parts of the lower to mid Mississippi Valley, Mid-South and parts of the Southeast.”

At least 10 tornadoes had been reported as of 8:30 p.m. ET. All but one were in central and southern Mississippi.

A strong storm that hit Lowndes County, Mississippi, this evening left behind a path of destruction, with reports of damaged homes, Lowndes County Sheriff Eddie Hawkins told CNN affiliate WTVA.

This comes as severe storms could hit a much wider area of the United States from Tuesday into early Wednesday, from the Gulf Coast to the Midwest, with tornadoes, damaging winds and hail, forecasters said.

But prediction center forecasters focused especially on Arkansas, Louisiana and Mississippi, saying “parameters appear favorable for strong and long-tracked tornadoes,” meaning ones that stay on the ground for an extended period, Tuesday afternoon and early evening in the watch area.

“Numerous tornadoes (are) expected with a few intense tornadoes likely,” along with scattered large hail and scattered damaging wind gusts up to 70 mph, forecasters said in the special tornado watch.

Overall, more than 41 million people from southeastern Texas eastward to Georgia and northward to central Indiana and Illinois are under at least a marginal threat of severe weather Tuesday, according to the Storm Prediction Center.

Separate from the special tornado watch, the prediction center laid out an area where it believed the largest potential for severe weather, including tornadoes, existed – covering 1.6 million people in east-central Louisiana; a sliver of southeastern Arkansas; much of Mississippi, including Jackson; and northwestern Alabama. The threat for that area – a Level 4 of 5, or moderate – is relatively rare for this time of year, and tornadoes, though they can happen year-round, are more frequent in the spring and summer.

“Severe thunderstorms in the fall and winter can be extremely impactful and may sometimes catch people off guard as thunderstorms tend to occur less frequently during the cooler months,” Bill Bunting, chief of forecast operations at the Storm Prediction Center, told CNN Weather.

A Level 3 of 5, or enhanced, risk zone encircles that area, covering 2.8 million people across parts of Mississippi and Louisiana as well as a small part of eastern Texas, southeastern Arkansas, southwestern Tennessee and western Alabama.

What is a long-track tornado?

Long-track tornadoes are tornadoes that are on the ground for an extended period of time. The majority of tornadoes are on the ground for just minutes, but with some severe events, there could be tornadoes on the ground for hours. This kind of tornado is known for causing widespread damage.

Some tornadoes could happen overnight Tuesday into Wednesday, making them even more threatening because it’s harder during those hours to alert people to take shelter.

“Another challenge with nighttime tornadoes, especially in the fall and winter, is that storms typically move very quickly, at times 50 or 60 mph,” Bunting said.

“This means that you must make decisions quickly and take shelter based on information contained in the severe thunderstorm or tornado warning, and not wait until the storm arrives,” Bunting added.

The same storm system also brought heavy snowfall to 13 states across the West and Upper Midwest, where millions of people were under winter weather advisories and winter storm warnings Tuesday morning.

Storms could cause flooding in the South

Generally about 2 to 4 inches of rain could fall in the south-central United States, and the total could be greater in far southern parts of Mississippi and Alabama, where the storms could stall, the Weather Prediction Center said.

That could cause flooding in those areas, where the soil is damp from recent rains, the prediction center said. Flood watches are in place Tuesday in parts of southeastern Louisiana and southern Mississippi and Alabama.

In anticipation of the storms, the Mississippi Emergency Management Agency urged residents to document property that could get damaged.

CNN values your feedback

A ‘particularly dangerous situation’ tornado watch in effect for parts of 3 southern states

Be prepared for severe weather and tornadoes

What is a long-track tornado?

Storms could cause flooding in the South

Read more about tornadoes