‘Widespread severe weather threat’ possible for millions in South

(CNN) — An outbreak of severe weather will threaten more than 40 million people this week from the southern Plains through the Southeast — with tornadoes, large hail, damaging winds and heavy rain all possible.

“The potential is there for significant severe weather,” said Meteorologist Jason Holmes at the National Weather Service (NWS) office in Birmingham, Alabama.

Long-track tornadoes are possible given the forecast weather pattern and environmental conditions, according to the NWS office in Mobile, Alabama.

These types of tornadoes are ones that consistently remain on the ground for an extended period of time, unlike a typical one which could be on the ground for just minutes.

The system that will be responsible for these strong storms is currently near the US west coast, but will make its trek through the Rocky Mountains and eject into the Plains by midweek, allowing for an atmospheric set-up conducive for dangerous storms to form.

“We’ve got increasingly warm and humid air over the Gulf of Mexico that will lift rapidly northward — those large scale conditions are quite favorable for severe storms. We think some of the smaller details that we often see on higher end days, especially with significant tornado potential, will also be in place,” said Bill Bunting, Chief of Forecast Operations at the Storm Prediction Center (SPC).

“This is a very strong system that we’ve been tracking the potential for severe storms as it develops and moves off to the northeast, from the Plains into the Ohio Valley,” Holmes told CNN.

Timing out the storms

This next system will introduce the threat for thunderstorms as early as Tuesday evening for much of Kansas, Oklahoma and northeastern and central Texas.

The highest risk, however, will likely be during the overnight hours of Tuesday and continuing into Wednesday morning. An isolated tornado will be possible, but the main risks will be large hail and damaging winds.

There will also be a separate risk for a few strong storms across the South during the day Tuesday, including parts of Mississippi, Alabama and Georgia.

“Our real day of focus right now is Wednesday. We could see a fairly widespread severe weather threat and potentially some high-end severe thunderstorms,” said Bunting.

Wednesday into Wednesday night is forecast to be the most active day in terms of severe thunderstorms this week. There is currently an ‘Enhanced Risk’ for severe weather across eight states in the South, according to the SPC. An ‘Enhanced Risk’ is a level 3 out of 5 in terms of its potential severity.This includes states like Arkansas, Mississippi and Alabama.

The SPC said an “Enhanced Risk” means “numerous severe storms are possible,” and all threats are possible in Wednesday’s set-up — tornadoes, large hail of at least golf ball size, and intense winds of at least 58 mph.

A morning round of showers and potentially thunderstorms are currently forecast to move through parts of the Gulf Coast states, but the main event will be ahead of the cold front Wednesday afternoon into Wednesday night. Near this cold front is where the most intense and tornadic storms could be.

There could be “potentially a few waves of severe weather, starting in the morning, then during the middle of the day, and then later in the evening as the cold front comes in,” said Holmes when discussing central Alabama’s forecast, a region currently in that “Enhanced Risk.”

The potential for multiple rounds of rain may lead to flooding in some locations. A widespread 1 to 2 inches of rainfall is forecast, with some locations receiving over 3 to 4 inches.

By Thursday, the risk for strong to severe thunderstorms will shift toward the US east coast. The region from northern Florida through southern Virginia is currently being monitored by the SPC for this risk, but it is too early to know the exact timing and threat details.

Severe storms typical for South

Severe thunderstorms are not unusual for this part of the country and during this time of the year. Historically, strong tornadoes in mid-March have been most prevalent in northern Mississippi and Alabama, which aligns closely with this week’s forecast storms.

“The details will play a significant role in just how bad things get and where the storms strike. I think what’s important is to know that it’s a typical early season, southeast US severe weather setup in the sense that storms will be fast-moving and they will continue after dark,” Bunting said.

“One dangerous aspect of tornadoes in the South is that they can occur in the middle of the night when people are sleeping unlike Tornado Alley storms that typically become less severe after sunset,” said CNN meteorologist Chad Myers.

Whenever severe weather threatens your area, it’s important to be prepared.

“It’s really important to heed the warning and not wait until you have visual confirmation (of the storm),” Bunting said. “This is the time for folks to have a plan in multiple ways to get the warnings.”

According to Holmes, it’s also important to know where to take shelter in the case a tornado warning gets issued. He says you need to go to the lowest floor of a sturdy building — not a mobile home — and to put as many walls as possible between you and the outdoors.

Along with tornadoes, there will likely also be large hail and frequent lightning, so it’s important to stay inside during the storm.