Two severe storm systems threaten millions in the United States.

(CNN) – Two separate storm systems, one from the Gulf Coast region and the other from the mountain west, are threatening millions of people with severe weather between Sunday and Monday.

The Gulf Coast organization is scheduled to arrive on Sunday. More than 15 million people can experience damaged winds, hail and some hurricanes from Lake Charles, Louisiana to Penzacola, Florida, and north of Memphis.

“Extreme weather (Level 2 of 5) will occur during the day on Sunday in southern Mississippi and southeastern Louisiana,” he explained. Office of the National Weather Service in New Orleans. “Damaging winds and hail are the biggest threats, but a hurricane or two cannot be ruled out.”

Flash flooding is a concern, especially in areas of Texas and Louisiana where heavy rains have been falling in recent days.

“The ground is already full in many of these areas, so it doesn’t take much to start a flood,” CNN meteorologist Haley Brink said. “In fact, parts of Texas have collected more than 4 inches of rain in the last 48 hours.”

Heavy storms and snow?

The second system passes through the western and central plains of the mountain on Sunday.

“Growth with strong highs and severe thunderstorms is also possible in the central high plains, where large hail and severe gases are a threat,” he said. Storm Forecast Center (SPC).

In western Kansas, the SPC has released a serious risk (Level 3 of 5).

By Sunday night, snow was forecast for higher altitudes in Colorado and Wyoming as cold winds came from behind.

Many cities on the front edge of the Rocky Mountains can go from several degrees above normal to many degrees above normal in just 48 hours.

Denver is one of those cities that feels the seasonal whiplash. On Saturday, the city hit 30 degrees Celsius, with its average high at the end of June and one degree above the May 1 record. On Monday, the city’s maximum temperature was just 8 degrees Celsius, which is at its highest level at the end of February.

The exceptionally warm winds in front of the front will trigger another day of severe storms, this time across the Mississippi River Valley area.

On Monday, more than 40 million people from Dallas, Texas to Columbus, Ohio, were threatened by severe storms. The main hazards are wind, hail and hurricane damage.

The biggest hurricane threat is from Tulsa, Oklahoma to Padukka, Kentucky.

The biggest concern of the Lower Ohio River Valley via the Osiris Plateau is the time of storms, often in the afternoon and overnight.

A Study A recent finding found that nocturnal hurricanes are twice as deadly.