From snow squalls to tornado warnings, the U.S. is being pummeled with severe storms this week. What do these weather terms mean?

From snow squalls in the Great Basin to tornado warnings in the Southeast and blizzard warnings in both the Plains and Pacific Northwest, many corners of the U.S. are being pummeled with severe weather this week. What do these weather terms mean – and what can Americans expect in the forecast? 

What is a snow squall?

A snow squall is an intense, but often short, period of moderate to heavy snowfall that can lead to significant snow accumulation, according to the National Weather Service's glossary. The burst of snow is often accompanied by strong winds and even lightning. 

A storm system moving west over the next few days will bring a strong cold front to the Great Basin and four corners region, bringing a risk of snow squalls, Zack Taylor, a meteorologist with the National Weather Service Weather Prediction Center, told CBS News. 

These "really intense bursts of snow showers produce intense snowfall rates," Taylor said, and can cause whiteout conditions. "It can be a pretty serious situation when you have snow squalls, generally for travelers and motorists, when you have rapidly deteriorating conditions mainly due to rapid snowfall rates," he said.

Snow squalls can generally happen anywhere that experiences winter weather, Taylor said. 

What is a tornado warning?

Tornado warnings are issued when people in affected areas should seek shelter from tornadoes immediately – even if they have not received a tornado watch, NWS says. A tornado watch is issued when the weather is favorable for tornadoes and can last four to eight hours. They usually happen in advance of the tornadoes to let people know they should prepare for severe weather, according to the National Weather Service.

Tornado warnings usually last about 30 minutes. 

Local National Weather Service offices will issue these warnings with details about where the tornado is located and what towns will be in its path. If the tornado is near the coast, a special marine warning may also accompany the tornado warning, or if there is also a thunderstorm, a flash flood warning may accompany it. 

A storm system that brought tornadoes to the Southeast earlier this week is winding down on Wednesday, Taylor said. Parts of the Florida panhandle were under a state of emergency Tuesday after several tornadoes touched down in the state. The storms were blamed for at least four deaths.

Another strong storm system will move through the Central and Eastern U.S. later this week, bringing with it another risk of strong winds and tornadoes, Taylor told CBS News. 

"With the storm system that is moving through beginning tomorrow [Thursday] and then continuing into Friday, there will be a risk of severe weather, including tornadoes, generally across the Mississippi Valley into portions of the mid-South." Taylor said, adding that Arkansas, Louisiana and Eastern Texas may also be at risk. "That does spread eastward for the day on Friday, so the risk will extend really for much of the Southeast. So, from Mississippi up through the Carolinas."

He said these areas may see strong winds and hail in addition to tornadoes. 

What is a blizzard warning?

Blizzard warnings are issued when winter storms bring significant snowfall that can reduces visibility to a quarter of a mile or less, and have sustained or frequent 35 mph or higher winds, according to the service. 

Earlier this week, parts of the Plains saw blizzard warnings. "It's not super rare to get the conditions that lead to blizzard conditions across the Plains. They're prone to strong winds and winter storms — any time those overlap, they can produce the very low visibility and the snowfall associated with [blizzards]," Taylor said.

On the other side of storm system moving across the East, there will be a cold side that may bring blizzard conditions to parts of the Midwest and Great Lakes later this week Taylor said. "Any time you get strong low pressure systems and winter weather, there's always going to be low-visibility and whiteout conditions and the possibility of reaching that blizzard criteria." 

There are also blizzard warnings in affect for parts of Washington, Oregon and Idaho, Taylor said. "Again, this is another really strong storm system, really intense, heavy snowfall. Winds will be very strong as well," he said.  

Sierra snow

A storm in the Sierra Nevada — athe mountain range between the Central Valley of California and the Great Basin — became the second within a week on Tuesday to bring snow to the region, CBS Sacramento reports. 

Storms like this are important because they often contribute to water supply. "The snowpack in the mountains in particular is important for drought relief and filling reservoirs. It's like saving up money in the bank during these events to be spent in the spring when the snow melts and fills the reservoirs," Weather Channel meteorologist Jacqui Jeras told CBS News in September when California was being hit with relentless rain. 

Scientists at the University of California, Berkeley Central Sierra Snow Lab hope the latest snow in the region can make a dent in the snowpack, according to CBS Sacramento.

The Sierra Nevada is still under winter storm warnings on Wednesday, Taylor said. "In some of the higher elevations of the Sierra in California we are looking at one to two feet of snow and even three feet, which are the highest peaks. This is probably, for the winter season, one of our notable winter storms that the Sierra is going to have. So far this season, it has been relatively quieter but this will be a pretty impactful winter storm," he said.

With it, the storm is likely to bring difficult driving conditions and even closed roads, Taylor said. 

While many parts of the state are not currently in a drought, this is the time of year when the weather can help keep areas from turning into a "drought situation," Taylor said. 

Costal flooding and king tides

A storm system moving onto the West Coast is bringing strong winds "and that typically leads to favorable conditions for coastal flooding, strong waves, stuff like that," Taylor said. 

On Wednesday morning, NWS issued a Coastal Flood Advisory in the Bay Area as low-lying areas were expected to flood due to high tides and heavy rainfall, CBS News Bay Area reports. So-called "king tides" were to blame.

"King tide" is a non-scientific term to describe extremely high ocean tides, according to the National Oceanic and Atmospheric Administration. Tides are affected by the gravitational pull of the moon and sun, and are usually higher when the moon is new or full.

Coast flooding was also seen in other parts of the U.S. this week. Heavy rain from Monday to Wednesday brought flooding to parts of the central Gulf Coast through the Northeast.

Arctic air

"The thing that I think is going to be a pretty big story is the Arctic air," Taylor said. "Very cold temperatures that are going to be plunging southward – initially across the Northern Rockies and then spreading southward." 

The storm systems passing across the northwest and central U.S. this week are expected to bring these cold temperatures behind them, he said. Portions of the Northern U.S. could plunge into the negative 20s, Taylor said. The Rockies and Plains will likely experience this cold blast early next week and it will move to the Eastern U.S.