(NEXSTAR) – A large swath of the midwestern and eastern United States is expected to be at risk for storms beginning on Friday evening, with more severe weather such as hail and damaging winds likely for certain regions. But the National Oceanic and Atmospheric Administration (NOAA) had also warned on Thursday of possible “nocturnal tornadoes,” weather phenomena known to be particularly dangerous.
Nocturnal tornadoes, as the name suggests, are tornadoes that occur overnight. Generally, tornadoes that occur during these hours are less common or less severe than their evening or daytime counterparts — but they’re twice as likely to kill, the NOAA has found.
In a report released earlier this year by NOAA’s Storm Prediction Center, researchers explored the difficulty in forecasting such storms and subsequently communicating the necessary warnings to the affected populations.
“Nocturnal tornadoes are difficult to forecast, difficult to see (and therefore confirm), and difficult to respond to because much of the population is asleep when they occur,” reads the report.
Forecasters have more trouble anticipating the storms and identifying them in real-time, they said, as these tornadoes tend to form rapidly amid “quasi-linear convective systems” — i.e., a family or line of storms moving together.
There’s also one region of the U.S. that seems to experience more nocturnal tornadoes than any other — the Southeast — where the tornadoes “tend to have higher wind shear values produces,” among other dangerous characteristics.
“The Southeast also has unique socioeconomic characteristics, including a higher mobile home population and a higher proportion of people living below the poverty line,” stated the report.
“These mobile homes are more susceptible to damage from weaker tornadoes, making them particularly dangerous during a tornadic event.”
The report, compiled by researchers with the NOAA, the University of Oklahoma, and the National Weather Center, among others, had also determined that the public was less confident they would see any warnings that were issued at night, and particularly between the hours of 12:00 a.m. and 4:00 a.m.
“We also show that individual characteristics like age and the number of weather information sources someone accesses impact confidence in one’s ability to receive warnings during this time frame,” the report reads.
Friday evening’s storms, meanwhile, are expected to affect the eastern U.S. (among other regions), including parts of thee Southeast.
“A few strong tornadoes, damaging gusts, and large hail are all expected beginning this evening across Arkansas and Missouri, with the greatest tornado threat close to the confluence of the Mississippi and Ohio Rivers,” the Storm Prediction Center wrote Friday morning. “The damaging wind and tornado threat will persist overnight while spreading eastward into the Tennessee Valley and northeastward across the Ohio Valley overnight.”