After record warmth on Thursday, storms are expected to flare up across parts of Nebraska and Iowa, from Friday into the weekend.
Forecasters are advising people, especially those with outdoor plans, to pay attention to changing conditions.
Of special concern is Friday night, when there’s an unusual risk of nighttime severe weather.
“It’s definitely something to keep an eye on,” said Alan Reppert, meteorologist with AccuWeather Inc., The World-Herald’s private weather consultant.
These springtime storms function differently from those of midsummer, he said. Most people in the Great Plains are used to storms dying out with nightfall as temperatures drop. But these storms have a different dynamic, so they could continue to spark and cause problems through Friday night.
The area at greatest risk of violent storms on Friday is central Nebraska.
Scattered, powerful supercells are possible, with damaging hail, strong winds, heavy rains and possibly a few tornadoes.
Sign up for World-Herald news alerts
Be the first to know when news happens. Get the latest breaking headlines sent straight to your inbox.
On Thursday, Omaha set a record high for the date, with the temperature peaking at 95 degrees.
The previous record for May 16 was 93, set in 1944 and 1939.
Another warm day is on tap Friday with highs approaching 90 in Omaha, but the cold front that has been the spark for these storms is dropping south.
As a result, temperatures will fall.
Late in the weekend into next week, daytime highs are forecast to drop back into the 60s, with overnight lows in the 50s and even the 40s.
1 of 8
Issued when conditions are favorable for damaging storms to develop. These watches typically cover a large area and are in effect for several hours. If a watch is issued, people should think about what they’ll do if a dangerous storm suddenly develops. For example, if you have outdoor plans, have an idea where you’ll go for shelter.
This is serious. It means that National Weather Service radar or a storm spotter has detected or seen a powerful storm. These types of storms are capable of causing serious damage, either from hail that is larger than an inch or winds that are in excess of 58 mph. These are targeted to just the area in the storm’s path, unlike a watch, which covers many counties. If you are outdoors and in the path of the storm, seek shelter or try to pull off the road to avoid driving in the storm. These storms can generate tornadoes with little warning.
Conditions are favorable for tornadoes to develop. Watches are issued for large areas and generally for a long period of time. Sometimes watches cover portions of several states and can last for hours. Have a plan for what you’ll do if a tornado suddenly develops. More serious is a tornado warning.
Head for shelter! Tornado warnings are issued when radar has detected rotation in a cloud or a storm spotter has seen a tornado. Take cover immediately if a warning is issued for your area. Even though you may not see the tornado, it could be there, hidden in rain, or it could drop from the sky above you without warning. Warnings typically last about 30 minutes. Local sirens will sound when warnings are issued. But keep in mind that some sirens could be disabled by the tornado, so you may not hear one.
A violent swirling column of air that stretches from a cloud to the ground, with winds in excess of 65 mph. Winds with a tornado can reach 300 mph or more. If you are watching a tornado and can’t tell what direction it is traveling in, then it is traveling toward you.
A swirling column of air that extends downward from a cloud but doesn’t reach the ground.
Hail must be 1-inch wide to be considered damaging. Keep in mind that wind direction often determines which side of a building or car is damaged.
A tornado that isn’t spawned by a powerful storm cell and typically stretches to the ground from a towering, but less threatening cloud. A waterspout occurs over water.