Isolated severe thunderstorms have been developing in the Upper Midwest this afternoon, with coverage expected to become more widespread this evening into the overnight. A Tornado Watch has already been issued in North Dakota, South Dakota and Minnesota, with additional watches possible later tonight. Over the next few hours, there is the potential for isolated tornadoes, mainly in eastern sections of North and South Dakota.
Rotation observed on radar in the Litchville area. Heavy rain in area so any tornado will be hard to see. #ndwx
— NWS Grand Forks (@NWSGrandForks) September 19, 2017
Hail greater than the size of a quarter and wind gusts above 60 mph are also possible. Large hail and strong winds will be the primary severe weather threat later tonight as the storms progress into Western Minnesota.
A cold front extends from a weak surface low through the Central Dakotas, preceded by a pre-frontal trough. The trough has produced isolated severe storms this afternoon. A warm front stretches from Central Minnesota through South North Dakota. Humidity levels increase along and south of the front, with dew points in the low to mid 60s. Instability will continue to increase into this evening as Jet Stream energy approaches from the High Plains.
The cold front will move into the Red River Valley later tonight and sweep through Minnesota overnight. Storms will begin to weaken toward sunrise Wednesday morning.
Stay tuned to WeatherNation on-air and online for the latest severe weather information.
For WeatherNation: Meteorologist Mace Michaels