Two separate rounds of severe weather, including the threat of tornadoes, will keep truckers on their toes this weekend in the Midwest and South. Some of the strongest and most damaging storms could develop after dark, making them all the more dangerous.
Thunderstorms will have far-reaching effects with the potential for locally heavy rain and gusty winds as far north as the Canada border and along the Eastern Seaboard by early next week.
Two storm systems will act as the triggers for severe weather as they swing east from the Rockies, tracking toward the central United States over the weekend. A dramatic clash of chilly air to the north and warm air to the south will help severe thunderstorms develop as a strong jet stream aloft provides plenty of energy and volatility to the atmosphere.
One key dynamic that is needed to fuel severe thunderstorms and tornadoes is moist air from the Gulf of Mexico, and that may not be in place until Saturday evening over portions of the central Plains.
“We have plenty of wind energy and we have the warmth for isolated severe thunderstorms to probably compensate for a lack of very moist air on Saturday afternoon and evening,” Bernie Rayno, AccuWeather chief on-air meteorologist, said. “The greatest risk with the brief thunderstorms during the first round of severe weather this weekend will be from damaging wind gusts, but there is the potential for a few isolated tornadoes as well.”
The risk of severe thunderstorms on Saturday afternoon will begin to increase from eastern Nebraska to northeastern Kansas but will likely reach its peak across Iowa, as well as northern and central Missouri, by early Saturday evening. Major cities at risk for severe storms, including an isolated tornado, include Kansas City, Missouri; Des Moines, Iowa; and Omaha, Nebraska.
Due to the strengthening nature of the storm system, there is the potential for strong, gusty thunderstorms to last well into the nighttime hours as they move through portions of Illinois, Wisconsin, Indiana, southern Minnesota and Michigan. Non-severe storms could reach as far east as Chicago and Cleveland and as far south as Memphis, Tennessee, and Little Rock, Arkansas.
As the first round of storms heads into Canada on Sunday, the second round will advance across the southern Plains.
“All facets of severe weather are possible with the setup on Sunday, ranging from damaging wind gusts and isolated tornadoes to large hail and flooding downpours,” AccuWeather Senior Meteorologist Tony Zartman said.
However, just like Saturday, not all of the ingredients for severe weather will necessarily come together at the same time and could limit the magnitude of the event.
Most of the jet stream energy will not swing into the primary severe weather threat area until Sunday night after prime daytime heating has subsided. The richest moisture from the Gulf of Mexico will also be mostly to the west of the zone.
The majority of storms are likely to wait until late Sunday afternoon or Sunday evening to erupt, but severe weather hazards may continue well into Sunday night over portions of the southern Plains and the lower Mississippi Valley. Cities at risk for severe weather Sunday include Dallas; Oklahoma City; Shreveport, Louisiana; Little Rock; and Memphis. Non-severe storms could hit as far north as the Ohio Valley and as far south as New Orleans.
The National Weather Service defines a thunderstorm as severe if it produces one or more of the following based on radar or eyewitness reports:
• Winds of at least 58 mph.
• Hail at least 1 inch in diameter.
• A tornado.
Major lanes of concern
• Interstate 20 from Shreveport to Dallas.
• Interstate 35 from Oklahoma City to Minneapolis.
• Interstate 40 from Oklahoma City to Memphis.
• Interstate 55 from Chicago to Memphis.
• Interstate 80 from Omaha to Chicago.
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