Disruptive and dangerous thunderstorms will erupt and advance from the central United States to the East Coast during the Memorial Day weekend, AccuWeather meteorologists warn.
"We are entering a very stormy period that coincides with the first unofficial holiday weekend of the summer," AccuWeather chief on-air meteorologist Bernie Rayno said, "Each day [and night] through Monday will bring its share of dangerous storms."
 |
In some of the more powerful instances, the AccuWeather Local StormMax&trade wind gust will reach or exceed Category 1 hurricane force, which is 74 mph. However, in the most extreme cases during the weekend, StormMax winds will be considerably higher.
Many areas in the Central and Eastern states will be hit by one or more rounds of thunderstorms this weekend. When accompanied by downpours and gusty winds, these can ruin outdoor gatherings, such as weddings, memorial parades or family cookouts.
 |
Strong wind gusts can hit some areas, knocking over trees, cutting power or damaging homes and businesses. In other cases, large hail can break windows, damage crops and dent vehicles. Torrential downpours associated with many storms can briefly flood streets, secondary rural and suburban roads and even major highways.
In a few extreme cases, inches of rain may pour down in an hour, leading to life-threatening flash flooding, especially in the Ozark Mountains and the southern Appalachians, which are popular locations for holiday camping trips.
 |
AccuWeather meteorologists are closely monitoring the situation from Saturday to Sunday as a large complex of severe thunderstorms may roll for hundreds of miles and could lead to dozens of damaging wind and flash flood incidents from central Oklahoma and Kansas to southern and central Missouri and northern Arkansas and perhaps to portions of Illinois, Indiana, Kentucky and Tennessee.
The StormMax wind gust for Saturday is rated at 100 mph for portions of the central and southern Plains to the mid-Mississippi Valley. That intensity is as strong as a Category 2 hurricane.
 |
Tornadoes are likely to occur in the most violent storms during the extended holiday weekend. The risk of tornadoes may be greatest over parts of the central and southern Plains on Saturday, the mid-Mississippi, Ohio, and Tennessee valleys on Sunday and then parts of the mid-Atlantic region on Memorial Day. In portions of the Central states, the risk of tornadoes may continue after dark on Friday, Saturday and Sunday.
Chicago will be at moderate risk of severe thunderstorms and a tornado on Friday. Oklahoma City and Tulsa, Oklahoma, will be at high risk for violent storms, including twisters, on Saturday. St. Louis and Lousiville, Kentucky, will be at a moderate risk of severe weather, including tornadoes, on Sunday.
Thunderstorms may threaten Sunday's Indianapolis 500, which is scheduled for early in the afternoon. Last year, over 300,000 people attended the world-famous race. With dangerous thunderstorms in the forecast, attendees should prepare for weather-related delays or postponements.
 |
A few hours later, another big auto race will occur at Charlotte Motor Speedway, North Carolina. NASCAR's grueling 600-mile stock car event runs well into the night. At this time, it appears that pop-up thunderstorms will be nearby and could trigger rain and lightning delays. Severe weather may hold up to the west over the North Carolina mountains.
While the extent of severe thunderstorms in the East on Memorial Day may be limited to parts of the region, the strongest storms still carry some risk of tornadoes. Cities at risk of severe weather on Monday include Washington, D.C., and Philadelphia. A cool breeze from the Atlantic may limit severe weather in New York City and Boston to perhaps later in the day or at night.
AccuWeather utilizes severe weather areas to alert the general public. The most common range from some (yellow) risk, where potentially damaging storms will affect part of the area, to moderate (orange), where numerous severe thunderstorms are anticipated. A high (red) risk zone is uncommon and denotes widespread severe thunderstorms. An extreme (burgundy) risk zone is rare but signifies the likelihood of an intense outbreak of severe weather.
 |
Any severe thunderstorm is capable of producing a brief tornado.
Motorists and those outdoors are strongly encouraged to watch for rapidly changing weather conditions.
As a general rule, if thunder can be heard, there is a risk of being struck by lightning, even in the absence of severe weather advisories. Avoid being caught in a multiple-vehicle accident by slowing down before torrential downpours arrive or exit the highway until the storm passes.
