The risk of damaging thunderstorms will spread into the Midwest and South Thursday and then into part of the East Friday.
As the outbreak spreads eastward, it is likely to produce a swath of downed trees, power outages, large hail and isolated flash flooding. There is also the risk of a few tornadoes.
An unusually strong storm system for late May will continue to roll out of the Plains and toward the Great Lakes during the balance of the week.
Cold upper levels of the atmosphere will combine with strong surface heating to produce the rapid development of thunderstorms.
The storms will bring a raised risk for hail since the air is so chilly aloft. However, since the storms will poke high into the atmosphere, where strong winds are present, some of the strong, high-level winds can reach down to the surface in the form of powerful downdrafts and horizontal gusts.
The early stages of the severe weather took aim at the Plains late Thursday, as thunderstorms dropped hail as large as grapefruits and generated wind gusts as high as 90 mph. Meteorologist Bill Deger has more on those damaging storms
Later today and into tonight, more severe storms will target a large area from Texas to the Ohio Valley with damaging winds, hail and even a few tornadoes.
As it is now, an outbreak of large, long-tracking tornadoes is generally not expected east of the Mississippi, but rather more on the order of the straight-line wind and hail scenario.
Even with the setup as it is, brief tornadoes are still possible with the event in portions of the Ohio, Tennessee valleys as well as part of the central Appalachians and East Coast.
People should take the severe weather threat seriously and keep an eye on rapidly changing weather conditions.
The greatest threat to lives from any thunderstorms is lightning. Seek shelter indoors as storms approach. If you can hear thunder, you are at risk for being struck by lightning.
The storm system is more typical of early April in terms of the potential for severe weather.
According to Chief Meteorologist Elliot Abrams, "The pattern coming up in June will seem more like April, while May may have seemed more like June for some folks."
Abrams was referring to the relatively weak land-based storms in the Central and Eastern states, while the tropics were active in May.
The upcoming pattern well into June will tend to favor stronger land-based storms and the likelihood of minimal tropical activity due to wind shear.
AccuWeather.com Meteorologist Bill Deger contributed to the content of this story.
The Memorial Day weekend will begin cool, windy and rainy in New England and part of the mid-Atlantic.
On the two-year anniversary of the EF-5 tornado that leveled Joplin, Mo., the town has deployed assistance to Moore, Okla.
The tornado tore through a path 17 miles long on Monday and had wind speeds as high as 200 mph.
Wednesday will be drier and less humid for recovery and clean up efforts.
The same storm system responsible for producing violent thunderstorms in Oklahoma recently will reach the Atlantic Seaboard later Thursday.
Strong thunderstorms impacted areas from Texas and Louisiana to New England with large hail and damaging winds.
Hallam, NE (2004)
The "Hallam" tornado touched on the ground for 2.5 miles and reached F4 status at it's peak intensity. 95% if the town of Hallan's buildings were damages or destroyed.
Liberal, KS (1933)
A powerful F4 tornado (winds 207-260 mph) hidden in a dust storm devastates the business district. 4 people were killed and 150 were injured. Tornado estimated to be 600 yards wide at times.
Atlantic City, NJ (1991)
Record high of 89 degrees after a record low of 38 degrees. Record lows were also set May 19,20, & 21st.