Update at 4:55 a.m. EDT Thursday:
This blog is no longer live, as the threat for severe weather has diminished. However, some thunderstorms still continue from the Ohio Valley into the Plains. Detailed reports of the event can be found below.
Powerful thunderstorms rumbled across areas of the Ohio Valley and the Plains back into the Rockies, triggering tornadoes, large hail, dangerous lightning and flooding rains on Wednesday into Thursday morning.
Tornadoes were reported near Aurora, Byers and Leader, Colorado, with hail and a tornado warning causing flight delays to Denver International Airport.
Tornadoes also touched down near American Falls, Idaho; Wheatland, Wyoming; and Voda, Kansas.
Thunderstorms that tracked across the region also produced hail up to baseball size and torrential downpours that led to localized flash flooding. A very isolated tornado cannot be ruled out.
4:26 a.m. EDT Thursday: Flooding occurring with debris in the streets near Seymour, Indiana, law enforcement reports.
4:13 a.m. EDT Thursday: Golf-ball-sized hail fell at Riddle, Indiana, reports NWS spotter.
4:08 a.m. EDT Thursday: About 15,000 Kentucky electric customers are without power, utilities report.
3:16 a.m. EDT Thursday: Strong thunderstorms moving into the Louisville, Kentucky, area.
2:53 a.m. EDT Thursday: More than 18,000 Kentucky electric customers are without service at this time, utilities report.
2:27 a.m. EDT Thursday: Dayton breaks May 21 rain record with 1.75 inches; old record was 1.28 inches, set in 2010.
2:08 a.m. EDT Thursday: About 1,600 Indiana electric customers were without service early Thursday, utilities report.
1:25 a.m. EDT Thursday: Trees down throughout Scott County, Indiana, law enforcement reports.
1:00 a.m. EDT Thursday: Law enforcement reporting wind damage in north-central Pennsylvania from near Trout Run to Jersey Shore.
11:53 p.m. EDT Wednesday: More than 2,100 Appalachian Power customers in West Virginia were without electricity, the utility reported.
11:40 p.m. EDT Wednesday: More than 370 flights were canceled and another 4,700 delayed in the U.S., according to FlightStats.
11:31 p.m. EDT Wednesday: Flash flooding occurring in Scottland, Illinois, law enforcement reported.
11:15 p.m. EDT Wednesday:3.40 inches of rain fell in the last eight hours at Champaign, Illinois, according to NWS observation.
10:40 p.m. EDT Wednesday: Forty feet of roadway is underwater due to flooding along Highway 26 in Wheatland, Wyoming, reports law enforcement.
10:34 p.m. EDT Wednesday: Major flooding reported by NWS near Cooksburg, Pennsylvania, as the Clarion River has hit 18.69 feet nearly breaking the record of 18.8 feet set in 1936.
10:22 p.m. EDT Wednesday: Hail totaling 2.75 inches in diameter reported 1 mile South of Perry, Illinois, according to NWS spotter.
9:35 p.m. EDT Wednesday: Flooding near Troy, Ohio.
8:49 p.m. EDT Wednesday: Flooding along I-70 near Fairborn, Ohio.
8:25 p.m. EDT Wednesday: Within the past three hours, a radar estimate puts more than five inches of rain in the center of Miami County, Ohio, near Troy and Tipp City.
8:12 p.m. EDT Wednesday: Due to flooding, I-70 closed east of Route 201 in both directions near Fairborn, Ohio, reports the Department of Highways.
7:58 p.m. EDT Wednesday: Cars reported stranded by flooding in Troy, Ohio, reports emergency manager. Numerous flood rescues taking place across Miami County.
7:35 p.m. EDT Wednesday: Due to thunderstorms, a ground stop remains in effect to arrival traffic destined to Denver International Airport, reports FAA.
7:16 p.m. EDT Wednesday: Tornado reported at 7:06 pm EDT two miles southeast of Leader, Colorado, reports NWS spotter.
6:45 p.m. EDT Wednesday: Watch the latest edition of AccuWeather LIVE at 7 p.m. EDT, discussing the most recent details about the powerful storms unfolding from Mississippi to New York.
5:50 p.m. EDT Wednesday:
PUSHING STUCK CARS TOWER & PENA pic.twitter.com/fvlFmyjFcG— Denver Police Dept. (@DenverPolice) May 21, 2014
4:50 p.m. EDT Wednesday: Confirmed tornado on the ground moving at 20 mph near Watkins, Colorado, reports NWS.
4:45 p.m. EDT Wednesday: Golf ball sized hail reported 6 miles southeast of Indianapolis, Indiana, at the intersection of I-65 and I-465, reports NWS trained spotter.
A budding tropical disturbance has the potential to strengthen significantly and reach Florida with strong winds, coastal flooding and torrential rainfall during Sunday and Monday.
Rounds of showers and thunderstorms will bring the potential for flash flooding and localized damaging wind gusts through Thursday.
A deadly earthquake struck central Italy at 3:36 a.m. local time on Wednesday with tremors felt as far away as the capital city of Rome.
Stargazers will want to dig out their binoculars and telescopes this weekend as Venus and Jupiter shine so close that they appear as one large, bright star in the evening sky.
One final surge of heat will encompass much of England and Wales from Tuesday through Thursday.
Following a taste of autumn chill to start the week, is summer heat and humidity over for the northeastern United States?
The remains of Typhoon Holly brought heavy rains and flooding to south-central Alaska with heavy snow inland. (4-foot drifts at Denali National Park).
Hampton Roads, VA (1990)
Very heavy rain fell during the morning, causing widespread flooding. There was also 7.33 inches of rain at Virginia Beach. Between 4 and 5 inches of rain fell at Hampton Roads.
Cloudburst at Guinea, VA - 9.25 inches of rain in only 40 minutes.