UPDATE @ 12:15 a.m.:
Close to 2 inches of rain fell in Wayne County and more than 1 inch in some spots north of Interstate 70, said Storm Center 7 Chief Meteorologist Jamie Simpson. Another inch is possible, mainly south of US 36.
"The threat of any wind damage is over, and lightning is about gone too, so it's just rain from here on out, mainly through 3 or 4 a.m. then tapering down and off from northwest to southeast, with the last ending around sunrise," Simpson said.
The flash flood watch has been continued through 8 a.m. for Butler, Champaign, Clark, Clinton, Darke, Greene, Logan, Mercer, Miami, Montgomery, Preble, Shelby and Warren counties in Ohio and Wayne County, Ind., according to the National Weather Service.
UPDATE @ 11:15 p.m.:
A line of strong storms will affect Miami County through 11:30 p.m., according to the National Weather Service. Storm hazards include winds up to 40 mph, the NWS reported.
UPDATE @ 10:15 p.m.:
Darke and Miami counties are under a flood advisory until 1:15 a.m., according to the National Weather Service, because more than 2 inches of rain is expected over the next three hours.
A line of strong thunderstorms will affect northern Preble and southern Darke counties in Ohio, and Wayne County, Ind., through 10:45 p.m., the National Weather Service reported.
UPDATE @ 9:46 p.m.:
Wayne County, Ind., is under a tornado warning until 10:15 p.m. The National Weather Service has indicated a severe thunderstorm north and east of Richmond, moving east at about 40 mph.
The storm is capable of producing a twister, Simpson and the weather service say.
UPDATE @7:20 p.m.:
The short-term threat of severe weather is over and probably the tornadic threat, Storm Center 7 Chief Meteorologist Jamie Simpson said.
The tornado watch is still in effect until 9 p.m., and radar indicated a tornado just northwest of Indianapolis, he said.
"The cold front in central Illinois will arrive towards midnight, but we now have some showers and thunderstorms developing ahead of it from north central Indiana to west central Indiana. Those should arrive, first northwest in the 8:30 to 9:30 p.m. time frame, but more importantly, after sunset, so the weakening process should have already begun," Simpson said.
The threat of some stronger winds will remain for a while after sunset. That, plus weakening storms along the cold front will keep a threat for heavy rain across the area from late evening through early morning, around 2 to 3 a.m. Thursday. This is why the flash flood watch will continue through morning, Simpson said.
UPDATE @6:45 p.m.
Dayton Power & Light Company say they are prepared for power failures resulting from severe weather.
"For the last two days we've been planning for this storm," said Kelly Millhouse, director of substation operations.
Extra staff is working, and additional resources can be tapped if needed, she said, to restore customers as quickly as possible in the event of outages.
UPDATE @5:45 p.m.:
The National Weather Service is reporting that a strong thunderstorm will affect eastern Mercer and western Auglaize counties through 6:15 p.m. The storm is moving east at 40 mph. Storm hazards include winds up to 40 mph, according to the NWS.
The National Weather Service is reporting that a strong thunderstorm will affect southern Mercer County through 5:45 p.m. Storm hazards include winds to 40 mph, according to the NWS.
Our team of Storm Center 7 meteorologists are closely watching a cell near Muncie, Ind., that is moving northeast toward Mercer County.
"Once that passes by the far northwest, it is possible we see very little in terms of strong to severe storms or heavy rain until the cold front approaches later this evening," said Storm Center 7 Chief Meteorologist Jamie Simpson. "By that time storms with the cold front will be much weaker after sunset."
A tornado watch remains in place through 9 p.m. for all but Clark, Greene, Warren and Clinton counties.
A flash flood watch is now in effect through 8 a.m. Thursday for the entire region.
The rest of today, there will be ongoing showers and thunderstorms across the northern Miami Valley, Storm Center 7 Chief Meteorologist Jamie Simpson said. There will be very little thunder and lightning, which means the threat of hail is small to nonexistent.
"There have been a few severe thunderstorm warnings in Indiana north and northeast of Indianapolis due to individual cells moving at 55 mph. Gusts to 60 mph are possible with these, and they will first impact the far northwest Miami Valley by 5 p.m.," Simpson said.
The batch of showers and storms is well ahead of the cold front, so the damaging wind threat might be over around 8 or 9 p.m. at the latest, he said.
An expected break between the rain early this evening and later tonight around midnight with the cold front should lessen the flood threat. The combination of that, plus soil that can handle 2 inches of rain means any flooding should be isolated.
"Gradually, rain tapers down overnight as we drop from the 70s this evening to the 60s by morning," he said.
The National Weather Service has issued a Tornado Watch in effect until 9 p.m. for Shelby, Auglaize, Montgomery, Butler, Logan, Preble, Darke and Mercer counties in Ohio and Randolph County in Indiana.
A flash flood watch goes into effect this afternoon through 8 a.m. tomorrow, according to the National Weather Service.
The watch is for Mercer, Auglaize, Darke, Shelby, Logan, Miami, Champaign, Clark, Preble, Montgomery, Greene, Butler and Warren counties, and parts of Indiana, including Richmond.
The NWS said multiple waves of showers and thunderstorms will bring the potential for heavy rain that could cause flash flooding.
A line of showers and storms will slowly intensify northwest late this afternoon and work through the area into the evening, said Storm Center 7 Meteorologist Rich Wirdzek.
"At the onset, some higher wind gusts could reach damaging speeds," he said.
Flash flooding will also be a concern as several hours of rain will be possible in many areas due to the slow movement of the rain.
"The rain should slowly work southeast of the area during the very early hours tomorrow, allowing for a drying trend before the morning commute starts," Wirdzek said.
Highs today will be in the mid-80s.
Thursday: Some late day sun is expected, with highs only reaching close to 70 degrees.
Friday: Highs will only hit in the upper-60s.
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