Updated 3:44 p.m.: Tornado Watch issued for areas north, west of Interstate 44

The National Weather Service has issued a Tornado Watch for much of the state north and west of a line that roughly follows Interstate 44.
The Norman Forecast Office says scattered showers and a few thunderstorms will move across central and eastern Oklahoma through the afternoon, bringing small hail and occasional lightning.
Tornado threat may increase after sunset as low level winds strengthen. Stay alert and be ready for quick action. #okwx
— NWS Norman (@NWSNorman) April 8, 2015
Any storms that do develop could become severe quickly, with the best chance for and any storms are likely in central Oklahoma after 8 p.m.
Updated 1:20 p.m.: SPC increases likelihood of tornadoes in north-central Oklahoma
The Norman-based Storm Prediction Center has upgraded the risk of severe thunderstorms, especially across the northernmost portions of Oklahoma near the Kansas border.
The SPC says there's now a Moderate Risk (its second-highest classification) of several tornadoes, including intense twisters, along with hail up to the size of baseballs and damaging straight-line winds.

National Weather Service warning coordination meteorologist Rick Smith says the SPC's map highlights the area where tornadoes are most likely, but they could also occur in the slight or enhanced areas. He says severe storms will most likely affect the Oklahoma City metro after 8 p.m.
1237pm - tornado potential far N OK will likely increase early evening hours as winds strengthen. A strong tornado is possible. #okwx
— Rick Smith (@ounwcm) April 8, 2015
Updated 7:54 a.m.: Storm timing could come during evening rush hour
Severe storms capable of producing tornadoes, large hail, and damaging winds could arrive in central and northern Oklahoma around 4 p.m. Wednesday and last through the evening.
"This is still not a slam dunk forecast. There is still some potential that we won't see very many storms today, but any storm that forms will have a very high potential to become severe," said Rick Smith, the Warning Coordination Meteorologist at the National Weather Service's Norman Forecast Office. "And this will include the drive home this afternoon, so you'll want to be sure to that you do not leave work or school this afternoon without checking the weather and avoid travel if there are severe thunderstorms, and especially tornadic storms, in the area."
Updated 6:34 a.m.: Tornado potential increasing throughout the state
Forecasters say the ingredients necessary for another round of bad weather are coming together for a series of storms, especially across northern Oklahoma.
"Where storms do develop they have the potential to produce large hail, damaging winds, and possibly tornadoes,” says National Weather Service Meteorologist Matthew Day. “The tornado potential is relatively low, but enough to warrant attention. Golf ball-to-tennis ball-sized hail, and 70-to-80 mile-per-hour winds will also be possible with these storms.”
The Norman-based Storm Prediction Center says seasonal warming and changes in the jet stream are behind the new round of severe weather. Cool air in place early this year suppressed thunderstorm development in much of the country, and until late March the U-S went more than a month without a twister.
Information from the Associated Press was used in this report
Original Post
The National Weather Service says a large storm system will move across the central United States this week, two weeks after tornadoes killed four people in central and northeast Oklahoma and damaged thousands of homes and businesses.
Norman Forecast Office meteorologist Vivek Mahale says a strong cap will limit storm development Tuesday, but instability means that any isolated storms that develop could become severe, with large hail and damaging straight-line winds.
“Wednesday looks to be the highest impact day for the week,” Mahale said. “"Any storms that develop have a moderate potential to produce a tornado. Golf ball to tennis ball-sized hail, and 70-80 mile-per-hour winds also will be possible.”
The threat of severe weather will move off to the east on Thursday.
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