Thunderstorms are expected to expand in coverage and intensity this afternoon and evening across Eastern Oklahoma Northwest Arkansas and will move eastward as a cold front moves into the region. A slight risk of severe weather will be possible with the greater potential through 1 am. The primary severe weather threats with these storms will be damaging straight line winds and large hail with also an isolated tornado threat possible. Additional storms will be possible during the overnight hours tonight across mainly Northeast Oklahoma and Northwest Arkansas as the upper level low moves overhead. Thunderstorm chances will decrease from west to east Saturday as the upper low exits the region.