An approaching storm system is bringing with it the threat of severe weather, including tornadoes and possible flooding, to Oklahoma.

The National Weather Service has issued a tornado watch for 12 counties in the far western part of the state until late Sunday. Besides tornadoes, large hail and strong winds are possible as storms develop along the dryline and a cold front.

In far eastern Oklahoma, a flash flood watch will be in effect for 13 counties from Monday afternoon to Wednesday morning. Forecasters say the slow-moving storm system could dump widespread amounts of 4 to 8 inches of precipitation and isolated rainfall totals approaching a foot.

The weather service warned that such heavy rainfall amounts could cause catastrophic flooding in those areas.