JACKSON (AP) — Much of Mississippi was under a severe weather watch Friday as a frontal system pushed showers, thunderstorms and potential tornadoes across the state.

A tornado watch area covering 50 counties was to expire during the late afternoon hours.

The biggest threat for thunderstorms packing damaging winds and possible tornadoes was generally along and south of the Natchez Trace, which runs from Tupelo in the northeast to Natchez in the southwest.

Northwest Mississippi and areas to the south of Natchez, including McComb, Hattiesburg and the Gulf Coast, were not in the watch box, which extended into Alabama.

Weather watchers had said earlier Friday that a dome of stable air was helping hold down the threat of thunderstorm development. But conditions changed as the day warmed.

A relatively quiet passage of the latest system would be good news for the thousands of homeowners across central Mississippi who suffered home and property damage during last week’s outbreak of tornadoes and powerful thunderstorms.

“That stable air we were looking at earlier (Friday) is wearing away finally and we’re starting to see showers and thunderstorms pop up on radar,” said Lynn Burse, with the National Weather Service office in Jackson. “This is a sign the door is opening for storms to intensify.”

As it gets warmer into the day the potential gets stronger,” Burse said. “The tornado risk is mainly into the early afternoon with these storms at this point. The main risk will be damaging winds.”

Storms rumbled across the Delta and to the northwest Thursday night but there were no reports of damage.

Any additional heavy rain, especially over Delta counties, would only add to the growing backwater problems in the Yazoo River Basin that already covers thousands of acres of low farm and timber lands. Meanwhile, flooding continues to create problems along the swollen Mississippi River from Greenville south to Natchez.

Saturday was expected to bring cooler temperatures and mostly sunny skies to most areas of the state.