Thunderstorms expected to move into Alabama will bring the threat of tornadoes and winds of up to 70 mph, forecasters said Monday.

“For Pike County, they’ve given us a window of 11 p.m. (tonight) to 8 a.m. Tuesday,” said Jeanna Barnes, EMA director. “That’s a big window.”

The severe storms were expected to enter the state from the west Monday evening and continue heading east through the overnight hours. Although Pike County had been under weather advisories since around 2 p.m. Monday, rains did not begin to fall until about 5 p.m.

“There’s sort of two stages moving through,” Barnes explained around 6 p.m. Monday. “Right now, we’re seeing the storms developing ahead of the squall line. The squall line is expected to arrive sometime in that overnight window.”

And with it, she said, comes the threat of damaging winds and heavy rains “For us, the biggest threat could come from straight-line winds,” Barnes said. “Winds in a severe thunderstorm can average 60 mph.”

The threat of tornadoes was highest in western parts of the state, authorities said.

“Right now, there’s a line of strong to severe thunderstorms as we speak right along the Mississippi River and that’s going to continue to progress east and that’s going to be our main threat,” said Matt Anderson, a meteorologist at the National Weather Service in Birmingham. A tornado watch issued Monday afternoon spanned an area of north, central and west Alabama that included the cities of Florence, Huntsville, Gadsden and Demopolis. A severe thunderstorm warning was issued in the Birmingham area and the National Weather Service issued a flash flood watch for an area south of Montgomery.

Alabama Power tweeted late Monday afternoon that the storms had already left 47,500 people without power.

Officials said 25,000 affected customers were in the metro Birmingham area.

Barnes said temperatures are expected to drop behind the squall line, which is preceding a cold front. Lows will drop to the 50s, with highs in the 70s.

The line of storms is expected to push into Georgia by Tuesday evening.