The National Weather Service has issued a severe thunderstorm watch until 9 p.m. for much of southeast Wisconsin including the Milwaukee metro area.

Wisconsin counties included in the watch are Milwaukee, Waukesha, Washington, Ozaukee, Racine, Kenosha, Sheboygan, Jefferson, Rock, Walworth, Green and Lafayette.

"Thunderstorms are expected to rapidly develop this afternoon along an approaching cold front and move across the watch area," the weather service Storm Prediction Center said in a statement. "Large hail and damaging wind gusts will be possible in the stronger (storms). An isolated tornado or two is also possible."

Overall, in southern Wisconsin, the best chance for severe storms is south of a line from Sheboygan to Darlington in far southwest Wisconsin.

Severe thunderstorms have already moved across portions of Washington and Ozaukee counties on Tuesday afternoon.

Given the conditions in the atmosphere, there is a chance that any storms that do develop could become strong and perhaps severe, said Chris Stumpf, a weather service meteorologist in Sullivan.

Hail would be the main threat from any storms that do turn severe, Stumpf said.

Prior to any storms arriving, it has been a nice spring day across southern Wisconsin.

Enjoy it while it lasts.

"It looks like we are going to be back into the 40s (for high temperatures) and colder as we go into the end of the week, the weekend and into early next week," Stumpf said.

That colder air will arrive on gusty northwest winds as a strong cold front moves through later Wednesday afternoon. Those winds will linger into Thursday night, according to the weather service.

Wind gusts to 40 mph are possible Thursday afternoon, the weather service said in a statement.

Contact Joe Taschler at (414) 224-2554 or jtaschler@gannett.com. Follow him on Twitter at @JoeTaschler or Facebook at facebook.com/joe.taschler.1.