Water-weary communities across southern Wisconsin watched hopefully as floodwaters in some areas started to subside but looked ahead nervously to a forecast that threatens another round of possibly severe thunderstorms Thursday night and early Friday.

The forecast calls for potentially heavy storms beginning Thursday evening that could dump another 1 to 2 inches of rain on southern Wisconsin.

"It is setting up to be a significant thunderstorm event," said meteorologist Bob Lindmeier, with WKOW-TV in Madison.

Gary Lepak, a dam safety engineer for the state Department of Natural Resources, said that's a scary prospect in Vernon County in southwestern Wisconsin, where numerous small dams have been near failure and 91 roads are closed due to flooding.

"That certainly does cause us some concern," Lepak said. "It depends on whether it comes over an hour or over 12 hours. ... We've dried out a little but not nearly enough. We do have a number of dams that are stressed out here in the western part of the state."

Lepak said engineers are considering deliberately breaching one strained earthen dam to relieve pent-up pressure and prevent a more catastrophic failure if more rains falls.

The National Weather Service Tuesday reported that water levels on the upper reaches of many flooded rivers were dropping but added that levels could still be rising downriver. For example, Lepak said Kickapoo River levels were moderating but noted the Baraboo River is still rising.

In Jefferson County, the Rock and Crawfish Rivers had not yet crested by late Tuesday and officials in Jefferson, Fort Atkinson and Milford were warning residents of major flooding yet to come.

"It may flood so fast, we may not even be able to get emergency vehicles in," said Fort Atkinson City Manager John Wilmet of the low-lying area near the Rock and Bark rivers. "The worst is yet to come."

Rock County worries

Similar fears were expressed in Rock County, where communities are bracing for the Rock River to crest at record levels, possibly as late as the weekend. The river topped the 10-foot flood stage at 1 p.m. Tuesday and was expected to rise to 13.5 feet Saturday or Sunday.

Gov. Jim Doyle, in a Tuesday afternoon news conference, said emergency officials are hoping floodwaters subside enough to relieve pressure on dams and bridges before Thursday night's expected storms.

The National Weather Service reported Tuesday afternoon that floodwaters in several southern counties appeared to be receding, a trend that, with dry weather, could continue today. In areas of Dane, Iowa and Rock counties, floodwaters started to recede and conditions were starting to improve.

Still, the weather service reported, widespread flooding continued to cause problems in Sauk County, with many roads and bridges closed in Baraboo. Flooding rivers may be a threat to the integrity of some bridges in Sauk and Columbia counties, the weather service said.

"These may put some bridges at risk, either by water flowing over the roadway or by decreasing the strength of the supports," a report Tuesday from the weather service said of the flooding. The report also indicated flood warnings for most areas are likely to stay in place through the end of the week.

FEMA to visit

Doyle asked the Federal Emergency Management Agency to conduct a damage assessment in anticipation of seeking a federal disaster declaration.

"Even as we struggle with the shock of the widespread damage across the state, we need to start getting an accurate assessment of the damage and resources needs to help speed the recovery," Doyle said.

Doyle said FEMA officials were expected to begin visiting affected areas Thursday. They will start with Sauk County and Lake Delton, where floodwaters gashed a new channel to the Wisconsin River and drained the lake, which is crucial to the area's tourism economy.

Lindmeier said one positive note about the forecast is that the predicted storms are likely to be more scattered and not as widespread as the weekend's storms that had much of the radar map of southern Wisconsin red and yellow.

"It's not going to be anything like the weekend situation where we had several waves of storms," Lindmeier said. "It was very unusual to see 9 to 10 inches of rainfall from southeast Minnesota all across through Vernon County and all the way to Milwaukee."