Strong winds again got the better of panels on the prow of U.S. Bank Stadium.

The 270-foot prow on the western facade of the building overlooking the plaza has been a trouble spot since last summer, not long after the panels went up.

With winds of up to 60 miles per hour in the past day, three panels came partly loose from the building's spiked prow near the five glass pivoting doors. The panels, partly made of zinc, are a signature component of the $1.1 billion building. But they've also been one of two significant problems.

Minneapolis-based M.A. Mortenson Co. already spent much of the fall reinforcing how the panels are held to the building. Previously, the panels were fastened only along the bottom edge. Then Mortenson attached panels on the top after some came loose.

In a statement Wednesday, company spokesman Cam Snyder said the newly loosened panels "had not yet received additional fasteners as a part of earlier remediation work. The damage is isolated and work crews will complete repairs as soon as it is safe to do so."

Mortenson has previously said the wind hits the building more forcefully in some areas than engineers initially expected. Snyder wasn't able to explain why the newly loose panels weren't reinforced given that they are close to some of the previously loose panels.

The building remains under warranty. A previous problem — failure of a moisture barrier on the building's parapet — was repaired by Mortenson at a cost of at least $3 million.

Rochelle Olson • 612-673-1747