The National Weather Service (NWS) issued a flash flood warning for several Western Pennsylvania communities Friday morning after a major ice jam formed around a bend in the Allegheny River roughly from Emlenton to Foxburg, located some 60 miles north of Pittsburgh. The Emlenton Fire Department warned people who live along the river and other flood-prone areas to be ready to leave at a moment’s notice. 

EMLENTON, Pa. – The National Weather Service (NWS) issued a flash flood warning for several Western Pennsylvania communities Friday morning after a major ice jam formed around a bend in the Allegheny River roughly from Emlenton to Foxburg, located some 60 miles north of Pittsburgh.

Images from the Emlenton Fire Department show pieces of ice packed across the river, including up to some waterfront properties.

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The department warned people who live along the river and other flood-prone areas to be ready to leave at a moment’s notice. They said the town fire siren will be used to communicate a sudden rise in water levels.

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The National Weather Service (NWS) issued a flash flood warning for several Western Pennsylvania communities Friday morning after a major ice jam formed around a bend in the Allegheny River roughly from Emlenton to Foxburg, some 60 miles north of Pittsburgh.

(Emlenton Fire Department/Facebook / FOX Weather)

The Emlenton Bridge, which carries Interstate 80, spans the jammed section of the river.

Ice jams occur when large, frequent swings in temperature cause river ice to break apart and pile up.

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Ice jams can hold back large amounts of water, causing major flooding upstream and significant flooding downstream when those jams finally break.

Check back for updates on this developing story.