Substantial rainfall has increased the threat for another round of flooding along the Cedar and Shell Rock Rivers in northeast Iowa.

The National Weather Service has issued a flood warning for all or portions of the Cedar and Shell Rock rivers in Black Hawk, Bremer and Butler counties through early next week. Moderate to minor flooding is forecast.

The Cedar River is expected to crest about 3.1 feet above its 13-foot flood stage at Waterloo early Saturday morning. The Shell Rock River at Shell Rock is forecast to rise about 1.1 feet above its 13.5-foot level Friday night. Both rivers should fall below flood stage by Sunday morning (Sept. 23, 2018).

So far, records indicate this is the second-wettest September ever in the Cedar Valley. As of 9 AM Wednesday, 9.08 inches of rain had fallen at the Waterloo Regional Airport since the beginning of the month. Forecasters are calling for the possibility of heavy rain through the overnight hours of Thursday morning with scattered thunderstorms likely the rest of the day.

Here are the latest flood warnings from the National Weather Service:

CEDAR RIVER

At Cedar Falls
* Until early Tuesday morning.
* At 9:45 AM Wednesday, the level was 83.2 feet, or 4.8 feet below flood Stage.
* Flood stage is 88.0 feet.
* No flooding is occurring and Moderate flooding is forecast.
* Forecast: Rise to flood stage Friday morning; continue rising to 91.9 feet (or 3.9 feet above flood stage) Saturday evening; then fall below flood stage early Tuesday morning.
* Impact: At 91.2 feet, water covers portions of Lake Street.

At Waterloo to Spring Creek near La Porte City:
* Until Monday afternoon.
* At 10:00 AM Wednesday, the stage was 7.8 feet, or 5.2 feet below flood stage.
* Flood stage is 13.0 feet.
* No flooding is occurring and Minor flooding is forecast.
* Forecast: Rise to flood stage early Saturday morning; continue rising to 16.1 feet (or 3.1 feet above flood stage) Sunday
morning; then go below flood stage Monday afternoon.
* Impact: At 16.0 feet, the Riverview Recreation Area is closed.

SHELL ROCK RIVER

At Shell Rock, or from Flood Creek near Clarksville to the Cedar River:
* Until early Sunday morning.
* At 9:45 AM Wednesday, the stage was 9.8 feet, or 3.7 feet below flood stage.
* Flood stage is 13.5 feet.
* No flooding is occurring and minor flooding is forecast.
* Forecast: Rise to flood stage early Friday morning; continue rising to 14.6 feet (or 1.1 feet above flood stage) Friday
evening; then go below flood stage early Sunday morning.
* Impact: At 14.0 feet, flooding occurs in Shell Rock -- primarily in residential yards.