Fifty inches of rain would exceed any previous Texas rainfall record, the National Weather Service announced Sunday.

"The breadth and intensity of this rainfall are beyond anything experienced before," NWS Weather Prediction Center posted on Twitter. "Catastrophic flooding is now underway and expected to continue for days."

As of 2 p.m. Sunday, the August rainfall total for Houston was 25.5 inches of rain, making this August the wettest month on record, surpassing June 2001, according to the NWS Houston.

The NWS determined the average rainfall in Harris County Emergency Management Network has exceeded that of Tropical Storm Allison in 2001. The rainfall from TS Allison took 5 days, and this rainfall has exceeded this amount in half the time.

Hourly totals for rain are expected to be about 3 inches, with some areas getting up to 6 inches per hour.

The NWS forecast predicts showers and thunderstorms "likely" in the Houston area through Wednesday night. There is a 50 percent chance of storms and thunderstorms Thursday and Friday, and it drops to a 40 percent chance for Friday night and Saturday.

Get the latest 7-day forecast here:

Seven-day forecast in Houston as of 2:30 p.m. Sunday.
Seven-day forecast in Houston as of 2:30 p.m. Sunday.