National Weather Service Issues Flash Flood Warning for Brookline

The National Weather Service has issued a flash flood warning for much of Eastern Massachusetts, including Brookline, as the region is pummeled by a summer storm that could dump as much as four inches of rain per hour.

In the warning, which was issued just after 3 p.m. Saturday, the service warned that flooding of urban streams was "occuring or imminent" and urged those living near rivers prone to flooding to seek higher ground immediately.

The service predicts that that run off from today's downpour will raise water levels of urban rivers and pool in low-lying streets and underpasses. Drivers are advised to avoid roadways with standing water.

The water level of Brookline's Muddy River shot from around 8 feet to more than 12 feet over the course of the day, but was still below the 15-foot flood stage as of 3:45 p.m., according to the United States Geological Survey.

The level of the Muddy River is known to rise quickly during heavy rains, as it did when the region was pounded by several days of heavy rains last March. Many nearby basements were flooded, and the MBTA was forced to shut down the D Line so it could block floodwaters from entering underground tunnels.

As of 3:30 p.m. Saturday, the MBTA was reporting delays of 15 to 20 minutes on the Green Line because of issues related to the weather. There were also reports of flooding in the basement of the Route 9 Fire Station.