More than 3 inches of rain fell across much of the Baltimore region overnight and into Thursday morning, and more heavy precipitation is forecast this afternoon.
As of 11 a.m., rainfall totals had surpassed 3 inches in many areas, with 3.83 inches reported in Rosedale and 3.3 inches in Elkridge, according to the National Weather Service. About 2.5 inches fell at Baltimore/Washington International Thurgood Marshall Airport, the region's point of record, including more than an inch during the morning rush hour.
Rain was even heavier overnight in the southern half of the state. The weather service reported more than 7 inches of rain in Prince Frederick, in Calvert County, and more than 6 inches in St. Mary's County. The weather prompted a two-hour delay for public schools in Wicomico County on the Eastern Shore.
Flood warnings were in effect Thursday morning in Howard County, northern Anne Arundel County, Baltimore City and the Baltimore County suburbs immediately surrounding it. The weather service canceled the warnings by midday, but warned that a system of heavy rain tracking northward over eastern North Carolina could bring an ill-timed deluge by the evening.
If that system reaches the Interstate 95 corridor at rush hour, it "would prove problematic," weather service forecasters wrote.
The rain likely contributing to major traffic problems Friday morning. Interstate 695 was closed in both directions near the Key Bridge after a tractor-trailer overturned. Another crash was reported on the northbound Jones Falls Expressway near the Pepsi sign in Woodberry.
The rain is falling from a slow-moving low-pressure system that moved in overnight from the Great Lakes. The system is pulling in tropical moisture that makes it even more potent. Thunderstorms and pockets of intense rainfall could inundate some areas with 6 inches of rain or more by early Saturday, forecasters warned.
While rain was slowing down by mid-morning Thursday, weather service meteorologists said they expect heavy rain to resume in the afternoon.
A flash flood watch remains in effect across Central Maryland through Friday morning.
Meteorologists urged residents to keep an eye on streams and drainage ditches, and be prepared to quickly seek higher ground.
They also warned of the dangers of fast-moving water. Just 6 inches of rushing water can knock over an adult, and a foot can carry away a small car.