May 27, 2018 at 10:00 PM
(This post, originally published at 5:30 p.m., was updated at 10:00 p.m.)
For the second time in two years, Main Street in Ellicott City was transformed into a raging river as thunderstorms lined up and unloaded torrential rain. The National Weather Service issued a flash-flood emergency for the city at 4:40 p.m. Sunday, its most severe flood alert, and reported water rescues underway.
“This is an EXTREMELY DANGEROUS AND POTENTIALLY CATASTROPHIC situation,” the National Weather Service warned.
Sunday’s flooding unfolded in a similar way to the 2016 flash flood in which six inches of rain fell in two hours and two people died. The National Weather Service said the 2016 event had a probability of occurrence of less than or equal to 1 in 1,000.
Incredibly, even more rain may have fallen during Sunday’s deluge. Radar suggests more than eight inches of rain fell around Ellicott City and Catonsville in just about three hours, mostly between 3:30 and 6:30 p.m. A weather station in Catonsville, where a flash flood emergency was also declared, registered nearly 13 inches of rain in just three hours Sunday afternoon.
The flash-flood emergency in Ellicott City was originally in effect until 7:30 p.m., but was extended to 10:30 p.m. Another emergency warning was issued for locations along the Patapsco River in Anne Arundel, Howard and Baltimore counties around 6 p.m., where gauge reports indicated that a major flash flood was occurring.
By 10 p.m., radar showed the thunderstorms had finally died off.
As the torrent engulfed Ellicott City early Sunday evening, officials urged anyone in the area seek higher ground and not to drive on flooded roads.
Strong thunderstorms formed and reformed in the zone between Ellicott City and Baltimore, unloading extreme rainfall in a process known as training. Flooding was also reported in downtown Baltimore and Columbia.
Atmospheric moisture levels — near record-high levels — fueled the onslaught of storms.
This is the 15th catastrophic flash flood to hit the Ellicott City area since 1768 according to Preservation Maryland.
Below are some photos and video. Please note that these videos are unedited and some contain foul language.